New targeted therapies for breast cancer: A focus on tumor microenvironmental signals and chemoresistant breast cancers

Breast cancer is the most frequent female malignancy worldwide. Current strategies in breast cancer therapy,including classical chemotherapy, hormone therapy, and targeted therapies, are usually associated with chemoresistance and serious adverse effects. Advances in our understanding of changes affecting the interactome in advanced and chemoresistant breast tumors have provided novel therapeutic targets, including, cyclin dependent kinases, mammalian target of rapamycin,Notch, Wnt and Shh. Inhibitors of these molecules recently entered clinical trials in mono- and combination therapy in metastatic and chemo-resistant breast cancers. Anticancer epigenetic drugs, mainly histone deacetylase inhibitors and DNA methyltransferase inhibitors, also entered clinical trials. Because of the complexity and heterogeneity of breast cancer, the future in therapy lies in the application of individualized tailored regimens. Emerging therapeutic targets and the implications for personalized-based therapy development in breast cancer are herein discussed.

A targetable pathway to eliminate TRA-1-60^(+)/TRA-1-81^(+)chemoresistant cancer cells

Chemoresistance is a primary cause of treatment failure in pancreatic cancer.Identifying cell surface markers specifically expressed in chemoresistant cancer cells(CCCs)could facilitate targeted therapies to overcome chemoresistance.We performed an antibody-based screen and found that TRA-1-60 and TRA-1-81,two‘stemness’cell surface markers,are highly enriched in CCCs.Further-more,TRA-1-60^(+)/TRA-1-81^(+)cells are chemoresistant compared to TRA-1-60^(-)/TRA-1-81^(-)cells.Transcriptome profiling identified UGT1A10,shown to be both necessary and sufficient to maintain TRA-1-60/TRA-1-81 expression and chemoresistance.From a high-content chemical screen,we identified Cymarin,which downregulates UGT1A10,eliminates TRA-1-60/TRA-1-81 expression,and increases chemosensitivity both in vitro and in vivo.Finally,TRA-1-60/TRA-1-81 expression is highly specific in primary cancer tissue and positively correlated with chemoresistance and short survival,which highlights their potentiality for targeted therapy.Therefore,we discovered a novel CCC surface marker regulated by a pathway that promotes chemoresistance,as well as a leading drug candidate to target this pathway.

TGF-β-regulated different iron metabolism processes in the development and cisplatin resistance of ovarian cancer

The impact of different iron metabolism processes(DIMP)on ovarian cancer remains unclear.In this study,we employed various gene chips and databases to investigate the role of DIMP in the initiation and development of ovarian cancer.cBioPortal was used to determine mutations in DIMP-associated genes in ovarian cancer.Kaplan-Meier plotter was used to examine the influence of DIMP on the prognosis of ovarian cancer.By analyzing 1669 serous ovarian cancer cases,we identified a range of mutations in iron metabolism genes,notably in those coding for the transferrin receptor(19%),melanotransferrin(19%),and ceruloplasmin(10%)in the iron import process,and glucose-6-phosphate isomerase(9%),hepcidin antimicrobial peptide(9%),metal regulatory transcription factor 1(8%),and bone morphogenetic protein 6(8%)in the iron regulation process.Compared to the unaltered group,the group with gene alterations exhibited a higher tumor mutation burden count(43 vs.54)and more advanced histologic grade(78.19%vs.87.90%).Compared to the normal ovarian counterparts,a reduction in expression was observed in 9 out of the 14 genes involved in iron utilization and 4 out of the 5 genes involved in iron export in ovarian cancer;in contrast,an increase in expression was observed in 2 out of the 3 genes involved in iron storage in ovarian cancer.Furthermore,in cisplatin-resistant cells compared to cisplatin-sensitive ones,the expression of all genes in iron storage and 13 out of 14 genes in iron import was decreased,while that of 8 out of the 10 genes in iron utilization was increased.In addition,survival curve analysis indicated that a higher expression in the majority of genes in the iron import process(12/21),or a reduced expression in most genes in the iron export process(4/5)correlated with poor progression-free survival.Additionally,TGF-βcould regulate the expression of most iron metabolism-associated genes;particularly,expression of genes involved in the iron storage process(2/2)was inhibited after TGF-β1 or TGF-β2 treatment.In conclusion,DIMP plays multifaceted roles in the initiation,chemo-resistance,and prognosis of ovarian cancer.Therapeutically targeting DIMP may pave the way for more tailored treatment approaches for ovarian cancer.

5-Fluorouracil dose escalation generated desensitized colorectal cancer cells with reduced expression of protein methyltransferases and no epithelial-to-mesenchymal transition potential

Background:Colorectal cancer(CRC)is one of the most frequently diagnosed cancers.In many cases,the poor prognosis of advanced CRC is associated with resistance to treatment with chemotherapeutic drugs such as 5-Fluorouracil(5-FU).The epithelial-to-mesenchymal transition(EMT)and dysregulation in protein methylation are two mechanisms associated with chemoresistance in many cancers.This study looked into the effect of 5-FU dose escalation on EMT and protein methylation in CRC.Materials and Methods:HCT-116,Caco-2,and DLD-1 CRC cell lines were exposed to dose escalation treatment of 5-FU.The motility and invasive potentials of the cells before and after treatment with 5-FU were investigated through wound healing and invasion assays.This was followed by aWestern blot which analyzed the protein expressions of the epithelial marker E-cadherin,mesenchymal marker vimentin,and the EMT transcription factor(EMTTF),the snail family transcriptional repressor 1(Snail)in the parental and desensitized cells.Western blotting was also conducted to study the protein expressions of the protein methyltransferases(PMTs),Euchromatic histone lysine methyltransferase 2(EHMT2/G9A),protein arginine methyltransferase(PRMT5),and SET domain containing 7/9(SETD7/9)along with the global lysine and arginine methylation profiles.Results:The dose escalation method generated 5-FU desensitized CRC cells with distinct morphological features and increased tolerance to high doses of 5-FU.The 5-FU desensitized cells experienced a decrease in migration and invasion when compared to the parental cells.This was reflected in the observed reduction in E-cadherin,vimentin,and Snail in the desensitized cell lines.Additionally,the protein expressions of EHMT2/G9A,PRMT5,and SETD7/9 also decreased in the desensitized cells and global protein lysine and arginine methylation became dysregulated with 5-FU treatment.Conclusion:This study showed that continuous,dose-escalation treatment of 5-FU in CRC cells generated 5-FU desensitized cancer cells that seemed to be less aggressive than parental cells.

Navigating the labyrinth of long non-coding RNAs in colorectal cancer:From chemoresistance to autophagy

Long non-coding RNAs(lncRNAs),with transcript lengths exceeding 200 nucleotides and little or no protein-coding capacity,have been found to impact colorectal cancer(CRC)through various biological processes.LncRNA expression can regulate autophagy,which plays dual roles in the initiation and progression of cancers,including CRC.Abnormal expression of lncRNAs is associated with the emergence of chemoresistance.Moreover,it has been confirmed that targeting autophagy through lncRNA regulation could be a viable approach for combating chemoresistance.Two recent studies titled“Human β-defensin-1 affects the mammalian target of rapamycin pathway and autophagy in colon cancer cells through long non-coding RNA TCONS_00014506”and“Upregulated lncRNA PRNT promotes progression and oxaliplatin resistance of colorectal cancer cells by regulating HIPK2 transcription”revealed novel insights into lncRNAs associated with autophagy and oxaliplatin resistance in CRC,respectively.In this editorial,we particularly focus on the regulatory role of lncRNAs in CRC-related autophagy and chemoresistance since the regulation of chemotherapeutic sensitivity by intervening with the lncRNAs involved in the autophagy process has become a promising new approach for cancer treatment.

Role of glioma stem cells in promoting tumor chemo- and radioresistance: A systematic review of potential targeted treatments

BACKGROUND Gliomas pose a significant challenge to effective treatment despite advancements in chemotherapy and radiotherapy.Glioma stem cells(GSCs),a subset within tumors,contribute to resistance,tumor heterogeneity,and plasticity.Recent studies reveal GSCs’role in therapeutic resistance,driven by DNA repair mechanisms and dynamic transitions between cellular states.Resistance mechanisms can involve different cellular pathways,most of which have been recently reported in the literature.Despite progress,targeted therapeutic approaches lack consensus due to GSCs’high plasticity.AIM To analyze targeted therapies against GSC-mediated resistance to radio-and chemotherapy in gliomas,focusing on underlying mechanisms.METHODS A systematic search was conducted across major medical databases(PubMed,Embase,and Cochrane Library)up to September 30,2023.The search strategy utilized relevant Medical Subject Heading terms and keywords related to including“glioma stem cells”,“radiotherapy”,“chemotherapy”,“resistance”,and“targeted therapies”.Studies included in this review were publications focusing on targeted therapies against the molecular mechanism of GSC-mediated re-sistance to radiotherapy resistance(RTR).RESULTS In a comprehensive review of 66 studies on stem cell therapies for SCI,452 papers were initially identified,with 203 chosen for full-text analysis.Among them,201 were deemed eligible after excluding 168 for various reasons.The temporal breakdown of studies illustrates this trend:2005-2010(33.3%),2011-2015(36.4%),and 2016-2022(30.3%).Key GSC models,particularly U87(33.3%),U251(15.2%),and T98G(15.2%),emerge as significant in research,reflecting their representativeness of glioma characteristics.Pathway analysis indicates a focus on phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin(mTOR)(27.3%)and Notch(12.1%)pathways,suggesting their crucial roles in resistance development.Targeted molecules with mTOR(18.2%),CHK1/2(15.2%),and ATP binding cassette G2(12.1%)as frequent targets underscore their importance in overcoming GSC-mediated resistance.Various therapeutic agents,notably RNA inhibitor/short hairpin RNA(27.3%),inhibitors(e.g.,LY294002,NVP-BEZ235)(24.2%),and monoclonal antibodies(e.g.,cetuximab)(9.1%),demonstrate versatility in targeted therapies.among 20 studies(60.6%),the most common effect on the chemotherapy resistance response is a reduction in temozolomide resistance(51.5%),followed by reductions in carmustine resistance(9.1%)and doxorubicin resistance(3.0%),while resistance to RTR is reduced in 42.4%of studies.CONCLUSION GSCs play a complex role in mediating radioresistance and chemoresistance,emphasizing the necessity for precision therapies that consider the heterogeneity within the GSC population and the dynamic tumor microenvironment to enhance outcomes for glioblastoma patients.

Ultra-conservative noncoding RNA uc.243 confers chemo-resistance by facilitating the efflux of the chemotherapeutic drug in ovarian cancer

Background:Despite improvements in objective response rates to cisplatin-based combination chemotherapy,the majority of advanced ovarian cancer remains suboptimal,resulting in poor survival.it has been found that non-coding RNAs(ncRNAs)not only participate in the transmission of signals between various cells but also participate in tumor immunity and anti-tumor immune responses,thereby regulating tumor occurrence and development.However,the function and detailed mechanism of ultraconserved RNA(ucRNA)in ovarian cancer chemoresistance is still unclear.Methods:Western blotting assay,Quantitative real-time PCR analysis(qPCR),and Kaplan-Meier Plotter analysis were performed to analyze the expression and prognosis of uc.243 in ovarian carcinoma.Cytotoxicity assay and Annexin V assay were performed to analyze the function of uc.243 in cisplatin resistance in ovarian cancer cells.RNA pull-down and qPCR experiments were performed to explore the molecular mechanism of uc.243 enhancing cisplatin resistance in ovarian cancer cells.Results:Herein,we found that uc.243 was remarkably upregulated and correlated with patient survival in chemoresistance ovarian cancer patients compared with chemo-sensitive ovarian cancer.Functional experiment displayed that uc.243 induced cisplatin resistance on ovarian cancer cells by facilitating the efflux of cisplatin(CDDP);but inhibiting the expression of uc.243 significantly reverses this function.Mechanistically,uc.243 can inhibit the binding of RNA binding protein DGCR8 microprocessor complex subunit to pri-miR-155,thereby inhibiting the cleavage of pri-miR-155 and decrease in mature miR-155,subsequently upregulates the expression of ATP binding cassette subfamily B member(ABCB1,ABCC2).Conclusion:Our research findings indicate that uc.243 can induce chemotherapy resistance in ovarian cancer,suggesting that it may become a new prognostic biomarker for malignant ovarian cancer.

Decoding Retinoblastoma: Differential Gene Expression

Background: Retinoblastoma, the most common intraocular pediatric cancer, presents complexities in its genetic landscape that necessitate a deeper understanding for improved therapeutic interventions. This study leverages computational tools to dissect the differential gene expression profiles in retinoblastoma. Methods: Employing an in silico approach, we analyzed gene expression data from public repositories by applying rigorous statistical models, including limma and de seq 2, for identifying differentially expressed genes DEGs. Our findings were validated through cross-referencing with independent datasets and existing literature. We further employed functional annotation and pathway analysis to elucidate the biological significance of these DEGs. Results: Our computational analysis confirmed the dysregulation of key retinoblastoma-associated genes. In comparison to normal retinal tissue, RB1 exhibited a 2.5-fold increase in expression (adjusted p Conclusions: Our analysis reinforces the critical genetic alterations known in retinoblastoma and unveils new avenues for research into the disease’s molecular basis. The discovery of chemoresistance markers and immune-related genes opens potential pathways for personalized treatment strategies. The study’s outcomes emphasize the power of in silico analyses in unraveling complex cancer genomics.

Down.regulation of E.cadherin enhances prostate cancer chemoresistance via Notch signaling

Background:The chemoresistance of prostate cancer(PCa)is invariably associated with the aggressiveness and metastasis of this disease.New emerging evidence indicates that the epithelial-to-mesenchymal transition(EMT)may play pivotal roles in the development of chemoresistance and metastasis.As a hallmark of EMT,E-cadherin is suggested to be a key marker in the development of chemoresistance.However,the molecular mechanisms underlying PCa chemoresistance remain unclear.The current study aimed to explore the association between EMT and chemoresistance in PCa as well as whether changing the expression of E-cadherin would affect PCa chemoresistance.Methods:Parental PC3 and DU145 cells and their chemoresistant PC3-Tx R and DU145-Tx R cells were analyzed.PC3-Tx R and DU145-Tx R cells were transfected with E-cadherin-expressing lentivirus to overexpress E-cadherin;PC3 and DU145 cells were transfected with small interfering RNA to silence E-cadherin.Changes of EMT phenotype-related markers and signaling pathways were assessed by Western blotting and quantitative real-time polymerase chain reaction.Tumor cell migration,invasion,and colony formation were then evaluated by wound healing,transwell,and colony formation assays,respectively.The drug sensitivity was evaluated using MTS assay.Results:Chemoresistant PC3-Tx R and DU145-Tx R cells exhibited an invasive and metastatic phenotype that associated with EMT,including the down-regulation of E-cadherin and up-regulation of Vimentin,Snail,and N-cadherin,comparing with that of parental PC3 and DU145 cells.When E-cadherin was overexpressed in PC3-Tx R and DU145-Tx R cells,the expression of Vimentin and Claudin-1 was down-regulated,and tumor cell migration and invasion were inhibited.In particular,the sensitivity to paclitaxel was reactivated in E-cadherin-overexpressing PC3-Tx R and DU145-Tx R cells.When E-cadherin expression was silenced in parental PC3 and DU145 cells,the expression of Vimentin and Snail was up-regulated,and,particularly,the sensitivity to paclitaxel was decreased.Interestingly,Notch-1 expression was up-regulated in PC3-Tx R and DU145-Tx R cells,whereas the E-cadherin expression was down-regulated in these cells comparing with their parental cells.The use ofγ-secretase inhibitor,a Notch signaling pathway inhibitor,significantly increased the sensitivity of chemoresistant cells to paclitaxel.Conclusion:The down-regulation of E-cadherin enhances PCa chemoresistance via Notch signaling,and inhibiting the Notch signaling pathway may reverse PCa chemoresistance.

Inhibition of autophagy significantly enhances combination therapy with sorafenib and HDAC inhibitors for human hepatoma cells

AIM: To clarify whether histone deacetylase inhibitors histone deacetylase inhibitors (HDACIs) can sensitize hepatocellular carcinoma (HCC) cells to sorafenib treatment. METHODS: Bax, Bcl-2, ATG5-ATG12, p21, and p27 protein levels in Hep3B, HepG2, and PLC/PRF/5 cells were examined by Western blot. CCK8 and a fluoro-metric caspase-3 assay were used to examine cellular viability and apoptosis levels. The effect of Beclin-1 on sensitization of HCC cells to sorafenib was examined by transfecting Beclin-1 siRNA into Hep3B, HepG2, and PLC/PRF/5 cells. RESULTS: Autophagy inhibition enhances the inhibitory effects of vorinostat and sorafenib alone or in combination on HCC cell growth. Vorinostat and sorafenib synergistically induced apoptosis and cell cycle alterations. Western blot data indicated that HDACIs and Beclin- 1 knockdown increased the p53 acetylation level. The knockdown of Beclin-1 enhanced the synergistic effect of the combination of vorinostat with sorafenib. CONCLUSION: HDACIs can sensitize HCC cells to sorafenib treatment by regulating the acetylation level of Beclin-1. (C) 2014 Baishideng Publishing Group Co., Limited. All rights reserved.

Pharmacogenetics research on chemotherapy resistance in colorectal cancer over the last 20 years

During the past two decades the first sequencing of the human genome was performed showing its high degree of inter-individual differentiation,as a result of large international research projects(Human Genome Project,the 1000 Genomes Project International HapMap Project,and Programs for Genomic Applications NHLBI-PGA).This period was also a time of intensive development of molecular biology techniques and enormous knowledge growth in the biology of cancer.For clinical use in the treatment of patients with colorectal cancer(CRC),in addition to fluoropyrimidines,another two new cytostatic drugs were allowed:irinotecan and oxaliplatin.Intensive research into new treatment regimens and a new generation of drugs used in targeted therapy has also been conducted.The last 20years was a time of numerous in vitro and in vivo studies on the molecular basis of drug resistance.One of the most important factors limiting the effectiveness of chemotherapy is the primary and secondary resistance of cancer cells.Understanding the genetic factors and mechanisms that contribute to the lack of or low sensitivity of tumour tissue to cytostatics is a key element in the currently developing trend of personalized medicine.Scientists hope to increase the percentage of positive treatment response in CRC patients due to practical applications of pharmacogenetics/pharmacogenomics.Over the past 20 years the clinical usability of different predictive markers has been tested among which only a few have been confirmed to have high application potential.This review is a synthetic presentation of drug resistance in the context of CRC patient chemotherapy.The multifactorial nature and volume of the issues involved do not allow the author to present a comprehensive study on this subject in one review.

p38α MAPK pathway:A key factor in colorectal cancer therapy and chemoresistance

Colorectal cancer (CRC) remains one of the most common malignancies in the world. Although surgical resection combined with adjuvant therapy is effective at the early stages of the disease, resistance to conventional therapies is frequently observed in advanced stages, where treatments become ineffective. Resistance to cisplatin, irinotecan and 5-fluorouracil chemotherapy has been shown to involve mitogen-activated protein kinase (MAPK) signaling and recent studies identified p38α MAPK as a mediator of resistance to various agents in CRC patients. Studies published in the last decade showed a dual role for the p38α pathway in mammals. Its role as a negative regulator of proliferation has been reported in both normal (including cardiomyocytes, hepatocytes, fibroblasts, hematopoietic and lung cells) and cancer cells (colon, prostate, breast, lung tumor cells). This function is mediated by the negative regulation of cell cycle progression and the transduction of some apoptotic stimuli. However, despite its anti-proliferative and tumor suppressor activity in some tissues, the p38α pathway may also acquire an oncogenic role involving cancer related-processes such as cell metabolism, invasion, inflammation and angiogenesis. In this review, we summarize current knowledge about the predominant role of the p38α MAPK pathway in CRC development and chemoresistance. In our view, this might help establish the therapeutic potential of the targeted manipulation of this pathway in clinical settings.

MicroRNAs:Promising chemoresistance biomarkers in gastric cancer with diagnostic and therapeutic potential

Gastric cancer(GC) is the fourth most common cancer worldwide and ranks second in global cancer mortality statistics. Perioperative chemotherapy plays an important role in the management and treatment of advanced stage disease. However,response to chemotherapy varies widely,with some patients presenting no or only minor response to treatment. Hence,chemotherapy resistance is a major clinical problem that impacts on outcome. Unfortunately,to date there are no reliable biomarkers available that predict response to chemotherapy before the start of the treatment,or that allow modification of chemotherapy resistance. MicroRNAs(miRNAs) could provide an answer to this problem. miRNAs are involved in the initiation and progression of a variety of cancer types,and there is evidence that miRNAs impact on resistance towards chemotherapeutic drugs as well. This current review aims to provide an overview about the potential clinical applicability of miRNAs as biomarkers for chemoresistance in GC.The authors focus in this context on the potential of miRNAs to predict sensitivity towards different chemotherapeutics,and on the potential of miRNAs to modulate sensitivity and resistance towards chemotherapy in GC.

Systematic review of the old and new concepts in the epithelial-mesenchymal transition of colorectal cancer

Epithelial-to-mesenchymal transition(EMT) is defined as the transformation of an epithelial cell into a spindle cell with the loss of membrane E-cadherin expression and the gain of mesenchymal markers positivity. In the field of colorectal cancer(CRC), first data about EMT was published in 1995 and more than 400 papers had been written up to March 2016. Most of them are focused on the molecular pathways and experimentally-proved chemoresistance. In the present article, an update in the field of EMT in CRC based on the review of the literature and personal experience of the authors is presented. The information about the molecular and immunohistochemical(IHC) particularities of these processes and their possible role in the prognosis of CRC were also up-dated. This article focuses on the IHC quantification of the EMT, the immunoprofile of tumor buds and on the relation between EMT, angiogenesis, and stem cells activation. The EMT-induced chemoresistance vs chemotherapyor radiotherapy-induced EMT and cellular senescence was also synthesized for both conventional and targeted therapy. As a future perspective, the EMTangiogenesis-stemness link could be used as a possible valuable parameter for clinical follow-up and targeted therapeutic oncologic management of patients with CRC. Association of dexamethasone and angiotensin converting enzyme inhibitors combined with conventional chemotherapies could have clinical benefits in patients with CRC. The main conclusion is that, although many studies have been published, the EMT features are still incompletely elucidated and newly discovered EMT markers provide confusing data in understanding this complicated process, which might have significant clinical impact.

Circular RNA circVAPA promotes chemotherapy drug resistance in gastric cancer progression by regulating miR-125b-5p/STAT3 axis

BACKGROUND Gastric cancer(GC)is a prevalent malignancy,leading to a high incidence of cancer-associated death.Cisplatin(DDP)-based chemotherapy is the principal therapy for clinical GC treatment,but DDP resistance is a severe clinical challenge and the mechanism remains poorly understood.Circular RNAs(circRNAs)have been identified to play crucial roles in modulating the chemoresistance of gastric cancer cells.AIM To explore the effect of circVAPA on chemotherapy resistance during GC progression.METHODS The effect of circVAPA on GC progression and chemotherapy resistance was analyzed by MTT assay,colony formation assay,Transwell assay,wound healing assay,and flow cytometry analysis in GC cells and DDP resistant GC cell lines,and tumorigenicity analysis in nude mice in vivo.The mechanism was investigated by luciferase reporter assay,quantitative real-time PCR,and Western blot analysis.RESULTS CircVAPA expression was up-regulated in clinical GC tissues compared with normal samples.CircVAPA depletion inhibited proliferation,migration,and invasion and increased apoptosis of GC cells.The expression of circVAPA,STAT3,and STAT3 downstream genes was elevated in DDP resistant SGC7901/DDP cell lines.CircVAPA knockdown attenuated the DDP resistance of GC cells.Mechanically,circVAPA was able to sponge miR-125b-5p,and miR-125b-5p could target STAT3 in the GC cells.MiR-125b-5p inhibitor reversed circVAPA depletion-enhanced inhibitory effect of DDP on GC cells,and STAT3 knockdown blocked circVAPA overexpression-induced proliferation of DDPtreated SGC7901/DDP cells.The depletion of STAT3 and miR-125b-5p inhibitor reversed circVAPA depletion-induced GC cell apoptosis.Functionally,circVAPA contributed to the tumor growth of SGC7901/DDP cells in vivo.CONCLUSION CircVAPA promotes chemotherapy resistance and malignant progression in GC by miR-125b-5p/STAT3 signaling.Our findings present novel insights into the mechanism by which circVAPA regulates chemotherapy resistance of GC cells.CircVAPA and miR-125b-5p may be considered as the potential targets for GC therapy.

Sox2 enhances the tumorigenicity and chemoresistance of cancer stem-like cells derived from gastric cancer

Gastric cancer stem-like cells（GCSCs） have been identified to possess the ability of self-renewal and tumor initi-ation.However,the mechanisms involved remain largely unknown.Here,we isolated and characterized the GCSCs by side population（SP） sorting procedure and cultured sphere cells（SC） from human gastric cancer cell lines SGC-7901,BGC-823,MGC-803,HGC-27 and MKN-28.The sorting and culture assay revealed that SP cells proliferated in an asymmetric division manner.In addition,SP cells exhibited a higher potential of spheroid colony formation and greater drug resistance than non-SP cells（NSP）.Moreover,the SC were found with enhanced capabilities of drug resistance in vitro and tumorigenicity in vivo.Sox2 mRNA and protein was highly and significantly overex-pressed in the SP cells and SC.Importantly,downregulation of Sox2 with siRNA obviously reduced spheroid colony formation and doxorubicin efflux,as well as increased apoptosis rate in sphere cells in vitro and suppressed tumori-genicity in vivo.These results suggest that both SP cells and cultured SC enrich with GCSCs and that Sox2 plays a pivotal role in sustaining stem cell properties and might be a potential target for gastric cancer therapy.

MiR-181b suppresses proliferation of and reduces chemoresistance to temozolomide in U87 glioma stem cells

MicroRNAs regulate self renewal and differentiation of cancer stem cells.There,we sought to identify the expression of miR-181b in glioma stem cells and investigate the biological effect of miR-181b on glioma stem cells in this study.MiR-181b expression was measured by real-time PCR in glioma stem cells isolated from U87 cells by FACS sorting.After miR-181b was overexpressed in U87 glioma stem cells by miR-181b lentiviral expression vector and/or treatment of temozolomide,secondary neurosphere assay,soft agar colony assay and MTT assay were performed.Compared with U87 cells,the expression of miR-181b was significantly decreased in U87 glioma stem cells.Overexpression of miR-181b decreased neurosphere formation by U87 glioma stem cells in vitro and suppressed colony formation in soft agar,and the cell growth inhibition rates increased in a time-dependent manner in U87 glioma stem cells infected with miR-181b lentivirus.Furthermore,miR-181b had a synergistic effect on temozolomide-induced inhibition of secondary neurosphere and soft agar colony,and on cell growth inhibition rates.MiR-181b functions as a tumor suppressor that suppresses proliferation and reduces chemoresistance to temozolomide in glioma stem cells.

Tim-3 promotes cell aggressiveness and paclitaxel resistance through NF-κB/STAT3 signalling pathway in breast cancer cells

Objective:Although T-cell immunoglobulin and mucin-domain containing molecule-3(Tim-3)has been recognized as a promising target for cancer immunotherapy,its exact role in breast cancer has not been fully elucidated.Methods:Tim-3 gene expression in breast cancer and its prognostic significance were analyzed.Associated mechanisms were then explored in vitro by establishing Tim-3-overexpressing breast cancer cells.Results:In a pooled analysis of The Cancer Genome Atlas(TCGA)database,Tim-3 gene expression levels were significantly higher(P<0.001)in breast cancer tissue,compared with normal tissues.Tim-3 was a prognosis indicator in breast cancer patients[relapse-free survival(RFS),P=0.004;overall survival(OS),P=0.099].Tim-3 overexpression in Tim-3 low breast cancer cells promoted aggressiveness of breast cancer cells,as evidenced by enhanced proliferation,migration,invasion,tight junction deterioration and tumor-associated tubal formation.Tim-3 also enhanced cellular resistance to paclitaxel.Furthermore,Tim-3 exerted its function by activating the NF-κB/STAT3 signalling pathway and by regulating gene expression[cyclin D1(CCND1),C-Myc,matrix metalloproteinase-1(MMP1),TWIST,vascular endothelial growth factor(VEGF)upregulation,concomitant with Ecadherin downregulation).Lastly,Tim-3 downregulated tight junction-associated molecules zona occludens(ZO)-2,ZO-1 and occludin,which may further facilitate tumor progression.Conclusions:Tim-3 plays an oncogenic role in breast cancer and may represent a potential target for antitumor therapy.

c-Met signaling in the development of tumorigenesis and chemoresistance: Potential applications in pancreatic cancer

Pancreatic ductal adenocarcinoma is the 4th leading cause of cancer deaths in the United States. The majority of patients are candidates only for palliative chemotherapy, which has proven largely ineffective in halting tumor progression. One proposed mechanism of chemoresistance involves signaling via the mesenchymal-epithelial transition factor protein (MET), a previously established pathway critical to cell proliferation and migration. Here, we review the literature to characterize the role of MET in the development of tumorigenesis, metastasis and chemoresistance, highlighting the potential of MET as a therapeutic target in pancreatic cancer. In this review, we characterize the role of c-Met in the development of tumorigenesis, metastasis and chemoresistance, highlighting the potential of c-Met as a therapeutic target in pancreatic cancer.

MiR-135a biogenesis and regulation in malignancy:a new hope for cancer research and therapy

MicroRNAs(miRNAs)are evolutionarily conserved small non-coding RNAs that affect posttranscriptional regulation by binding to the 3′-untranslated region of target messenger RNAs.MiR-135a is a critical miRNA that regulates gene expression,and many studies have focused on its function in cancer research.MiR-135a is dysregulated in various cancers and regulates cancer cell proliferation and invasionvia several signaling pathways,such as the MAPK and JAK2/STAT3 pathways.MiR-135a has also been found to promote or inhibit the epithelial-mesenchymal transition and chemoresistance in different cancers.Several studies have discovered the value of miR-135a as a novel biomarker for cancer diagnosis and prognosis.These studies have suggested the potential of therapeutically manipulating miR-135a to improve the outcome of cancer patients.Although these findings have demonstrated the role of miR-135a in cancer progression and clinical applications,a number of questions remain to be answered,such as the dual functional roles of miR-135a in cancer.In this review,we summarize the available studies regarding miR-135a and cancer,including background on the biogenesis and expression of miR-135a in cancer and relevant signaling pathways involved in miR-135a-mediated tumor progression.We also focus on the clinical application of miR-135a as a biomarker in diagnosis and as a therapeutic agent or target in cancer treatment,which will provide a greater level of insight into the translational value of miR-135a.