Imipramine protects retinal ganglion cells from oxidative stress through the tyrosine kinase receptor B signaling pathway

Retinal ganglion cell（RGC） degeneration is irreversible in glaucoma and tyrosine kinase receptor B（Trk B）-associated signaling pathways have been implicated in the process.In this study,we attempted to examine whether imipramine,a tricyclic antidepressant,may protect hydrogen peroxide（H_2O_2）-induced RGC degeneration through the activation of the Trk B pathway in RGC-5 cell lines.RGC-5 cell lines were pre-treated with imipramine 30 minutes before exposure to H_2O_2.Western blot assay showed that in H_2O_2-damaged RGC-5 cells,imipramine activated Trk B pathways through extracellular signal-regulated protein kinase/Trk B phosphorylation.TUNEL staining assay also demonstrated that imipramine ameliorated H_2O_2-induced apoptosis in RGC-5 cells.Finally,Trk B-Ig G intervention was able to reverse the protective effect of imipramine on H_2O_2-induced RGC-5 apoptosis.Imipramine therefore protects RGCs from oxidative stress-induced apoptosis through the Trk B signaling pathway.

Levetiracetam induces tyrosine kinase receptor B expression in SH-SY5Y cells

Tyrosine kinase receptor B （TrkB） plays an important role in long-term potentiation and memory formation.The present study used all-trans retinoic acid to induce TrkB expression in SH-SY5Y cells,and observed the effects of levetiracetam （LEV） on TrkB expression.Following exposure to 10,50,and 100 μg/mL LEV,the number of TrkB-positive cells,and average absorbance value were increased.Results demonstrated that LEV can induce TrkB expression in SH-SY5Y cells.

Role of Tyrosine Kinase Receptors in Growth Factor Mediated Signal Transduction, with Specific Reference to MAPK/Rasand p13k-Akt Containing Pathways in Oncogenesis: A Qualitative Database Review

Receptor Tyrosine kinases (RTKs) play a crucial role in the signal transduction pathways at cellular levels. RTK plays a vital role in cellular communication and transmission of signals to the adjacent cells and regulates different functions of the cell, such as cellular growth, differentiation, metabolism and motility. RTK s triggers growth factor receptors such as epidermal growth factor, insulin growth factor-1 receptor, platelet derived growth factor receptor, and fibro blast growth factor receptor and vascular endothelial growth factor receptor, thereby initiating and regulating cell growth and proliferation. MAPK/RAS and PI3/AKT pathways are the major pathways of RTK’s function. Dysregulation of these RTK’s and pathways often leads to many diseases such as Noonan Syndrome, Logius Syndrome, CFC syndrome and different types of cancer. Point mutation and over expression of receptors and mutations in Ras leads to 30% of human cancers. Also over expression of different growth factor receptors by RTK too lead to several types of cancers as Glioblastoma, Thyroid cancer, Colon cancer and Non-small cell lung cancer. PTEN mutation in PI3/AKT pathway often leads to carcinoma relative to Thyroid, Skin, Large intestine, eye and Bone. Therefore, these RTK’s often used as targets for cancer therapies. The medical sector uses various types of small molecule tyrosine kinase inhibitors such as ATP competitive inhibitors, Allosteric inhibitors and covalent inhibitors which are known as Afatinib, Crizotinib, Eroltinib, Icotinib, Lepatinib and Lenvatinib in treatment and management of differential carcinomas.

Advanced Lung Adenocarcinoma with EGFR 19-del Mutation Transformed into SCC after EGFR-tyrosine Kinase inhibitors Treatment:A Case report

BACKGROUND Epidermal growth factor receptor tyrosine kinase inhibitors(EGFR-TKIs)significantly improve the survival of patients with Epidermal growth factor receptor(EGFR)sensitive mutations in non-small cell lung cancer(NSCLC).CASE SUMMARY A 67-year-old female patient in advanced lung adenocarcinoma suffered from drug resistance after EGFR-TKIs treatment.Secondary pathological tissue biopsy confirmed squamous cell carcinoma(SCC)transformation.Patients inevitably encountered drug resistance issues after receiving EGFR-TKIs treatment for a certain period of time,while EGFR-TKIs can significantly improve the survival of patients with EGFR-sensitive mutations in NSCLC.Notably,EGFR-TKIs resistance includes primary and acquired.Pathological transformation is one of the mechanisms of acquired resistance in EGFR-TKIs,with SCC transformation being relatively rare.Our results provide more detailed results of the patient’s diagnosis and treatment process on SCC transformation after EGFR-TKIs treatment for lung adenocarcinoma.CONCLUSION Squamous cell carcinoma transformation is one of the acquired resistance mechanisms of EGFR-TKIs in advanced lung adenocarcinoma with EGFR mutations.

Advanced lung adenocarcinoma with EGFR 19-del mutation transforms into squamous cell carcinoma after EGFR tyrosine kinase inhibitor treatment

In this editorial we comment on the article by Ji et al.We focus specifically on the EGFR tyrosine kinase inhibitor(EGFR-TKI)treatment and the development of drug resistance to EGFR-TKIs.

Expression of tyrosine kinase receptor C in the segments of the spinal cord and the cerebral cortex after cord transection in adult rats

Objective To investigate the role of tyrosine kinase receptor C（TrkC）,the receptor of neurotrophin-3（NT-3）,in neuroplasticity following spinal cord injury（SCI）.Methods Rats with cord transection were allowed to survive for 1,3,7 and 14 d post operation（dpo）.TrkC expressions at lower thoracic levels of the spinal cord and in precentral gyrus of cerebral cortex were investigated.Results TrkC protein levels at both the site of injury（T10-T11） and the neighboring segments（T9 and T12） in the spinal cord decreased significantly at 1-7 dpo,followed by a rapid increase at 14 dpo.The temporal changes in TrkC mRNA expression level showed a similar pattern with that of TrkC protein.In addition,the levels of TrkC protein and mRNA at the site of injury（T10-T11） were significantly higher than those at the neighboring spinal segments（T9 and T12）.Besides,the levels of TrkC protein and mRNA were higher at the rostral segment than at the caudal segment.However,in the motor cortex,TrkC protein was not detected and TrkC mRNA was expressed at a very low level.Conclusion These results suggest that TrkC may be involved in neuroplasticity after SCI.

Targeting receptor tyrosine kinases in gastric cancer

Molecularly targeted therapeutic agents are constantly being developed and have been shown to be effective in various clinical trials. One group of representative targeted oncogenic kinases, the receptor tyrosine kinases (RTKs), has been associated with gastric cancer development. Trastuzumab, an inhibitor of ERBB2, has been approved for the treatment of gastric cancer, although other receptor tyrosine kinases, such as epidermal growth factor receptor, vascular endothelial growth factor, platelet-derived growth factor receptor, c-Met, IGF-1R and fibroblast growth factor receptor 2, are also activated in gastric cancer. The promising results of the trastuzumab clinical trial for gastric cancer resulted in the approval of trastuzumab-based therapy as a first-line treatment for human epidermal growth factor receptor 2-positive patients. On the other hand, the trial examining bevacizumab in combination with conventional chemotherapy did not meet its primary goal of increasing the overall survival time of gastric cancer patients; however, a significantly higher response rate and a longer progression-free survival were observed in the bevacizumab arm of the trial. Other clinical trials, especially phase III trials that have tested drugs targeting RTKs, such as cetuximab, panitumumab, gefitinib, erlotinib, figitumumab, sorafenib, sunitinib and lapatinib, have shown that these drugs have modest effects against gastric cancer. This review summarizes the recent results from the clinical trials of molecularly targeted drugs and suggests that further improvements in the treatment of advanced gastric cancer can be achieved through the combination of conventional drugs with the new molecularly targeted therapies.

Pathogenesis of RON receptor tyrosine kinase in cancer cells: activation mechanism, functional crosstalk, and signaling addiction

The RON receptor tyrosine kinase, a member of the MET proto-oncogene family, is a pathogenic factor im- plicated in tumor malignancy. Specifically, aberrations in RON signaling result in increased cancer cell growth, survival, invasion, angiogenesis, and drug resistance. Biochemical events such as ligand binding, receptor over- expression, generation of structure-defected variants, and point mutations in the kinase domain contribute to RON signaling activation. Recently, functional crosstalk between RON and signaling proteins such as MET and EFGR has emerged as an additional mechanism for RON activation, which is critical for tumorigenic develop- ment. The RON signaling crosstalk acts either as a regulatory feedback loop that strengthens or enhances tumor- igenic phenotype of cancer cells or serves as a signaling compensatory pathway providing a growth/survival ad- vantage for cancer cells to escape targeted therapy. Moreover, viral oncoproteins derived from Friend leukemia or Epstein-Barr viruses interact with RON to drive viral oncogenesis. In cancer cells, RON signaling is integrated into cellular signaling network essential for cancer cell growth and survival. These activities provide the mo- lecular basis of targeting RON for cancer treatment. In this review, we will discuss recent data that uncover the mechanisms of RON activation in cancer cells, review evidence of RON signaling crosstalk relevant to cancer malignancy, and emphasize the significance of the RON signaling addiction by cancer cells for tumor therapy. Understanding aberrant RON signaling will not only provide insight into the mechanisms of tumor pathogenesis, but also lead to the development of novel strategies for molecularly targeted cancer treatment.

Neurotrophic receptor tyrosine kinase family members in secretory and non-secretory breast carcinomas

BACKGROUND Breast cancer is the most common female cancer and a major cause of morbidity and mortality.Progress in breast cancer therapeutics has been attained with the introduction of targeted therapies for specific sub-sets.However,other subsets lack targeted interventions and thus there is persisting need for identification and characterization of molecular targets in order to advance breast cancer therapeutics.AIM To analyze the role of lesions in neurotrophic receptor tyrosine kinase(NTRK)genes in breast cancers.METHODS Analysis of publicly available genomic breast cancer datasets was performed for identification and characterization of cases with fusions and other molecular abnormalities involving NTRK1,NTRK2 and NTRK3 genes.RESULTS NTRK fusions are present in a small number of breast cancers at the extensive GENIE project data set which contains more than 10000 breast cancers.These cases are not identified as secretory in the database,suggesting that the histologic characterization is not always evident.In the breast cancer The Cancer Genome Atlas(TCGA)cohort the more common molecular lesion in NTRK genes is amplification of NTRK1 observed in 7.9% of breast cancers.CONCLUSION Neurotrophin receptors molecular lesions other than fusions are observed more often than fusions.However,currently available NTRK inhibitors are effective mainly for fusion lesions.Amplifications of NTRK1,being more frequent in breast cancers,could be a viable therapeutic target if inhibitors efficacious for them become available.

Expression and functional study of cholecystokinin-A receptors on the interstitial Cajal-like cells of the guinea pig common bile duct

BACKGROUND Many studies have shown that interstitial Cajal-like cell(ICLC)abnormalities are closely related to a variety of dynamic gastrointestinal disorders.ICLCs are pacemaker cells for gastrointestinal movement and are involved in the transmission of nerve impulses.AIM To elucidate the expression profile and significance of cholecystokinin-A(CCK-A)receptors in ICLCs in the common bile duct(CBD),as well as the role of CCK in regulating CBD motility through CCK-A receptors on CBD ICLCs.METHODS The levels of tyrosine kinase receptor(c-kit)and CCK-A receptors in CBD tissues and isolated CBD cells were quantified using the double immunofluorescence labeling technique.The CCK-mediated enhancement of the movement of CBD muscle strips through CBD ICLCs was observed by a muscle strip contraction test.RESULTS Immunofluorescence showed co-expression of c-kit and CCK-A receptors in the CBD muscularis layer.Observations of isolated CBD cells showed that c-kit was expressed on the surface of ICLCs,the cell body and synapse were colored and polygonal,and some cells presented protrusions and formed networks adjacent to the CBD while others formed filaments at the synaptic terminals of local cells.CCK-A receptors were also expressed on CBD ICLCs.At concentrations ranging from 10^(-6) mol/L to 10^(-10) mol/L,CCK promoted CBD smooth muscle contractility in a dose-dependent manner.In contrast,after ICLC removal,the contractility mediated by CCK in CBD smooth muscle decreased.CONCLUSION CCK-A receptors are highly expressed on CBD ICLCs,and CCK may regulate CBD motility through the CCK-A receptors on ICLCs.

Efficacy of EGFR Tyrosine Kinase Inhibitors in Non-small Cell Lung Cancer Patients Harboring Different Types of EGFR Mutations:A Retrospective Analysis

With the development of molecular pathology, many types of epidermal growth factor receptor（EGFR） mutations have been identified. The efficacy of EGFR tyrosine kinase inhibitors（EGFR-TKIs） in non-small cell lung cancer（NSCLC） patients with different types of EGFR mutations, especially in patients with single rare mutations or complex mutations（co-occurrence of two or more different mutations）, has not been fully understood. This study aimed to examine the efficacy of EGFR-TKIs in NSCLC patients with different types of EGFR mutations. Clinical data of 809 NSCLC patients who harbored different types of EGFR mutations and treated from January 2012 to October 2016 at Renmin Hospital and Zhongnan Hospital, Wuhan, were retrospectively reviewed. The clinical characteristics of these patients and the efficacy of EGFR-TKIs were analyzed. Among these patients, 377 patients had only the EGFR del-19 mutation, 362 patients the EGFR L858R mutation in exon 21, 33 patients single rare mutations and 37 patients complex mutations. Among these 809 patients, 239 patients were treated with EGFR-TKIs. In all the 239 patients, the disease control rate（DCR） was 93.7% with two patients（0.2%） achieving complete response（CR）, the median progression free survival（PFS） was 13.0 months（95% confidence interval [CI], 11.6–14.4 months）, and the median overall survival（OS） was 55.0 months（95% CI, 26.3–83.7 months）. Subgroup analysis revealed that the DCR in patients harboring single rare or complex mutations of EGFR was significantly lower than in those with del-19 or L858 R mutation（P〈0.001）. Patients with classic mutations（del-19 and/or L858 R mutations） demonstrated longer PFS（P〈0.001） and OS（P=0.017） than those with uncommon mutations（single rare and/or complex mutations）. Furthermore, the patients with single rare mutations had shorter median OS than in those with other mutations. Multivariate Cox regression analysis identified that the type of EGFR mutations was an independent risk factor for PFS（hazard ratio [HR]=0.308, 95% CI, 0.191–0.494, P〈0.001） and OS（HR=0.221, 95% CI, 0.101–0.480, P〈0.001）. The results suggest that the single rare or complex EGFR mutations confer inferior efficacy of EGFR-TKIs treatment to the classic mutations. The prognosis of the single rare EGFR mutations is depressing. EGFR-TKIs may be not a good choice for NSCLC patients with single rare mutations of EGFR. Further studies in these patients with uncommon mutations（especially for the patients with single rare mutations） are needed to determine a better precision treatment.

The efficacy of Kanglaite injection during treatment with tyrosine kinase inhibitor in elderly patients with non-small cell lung cancer

Objective Epidermal growth factor receptor–tyrosine kinase inhibitors(EGFR–TKIs) are widely used in the treatment of EGFR mutation-positive non-small cell lung cancer(NSCLC) patients. The Kanglaite injection(KLT) is a novel broad-spectrum anti-cancer injection produced from traditional Chinese medicinal herbs(coix seed). After its approval in 1995, KLT has become the most popular anti-cancer drug in China. As of this writing, no standard treatment guideline is available for elder patients with NSCLC, and the role of traditional Chinese medicinal herbs, including KLT, combined with TKI treatment remains unknown. This retrospective study evaluated the efficacy and safety of KLT in elderly NSCLC patients during TKI treatment.Methods Thirty elderly patients aged 71-79 years with histopathologically confirmed NSCLC attending the General Hospital of the Shenyang Military Region were enrolled in the study and received EGFR-TKI treatment. All participants received 200 m L KLT injections at the same time on days 1–21. Erlotinib(150 mg) or gefitinib(250 mg) was administered daily from days 1 to 21, and the cycle was repeated every 21 days. The endpoint of the primary study was the disease control rate.Results Thirty elderly patients were enrolled in this study. The objective response rate was 21.3% [95% confidence interval(CI): 8.6% to 35.2%], whereas the disease control rate was 80.4%(95% CI: 71.8% to 97.0%). The grade 3 or 4 adverse effects included leucopenia(13.7%), neutropenia(13.4%), anemia(2.9%), and nausea or vomiting(2.7%). Conclusion The administration of KLT combined with erlotinib or gefitinib showed high efficacy in elderly NSCLC patients. The adverse effects of the drug combination were well tolerated by the patients. KLT combined with TKI treatment might provide a satisfactory therapeutic strategy for elderly NSCLC patients.

Pan-TRK positive uterine sarcoma in immunohistochemistry without neurotrophic tyrosine receptor kinase gene fusions:A case report

BACKGROUND The classification of uterine sarcomas is based on distinctive morphological and immunophenotypic characteristics,increasingly supported by molecular genetic diagnostics.Data on neurotrophic tyrosine receptor kinase(NTRK)gene fusionpositive uterine sarcoma,potentially aggressive and morphologically similar to fibrosarcoma,are limited due to its recent recognition.Pan-TRK immunohistochemistry(IHC)analysis serves as an effective screening tool with high sensitivity and specificity for NTRK-fusion malignancies.CASE SUMMARY We report a case of a malignant mesenchymal tumor originating from the uterine cervix,which was pan-TRK IHC-positive but lacked NTRK gene fusions,accompanied by a brief literature review.A 55-year-old woman presented to the emergency department with abdominal pain and distension,exhibiting significant ascites and multiple solid pelvic masses.Pelvic examination revealed a tumor encompassing the uterine cervix,extending to the vagina and uterine corpus.A punch biopsy of the cervix indicated NTRK sarcoma with positive immunochemical pan-TRK stain.However,subsequent next generation sequencing revealed no NTRK gene fusion,leading to a diagnosis of poorly differentiated,advanced-stage sarcoma.CONCLUSION The clinical significance of NTRK gene fusion lies in potential treatment with TRK inhibitors for positive sarcomas.Identifying such rare tumors is crucial due to the potential applicability of tropomyosin receptor kinase inhibitor treatment.

Effects of laser photocoagulation on serum angiopoietin-1, angiopoietin-2, angiopoietin-1/angiopoietin-2 ratio, and soluble angiopoietin receptor Tie-2 levels in type 2 diabetic patients with proliferative diabetic retinopathy

·AIM: To determine the effects of laser photocoagulation on serum levels of angiopoietin-1(Ang-1),angiopoietin-2(Ang-2), soluble angiopoietin receptor Tie-2(Tie-2), Ang-1/Ang-2 ratio and vascular endothelial growth factor(VEGF) in patients with type 2diabetes mellitus(T2DM) and proliferative diabetic retinopathy(PDR). We also explored the role of the Ang/Tie system in PDR.·METHODS:Totally 160patientswithT2 DM, including50 patients with non-diabetic retinopathy(NDR), 58 patients with non-proliferative diabetic retinopathy(NPDR), and52 patients with PDR were enrolled in this study. Serum Ang-1, Ang-2, Tie-2 receptor and VEGF levels were measured using enzyme-linked immunosorbent assays for all patients and were repeated in 26 patients who underwent laser photocoagulation two months after the procedure.·RESULTS:ThemedianlevelsofAng-2andVEGFinserum were significantly higher in the NPDR group(4.23 ng/mL and 303.2 pg/mL, respectively) compared to the NDR group(2.67 ng/mL and 159.8 pg/mL, respectively, P 【0.01), with the highest level in the PDR group(6.26 ng/mL and531.2 pg/mL, respectively, P 【0.01). The median level of Ang-1 was significantly higher in the NPDR group(10.77ng/mL) compared to the NDR group(9.31 ng/mL) and the PDR groups(9.54 ng/mL)(P 【0.05), while no difference was observed between the PDR and NDR groups. Ang-1/Ang-2 ratio of PDR group was lowest in three groups(1.49 vs 2.69 and 2.90, both P 【0.01). The median level of Tie-2was not significantly different among three groups(P 】0.05).Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups(both P 【0.05). Among the 26 patients who underwent laser photocoagulation, serum Ang-2 and VEGF levels significantly decreased(both P 【0.05), whereas serum Ang-1 level and Ang-1/Ang-2ratio were weakly increased(P 】0.05). The median levels of Ang-2 and VEGF in serum were highest in PDR group,however, Ang-1/Ang-2 ratio of PDR group was lowest in three groups.·CONCLUSION: Laser photocoagulation can reduce serum Ang-2 and VEGF levels. The Ang/Tie system and VEGF play an important role in the development and progression of T2 DM patients with PDR.

Associations Between Epidermal Growth Factor Receptor Gene Mutation and Serum Tumor Markers in Advanced Lung Adenocarcinomas: A Retrospective Study

Objective To investigate the associations between epidermal growth factor receptor （EGFR） gene mutations and serum tumor markers in advanced lung adenocarcinomas. Methods We investigated the association between EGFR gene mutations and clinical features, including serum tumor marker levels, in 97 advanced lung adenocarcinomas patients who did not undergo the treatment of EGlaR tyrosine kinase inhibitors. EGFR gene mutation was detected by real-time PCR at exons 18, 19, 20, and 21. Serum tumor marker concentrations were analyzed by chemiluminescence assay kit at the same time. Results EGFR gene mutations were detected in 42 （43%） advanced lung adenocarcinoma patients. Gender （P=0.003）, smoking status （P=0.001）, and abnormal serum status of carcinoembryonic antigen （CEA, P=0.028） were significantly associated with EGFR gene mutation incidence. Multivariate analysis showed the abnormal CEA level in serum was independently associated with the incidence of EGFR gene mutation （P=0.046） with an odds ratio of 2.613 （95% Ch 1.018-6.710）. However, receiver operating characteristic （ROC） curve analysis revealed CEA was not an ideal predictive marker for EGFR gene mutation status in advanced lung adenocarcinoma （the area under the ROC curve was 0.608, P=0.069）. Conclusions EGFR gene mutation status is significantly associated with serum CEA status in advanced lung adenocarcinmoas. However, serum CEA is not an ideal predictor for EGFR mutation.

Involvement of Met receptor pathway in aggressive behavior of colorectal cancer cells induced by parathyroid hormone-related peptide

BACKGROUND Parathyroid hormone-related peptide(PTHrP)plays a key role in the development and progression of many tumors.We found that in colorectal cancer(CRC)HCT116 cells,the binding of PTHrP to its receptor PTHR type 1(PTHR1)activates events associated with an aggressive phenotype.In HCT116 cell xenografts,PTHrP modulates the expression of molecular markers linked to tumor progression.Empirical evidence suggests that the Met receptor is involved in the development and evolution of CRC.Based on these data,we hypothesized that the signaling pathway trigged by PTHrP could be involved in the transactivation of Met and consequently in the aggressive behavior of CRC cells.AIM To elucidate the relationship among PTHR1,PTHrP,and Met in CRC models.METHODS For in vitro assays,HCT116 and Caco-2 cells derived from human CRC were incubated in the absence or presence of PTHrP(1-34)(10-8 M).Where indicated,cells were pre-incubated with specific kinase inhibitors or dimethylsulfoxide,the vehicle of the inhibitors.The protein levels were evaluated by Western blot technique.Real-time polymerase chain reaction(RT-qPCR)was carried out to determine the changes in gene expression.Wound healing assay and morpho logical monitoring were performed to evaluate cell migration and changes related to the epithelialmesenchymal transition(EMT),respectively.The number of viable HCT116 cells was counted by trypan blue dye exclusion test to evaluate the effects of irinotecan(CPT-11),oxaliplatin(OXA),or doxorubicin(DOXO)with or without PTHrP.For in vivo tests,HCT116 cell xenografts on 6-wk-old male N:NIH(S)_nu mice received daily intratumoral injections of PTHrP(40μg/kg)in 100μL phosphate-buffered saline(PBS)or the vehicle(PBS)as a control during 20 d.Humanitarian slaughter was carried out and the tumors were removed,weighed,and fixed in a 4%formaldehyde solution for subsequent treatment by immunoassays.To evaluate the expression of molecular markers in human tumor samples,we studied 23 specimens obtained from CRC patients which were treated at the Hospital Interzonal de Graves y Agudos Dr.JoséPenna(Bahía Blanca,Buenos Aires,Argentina)and the Hospital Provincial de Neuquén(Neuquén,Neuquén,Argentina)from January 1990 to December 2007.Seven cases with normal colorectal tissues were assigned to the control group.Tumor tissue samples and clinical histories of patients were analyzed.Paraffin-embedded blocks from primary tumors were reviewed by hematoxylin-eosin staining technique;subsequently,representative histological samples were selected from each patient.From each paraffin block,tumor sections were stained for immunohistochemical detection.The statistical significance of differences was analyzed using proper statistical analysis.The results were considered statistically significant at P<0.05.RESULTS By Western blot analysis and using total Met antibody,we found that PTHrP regulated Met expression in HCT116 cells but not in Caco-2 cells.In HCT116 cells,Met protein levels increased at 30 min(P<0.01)and at 20 h(P<0.01)whereas the levels diminished at 3 min(P<0.05),10 min(P<0.01),and 1 h to 5 h(P<0.01)of PTHrP treatment.Using an active Met antibody,we found that where the protein levels of total Met decreased(3 min,10 min,and 60 min of PTHrP exposure),the status of phosphorylated/activated Met increased(P<0.01)at the same time,suggesting that Met undergoes proteasomal degradation after its phosphorylation/activation by PTHrP.The increment of its protein level after these decreases(at 30 min and 20 h)suggests a modulation of Met expression by PTHrP in order to improve Met levels and this idea is supported by our observation that the cytokine increased Met mRNA levels at least at 15 min in HCT116 cells as revealed by RT-qPCR analysis(P<0.05).We then proceeded to evaluate the signaling pathways that mediate the phosphorylation/activation of Met induced by PTHrP in HCT116 cells.By Western blot technique,we observed that PP1,a specific inhibitor of the activation of the protooncogene protein tyrosine kinase Src,blocked the effect of PTHrP on Met phosphorylation(P<0.05).Furthermore,the selective inhibition of the ERK 1/2 mitogen-activated protein kinase(ERK 1/2 MAPK)using PD98059 and the p38 MAPK using SB203580 diminished the effect of PTHrP on Met phosphorylation/activation(P<0.05).Using SU11274,the specific inhibitor of Met activation,and trypan blue dye exclusion test,Western blot,wound healing assay,and morphological analysis with a microscope,we observed the reversal of cell events induced by PTHrP such as cell proliferation(P<0.05),migration(P<0.05),and the EMT program(P<0.01)in HCT116 cells.Also,PTHrP favored the chemoresistance to CPT-11(P<0.001),OXA(P<0.01),and DOXO(P<0.01)through the Met pathway.Taken together,these findings suggest that Met activated by PTHrP participates in events associated with the aggressive phenotype of CRC cells.By immunohistochemical analysis,we found that PTHrP in HCT116 cell xenografts enhanced the protein expression of Met(0.190±0.014)compared to tumors from control mice(0.110±0.012;P<0.05)and of its own receptor(2.27±0.20)compared to tumors from control mice(1.98±0.14;P<0.01).Finally,assuming that the changes in the expression of PTHrP and its receptor are directly correlated,we investigated the expression of both Met and PTHR1 in biopsies of CRC patients by immunohistochemical analysis.Comparing histologically differentiated tumors with respect to those less differentiated,we found that the labeling intensity for Met and PTHR1 increased and diminished in a gradual manner,respectively(P<0.05).CONCLUSION PTHrP acts through the Met pathway in CRC cells and regulates Met expression in a CRC animal model.More basic and clinical studies are needed to further evaluate the PTHrP/Met relationship.

Interplay between TGF-β signaling and receptor tyrosine kinases in tumor development

Transforming growth factor-β(TGF-β) signaling regulates cell proliferation, differentiation, migration and death, and plays a critical role in embryogenesis and tissue homeostasis. Its deregulation results in various diseases including tumor formation.Receptor tyrosine kinases(RTKs), such as epidermal growth factor receptor(EGFR), fibroblast growth factor receptor(FGFR),vascular endothelial growth factor receptor(VEGFR) and platelet-derived growth factor receptor(PDGFR), also play key roles in the development and progression of many types of tumors. It has been realized that TGF-β signaling and RTK pathways interact with each other and their interplay is important for cancer development. They are mutually regulated and cooperatively modulate cell survival and migration, epithelial-mesenchymal transition, and tumor microenvironment to accelerate tumorigenesis and tumor metastasis. RTKs can modulate Smad-dependent transcription or cooperate with TGF-β to potentiate its oncogenic activity,while TGF-β signaling can in turn control RTK signaling by regulating their activities or expression. This review summarizes current understandings of the interplay between TGF-β signaling and RTKs and its influence on tumor development.

Expression of the recepteur d＇originenantais receptor tyrosine kinase in non-small cell lung cancer and its clinical significance

Background Recepteur d＇originenantais （RON） is a receptor tyrosine kinase （RTK） that belongs to the MET proto-oncogene family. The aim of this study was to investigate the expression of RON receptor tyrosine kinase in human non-small cell lung cancer （NSCLC） and its relationship with clinical pathology of NSCLC and prognosis. Methods RON protein expression by immunohistochemistry （IHC） in 96 NSCLC specimens was evaluated and compared with the clinical pathology and prognosis, and 20 para-neoplastic tissues were included as controls. RON mRNA and protein expression in 25 fresh tissue samples of lung cancer and 10 normal lung tissues were also analyzed by reverse transcription-polymerase chain reaction （RT-PCR） and Western blotting. Results The rate of positive RON expression differed significantly between NSCLC tissues （55.2%, 53/96） and para-neoplastic tissues （5%, 1/20） （P 〈0.001）. RON protein expression was not found to be associated with gender or age. However, RON expression positively correlated with clinical TNM stage （P=0.004）, histological types （P=-0.001）, lymph node metastasis （P=0.012） and differentiation （P=0.035）. RT-PCR and Western blotting analysis also confirmed that the expression of RON mRNA and protein was significantly increased in the NSCLC tissues versus normal tissues. In addition, RON expression was associated with a poor prognosis for patients with NSCLC （P=0.045）. Conclusions The expression of RON protein and mRNA is significant in human NSCLC and low in para-neoplastic and normal tissues. Elevated RON expression may contribute to the occurrence, progression and metastasis of NSCLC, inferring that it could be useful as a new prognostic indicator for patients with NSCLC.

Resistance to receptor tyrosine kinase inhibition in cancer： molecular mechanisms and therapeutic strategies

Drug resistance is a major factor that limits the efficacy of targeted cancer therapies. In this review, we discuss the main known mechanisms of resistance to receptor tyrosine kinase inhibitors, which are the most prevalent class of targeted therapeutic agent in current clinical use. Here we focus on bypass track resistance, which involves the activation of alternate signaling molecules by tumor cells to bypass inhibition and maintain signaling output, and consider the problems of signaling pathway redundancy and how the activation of different receptor tyrosine kinases translates into intracellular signal transduction in different cancer types. This information is presented in the context of research strategies for the discovery of new targets for pharmacological intervention, with the goal of overcoming resistance in order to improve patient outcomes.

Paradigm shift of chemotherapy and systemic treatment for biliary tract cancer

Biliary tract cancers(BTC)are frequently identified at late stages and have a poor prognosis due to limited systemic treatment regimens.For more than a decade,the combination of gemcitabine and cis-platin has served as the first-line standard treatment.There are few choices for second-line chemo-therapy.Targeted treatment with fibroblast growth factor receptor 2 inhibitors,neurotrophic tyrosine receptor kinase inhibitors,and isocitrate dehydrogenase 1 inhibitors has had important results.Immune checkpoint inhibitors(ICI)such as pembrolizumab are only used in first-line treatment for microsatellite instability high patients.The TOPAZ-1 trial's outcome is encouraging,and there are several trials underway that might soon put targeted treatment and ICI combos into first-line options.Newer targets and agents for existing goals are being studied,which may represent a paradigm shift in BTC management.Due to a scarcity of targetable mutations and the higher toxicity profile of the current medications,the new category of drugs may occupy a significant role in BTC therapies.