BACKGROUND Radiotherapy stands as a promising therapeutic modality for colorectal cancer(CRC);yet,the formidable challenge posed by radio-resistance significantly undermines its efficacy in achieving CRC remission.AIM...BACKGROUND Radiotherapy stands as a promising therapeutic modality for colorectal cancer(CRC);yet,the formidable challenge posed by radio-resistance significantly undermines its efficacy in achieving CRC remission.AIM To elucidate the role played by microRNA-298(miR-298)in CRC radio-resistance.METHODS To establish a radio-resistant CRC cell line,HT-29 cells underwent exposure to 5 gray ionizing radiation that was followed by a 7-d recovery period.The quantification of miR-298 levels within CRC cells was conducted through quantitative RT-PCR,and protein expression determination was realized through Western blotting.Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and proliferation by clonogenic assay.Radio-induced apoptosis was discerned through flow cytometry analysis.RESULTS We observed a marked upregulation of miR-298 in radio-resistant CRC cells.MiR-298 emerged as a key determinant of cell survival following radiation exposure,as its overexpression led to a notable reduction in radiation-induced apoptosis.Intriguingly,miR-298 expression exhibited a strong correlation with CRC cell viability.Further investigation unveiled human dual-specificity tyrosine(Y)-regulated kinase 1A(DYRK1A)as miR-298’s direct target.CONCLUSION Taken together,our findings underline the role played by miR-298 in bolstering radio-resistance in CRC cells by means of DYRK1A downregulation,thereby positioning miR-298 as a promising candidate for mitigating radioresistance in CRC.展开更多
Objective: To study the effect of active compound 6F and A from Pteris semipinnata L.(PsL) on the activities of DNA topoisomerase (TOPO) I and II, activities of cytosolic and membrane TPK, and expression of oncogene c...Objective: To study the effect of active compound 6F and A from Pteris semipinnata L.(PsL) on the activities of DNA topoisomerase (TOPO) I and II, activities of cytosolic and membrane TPK, and expression of oncogene c-myc in lung adenocarcinoma cells. Methods: The effect of compound 6F and A on activities of cytosolic and membrane TPK was measured by scintillation counting; the effect of compound A on expression of oncogene c-myc was determined by flow cytometry indirect fluorimetry. Results: compound 6F and A could inhibit the activities of TOPO I, and they strongly inhibited the TOPO II in 0.01 mg/L and 10.0 mg/L respectively. Compound A slightly inhibited the activities of membrane TPK, but not the cytosolic one. Compound A could inhibit the expression of oncogene c-myc. Conclusion: Topoisomerases are target of compound 6F and A. Compound A could slightly inhibit the activities of TPK, and showed an inhibitory effect on the expression of oncogene c-myc.展开更多
Objective: To survey the role of protein tyrosine kinases (PTKs) in the pathogenesis of several hematopoietic malignancies. Methods: By reviewing the published laboratory and clinical studies on PTK-related oncoprotei...Objective: To survey the role of protein tyrosine kinases (PTKs) in the pathogenesis of several hematopoietic malignancies. Methods: By reviewing the published laboratory and clinical studies on PTK-related oncoproteins and their causative role in some leukemias and lymphomas. Results: Protein tyrosine kinases are key participants in signal transduction pathways that regulate cellular growth, activation and differentiations. Aberrant PTK activity resulting from gene mutation (often accompanying chromosome translocation) plays an etiologic role in several clonal hematopoietic malignancies. For example, the PTK product of the BCR-ABL fusion gene resulting from the t (9; 22) translocation exhibits several fold higher tyrosine kinase activity than the product of the ABL gene. Evidence suggests that the BCR-ABL oncoprotein alone is sufficient to case chronic myelogenous leukemia (CML) and other Ph positive acute leukemia. PTK over-activity resulting from chromosomal translocations creating TEL-ABL, TEL-JAK2 and TEL-PDGFRβ fusion proteins plays an important role in the pathogenesis of other types of leukemia. Another example occurs in anaplastic large cell lymphoma (ALCL). Experimental and clinical evidences indicate that translocations involving ALK gene on chromosome 2p23, most commonly resulting in an NPM-ALK fusion oncogene, result in constitutive activation of ALK and cause ALCL. This group of lymphomas is now named ALK positive lymphoma or ALKoma. Conclusion: Genetic lesions creating aberrant fusion proteins that result in excessive PTK activity are increasingly being recognized as central to the pathogenesis of hemotopoietic malignancies. These chimeric PTK molecules represent attractive disease-specific targets against which new classes therapeutic agents are being developed.展开更多
AIMTo evaluate whether protein tyrosine phosphatase 1B (PTP1B) contributed to initiate human retinal pigment epithelium cells (A)-19 migration and investigate the signaling pathways involved in this process.METHODSARP...AIMTo evaluate whether protein tyrosine phosphatase 1B (PTP1B) contributed to initiate human retinal pigment epithelium cells (A)-19 migration and investigate the signaling pathways involved in this process.METHODSARPE-19 cells were cultured and treated with the siRNA-PTP1B. Expression of PTP1B was confirmed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). AG1478 [a selective inhibitor of epidermal growth factor receptor (EGFR)] and PD98059 (a specific inhibitor of the activation of mitogen-activated protein kinase) were used to help to determine the PTP1B signaling mechanism. Western blot analysis verified expression of EGFR and extracellular signal-regulated kinase (ERK) in ARPE-19 cells. The effect of siRNA-PTP1B on cell differentiation was confirmed by immunostaining for α-smooth muscle actin (α-SMA) and qRT-PCR. Cell migration ability was analyzed by transwell chamber assay.RESULTSThe mRNA levels of PTP1B were reduced by siRNA-PTP1B as determined by qRT-PCR assay. SiRNA-PTP1B activated EGFR and ERK phosphorylation. α-SMA staining and qRT-PCR assay demonstrated that siRNA-PTP1B induced retinal pigment epithelium (RPE) cells to differentiate toward better contractility and motility. Transwell chamber assay proved that PTP1B inhibition improved migration activity of RPE cells. Treatment with AG1478 and PD98059 abolished siRNA-PTP1B-induced activation of EGFR and ERK, α-SMA expression and cell migration.CONCLUSIONPTP1B inhibition promoted myofibroblast differentiation and migration of ARPE-19 cells, and EGFR/ERK signaling pathway played important role in migration process.展开更多
AIM:To investigate the role of protein tyrosine phosphorylation in gastric wound formation and repair following ulceration. METHODS:Gastric lesions were induced in rats using restraint cold stress.To investigate the e...AIM:To investigate the role of protein tyrosine phosphorylation in gastric wound formation and repair following ulceration. METHODS:Gastric lesions were induced in rats using restraint cold stress.To investigate the effect of oxidative and nitrosative cell stress on tyrosine phosphorylation during wound repair,total activity of protein tyrosine kinase(PTK),protein tyrosine phosphatase (PTP),antioxidant enzymes,nitric oxide synthase (NOS), 2',5'-oligoadenylate synthetase,hydroxyl radical and zinc levels were assayed in parallel. RESULTS:Ulcer provocation induced an immediate decrease in tyrosine kinase(40% in plasma membranes and 56% in cytosol,(P<0.05) and phosphatase activity (threefold in plasma membranes and 3.3-fold in cytosol),followed by 2.3-2.4-fold decrease (P<0.05) in protein phosphotyrosine content in the gastric mucosa. Ulceration induced no immediate change in superoxide dismutase (SOD) activity,30% increase (P<0.05) in catalase activity,2.3-fold inhibition (P<0.05) of glutathione peroxidase,3.3-fold increase (P<0.05) in hydroxyl radical content,and 2.3-fold decrease (P<0.05) in zinc level in gastric mucosa.NOS activity was three times higher in gastric mucosa cells after cold stress. Following ulceration,PTK activity increased in plasma membranes and reached a maximum on day 4 after stress (twofold increase,P<0.05),but remained inhibited(1.6-3-fold decrease on days 3,4 and 5,P<0.05) in the cytosol.Tyrosine phosphatases remained inhibited both in membranes and cytosol(1.5-2.4-fold,P< 0.05).NOS activity remained increased on days 1,2 and 3(3.8-,2.6-,2.2-fold,respectively,P<0.05).Activity of SOD increased 1.6 times(P<0.05)days 4 and 5 after stress.Catalase activity normalized after day 2. Glutathione peroxidase activity and zinc level decreased (3.3-and 2-fold,respectively,P<0.05)on the last day. Activity of 2',5'-oligoadenylate synthethase increased 2.8-fold (P<0.05) at the beginning,and 1.6-2.3-fold (P<0.05) during ulcer recuperation,and normalized on day 5,consistent with slowing of inflammation processes. CONCLUSION:These studies show diverse changes in total tyrosine kinase activity in gastric mucosa during the recovery process.Oxidative and nitrosative stress during lesion formation might lead to the observed reduction in tyrosine phosphorylation during ulceration.展开更多
There have been significant improvements in the detection and treatment of breast cancer in recent decades. However, there is still a need to develop more effective therapeutic techniques that are patient specific wit...There have been significant improvements in the detection and treatment of breast cancer in recent decades. However, there is still a need to develop more effective therapeutic techniques that are patient specific with reduced toxicity leading to further increases in patients' overall survival; the ongoing progress in understanding recurrence, resistant and spread also needs to be maintained. Better understanding of breast cancer pathology, molecular biology and progression as well as identification of some of the underlying factors involved in breast cancer tumourgenesis and metastasis has led to the identification of novel therapeutic targets. Over a number of years interest has risen in breast tumour kinase(Brk) also known as protein tyrosine kinase 6; the research field has grown and Brk has been described as a desirable therapeutic target in relation to tyrosine kinase inhibition as well as disruption of its kinase independent activity. This review will outline the current "state of play" with respect to targeted therapy for breast cancer, as well as discussing Brk's role in the processes underlying tumour development and metas-tasis and its potential as a therapeutic target in breast cancer.展开更多
Aberrant forms of the anaplastic lymphoma kinase(ALK) are involved in the pathogenesis of several types of cancer, including anaplastic large cell lymphoma, non-small-cell lung cancer(NSCLC), inflammatory myofibroblas...Aberrant forms of the anaplastic lymphoma kinase(ALK) are involved in the pathogenesis of several types of cancer, including anaplastic large cell lymphoma, non-small-cell lung cancer(NSCLC), inflammatory myofibroblastic tumors, colorectal cancer, neuroblastoma and others. In general, the ALK catalytic domain is rearranged and fused to a dimerization domain encoded by an unrelated gene. Less frequently, full-length ALK is activated by point mutations. The common theme is unregulated firing of ALK downstream signalling, leading to uncontrolled cell division and increased cell survival. ALK-driven tumors can be treated with Crizotinib, an orally available dual ALK/MET inhibitor, currently approved for advanced ALK-positive NSCLCs. Crizotinibtreated patients achieve high response rates, with an excellent toxicity profile. However, drug-resistant disease often develops, particularly in NSCLC patients. The processes leading to drug resistance include both ALKdependent(point mutations or gene amplification), as well as ALK-independent mechanisms, which are here briefly discussed. Recently, Ceritinib has been approved for Crizotinib-refractory NSCLC, further extending patients' survival, but resistance again emerged. Novel ALK kinase inhibitors are currently under clinical development, showing great promise for improved efficacy in drugresistance disease. It is opinion of the author that drugresistance is likely to arise under any treatment, due to intrinsic heterogeneity and adaptability of cancer. To prevent or delay this phenomenon, we need to treat less advanced disease, with drugs that are rapidly effective in order not to allow enough time for tumor evolution, and we want to have more and more drugs with nonoverlapping resistance profiles, for subsequent lines of targeted therapy. Finally, the use of drug combinations may exponentially decrease the chances of resistance.展开更多
BACKGROUND： Electromagnetic radiation can influence dopamine （DA） synthesis in brain tissues or ceils, but electromagnetic frequencies, intensities, and radiation time can produce different effects. In addition, th...BACKGROUND： Electromagnetic radiation can influence dopamine （DA） synthesis in brain tissues or ceils, but electromagnetic frequencies, intensities, and radiation time can produce different effects. In addition, the signal pathway by which electromagnetic radiation influences DA synthesis remains controversial. OBJECTIVE： To determine tyrosine hydroxylase （TH） expression in PC12 cells and DA levels in cell culture media after different periods of low-frequency pulsed electric field （LF-PEF） stimulation, and to determine how LF-PEF signaling stimulates TH synthesis using inhibitors. DESIGN, TIME AND SETTING： A parallel, controlled, cell experiment was performed at the Laboratory of Cell Biology, School of Life Science, East China Normal University, between January and October 2006. MATERIALS： PC12 cells were purchased from the Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, China. Nerve growth factor was purchased from PeproTech, USA. The protein kinase A inhibitor, H-89, and mitogen-activated protein kinase kinase inhibitor, U0126, were purchased from Sigma, USA. METHODS： （1） Following routine culture in Dulbecco＇s modified eagle medium, primary PC12 cells were stimulated under LF-PEF （pulse frequency 50.Hz, pulse width 20 μs, peak field strength 1 V/m） for 5, 10, 15, 20, and 30 minutes. （2） Inhibitors （H-89 or U0126, 1 μmol/L） were added 30 minutes before LF-PEF stimulation for 10 minutes. MAIN OUTCOME MEASURES： （1） TH expression was determined by Western blot in PC12 cells at 0.5, 1,2, 3, and 4 days after LF-PEF stimulation. Similarly, DA was measured by high-performance liquid chromatography in media at 2, 3, 4, or 5 days after LF-PEE （2） TH expression was detected 1 day after H-89 or U0126 treatment and LF-PEE RESULTS： （1） Short-term LF-PEF stimulation （5 and 10 minutes） increased TH expression and media DA levels after short-term culture （2 days） （P 〈 0.01）, but both parameters decreased with longer culture （3 4 days） （P 〈 0.01）. Long-term LF-PEF stimulation （15, 20, or 30 minutes） decreased TH and DA synthesis, followed by a rapid increase （P 〈 0.01）. （2） H89 could completely inhibit TH expression in PC12 cells stimulated by LF-PEF for 10 minutes, while the inhibition rate of U0126 was 53.2%. CONCLUSION： Short-term LF-PEF first promotes then inhibits, while long-term LF-PEF first inhibits then promotes, TH and DA synthesis. LF-PEF stimulation regulates TH expression primarily by activating protein kinase A to regulate DA synthesis.展开更多
Obejctives To study mitogen activated protein kinase (MAPKs) activation in fibroblast like synoviocytes (FLS) of rheumatoid arthritis (RA) under the stimulation of IL 1β, and to elucidate the role of protein tyro...Obejctives To study mitogen activated protein kinase (MAPKs) activation in fibroblast like synoviocytes (FLS) of rheumatoid arthritis (RA) under the stimulation of IL 1β, and to elucidate the role of protein tyrosine kinase (PTK) in the activation of MAPKs Methods Primary cultures of RA FLS were used Western blot was applied to examine transient changes in protein tyrosine phosphorylation status and MAPKs activation in RA FLS stimulated with IL 1β at various doses, and over different periods Genistein, the specific PTK inhibitor, was used to evaluate the inhibitory role in activation of MAPKs by IL 1β Results IL 1β transiently increased protein tyrosine phosphorylation, and activated the MAPKs cascades (mainly ERK 2, JNK 2 and P 38 ) in RA FLS There was no obvious difference in MAPKs activation among different doses of IL 1β (1?IU/ml,10?IU/ml, 100?IU/ml), but the peak activation of ERK 2, JNK 2 and P 38 took place at 5?min, 15?min and 1?min, respectively, after stimulation with IL 1β The activation of ERK 2 was inhibited by genistein, but the inhibitory role on that of JNK and P 38 was relatively weak Conclusions During signal transduction of IL 1β in RA FLS, tyrosine phosphorylation was increased transiently, the MAPKs cascade was activated in a few minutes, and there was heterogenicity in the activation among three subfamily members PTK had a role in the activation of ERK, but had weak effects on that of JNK and P 38展开更多
We recently found that growth factor receptor-bound(Grb)protein 14 is a novel physiological modulator of photoreceptor specific cyclic nucleotide-gated channel alpha subunit(CNGA1).Grb14 promotes the CNG channel closu...We recently found that growth factor receptor-bound(Grb)protein 14 is a novel physiological modulator of photoreceptor specific cyclic nucleotide-gated channel alpha subunit(CNGA1).Grb14 promotes the CNG channel closure through its Ras-associating(RA)domain.In the current study we show that this RA domain-mediated inhibition of rod CNG channel is electrostatic in nature.Grb14 competes with cGMP for the CNGA1 binding pocket and electrostatically interacts with Arg^(559) through a negatively chargedβ-turn at its RA domain.Moreover,the three Glu residues(180–182)in Grb14 are absolutely critical for electrostatic interaction with the cGMP binding pocket and resultant inhibition.Our study also demonstrates that substitution of Lys^(140) for Ala or in combination with polyglutamte mutants of Grb14 results in a significantly reduced binding with CNGA1.These results suggest that in addition to Glu^(180–182) and Lys^(140),other residues in Grb14 may be involved in the electrostatic interaction with CNGA1.The RA domain is highly conserved among the members of Grb7 family of proteins,which includes Grb7,Grb10 and Grb14.Further,only Grb14 is able to modulate the channel activity,but not Grb7 and Grb10.All together,it suggests the existence of a divergence in RA domains among the members of the Grb7 family.展开更多
基金This study was reviewed and approved by the Experimental Animal Ethics Committee of the First Affiliated Hospital of Guangxi Medical University(Approval No.2023-E386-01).
文摘BACKGROUND Radiotherapy stands as a promising therapeutic modality for colorectal cancer(CRC);yet,the formidable challenge posed by radio-resistance significantly undermines its efficacy in achieving CRC remission.AIM To elucidate the role played by microRNA-298(miR-298)in CRC radio-resistance.METHODS To establish a radio-resistant CRC cell line,HT-29 cells underwent exposure to 5 gray ionizing radiation that was followed by a 7-d recovery period.The quantification of miR-298 levels within CRC cells was conducted through quantitative RT-PCR,and protein expression determination was realized through Western blotting.Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and proliferation by clonogenic assay.Radio-induced apoptosis was discerned through flow cytometry analysis.RESULTS We observed a marked upregulation of miR-298 in radio-resistant CRC cells.MiR-298 emerged as a key determinant of cell survival following radiation exposure,as its overexpression led to a notable reduction in radiation-induced apoptosis.Intriguingly,miR-298 expression exhibited a strong correlation with CRC cell viability.Further investigation unveiled human dual-specificity tyrosine(Y)-regulated kinase 1A(DYRK1A)as miR-298’s direct target.CONCLUSION Taken together,our findings underline the role played by miR-298 in bolstering radio-resistance in CRC cells by means of DYRK1A downregulation,thereby positioning miR-298 as a promising candidate for mitigating radioresistance in CRC.
基金the National Natural Science Foundation of China (No. 39870900) and the key project grant from Guangdong Province Science and Te
文摘Objective: To study the effect of active compound 6F and A from Pteris semipinnata L.(PsL) on the activities of DNA topoisomerase (TOPO) I and II, activities of cytosolic and membrane TPK, and expression of oncogene c-myc in lung adenocarcinoma cells. Methods: The effect of compound 6F and A on activities of cytosolic and membrane TPK was measured by scintillation counting; the effect of compound A on expression of oncogene c-myc was determined by flow cytometry indirect fluorimetry. Results: compound 6F and A could inhibit the activities of TOPO I, and they strongly inhibited the TOPO II in 0.01 mg/L and 10.0 mg/L respectively. Compound A slightly inhibited the activities of membrane TPK, but not the cytosolic one. Compound A could inhibit the expression of oncogene c-myc. Conclusion: Topoisomerases are target of compound 6F and A. Compound A could slightly inhibit the activities of TPK, and showed an inhibitory effect on the expression of oncogene c-myc.
基金This work was partially supported by a grant from World Health Organization Fellowship (XS) (WPRO AWARD No. 0008/99).
文摘Objective: To survey the role of protein tyrosine kinases (PTKs) in the pathogenesis of several hematopoietic malignancies. Methods: By reviewing the published laboratory and clinical studies on PTK-related oncoproteins and their causative role in some leukemias and lymphomas. Results: Protein tyrosine kinases are key participants in signal transduction pathways that regulate cellular growth, activation and differentiations. Aberrant PTK activity resulting from gene mutation (often accompanying chromosome translocation) plays an etiologic role in several clonal hematopoietic malignancies. For example, the PTK product of the BCR-ABL fusion gene resulting from the t (9; 22) translocation exhibits several fold higher tyrosine kinase activity than the product of the ABL gene. Evidence suggests that the BCR-ABL oncoprotein alone is sufficient to case chronic myelogenous leukemia (CML) and other Ph positive acute leukemia. PTK over-activity resulting from chromosomal translocations creating TEL-ABL, TEL-JAK2 and TEL-PDGFRβ fusion proteins plays an important role in the pathogenesis of other types of leukemia. Another example occurs in anaplastic large cell lymphoma (ALCL). Experimental and clinical evidences indicate that translocations involving ALK gene on chromosome 2p23, most commonly resulting in an NPM-ALK fusion oncogene, result in constitutive activation of ALK and cause ALCL. This group of lymphomas is now named ALK positive lymphoma or ALKoma. Conclusion: Genetic lesions creating aberrant fusion proteins that result in excessive PTK activity are increasingly being recognized as central to the pathogenesis of hemotopoietic malignancies. These chimeric PTK molecules represent attractive disease-specific targets against which new classes therapeutic agents are being developed.
基金Supported by Shandong Provincial Natural Science Foundation,China(No.ZR2012HQ004)the Research Fund for Fundamental Research Project of Qingdao(No.13-1-4-180-jch)+1 种基金the Scientific Research Fund of Huangdao District of Qingdao City(No.2014-1-74)the Young People Scientific Research Fund of Affiliated Hospital,Qingdao University(No.QDFY134)
文摘AIMTo evaluate whether protein tyrosine phosphatase 1B (PTP1B) contributed to initiate human retinal pigment epithelium cells (A)-19 migration and investigate the signaling pathways involved in this process.METHODSARPE-19 cells were cultured and treated with the siRNA-PTP1B. Expression of PTP1B was confirmed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). AG1478 [a selective inhibitor of epidermal growth factor receptor (EGFR)] and PD98059 (a specific inhibitor of the activation of mitogen-activated protein kinase) were used to help to determine the PTP1B signaling mechanism. Western blot analysis verified expression of EGFR and extracellular signal-regulated kinase (ERK) in ARPE-19 cells. The effect of siRNA-PTP1B on cell differentiation was confirmed by immunostaining for α-smooth muscle actin (α-SMA) and qRT-PCR. Cell migration ability was analyzed by transwell chamber assay.RESULTSThe mRNA levels of PTP1B were reduced by siRNA-PTP1B as determined by qRT-PCR assay. SiRNA-PTP1B activated EGFR and ERK phosphorylation. α-SMA staining and qRT-PCR assay demonstrated that siRNA-PTP1B induced retinal pigment epithelium (RPE) cells to differentiate toward better contractility and motility. Transwell chamber assay proved that PTP1B inhibition improved migration activity of RPE cells. Treatment with AG1478 and PD98059 abolished siRNA-PTP1B-induced activation of EGFR and ERK, α-SMA expression and cell migration.CONCLUSIONPTP1B inhibition promoted myofibroblast differentiation and migration of ARPE-19 cells, and EGFR/ERK signaling pathway played important role in migration process.
基金Supported by Travel grants from The Physiological Society(UKand Eire),Federation of European Physiological SocietiesThe Cousins Center for Psychoneuroimmunology at the UCLA Neuropsychiatric Institute travel assistant award
文摘AIM:To investigate the role of protein tyrosine phosphorylation in gastric wound formation and repair following ulceration. METHODS:Gastric lesions were induced in rats using restraint cold stress.To investigate the effect of oxidative and nitrosative cell stress on tyrosine phosphorylation during wound repair,total activity of protein tyrosine kinase(PTK),protein tyrosine phosphatase (PTP),antioxidant enzymes,nitric oxide synthase (NOS), 2',5'-oligoadenylate synthetase,hydroxyl radical and zinc levels were assayed in parallel. RESULTS:Ulcer provocation induced an immediate decrease in tyrosine kinase(40% in plasma membranes and 56% in cytosol,(P<0.05) and phosphatase activity (threefold in plasma membranes and 3.3-fold in cytosol),followed by 2.3-2.4-fold decrease (P<0.05) in protein phosphotyrosine content in the gastric mucosa. Ulceration induced no immediate change in superoxide dismutase (SOD) activity,30% increase (P<0.05) in catalase activity,2.3-fold inhibition (P<0.05) of glutathione peroxidase,3.3-fold increase (P<0.05) in hydroxyl radical content,and 2.3-fold decrease (P<0.05) in zinc level in gastric mucosa.NOS activity was three times higher in gastric mucosa cells after cold stress. Following ulceration,PTK activity increased in plasma membranes and reached a maximum on day 4 after stress (twofold increase,P<0.05),but remained inhibited(1.6-3-fold decrease on days 3,4 and 5,P<0.05) in the cytosol.Tyrosine phosphatases remained inhibited both in membranes and cytosol(1.5-2.4-fold,P< 0.05).NOS activity remained increased on days 1,2 and 3(3.8-,2.6-,2.2-fold,respectively,P<0.05).Activity of SOD increased 1.6 times(P<0.05)days 4 and 5 after stress.Catalase activity normalized after day 2. Glutathione peroxidase activity and zinc level decreased (3.3-and 2-fold,respectively,P<0.05)on the last day. Activity of 2',5'-oligoadenylate synthethase increased 2.8-fold (P<0.05) at the beginning,and 1.6-2.3-fold (P<0.05) during ulcer recuperation,and normalized on day 5,consistent with slowing of inflammation processes. CONCLUSION:These studies show diverse changes in total tyrosine kinase activity in gastric mucosa during the recovery process.Oxidative and nitrosative stress during lesion formation might lead to the observed reduction in tyrosine phosphorylation during ulceration.
文摘There have been significant improvements in the detection and treatment of breast cancer in recent decades. However, there is still a need to develop more effective therapeutic techniques that are patient specific with reduced toxicity leading to further increases in patients' overall survival; the ongoing progress in understanding recurrence, resistant and spread also needs to be maintained. Better understanding of breast cancer pathology, molecular biology and progression as well as identification of some of the underlying factors involved in breast cancer tumourgenesis and metastasis has led to the identification of novel therapeutic targets. Over a number of years interest has risen in breast tumour kinase(Brk) also known as protein tyrosine kinase 6; the research field has grown and Brk has been described as a desirable therapeutic target in relation to tyrosine kinase inhibition as well as disruption of its kinase independent activity. This review will outline the current "state of play" with respect to targeted therapy for breast cancer, as well as discussing Brk's role in the processes underlying tumour development and metas-tasis and its potential as a therapeutic target in breast cancer.
基金Supported by The Italian Association for Cancer Research,AIRC 2013 IG-14249
文摘Aberrant forms of the anaplastic lymphoma kinase(ALK) are involved in the pathogenesis of several types of cancer, including anaplastic large cell lymphoma, non-small-cell lung cancer(NSCLC), inflammatory myofibroblastic tumors, colorectal cancer, neuroblastoma and others. In general, the ALK catalytic domain is rearranged and fused to a dimerization domain encoded by an unrelated gene. Less frequently, full-length ALK is activated by point mutations. The common theme is unregulated firing of ALK downstream signalling, leading to uncontrolled cell division and increased cell survival. ALK-driven tumors can be treated with Crizotinib, an orally available dual ALK/MET inhibitor, currently approved for advanced ALK-positive NSCLCs. Crizotinibtreated patients achieve high response rates, with an excellent toxicity profile. However, drug-resistant disease often develops, particularly in NSCLC patients. The processes leading to drug resistance include both ALKdependent(point mutations or gene amplification), as well as ALK-independent mechanisms, which are here briefly discussed. Recently, Ceritinib has been approved for Crizotinib-refractory NSCLC, further extending patients' survival, but resistance again emerged. Novel ALK kinase inhibitors are currently under clinical development, showing great promise for improved efficacy in drugresistance disease. It is opinion of the author that drugresistance is likely to arise under any treatment, due to intrinsic heterogeneity and adaptability of cancer. To prevent or delay this phenomenon, we need to treat less advanced disease, with drugs that are rapidly effective in order not to allow enough time for tumor evolution, and we want to have more and more drugs with nonoverlapping resistance profiles, for subsequent lines of targeted therapy. Finally, the use of drug combinations may exponentially decrease the chances of resistance.
基金the National Natural Science Foundation of China,No.50677022
文摘BACKGROUND： Electromagnetic radiation can influence dopamine （DA） synthesis in brain tissues or ceils, but electromagnetic frequencies, intensities, and radiation time can produce different effects. In addition, the signal pathway by which electromagnetic radiation influences DA synthesis remains controversial. OBJECTIVE： To determine tyrosine hydroxylase （TH） expression in PC12 cells and DA levels in cell culture media after different periods of low-frequency pulsed electric field （LF-PEF） stimulation, and to determine how LF-PEF signaling stimulates TH synthesis using inhibitors. DESIGN, TIME AND SETTING： A parallel, controlled, cell experiment was performed at the Laboratory of Cell Biology, School of Life Science, East China Normal University, between January and October 2006. MATERIALS： PC12 cells were purchased from the Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, China. Nerve growth factor was purchased from PeproTech, USA. The protein kinase A inhibitor, H-89, and mitogen-activated protein kinase kinase inhibitor, U0126, were purchased from Sigma, USA. METHODS： （1） Following routine culture in Dulbecco＇s modified eagle medium, primary PC12 cells were stimulated under LF-PEF （pulse frequency 50.Hz, pulse width 20 μs, peak field strength 1 V/m） for 5, 10, 15, 20, and 30 minutes. （2） Inhibitors （H-89 or U0126, 1 μmol/L） were added 30 minutes before LF-PEF stimulation for 10 minutes. MAIN OUTCOME MEASURES： （1） TH expression was determined by Western blot in PC12 cells at 0.5, 1,2, 3, and 4 days after LF-PEF stimulation. Similarly, DA was measured by high-performance liquid chromatography in media at 2, 3, 4, or 5 days after LF-PEE （2） TH expression was detected 1 day after H-89 or U0126 treatment and LF-PEE RESULTS： （1） Short-term LF-PEF stimulation （5 and 10 minutes） increased TH expression and media DA levels after short-term culture （2 days） （P 〈 0.01）, but both parameters decreased with longer culture （3 4 days） （P 〈 0.01）. Long-term LF-PEF stimulation （15, 20, or 30 minutes） decreased TH and DA synthesis, followed by a rapid increase （P 〈 0.01）. （2） H89 could completely inhibit TH expression in PC12 cells stimulated by LF-PEF for 10 minutes, while the inhibition rate of U0126 was 53.2%. CONCLUSION： Short-term LF-PEF first promotes then inhibits, while long-term LF-PEF first inhibits then promotes, TH and DA synthesis. LF-PEF stimulation regulates TH expression primarily by activating protein kinase A to regulate DA synthesis.
基金ThestudywassupportedbythegrantfromtheNationalNaturalScienceFundationofChina (No 39730 430 )
文摘Obejctives To study mitogen activated protein kinase (MAPKs) activation in fibroblast like synoviocytes (FLS) of rheumatoid arthritis (RA) under the stimulation of IL 1β, and to elucidate the role of protein tyrosine kinase (PTK) in the activation of MAPKs Methods Primary cultures of RA FLS were used Western blot was applied to examine transient changes in protein tyrosine phosphorylation status and MAPKs activation in RA FLS stimulated with IL 1β at various doses, and over different periods Genistein, the specific PTK inhibitor, was used to evaluate the inhibitory role in activation of MAPKs by IL 1β Results IL 1β transiently increased protein tyrosine phosphorylation, and activated the MAPKs cascades (mainly ERK 2, JNK 2 and P 38 ) in RA FLS There was no obvious difference in MAPKs activation among different doses of IL 1β (1?IU/ml,10?IU/ml, 100?IU/ml), but the peak activation of ERK 2, JNK 2 and P 38 took place at 5?min, 15?min and 1?min, respectively, after stimulation with IL 1β The activation of ERK 2 was inhibited by genistein, but the inhibitory role on that of JNK and P 38 was relatively weak Conclusions During signal transduction of IL 1β in RA FLS, tyrosine phosphorylation was increased transiently, the MAPKs cascade was activated in a few minutes, and there was heterogenicity in the activation among three subfamily members PTK had a role in the activation of ERK, but had weak effects on that of JNK and P 38
基金by grants from the NIH(EY016507EY00871EY12190).CNGA1 and CNGB1 subunit channel antibodies were a kind gift from Dr.Robert Molday,University of British Columbia(Canada).
文摘We recently found that growth factor receptor-bound(Grb)protein 14 is a novel physiological modulator of photoreceptor specific cyclic nucleotide-gated channel alpha subunit(CNGA1).Grb14 promotes the CNG channel closure through its Ras-associating(RA)domain.In the current study we show that this RA domain-mediated inhibition of rod CNG channel is electrostatic in nature.Grb14 competes with cGMP for the CNGA1 binding pocket and electrostatically interacts with Arg^(559) through a negatively chargedβ-turn at its RA domain.Moreover,the three Glu residues(180–182)in Grb14 are absolutely critical for electrostatic interaction with the cGMP binding pocket and resultant inhibition.Our study also demonstrates that substitution of Lys^(140) for Ala or in combination with polyglutamte mutants of Grb14 results in a significantly reduced binding with CNGA1.These results suggest that in addition to Glu^(180–182) and Lys^(140),other residues in Grb14 may be involved in the electrostatic interaction with CNGA1.The RA domain is highly conserved among the members of Grb7 family of proteins,which includes Grb7,Grb10 and Grb14.Further,only Grb14 is able to modulate the channel activity,but not Grb7 and Grb10.All together,it suggests the existence of a divergence in RA domains among the members of the Grb7 family.
