Deciphering resistancemechanisms and novel strategies to overcome drug resistance in ovarian cancer:a comprehensive review

Ovarian cancer is among the most lethal gynecological cancers,primarily due to the lack of specific symptoms leading to an advanced-stage diagnosis and resistance to chemotherapy.Drug resistance(DR)poses the most significant challenge in treating patients with existing drugs.The Food and Drug Administration(FDA)has recently approved three new therapeutic drugs,including two poly(ADP-ribose)polymerase(PARP)inhibitors(olaparib and niraparib)and one vascular endothelial growth factor(VEGF)inhibitor(bevacizumab)for maintenance therapy.However,resistance to these new drugs has emerged.Therefore,understanding the mechanisms of DR and exploring new approaches to overcome them is crucial for effective management.In this review,we summarize the major molecular mechanisms of DR and discuss novel strategies to combat DR.

Role of targeting ferroptosis as a component of combination therapy in combating drug resistance in colorectal cancer

Colorectal cancer(CRC)is a form of cancer that is often resistant to chemotherapy,targeted therapy,radiotherapy,and immunotherapy due to its genomic instability and inflammatory tumor microenvironment.Ferroptosis,a type of non-apoptotic cell death,is characterized by the accumulation of iron and the oxidation of lipids.Studies have revealed that the levels of reactive oxygen species and glutathione in CRC cells are significantly lower than those in healthy colon cells.Erastin has emerged as a promising candidate for CRC treatment by diminishing stemness and chemoresistance.Moreover,the gut,responsible for regulating iron absorption and release,could influence CRC susceptibility through iron metabolism modulation.Investigation into ferroptosis offers new insights into CRC pathogenesis and clinical management,potentially revolutionizing treatment approaches for therapy-resistant cancers.

FGF2 promotes the chemotherapy resistance in colon cancer cells through activating PI3K/Akt signaling pathway

Background:To investigate the role of fibroblast growth factor 2(FGF2)in chemotherapy resistance of colon cancer.Methods:An HCT116/5-fluorouracil(5-FU)-resistant cell line was established,and FGF2 levels were detected in a sensitive cell group(HCT116)and a resistant cell group(HCT1116-R)using different methods.Fibroblast growth factor 2 levels in the medium were determined by enzyme-linked immunoassay.The protein expressions of FGF2,fibroblast growth factor receptor 1(FGFR1),and phospho-FGFR1 were assessed by Western blotting,and FGF2 mRNA levels were detected by quantitative real-time polymerase chain reaction.Fibroblast growth factor 2 recombinant protein was added to sensitive cells,and FGFR inhibitor AZD4547 was added to resistant cells,and the cell survival rate was determined using the cell counting kit-8 method and the protein expressions of PI3K(phosphatidylinositol 3 kinase),p-PI3K(phospho-PI3K),Akt(protein kinase B),p-Akt(phospho-Akt),mammalian target of rapamycin(mTOR),p-mTOR(phospho-mTOR),Bad(Bcl-xL/Bcl-2-associated death promoter),NF-κB(nuclear factorκB),GSK-3(glycogen synthase kinase-3),FKHR(forkhead box protein O1),and PTEN(phosphatase and tensin homolog deleted on chromosome ten)were detected by Western blotting.Results:Fibroblast growth factor 2 protein and mRNA expression levels in the HCT116-R group were significantly higher than those in the HCT116 group.Fibroblast growth factor 2 increased the survival rate of HCT116 cells;improved tolerance to 5-FU;upregulated p-PI3K,p-Akt,and p-mTOR;and downregulated Bad.The FGFR inhibitor AZD4547 decreased cell survival rate and tolerance to 5-FU;downregulated p-PI3K,p-Akt,and p-mTOR expression;and upregulated Bad.Conclusions:Fibroblast growth factor 2 promotes chemotherapy tolerance in colon cancer cells by activating the Akt/mTOR and Akt/Bad signaling pathways downstream of PI3K.

CK2αcauses stemness and chemotherapy resistance in liver cancer through the Hedgehog signaling pathway

Background:Liver cancer is one of the major causes of cancer-related deaths globally.Cancer cell stem-ness and chemotherapy resistance contribute to the high mortality.Although evidence indicates that the alpha subunit of protein kinase 2(CK2α)is involved in several human cancers,its function in liver cancer remains unknown.In the present study,we aimed to elucidate the role of CK2αin liver cancer.Methods:We examined the role of CK2αregulation in stemness and chemotherapy resistance capacity of liver cancer cells.MTT assays,tumor sphere formation assays,RT-PCR,flow cytometry,Western blotting assay,clonogenicity assay,matrigel invasion assay and bioinformatics were conducted in this study.Results:CK2αexpression in the liver cancer tissues was notably upregulated compared with that in the corresponding non-tumorous tissues.The overexpression of CK2αpromoted tumor sphere formation,increased the percentage of CD133(+)and side population cells,caused the resistance of liver cancer cells to 5-FU treatment,increased the expression levels of NANOG,OCT4,SOX2,Gli1 and Ptch1,and enhanced the ability of CD133(+)cell clone formation and invasion.Consistently,the downregulation of CK2αhad the opposite effects.CK2αsilencing inhibited the Hedgehog pathway by reducing the expression of Gli1 and Ptch1.Mechanistically,CK2αregulation on liver cancer cell stemness and chemotherapy resistance was found to be involved in the Hedgehog signaling pathway.Conclusions:Our study may bring some new insights into the occurrence of liver cancer.Furthermore,these findings suggest that targeting CK2αmay be a novel therapeutic strategy for patients with liver cancer.

The DMRTA1-SOX2 positive feedback loop promotes progression and chemotherapy resistance of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma(ESCC)is among the most prevalent causes of cancer-related death in patients worldwide.Resistance to immunotherapy and chemotherapy results in worse survival outcomes in ESCC.It is urgent to explore the underlying molecular mechanism of immune evasion and chemoresistance in ESCC.Here,we conducted RNA-sequencing analysis in ten ESCC tissues from cisplatin-based neoadjuvant chemotherapy patients.We found that DMRTA1 was extremely upregulated in the non-pathologic complete response(non-pCR)group.The proliferation rate of esophageal squamous carcinoma cells was markedly decreased after knockdown of DMRTA1 expression,which could increase cisplatin sensitivity in ESCC.Additionally,suppression of DMRTA1 could decrease the immune escape of esophageal squamous carcinoma cells.Further mechanistic studies suggest that DMRTA1 can promote its expression by binding to the promoter of SOX2,which plays important roles in the progression and chemoresistance of ESCC in the form of positive feedback.Therefore,DMRTA1 could be a potential target to suppress immune escape and overcome chemoresistance in ESCC.

A radiomics prognostic scoring system for predicting progression-free survival in patients with stageⅣnon-small cell lung cancer treated with platinum-based chemotherapy

Objective:To develop and validate a radiomics prognostic scoring system(RPSS)for prediction of progressionfree survival(PFS)in patients with stageⅣnon-small cell lung cancer(NSCLC)treated with platinum-based chemotherapy.Methods:In this retrospective study,four independent cohorts of stageⅣNSCLC patients treated with platinum-based chemotherapy were included for model construction and validation(Discovery:n=159;Internal validation:n=156;External validation:n=81,Mutation validation:n=64).First,a total of 1,182 three-dimensional radiomics features were extracted from pre-treatment computed tomography(CT)images of each patient.Then,a radiomics signature was constructed using the least absolute shrinkage and selection operator method(LASSO)penalized Cox regression analysis.Finally,an individualized prognostic scoring system incorporating radiomics signature and clinicopathologic risk factors was proposed for PFS prediction.Results:The established radiomics signature consisting of 16 features showed good discrimination for classifying patients with high-risk and low-risk progression to chemotherapy in all cohorts(All P<0.05).On the multivariable analysis,independent factors for PFS were radiomics signature,performance status(PS),and N stage,which were all selected into construction of RPSS.The RPSS showed significant prognostic performance for predicting PFS in discovery[C-index:0.772,95%confidence interval(95%CI):0.765-0.779],internal validation(C-index:0.738,95%CI:0.730-0.746),external validation(C-index:0.750,95%CI:0.734-0.765),and mutation validation(Cindex:0.739,95%CI:0.720-0.758).Decision curve analysis revealed that RPSS significantly outperformed the clinicopathologic-based model in terms of clinical usefulness(All P<0.05).Conclusions:This study established a radiomics prognostic scoring system as RPSS that can be conveniently used to achieve individualized prediction of PFS probability for stageⅣNSCLC patients treated with platinumbased chemotherapy,which holds promise for guiding personalized pre-therapy of stageⅣNSCLC.

Cutting the root:the next generation of T cells engagers against cancer stem cells to overcome drug resistance in triple-negative breast cancer

Triple-negative breast cancer(TNBC)is the most difficult type of breast cancer to treat.TNBC is defined by the lack of expression of three receptors:estrogen receptor(ER);progesterone receptor(PR);and human epidermal growth factor receptor 2(HER2).Chemotherapy is currently first-line treatment for TNBC;however,due to the high heterogeneity of TNBC,most patients eventually develop chemotherapy resistance,which is associated with a poor prognosisl-2.Emerging immune checkpoint blockade(ICB)therapies have been shown to have promising therapeutic efficacy in treating solid tumors.A phase III clinical trial reported that the combination of ICB and chemotherapy lengthened progression-free survival in patients with metastatic PD-L1+TNBC3;however,most patients had primary resistance or acquired resistance to ICB.Thus,the intrinsic mechanisms underlying ICB resistance are still under investigation4.

Deciphering key genes involved in cisplatin resistance in kidney renal clear cell carcinoma through a combined in silico and in vitro approach

The low survival rate of Kidney renal clear cell carcinoma(KIRC)patients is largely attributed to cisplatin resistance.Rather than focusing solely on individual proteins,exploring protein-protein interactions could offer greater insight into drug resistance.To this end,a series of in silico and in vitro experiments were conducted to identify hub genes in the intricate network of cisplatin resistance-related genes in KIRC chemotherapy.The genes involved in cisplatin resistance across KIRC were retrieved from the National Center for Biotechnology Information(NCBI)database using search terms as“Kidney renal clear cell carcinoma”and“Cisplatin resistance”.The genes retrieved were analyzed for hub gene identification using the STRING database and Cytoscape tool.Expression and promoter methylation profiling of the hub genes was done using UALCAN,GEPIA,OncoDB,and HPA databases.Mutational,survival,functional enrichment,immune cell infiltration,and drug prediction analyses of the hub genes were performed using the cBioPortal,GEPIA,GSEA,TIMER,and DrugBank databases.Lastly,expression and methylation levels of the hub genes were validated on two cisplatin-resistant RCC cell lines(786-O and A-498)and a normal renal tubular epithelial cell line(HK-2)using two high throughput techniques,including targeted bisulfite sequencing(bisulfite-seq)and RT-qPCR.A total of 124 genes were identified as being associated with cisplatin resistance in KIRC.Out of these genes,MCL1,IGF1R,CCND1,and PTEN were identified as hub genes and were found to have significant(p<0.05)variations in their mRNA and protein expressions and effects on the overall survival(OS)of the KIRC patients.Moreover,an aberrant promoter methylation pattern was found to be associated with the dysregulation of the hub genes.In addition to this,hub genes were also linked with different cisplatin resistance-causing pathways.Thus,hub genes can be targeted with Alvocidib,Estradiol,Tretinoin,Capsaicin,Dronabinol,Metribolone,Calcitriol,Acetaminophen,Acitretin,Cyclosporine,Azacitidine,Genistein,and Resveratrol drugs.As the pathogenesis of KIRC is complex,targeting hub genes and associated pathways involved in cisplatin resistance could bring a milestone change in the drug discovery and management of drug resistance,which might uplift overall survival among KIRC patients.

Associations of genetic polymorphisms of the transporters organic cation transporter 2(OCT2),multidrug and toxin extrusion 1(MATE1),and ATP-binding cassette subfamily C member 2(ABCC2) with platinum-based chemotherapy response and toxicity in non-small cel

Background:Platinum-based chemotherapy is the first-line treatment of non-small cell lung cancer(NSCLC);it is therefore important to discover biomarkers that can be used to predict the efficacy and toxicity of this treatment.Four important transporter genes are expressed in the kidney,including organic cation transporter 2(OCT2),multidrug and toxin extrusion 1(MATEl),ATP-binding cassette subfamily B member 1 {ABCB1),and ATP-binding cassette subfamily C member 2(ABCC2),and genetic polymorphisms in these genes may alter the efficacy and adverse effects of platinum drugs.This study aimed to evaluate the association of genetic polymorphisms of these transporters with platinumbased chemotherapy response and toxicity in NSCLC patients.Methods:A total of 403 Chinese NSCLC patients were recruited for this study.All patients were newly diagnosed with NSCLC and received at least two cycles of platinum-based chemotherapy.The tumor response and toxicity were evaluated after two cycles of treatment,and the patients' genomic DNA was extracted.Seven single-nucleotide polymorphisms in four transporter genes were selected to investigate their associations with platinum-based chemotherapy toxicity and response.Results:OCT2 rs316019 was associated with hepatotoxicity(P = 0.026) and hematological toxicity(P = 0.039),and MATEl rs2289669 was associated with hematological toxicity induced by platinum(P = 0.016).In addition,ABCC2rs717620 was significantly associated with the platinum-based chemotherapy response(P = 0.031).ABCB1 polymorphisms were associated with neither response nor toxicity.Conclusion:OCT2 rs316019,MATEl rs2289669,and ABCC2 rs717620 might be potential clinical markers for predicting chemotherapy toxicity and response induced by platinum-based treatment in NSCLC patients.Trial registration Chinese Clinical Trial Registry

Identification and validation of Temozolomide resistance hub gene LncRNA MOCS2-DT in glioblastoma

Background:Temozolomide(TMZ)is an important adjuvant chemotherapy drug after glioma surgery.However,with the progress of treatment,most patients will gradually develop drug resistance.Long non-coding RNA(lncRNA)in the prediction and reversal of chemotherapy drug resistance possesses great potential.Methods:1.The clinical data and RNA expression matrix of glioma patients were downloaded from the Chinese Glioma Genome Atlas(CGGA),and the clinical data and RNA expression profiles of 47 patients who only received TMZ chemotherapy after surgery were selected;2.WGCNA was performed on RNA expression profiles to find modules highly correlated with survival time and lncRNAs with high connectivity in modules.Core lncRNA were further screened from the GEO database(P<0.05);survival analysis,correlation analysis,enrichment analysis and co-expression analysis were performed;and 3.A TMZ concentration gradient induced glioma-resistant cells(U251TR).Cell proliferation toxicity assays and real-time quantitative PCR were used to verify the core lncRNA and identify the biological characteristics of U251TR.Results:1.According to the WGCNA analysis,it was found that the pink module is highly correlated with survival time and that there are 17 core lncRNAs with high connectivity in the pink module.2.The expression of the core lncRNA MOCS2-DT in the U251 resistant strain was significantly lower than that in the sensitive strain(P<0.05).3.U251TR cells had significantly larger cell bodies with irregular shapes.U251TR cells had a stronger tolerance to TMZ than U251 cells,and the resistance index was about four times higher(P<0.05).4.The expression levels of MGMT and ABCG2 in U251TR cells were significantly higher than those in parental U251 cells(P<0.05),and the expression levels of MOCS2-DT in U251TR cells were significantly lower than those in parental U251 cells(P<0.05).5.The survival time and survival rate of patients with low expression of MOCS2-DT were significantly lower than those of patients with high expression of MOCS2-DT in patients who only received TMZ chemotherapy after surgery.6.The enrichment analysis results show that the mRNA co-expressed with MOCS2-DT is enriched in synapse organization,regulation of membrane potential and signal release,indicating that MOCS2-DT is closely related to these functions.Conclusion:Targeted regulation of MOCS2-DT may reverse the drug resistance of glioma,improve the prognosis of patients and prolong the survival time of patients.

Nuclear heat shock protein 110 expression is associated with poor prognosis and hyperthermo-chemotherapy resistance in gastric cancer patients with peritoneal metastasis

AIM To investigate the significance of heat shock protein 110(HSP110) in gastric cancer(GC) patients with peritoneal metastasis undergoing hyperthermochemotherapy.METHODS Primary GC patients(n = 14) with peritoneal metastasis or positive peritoneal lavage cytology who underwent distal or total gastrectomy between April 2000 and December 2011 were enrolled in this study. The patients underwent postoperative intraperitoneal hyperthermo-chemotherapy using a Thermotron RF-8 heating device two weeks after surgery. We analyzed nuclear HSP110 expression in surgically resected tumors using immunohistochemistry. Additionally, the effect of HSP110 suppression on hyptherthermochemosensitivity was assessed in vitro in the MKN45 GC cell line using the HSP inhibitor KNK437. RESULTS HSP110 immnohistochemical staining in 14 GC patients showed that five(35.7%) samples belonged to the low expression group, and nine(64.3%) samples belonged to the high expression group. Progression-free survival was significantly shorter in the HSP110 high-expression group than in the low-expression group(P = 0.0313). However, no significant relationships were identified between HSP110 expression and the clinicopathological characteristics of patients. Furthermore, high HSP110 expression was not an independent prognostic factor in GC patients with peritoneal metastasis(P = 0.0625). HSP110 expression in MKN45 cells was suppressed by KNK437 at the hyperthermic temperature of 43 ℃ in vitro. Comparison of MKN45 cell proliferation in the presence and absence of KNK437 at 43 ℃, revealed that proliferation was significantly decreased when HSP110 was inhibited by KNK437. Additionally, HSP110 suppression via HSP inhibitor treatment increased cellular sensitivity to hyperthermo-chemotherapy in vitro.CONCLUSION The expression of nuclear HSP110 in GC patients might be a new marker of chemosensitivity and a therapeutic target for patients who are tolerant to existing hyperthermo-chemotherapies.

Chemotherapy and drug resistance status of malaria parasite in northeast India

India reports the highest number of malaria cases in Southeast Asia,of which Plasmodium falciparum contribute more than half of the cases every year.North eastern states of India contribute only 3.96%of country’s population but account for】10%of total reported malaria cases.11%of Plasmodium falciparum cases and 20%of malaria related deaths annually.In India,chloroquine resistance was reported for the first time from northeast region and since then chloroquine treatment failure is being reported from many parts of the region.Increased chloroquine treatment failure has led to change of the drug policy to artemisinin combination therapy as first line of malaria treatment in the region.However,replacing chloroquine to artemisinin combination therapy has not shown significant difference in the overall malaria incidence in the region,The present review addresses the current malaria situation of northeastern region of India in the light of antimalarials drug resistance.

Weight Loss and Gastrointestinal Symptoms in Advanced Cancer Patients Treated with Platinum-based Chemotherapy

Objective This study assessed the weight loss changes and gastrointestinal symptoms in patients with advanced tumors receiving platinum-containing chemotherapy.Methods We retrospectively reviewed 297 patients with advanced cancers[124 gastrointestinal(GI)cancer patients,119 lung cancer patients and 54 head and neck cancer(HNC)patients]receiving first-line chemotherapy at Tongji Hospital.The patients’changes in body weight,body mass index(BMI),and biochemical parameters(serum haemoglobin and albumin levels)were compared before and after two chemotherapy cycles.Results More than half[54.88%(163/297)]of the patients had experienced unintentional weight loss in the 6 months before chemotherapy,and weight loss≥5%and≥10%of the body mass was noted in 35.69%and 20.20%of the patients,respectively.After two cycles of platinum-based chemotherapy,the proportions of patients with a>5%reduction in body weight among patients with GI,lung,and head and neck cancers were 47.5%(59/124),44.53%(53/119),and 46.2%(25/54),respectively.The patients with GI and lung cancers were more vulnerable to extreme weight loss(≥10%)than those with HNC(P=0.025).The serum hemoglobin levels were also remarkably decreased relative to those before chemotherapy(all P<0.05).Common GI symptoms reported by all patients included anorexia(61.28%),vomiting(52.53%),and nausea(51.18%).A higher proportion of patients with≥10%weight loss experienced anorexia and vomiting(OR=12.21 and 3.61,P=0.008 and 0.047,respectively).Conclusions For advanced cancer patients receiving platinum-based chemotherapy,the GI symptoms are the major factor related to their nutritional status.Appropriate nutritional screening,evaluation and treatment should be applied during the treatment of cancer in order to reduce GI symptoms and improve the patient’s nutritional status.

A chemotherapy-driven increase in Mcl-1 mediates the effect of miR-375 on cisplatin resistance in osteosarcoma cells

Osteosarcoma(OS)is one of the most difficult cancers to treat due to its resistance to chemotherapy.The essential role played by Mel-l in promoting chemoresistance has been observed in a variety of cancers,including OS,while the underlying mechanism remains unclear.We investigated the expression of Mcl-1 in 42 paired OS specimens obtained before and after adjuvant chemotherapy,and its correlation with clinicopathological characteristics.Loss and gain of function studies were performed to analyze the effects of Mcl-1 modulations on the chemosensitivity,and the mechanism involved in the deregulation of Mcl-1 in OS cells.

Efficacy and Risk Factors Associated to Resistance to Single-Agent Chemotherapy in Low-Risk Gestational Trophoblastic Neoplasia

Objectives: This study aimed to assess efficacy of intramuscular methotrexate 8-day protocol in the treatment of low-risk gestational trophoblastic neoplasia and also identify prognostic factors associated with treatment failure, necessitating second line chemotherapy. Methods: This study was performed at Gynaecologic and Obstetric Clinic of Dakar Teaching Hospital, the reference Centre of Gestational Trophoblastic Disease in Senegal. At the beginning of 2011, patients were followed according to FIGO’s recommendations. From 2011 to 2014, we diagnosed 88 low-risk gestational trophoblastic neoplasia (GTN) patients (WHO score < 7). Low-risk patients started their treatment with methotrexate (MTX) based on the 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day. Resistance to treatment was the main outcome. We studied the association of different prognostic factors included in the World Health Organisation (WHO) scoring system and resistance to the initial single agent chemotherapy. Results: Eighty-eight patients were diagnosed for GTN during the study period. Average age was 31 years. The antecedent pregnancy was molar in 98.1% of cases. Seventy-four patients underwent remission after single agent-chemotherapy. Resistance rate to single-agent chemotherapy was 15.9% (14 patients). Nine of them achieved remission after second line chemotherapy. WHO score was significantly associated with the risk of resistance to single-agent chemotherapy. Other variables included in the WHO as age, antecedent pregnancy, pre-treatment hCG, tumour size and FIGO stage were not significantly associated with resistance. We report five fatal cases. Conclusion: The 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day is effective for women with LRGTN. The only significant prognostic factor for failure is pretreatment WHO score. We highly recommend the use of this protocol particularly in developing countries where methotrexate is available, affordable and relatively safe.

Molecular mechanisms of chemoresistance in gastric cancer

Gastric cancer is the fourth most common cancer and the second leading cause of cancer deaths worldwide.Chemotherapy is one of the major treatments for gastric cancer,but drug resistance limits the effectiveness of chemotherapy,which results in treatment failure.Resistance to chemotherapy can be present intrinsically before the administration of chemotherapy or it can develop during chemotherapy.The mechanisms of chemotherapy resistance in gastric cancer are complex and multifactorial.A variety of factors have been demonstrated to be involved in chemoresistance,including the reduced intracellular concentrations of drugs,alterations in drug targets,the dysregulation of cell survival and death signaling pathways,and interactions between cancer cells and the tumor microenvironment.This review focuses on the molecular mechanisms of chemoresistance in gastric cancer and on recent studies that have sought to overcome the underlying mechanisms of chemoresistance.

Plasma proteome profiling reveals biomarkers of chemotherapy resistance in patients with advanced colorectal cancer

Colorectal cancer(CRC)is one of the most common cancers.Patients with advanced CRC can only rely on chemotherapy to improve outcomes.However,primary drug resistance frequently occurs and is difficult to predict.Changes in plasma protein composition have shown potential in clinical diagnosis.Thus,it is urgent to identify potential protein biomarkers for primary resistance to chemotherapy for patients with CRC.Automatic sample preparation and high-throughput analysis were used to explore potential plasma protein biomarkers.Drug susceptibility testing of circulating tumor cells(CTCs)has been investigated,and the relationship between their values and protein expressions has been discussed.In addition,the differential proteins in different chemotherapy outcomes have been analyzed.Finally,the potential biomarkers have been detected via enzyme-linked immunosorbent assay(ELISA).Plasma proteome of 60 CRC patients were profiled.The correlation between plasma protein levels and the results of drug susceptibility testing of CTCs was performed,and 85 proteins showed a significant positive or negative correlation with chemotherapy resistance.Forty-four CRC patients were then divided into three groups according to their chemotherapy outcomes(objective response,stable disease,and progressive disease),and 37 differential proteins were found to be related to chemotherapy resistance.The overlapping proteins were further investigated in an additional group of 79 patients using ELISA.Protein levels of F5 and PROZ significantly increased in the progressive disease group compared to other outcome groups.Our study indicated that F5 and PROZ proteins could represent potential biomarkers of resistance to chemotherapy in advanced CRC patients.

MicroRNA signatures in chemotherapy resistant esophageal cancer cell lines

AIM:To investigate expression of microRNA(miRNA)and potential targets in chemotherapy resistant esoph-ageal cancer cell lines.METHODS:An in-vitro model of acquired chemotherapy resistance in esophageal adeno-(EAC)and squamous cell carcinoma(ESCC)cells was used,and microRNA expression profiles for cisplatin or 5-fluorouracil(5-FU)resistant variants vs chemotherapy sensitive controls were compared using microarray and quantitative real-time polymerase chain reaction(PCR).The expression of chemotherapy-relevant genes potentially targeted by the dysregulated microRNAs in the chemotherapy resistant variants was also evaluated.RESULTS:Chemotherapy resistant sublines were found to have specific miRNA signatures,and these miRNA signatures were different for the cisplatin vs 5-FU resistant cells from the same tumor cell line,and also for EAC vs ESCC cells with resistance to the same specific chemotherapy agent.Amongst others,miR-27b-3p,miR-193b-3p,miR-192-5p,miR-378 a-3p,miR-125a-5p and miR-18a-3p were dysregulated,consistent with negative posttranscriptional control of KRAS,TYMS,ABCC3,CBL-B and ERBB2 expression via these miRNAs.CONCLUSION:The current study supports the hypothesis that microRNA expression has an impact on chemotherapy resistance in esophageal cancer.

Breast Cancer Resistance Protein Expression and 5-Fluorouracil Resistance

Objective To filtrate breast cancer resistance protein （BCRP）-mediated resistant agents and to investigate clinical relationship between BCRP expression and drug resistance. Methods MTT assay was performed to filtrate BCRP-mediated resistant agents with BCRP expression cell model and to detect chemosensitivity of breast cancer tissue specimens to these agents. A high performance liquid chromatography （HPLC） assay was established, and was used to measure the relative dose of intracellular retention resistant agents. RT-PCR and immunohistochemistry （IHC） were employed to investigate the BCRP expression in breast cancer tissue specimens. Results MTT assay showed that the expression of BCRP increased with the increasing resistance of 5-fluorouracil （5-Fu） （P〈0.05, n=3） in the cell model, while HPLC assay indicated that the intracellular retention dose of 5-Fu was significantly correlated with the expression of BCRP （t=-0.897, P〈0.05, n=3）. A total of 140 breast cancer tissue specimens were collected. BCRP-positive expression was detected in forty-seven specimens by both RT-PCR and IHC. As shown by MTT assay subsequently, the resistance index （RI） of 47 BCRP-positive breast cancer tissue specimens to 5-Fu was 7-12 times as high as that of adjacent normal tissue samples. BCRP expression was related to 5-Fu resistance （R2=0.8124, P〈0.01）. Conclusion Resistance to 5-Fu can be mediated by BCRR Clinical chemotherapy for breast cancer patients can be optimized based on BCRP-positive expression.

Artemisinin resistance or tolerance in human malaria patients

Malaria is a major cause of morbidity and mortality in the developing world.This situation is mainly due to emergence of resistance to most antimalarial drugs currently available. Artemisinin-based combination treatments are now first-line drugs for Plasmodium falciparum (P.falciparum) malaria.Artemisinin(qinghaosu) and its derivatives are the most rapid acting and efficacious antimalarial drugs.This review highlights most recent investigations into the emergence of artemisinin resistance in falciparum malaria patients on the Thai-Cambodian border,a historical epicenter for multidrug resistance spread spanning over 50 years.The study presents the first evidence that highlights the parasites reduced susceptibility to artemisinin treatment by prolonged parasite-clearance times,raising considerable concern on resistance development.Although the exact mechanism of action remains unresolved,development of resistance was proposed based from both in vitro experiments and human patients.Lines of evidence suggested that the parasites in the patients are in dormant forms,presumably tolerate to the drug pressure.The World Health Organization has launched for prevention and/or containment of the artemisinin-resistant malaria parasites.Taken together,the emergence of artemisinin resistance to the most potent antidote for falciparum malaria,poses a serious threat to global malaria control and prompts renewed efforts for urgent development of new antimalarial weapons.