Biomarker For Chemoresistance Research Articles

Knockdown of TMEM45A overcomes multidrug resistance and epithelial-mesenchymal transition in human colorectal cancer cells through inhibition of TGF-β signalling pathway.

Colorectal cancer (CRC), a leading cause of cancer death, has recently been known as the most prevalent malignancy worldwide. Although chemotherapy is an important therapeutic option for CRC patients, multidrug resistance (MDR) stillremains a major cause of chemotherapy failure. Transmembrane protein 45A (TMEM45A) has been found highly expressed in various cancers, and is also proposed as an interesting biomarker for chemoresistance. However, the association between TMEM45A and MDR in CRC remains unclear. This study aimed to investigate the key role of TMEM45A in CRC by knockdown of its expression in 5-FU-resistant CRC cells (HCT-8/5-FU and SW480/5-FU) and their parental cells (HCT-8 and SW480). Data showed that TMEM45A was significantly up-regulated in HCT-8/5-FU and SW480/5-FU cells in comparison with their parental HCT-8 and SW480 cells. Knockdown of TMEM45A enhanced 5-FU sensitivity and 5-FU-induced apoptosis in HCT-8/5-FU and SW480/5-FU cells. It was also found that inhibition of TMEM45A increased the intracellular accumulation of Rhodamine-123 and down-regulated the expression of MDR1 in HCT-8/5-FU and SW480/5-FU cells. In addition, knockdown of TMEM45A suppressed migration and invasion of HCT-8/5-FU and SW480/5-FU cells. Furthermore, knockdown of TMEM45A not only attenuated MDR-enhanced epithelial-mesenchymal transition (EMT), but also suppressed MDR-enhanced activation of the TGF-β signalling pathway in HCT-8/5-FU and SW480/5-FU cells. Taken together, our study suggests that knockdown of TMEM45A can effectively overcome MDR and inhibit EMT via suppression of the TGF-β signalling pathway in human CRC cells, and that targeting TMEM45A will be a potential strategy in the treatment of MDR in CRC.

Molecular characterization of ageratum enation virus and beta satellite associated with leaf curl disease of fenugreek in India

Cisplatn is one of the chemotherapy for the treatment of triple‐negatve breast cancer (TNBC), but its effectveness is limited because of the phenomenon of chemoresistance. miR‐638 was shown to regulate chemoresistance; however, it has never been validated in the cisplatn‐resistant tumor from patents. This present study aimed to identfy the key gene regulatory networks of miR‐638 and evaluate the potental role of the miR‐638 and its targets as potental prognosis biomarkers for cisplatn‐resistance triple‐negatve breast cancer patents. The miR‐638 target was obtained from the miRecords database while the mRNA of chemoresistance biomarker candidate was obtained from the GSE18864 of GEO database, which is mRNA of cisplatn‐resistance TNBC patents. CCND1 and FZD7 are potental candidates for cisplatn chemoresistance biomarkers in patents with TNBC. Moreover, a Kaplan‐Meier survival plot showed that breast cancer patents with low mRNA levels of FZD7 had signifcantly worse overall survival than those in higher mRNA expression group. Taken together, miR‐638 plays a role in cisplatn resistance mechanism through a mechanism involving its target gene CCND1 and FZD7. Overall, miR‐638, CCND1, and FZD7 are candidates for cisplatn biomarker resistance in TNBC.

Data mining analysis of miR-638 and key genes interaction in cisplatin resistant triple-negative breast cancer

Cisplatn is one of the chemotherapy for the treatment of triple‐negatve breast cancer (TNBC), but its effectveness is limited because of the phenomenon of chemoresistance. miR‐638 was shown to regulate chemoresistance; however, it has never been validated in the cisplatn‐resistant tumor from patents. This present study aimed to identfy the key gene regulatory networks of miR‐638 and evaluate the potental role of the miR‐638 and its targets as potental prognosis biomarkers for cisplatn‐resistance triple‐negatve breast cancer patents. The miR‐638 target was obtained from the miRecords database while the mRNA of chemoresistance biomarker candidate was obtained from the GSE18864 of GEO database, which is mRNA of cisplatn‐resistance TNBC patents. CCND1 and FZD7 are potental candidates for cisplatn chemoresistance biomarkers in patents with TNBC. Moreover, a Kaplan‐Meier survival plot showed that breast cancer patents with low mRNA levels of FZD7 had signifcantly worse overall survival than those in higher mRNA expression group. Taken together, miR‐638 plays a role in cisplatn resistance mechanism through a mechanism involving its target gene CCND1 and FZD7. Overall, miR‐638, CCND1, and FZD7 are candidates for cisplatn biomarker resistance in TNBC.

New avenues in pancreatic cancer: exploiting microRNAs as predictive biomarkers and new approaches to target aberrant metabolism

ABSTRACTIntroduction: Most pancreatic cancer patients are diagnosed at advanced-stages and first-line regimens (FOLFIRINOX and gemcitabine/nab-paclitaxel) provide limited survival advantage and are associated with considerable toxicities. In this grim scenario, novel treatments and biomarkers are warranted.Areas covered: MicroRNAs (miRNAs) emerged as biomarkers for cancer prognosis and chemoresistance and blood-based miRNAs are being evaluated as indicators of therapeutic activity. Moreover, aberrant metabolism, such as aerobic glycolysis, has been correlated to tumor aggressiveness and poor prognosis. Against this background, innovative approaches to tackle metabolic aberrations are being implemented and glycolytic inhibitors targeting lactate dehydrogenase-A (LDH-A) showed promising effects in preclinical models. A PubMed search was used to compile relevant publications until February 2019.Expert opinion: Analysis of tissue/circulating miRNA might improve selection for optimal treatment regimens. For instance, miR-181a modulation seems to predict response to FOLFIRINOX. However, we need further studies to validate predictive miRNA profiles, as well as to exploit miRNAs for treatment-tailoring. Several miRNAs have also a key role in regulating metabolic aberrations. Since preliminary evidence supports the development of new agents targeting these aberrations, such as LDH-A inhibitors, the identification of biomarkers for these treatments, including the above-mentioned miRNAs, should shorten the gap between preclinical studies and personalized therapies.

1750P - Multi-level proteomics identifies FABP5 as a primary chemoresistance mediator in extensive-stage small cell lung cancer

BackgroundSmall cell lung cancer (SCLC), a highly invasive neuroendocrine tumor, accounts for approximately 15% of all new diagnosed lung cancer. Primary disease is highly sensitive to chemotherapy as well as radiotherapy, recurrences occur quickly, and less effective to subsequent therapies than the initial chemotherapy, the response rate of second-line therapy topotecan is only 22%. Drug resistance, is the main reason for failure of SCLC chemotherapy. Here, we quantitatively analyzed the proteomes of Cisplatin/Etoposide-resistant and -sensitive ES-SCLC patients from minute amounts of formalin-fixed and paraffin-embedded (FFPE) tissues. FABP5 was identified to be related with primary chemosensitivity, and may be an important mediator of Cisplatin/Etoposide-induced cell death. Methods51 tissue samples were collected from ES-SCLC patients who underwent Cisplatin and Etoposide chemotherapy in Zhe Jiang Cancer Hospital from January 2015 to November 2017. The 51 cases included 23 chemosensitive patients and 28 chemoresistant patients. System-wide quantitative proteomics approach was applied on the cohort of chemo-resistant and -sensitive tissues, and label free protein quantification was performed. Realtime-PCR was performed to assess the mRNA expression in H69 and multi-drug resistant H69AR cells. ResultsA total of 4,485 proteins were identified and quantified, more than 50% proteins were 10-70KD, Proteins with a fold difference greater than 1.5 (up/down) and a P value (t test) less than 0.05 were considered differentially expressed proteins, few overall proteome changes across the two groups. Comparison of the two-group found that FABP5 was significantly decreased in drug-resistant patients. Consistent with the protein level in tumor tissues, FABP5 mRNA was down-regulated in H69AR cells. FABP5 expression strongly correlated with decreased disease-free survival and overall survival in ES-SCLC patients. ConclusionsThese data revealed FABP5 may serve as a potential biomarker for primary chemoresistance and prognostic factor for patients with ES-SCLC, which need further research. Legal entity responsible for the studyYamei Chen. FundingNational Natural Science Foundation of China (grant numbers 81672972). DisclosureAll authors have declared no conflicts of interest.

MicroRNAs as Potential Biomarkers for Chemoresistance in Adenocarcinomas of the Esophagogastric Junction.

Concerning adenocarcinomas of the esophagogastric junction, neoadjuvant chemotherapy is regularly implemented, but patients' response varies greatly, with some cases showing no therapeutic effect, being deemed as chemoresistant. Small, noncoding RNAs (miRNAs) have evolved as key players in biological processes, including malignant diseases, often promoting tumor growth and expansion. In addition, specific miRNAs have been implicated in the development of chemoresistance through evasion of apoptosis, cell cycle alterations, and drug target modification. We performed a retrospective study of 33 patients receiving neoadjuvant chemotherapy by measuring their miRNA expression profiles. Histologic tumor regression was evaluated using resection specimens, while miRNA profiles were prepared using preoperative biopsies without prior therapy. A preselected panel of 96 miRNAs, known to be of importance in various malignancies, was used to test for significant differences between responsive (chemosensitive) and nonresponsive (chemoresistant) cases. The cohort consisted of 12 nonresponsive and 21 responsive cases with the following 4 miRNAs differentially expressed between both the groups: hsa-let-7f-5p, hsa-miRNA-221-3p, hsa-miRNA-31-5p, and hsa-miRNA-191-5p. The former 3 showed upregulation in chemoresistant cases, while the latter showed upregulation in chemosensitive cases. In addition, significant correlation between high expression of hsa-miRNA-194-5p and prolonged survival could be demonstrated (p value <0.0001). In conclusion, we identified a panel of 3 miRNAs predicting chemoresistance and a single miRNA contributing to chemosensitivity. These miRNAs might function as prognostic biomarkers and enable clinicians to better predict the effect of one or more reliably select patients benefitting from (neoadjuvant) chemotherapy.

Analysis of Differentially Expressed MicroRNAs and Circulating Tumor Cells as Predictive Biomarkers of Platinum Chemoresistance in Primary Ovarian Carcinomas: A Prospective Study

Lesson Learned.Circulating tumor cells, microRNA markers, or other biomarkers merit examination as part of correlative scientific analyses in prospective clinical trials.Background.Platinum chemotherapy resistance occurs in approximately 25% of patients with ovarian carcinoma; however, no biomarkers of ovarian carcinoma chemoresistance have been validated. We performed a prospective trial designed to identify tumor‐based predictive biomarkers of platinum resistance.Methods.Tumor specimens were collected from 29 women with newly diagnosed histopathologically proven primary ovarian carcinoma. Of these, 23 women had specimens accessible for assessment and outcome data available regarding chemosensitive versus chemoresistance status via review of the medical record. Tumor slices were stained with antibodies against two microRNAs (miRNAs 29b and 199a) differentially expressed in chemoresistant ovarian cancer cell lines. Additionally, blood samples obtained at the time of diagnosis were analyzed for the presence of circulating tumor cells (CTCs).Results.The average age of the patients was 64 years, and 82.6% had high‐grade epithelial carcinomas. The baseline median CA‐125 was 464 (range 32–2,782). No statistically significant differences were observed in miR29b or 199a expression in platinum‐resistant/refractory versus platinum‐sensitive tumors. Furthermore, the presence of CTCs was not found to be statistically significantly predictive of eventual platinum resistance.Conclusion.Our analysis showed no differences in miR29b and 199a expression, and differences in baseline CTCs in women with newly diagnosed ovarian tumors were not statistically significant.

Tumor stroma proportion to predict platinum chemoresistance in primary ovarian carcinomas: A prospective study.

5581 Background: Platinum chemotherapy resistance occurs in approximately 25% of patients with ovarian carcinoma and represents a major barrier to effective care of this patient population. To date there are no effective nor validate predictive biomarkers of chemoresistance of ovarian carcinomas. We performed a prospective trial designed to enroll patients with ovarian masses suspicious for ovarian cancer, with the goal of identifying tumor-based predictive biomarkers of platinum resistance. Methods: 60 women were enrolled on the study. Tumor specimens were collected from 49 of these women with newly diagnosed pelvic masses, of which 29 were found to have histopathologically proven primary ovarian carcinoma. Of these primary malignant cases, 24 had specimens accessible for assessment of tumor-stroma proportion and data available regarding chemosensitive vs chemoresistance status via review of the medical record using a UMN IRB-approved protocol. Tumor slices were stained with H&amp;E and also for antibodies against two microRNAs (29b and 199a) differentially expressed in ovarian cancer cell lines. Tumor-stroma proportions were assessed by two experienced pathologists blinded to chemoresistance status, with &lt;50% stroma scored as low proportion, &gt;50% scored as high proportion. Results: The average age of assessed patients with malignant tumors was 62. 87.5% had high-grade epithelial carcinomas. Baseline median CA-125 was 416 (range 32-2782). 80% of ovarian cancer patients with chemoresistance had tumor stroma proportions &gt;50%; 73.7% of cancer patients with chemosensitive tumors had proportions &lt;50% (p-value: 0.047). Expression of miR29b or 199a did not significantly correlate with chemoresistance. Conclusions: Tumor-stroma proportion is a useful predictive biomarker of platinum chemoresistance. If validated in larger datasets, it would be a relatively inexpensive and helpful tool for tailoring treatment strategies and clinical decision-making in women with ovarian cancer.

Semaphorin 3A (SEMA3A), protocadherin 9 (PCdh9), and S100 calcium binding protein A3 (S100A3) as potential biomarkers of carcinogenesis and chemoresistance of different neoplasms, including ovarian cancer - review of literature.

Ovarian cancer is the fifth leading cause of cancer-related deaths in women. Its high mortality rate results from lack of adequate and sensitive methods allowing for the detection of the early stages of the disease, as well as low efficiency of the treatment, caused by the cytotoxic drug resistance of cancer cells. Unfortunately, tumours are able to develop new pathways and protective mechanisms that allow them to survive toxic conditions of chemotherapy. Therefore, intensive search for new genes and proteins involved in resistance to cytotoxic drugs is still needed, especially from a clinical point of view. The article presents an overview of the available literature on the role of semaphorin 3A (SEMA3A), protocadherin 9 (PCDH9), and S100 calcium binding protein A3 (S100A3) in carcinogenesis and chemoresistance of various tumors including ovarian cancer. As it turns out, the role of described genes/proteins is not limited only to their native biological activity but they function also as an oncogenic or suppressor factors in the tumor development. Moreover, they can also play an important role in development of drug resistance, as it was shown in ovarian cancer cell lines.

MicroRNA let-7g acts as tumor suppressor and predictive biomarker for chemoresistance in human epithelial ovarian cancer

Remarkable deregulation of microRNAs has been demonstrated in epithelial ovarian cancer (EOC). In particular, some of the let-7 miRNA family members have been proposed as tumor suppressors. Here, we explored the functional roles of let-7g in EOC. The ectopic overexpression of let-7g in OVCAR3 and HEY-A8 EOC cells induced i) a down-regulation of c-Myc and cyclin-D2 thus promoting cell cycle arrest, ii) a reduction of Vimentin, Snail and Slug thus counteracting the progression of epithelial to mesenchymal transition, iii) a chemosensitization to cis-platinum treatment. Next, analysis of human EOC tissues revealed that let-7g expression was significantly reduced in tumor tissue specimens of patients with EOC compared to their non-tumor counterparts (p = 0.0002). Notably, low let-7g tissue levels were significantly associated with acquired chemoresistance of patients with late-stage of EOC (n = 17, p = 0.03194). This finding was further validated in the serum samples collected from the same cohort of patients (n = 17, p = 0.003). To conclude, we demonstrate that let-7g acts as tumor suppressor and might be used to disable EOC tumor progression and chemoresistance to cis-platinum-based chemotherapy. Furthermore, we propose that decreased expression of let-7g could serve as a tissue and serum biomarker able to predict the chemo-resistant features of EOC patients.

Cytometry of Reaction Rate Constant: Measuring Reaction Rate Constant in Individual Cells To Facilitate Robust and Accurate Analysis of Cell-Population Heterogeneity.

Robust and accurate analysis of cell-population heterogeneity is challenging but required in many areas of biology and medicine. In particular, it is pivotal to the development of reliable cancer biomarkers. Here, we prove that cytometry of reaction rate constant (CRRC) can facilitate such analysis when the kinetic mechanism of a reaction associated with the heterogeneity is known. In CRRC, the cells are loaded with a reaction substrate, and its conversion into a product is followed by time-lapse fluorescence microscopy at the single-cell level. A reaction rate constant is determined for every cell, and a kinetic histogram "number of cells versus the rate constant" is used to determine quantitative parameters of reaction-based cell-population heterogeneity. Such parameters include, for example, the number and sizes of subpopulations. In this work, we applied CRRC to a reaction of substrate extrusion from cells by ATP-binding cassette (ABC) transporters. This reaction is viewed as a potential basis for predictive biomarkers of chemoresistance in cancer. CRRC proved to be robust (insensitive to variations in experimental settings) and accurate for finding quantitative parameters of cell-population heterogeneity. In contrast, a typical nonkinetic analysis, performed on the same data sets, proved to be both nonrobust and inaccurate. Our results suggest that CRRC can potentially facilitate the development of reliable cancer biomarkers on the basis of quantitative parameters of cell-population heterogeneity. A plausible implementation scenario of CRRC-based development, validation, and clinical use of a predictor of ovarian cancer chemoresistance to its frontline therapy is presented.

Regional methylome profiling reveals dynamic epigenetic heterogeneity and convergent hypomethylation of stem cell quiescence-associated genes in breast cancer following neoadjuvant chemotherapy

BackgroundNeoadjuvant chemotherapy (NAC) induces a pathological complete response (pCR) in ~ 30% of patients with breast cancer. However, aberrant DNA methylation alterations are frequent events during breast cancer progression and acquisition of chemoresistance. We aimed to characterize the inter- and intra-tumor methylation heterogeneity (MH) in breast cancer following NAC.MethodsDNA methylation profiles of spatially separated regions of breast tumors before and after NAC treatment were investigated using high-density methylation microarray. Methylation levels of genes of interest were further examined using multiplexed MethyLight droplet digital PCR (ddPCR).ResultsWe have discovered different levels of intra-tumor MH in breast cancer patients. Moreover, NAC dramatically altered the methylation profiles and such changes were highly heterogeneous between the patients. Despite the high inter-patient heterogeneity, we identified that stem cell quiescence-associated genes ALDH1L1, HOPX, WNT5A and SOX9 were convergently hypomethylated across all the samples after NAC treatment. Furthermore, by using MethyLight ddPCR, we verified that the methylation levels of these 4 genes were significantly lower in breast tumor samples after NAC than those before NAC.ConclusionsOur study has revealed that NAC dramatically alters epigenetic heterogeneity in breast cancer and induces convergent hypomethylation of stem cell quiescence-associated genes, ALDH1L1, HOPX, WNT5A and SOX9, which can potentially be developed as therapeutic targets or biomarkers for chemoresistance.

Use of MRI, metabolomic, and genomic biomarkers to identify mechanisms of chemoresistance in glioma.

Gliomas are the most common form of central nervous system tumor. The most prevalent form, glioblastoma multiforme, is also the most deadly with mean survival times that are less than 15 months. Therapies are severely limited by the ability of these tumors to develop resistance to both radiation and chemotherapy. Thus, new tools are needed to identify and monitor chemoresistance before and after the initiation of therapy and to maximize the initial treatment plan by identifying patterns of chemoresistance prior to the start of therapy. Here we show how magnetic resonance imaging, particularly sodium imaging, metabolomics, and genomics have all emerged as potential approaches toward the identification of biomarkers of chemoresistance. This work also illustrates how use of these tools together represents a particularly promising approach to understanding mechanisms of chemoresistance and the development individualized treatment strategies for patients.

Biological indicators of chemoresistance: an ex vivo analysis of \u03b3H2AX and p53 expression in feline injection-site sarcomas

BackgroundThe response of soft tissue sarcomas to cytotoxic chemotherapy is inconsistent. Biomarkers of chemoresistance or chemosensitivity are needed in order to identify appropriate patients for treatment. Given that many chemotherapeutics kill cells through direct DNA interactions, we hypothesized that upregulation of DNA damage response mechanisms would confer resistance to cytotoxic chemotherapy in sarcomas. To study this, we used spontaneously-occurring feline injection-site sarcomas (FISS).MethodsγH2AX and p53 expression were determined in biopsy samples of FISS. γH2AX expression was determined via immunohistochemistry whereas p53 expression was determined via qRT-PCR. Cell lines derived from these sarcoma biopsies were then treated with carboplatin (N = 11) or doxorubicin (N = 5) and allowed to grow as colonies. Colony forming-ability of cells exposed to chemotherapy was compared to matched, untreated cells and expressed as percent survival relative to controls. ImageJ was used for quantification. A mixed model analysis was performed to determine if an association existed between relative survival of the treated cells and γH2AX or p53 expression in the original tumors. Cell lines were validated via vimentin expression or growth as subcutaneous sarcomas in nude mice.ResultsAn association was detected between γH2AX expression and relative survival in cells exposed to carboplatin (P = 0.0250). In the 11 FISS tumors evaluated, γH2AX expression ranged from 2.2 to 18.8% (mean, 13.3%). Cells from tumors with γH2AX expression higher than the sample population mean had fourfold greater relative survival after carboplatin exposure than cells from tumors with γH2AX expression less than the mean. There was no association between relative survival after carboplatin exposure and p53 expression (P = 0.1608), and there was no association between relative survival after doxorubicin exposure and either γH2AX (P = 0.6124) or p53 (P = 0.8645) expression. Four cell lines were validated via growth as sarcomas in nude mice. Vimentin expression was confirmed in the other 7 cell lines.ConclusionsγH2AX expression, but not wild type p53, may potentially serve as a biomarker of resistance to platinum therapeutics in soft tissue sarcomas. To further investigate this finding, prospective, in vivo studies are indicated in animal models.

Histone deacetylase inhibitor targets CD123/CD47-positive cells and reverse chemoresistance phenotype in acute myeloid leukemia.

Chemoresistance may be due to the survival of leukemia stem cells (LSCs) that are quiescent and not responsive to chemotherapy or lie on the intrinsic or acquired resistance of thespecific pool of AML cells. Here, we found, among well-established LSC markers, only CD123 and CD47 are correlated with AML cell chemosensitivities across cell lines and patient samples. Further study reveals that percentages of CD123+CD47+ cells significantly increased in chemoresistant lines compared to parental cell lines. However, stemness signature genes are not significantly increased in resistant cells. Instead, gene changes are enriched in cell cycle and cell survival pathways. This suggests CD123 may serve as a biomarker for chemoresistance, but not stemness of AML cells. We further investigated the role of epigenetic factors in regulating the survival of chemoresistant leukemia cells. Epigenetic drugs, especially histone deacetylase inhibitors (HDACis), effectively induced apoptosis of chemoresistant cells. Furthermore, HDACi Romidepsin largely reversed gene expression profile of resistant cells and efficiently targeted and removed chemoresistant leukemia blasts in xenograft AML mouse model. More interestingly, Romidepsin preferentially targets CD123+ cells, while chemotherapy drug Ara-C mainly targeted fast-growing, CD123- cells. Therefore, Romidepsin alone or in combination with Ara-C may be a potential treatment strategy for chemoresistant patients.

PO-497 Microtubule regulatory proteins as predictive biomarkers of taxane-based chemoresistance in breast cancer?

IntroductionNeo-adjuvant chemotherapy combining taxanes and anthracyclines represents an interesting option for a number of breast cancer patients. However, the proportion of patients who achieve a pathological complete response (pCR) after treatment remains low, reaching 15%–20% in the whole population. Thus, identifying predictive biomarkers of drug resistance is necessary to select the patients who are most likely to benefit from chemotherapy. Taxanes (paclitaxel, docetaxel) are potent stabilisers of the microtubule cytoskeleton, which functions are tightly regulated by a panel of MT-associated proteins and mitotic kinases. In the present study, we evaluated whether taxane resistance in breast cancer may be associated with alterations of genes encoding MT-regulatory proteins.Material and methodsExpression levels of 411 MT-related genes were analysed from Affymetrix U133 microarray of breast tumours from three independent multicentered clinical trials, namely REMAGUS-02 (115 patients), REMAGUS-04 (142 patients) and MD Anderson (133 patients). Only patients treated with neoadjuvant taxane-based chemotherapy were included in this study. Expression level of MT-related genes in tumours was compared with the ability to achieve pCR.Results and discussionsBy comparing expression levels of 411 MT-related genes in three independent cohorts of breast cancer patients treated with taxane-based neo-adjuvant chemotherapy, we have identified a total of 94 MT-related genes that are differentially expressed in tumours with pCR. Among those, 18 MT-related genes are common to the three cohorts. Interestingly, all these genes appear as potential prognostic biomarkers of overall survival. Ongoing studies aim at functionally validating these candidates using siRNA screening in two different breast cancer cell lines.ConclusionThis study should lead to the identification of novel predictive biomarkers to select breast cancer patients who are likely to benefit from taxane-based chemotherapy. This should also pave the way for future targeted treatments of chemoresistant breast tumours.

Hypoxic tumor microenvironment activates GLI2 via HIF-1α and TGF-β2 to promote chemoresistance in colorectal cancer

Colorectal cancer patients often relapse after chemotherapy, owing to the survival of stem or progenitor cells referred to as cancer stem cells (CSCs). Although tumor stromal factors are known to contribute to chemoresistance, it remains not fully understood how CSCs in the hypoxic tumor microenvironment escape the chemotherapy. Here, we report that hypoxia-inducible factor (HIF-1α) and cancer-associated fibroblasts (CAFs)-secreted TGF-β2 converge to activate the expression of hedgehog transcription factor GLI2 in CSCs, resulting in increased stemness/dedifferentiation and intrinsic resistance to chemotherapy. Genetic or small-molecule inhibitor-based ablation of HIF-1α/TGF-β2-mediated GLI2 signaling effectively reversed the chemoresistance caused by the tumor microenvironment. Importantly, high expression levels of HIF-1α/TGF-β2/GLI2 correlated robustly with the patient relapse following chemotherapy, highlighting a potential biomarker and therapeutic target for chemoresistance in colorectal cancer. Our study thus uncovers a molecular mechanism by which hypoxic colorectal tumor microenvironment promotes cancer cell stemness and resistance to chemotherapy and suggests a potentially targeted treatment approach to mitigating chemoresistance.

Identification of biomarkers associated with partial epithelial to mesenchymal transition in the secretome of slug over-expressing hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. Complete epithelial to mesenchymal transition (EMT) has long been considered as a crucial step for metastasis initiation. It has, however, become apparent that many carcinoma cells can metastasize without complete loss of epithelial traits or with incomplete gain of mesenchymal traits, i.e., partial EMT. Here, we aimed to determine the similarities and differences between complete and partial EMT through over-expression of the EMT-associated transcription factor Slug in different HCC-derived cell lines. Slug over-expressing HCC-derived HepG2 and Huh7 cells were assessed for their EMT, chemo-resistance and stemness features using Western blotting, qRT-PCR, neutral red uptake, doxorubicin accumulation and scratch wound healing assays. We also collected conditioned media from Slug over-expressing HCC cells and analyzed its exosomal protein content for the presence of chemo-resistance and partial EMT markers using MALDI-TOF/TOF and ELISA assays, respectively. We found that Slug over-expression resulted in the induction of both complete and partial EMT in the different HCC-derived cell lines tested. Complete EMT was characterized by downregulation of E-cadherin and upregulation of ZEB2. Partial EMT was characterized by upregulation of E-cadherin and downregulation of vimentin and ZEB2. Interestingly, we found that Slug induced chemo-resistance through downregulation of the ATP binding cassette (ABC) transporter ABCB1 and upregulation of the ABC transporter ABCG2, as well as through expression of CD133, a stemness marker that exhibited a similar expression pattern in cells with either a complete or a partial EMT phenotype. In addition, we found that Slug-mediated partial EMT was associated with enhanced exosomal secretion of post-translationally modified fibronectin 1 (FN1), collagen type II alpha 1 (COL2A1) and native fibrinogen gamma chain (FGG). From our data we conclude that the exosomal proteins identified may be considered as potential non-invasive biomarkers for chemo-resistance and partial EMT in HCC.

STAT3 as a promising chemoresistance biomarker associated with the CD44+/high/CD24-/low/ALDH+ BCSCs-like subset of the triple-negative breast cancer (TNBC) cell line

The cancer stem cell (CSC) concept is currently employed to explain the mechanism of multidrug resistance that is implicated in the reduced efficacy of many chemotherapeutic agents, consequently leading to metastatic spread and disease relapse. We searched for potential predictive markers of doxorubicin (DOX) resistance in breast cancer stem cells (BCSCs) of the BT-549 human triple-negative breast cancer (TNBC) cell line classified as a claudin-low subtype. In this study, we show that BT-549 presents a BCSCs-like subset determined by a CD44+/high/CD24-/low/ALDH1+ phenotype. The CD44+/high/CD24-/low/ALDH+ BCSCs-like subset presented the downregulation of a majority of the genes analyzed (64 genes), and only 3 genes were upregulated after DOX treatment. Among the upregulated genes, MAPK3, PRKCZ and STAT3, STAT3 presented a higher level of upregulation in the DOX-treated CD44+/high/CD24-/low/ALDH+ BCSCs-like subset. The identification of biomarkers that predict antitumor responses is at the top of cancer research priorities. STAT3 was highlighted as a molecular signature in the CD44+/high/CD24-/low/ALDH1+ BCSCs-like subset obtained from the TNBC BT-549 cell line related to DOX resistance. A majority of the evaluated genes in the EGF pathway appear to be not associated with DOX resistance, as observed in the CD44+/high/CD24-/low/ALDH1+ BCSCs-like subset.

Three-Dimensional Cellular Arrangement in Epithelial Ovarian Cancer Cell Lines TOV-21G and SKOV-3 is Associated with Apoptosis-Related miRNA Expression Modulation.

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy, and the lack of chemoresistance biomarkers contributes to the poor prognosis. Cancer stem cells (CSC) have been investigated in EOC to understand its relationship with chemoresistance and recurrence. In this context, in vitro cultivation-models are important tools for CSC studies. MicroRNAs (miRNAs) play key roles in cancer, CSC regulation and apoptosis. Thus, this study aims to evaluate the tumorsphere model as CSC-enrichment method in EOC studies and investigate apoptosis-related miRNAs in tumorspheres-derived EOC cell lines. TOV-21G and SKOV-3 were cultured in monolayer and tumorspheres. Genetic profiles of cell lines were obtained using COSMIC database. CD24/CD44/CD146/CD177 and ALDH1 markers were evaluated in cell lines and tumorspheres-derived by flow cytometry. Eleven miRNAs were selected by in silico analysis for qPCR analysis. According to COSMIC, TOV-21G and SKOV-3 have eight and nine cancer-related mutations, respectively. TOV-21G showed a CD44+/high/CD24-/low/CD117-/low/CD146-/low/ALDH1low profile in both culture models; thus, no significant difference between cultivation models was identified. SKOV-3 showed a CD44+/high/CD24+/high/ CD117-/low/CD146-/low/ALDH1low profile in both culture models, although the tumorsphere model showed a significant increase in CD24+/high subpopulation (ovarian CSC-like). Among eleven miRNAs, we observed differences in miRNA expression between culture models. MiR-26a was overexpressed in TOV-21G tumorspheres, albeit downregulated in SKOV-3 tumorspheres. MiR-125b-5p, miR-17-5p and miR-221 was downregulated in tumorsphere model in both cell lines. Given that tumorsphere-derived SKOV-3 had a higher ratio of CD24+/high cells, we suggest that miR-26a, miR-125b-5p, miR-17-5p and miR-221 downregulation could be related to poor EOC prognosis.