Expression Of Drug Resistance Genes Research Articles

Transcriptional regulation of drug resistance mechanisms in Salmonella: where we stand and what we need to know.

Salmonellae have evolved a wide range of molecular mechanisms to neutralize the effect of antibiotics and evade the host immune system response. These mechanisms are exquisitely controlled by global and local regulators and enable the pathogens to use its energy as per need and hence allow the pathogen to economize the consumption of energy by its cellular machinery. Several families that regulate the expression of different drug resistance genes are known; some of these are: the TetR family (which affects tetracycline resistance genes), the AraC/XylS family (regulators that can act as both transcriptional activators and repressors), two-component signal transduction systems (e.g. PhoPQ, a key regulator for virulence), mercury resistance Mer-R and multiple antibiotic resistance Mar-R regulators, LysR-type global regulators (e.g. LeuO) and histone-like protein regulators (involved in the repression of newly transferred resistance genes). This minireview focuses on the role of different regulators harbored by the Salmonella genome and characterized for mediating the drug resistance mechanisms particularly via efflux and influx systems. Understanding of such transcriptional regulation mechanisms is imperative to address drug resistance issues in Salmonella and other bacterial pathogens.

Differential expression of drug resistance genes in CD146 positive dental pulp derived stem cells and CD146 negative fibroblasts.

IntroductionThe stem cell portion of the dental pulp derived cultures (DPSCs) showed a higher resistance to cytotoxic effect of restorative dental materials compared to pulpal fibroblasts (DPFs). Here, we aimed to compare the expression of some drug resistant genes between these cells.Methods and materialsTo separate DPSCs from DPFs, we used magnetic cell sorting technique based on CD146 expression. To assess the stem cell properties, the positive and negative portions underwent colony forming assays and were induced to be differentiated into the adipocytes, osteoblasts, hepatocytes, and neural cells. Cell surface antigen panels were checked using immune fluorescence and flow‐cytometry techniques. The mRNA expression of 14 ABC transporters including ABCA2, ABCB1, ABCB11, ABCC1, ABCC2, ABCC3, ABCC4, ABCC5‐2, ABCC5‐4,ABCC5‐13, ABCC6, ABCC10, ABCC11, and ABCG2 genes was assessed, using quantitative RT‐PCR technique.ResultsOnly the CD146 positive portion could be differentiated into the desired fates, and they formed higher colonies (16.7 ± 3.32 vs. 1.7 ± 1.67, p < .001). The cell surface antigen panels were the same, except for CD146 and STRO‐1 markers which were expressed only in the positive portion. Among the ABC transporter genes studied, the positive portion showed a higher expression (approximately two‐fold) of ABCA2, ABCC5‐13, and ABCC5‐2 genes.ConclusionDental pulp stem cells which can be separated from dental pulp fibroblasts based on CD146 expression, express higher levels of some drug resistance genes which probably accounts for their features of more resistance to cytotoxic effects of some dental materials. This needs to be more validated in future.

Drug resistance gene expression and chemotherapy sensitivity detection in Chinese women with different molecular subtypes of breast cancer.

Objective:The aim of the study was to identify specific chemosensitivity drugs for various molecular subtypes of breast tumors in Chinese women, by detecting the expression of drug resistance genes and by using the drug sensitivity test on different molecular subtypes of breast cancers.Methods:The expression of drug resistance genes including Topo II, GST-π, P-gp, LRP, and CD133 were detected with immunohistochemistry in a tissue microarray. Drug sensitivity tests included those for paclitaxel, epirubicin, carboplatin, vinorelbine, and fluorouracil and were conducted on primary cancer tissue cells and cell lines, including the T47D, BT-474, and MDA-MB-231 cells and human breast cancer xenografts in nude mice.Results:The different drug resistant genes Topo II, GST-π, P-gp, and LRP were differentially expressed among different molecular subtypes of breast cancers (P < 0.05). Positive expression of CD133 was highest in basal-like breast cancer (P < 0.05). Kaplan-Meier survival analysis showed that positive expressions of Topo II and CD133 both correlated with shorter disease-free survival (DFS) (P < 0.05) and overall survival (P < 0.05), and positive expression of LRP correlated only with shorter DFS (P < 0.05). BT-474 showed chemosensitivity to paclitaxel and epirubicin, while MDA-MB-231 showed chemosensitivities to paclitaxel, epirubicin, carboplatin, and fluorouracil (T/C ≤ 50%). The basal-like and HER2+ breast cancer primary cells showed chemosensitivities to paclitaxel and epirubicin with significant differences compared with luminal breast cancer primary cells (P < 0.05).Conclusions:The differential expression of drug resistance genes and the differential chemosensitivities of drugs in different molecular subtype of breast cancers suggested that individual treatment should be given for each type of breast cancer.

Restoration of RNA helicase DDX5 suppresses hepatitis B virus (HBV) biosynthesis and Wnt signaling in HBV-related hepatocellular carcinoma.

Rationale: RNA helicase DDX5 is downregulated during hepatitis B virus (HBV) replication, and poor prognosis HBV-related hepatocellular carcinoma (HCC). The aim of this study is to determine the mechanism and significance of DDX5 downregulation for HBV-driven HCC, and identify biologics to prevent DDX5 downregulation.Methods: Molecular approaches including immunoblotting, qRT-PCR, luciferase transfections, hepatosphere assays, Assay for Transposase-Accessible Chromatin sequencing (ATAC-seq), and RNA-seq were used with cellular models of HBV replication, HBV infection, and HBV-related liver tumors, as well as bioinformatic analyses of liver cancer cells from two independent cohorts.Results: We demonstrate that HBV infection induces expression of the proto-oncogenic miR17~92 and miR106b~25 clusters which target the downregulation of DDX5. Increased expression of these miRNAs is also detected in HBV-driven HCCs exhibiting reduced DDX5 mRNA. Stable DDX5 knockdown (DDX5KD) in HBV replicating hepatocytes increased viral replication, and resulted in hepatosphere formation, drug resistance, Wnt activation, and pluripotency gene expression. ATAC-seq of DDX5KD compared to DDX5 wild-type (WT) cells identified accessible chromatin regions enriched in regulation of Wnt signaling genes. RNA-seq analysis comparing WT versus DDX5KD cells identified enhanced expression of multiple genes involved in Wnt pathway. Additionally, expression of Disheveled, DVL1, a key regulator of Wnt pathway activation, was significantly higher in liver cancer cells with low DDX5 expression, from two independent cohorts. Importantly, inhibitors (antagomirs) to miR17~92 and miR106b~25 restored DDX5 levels, reduced DVL1 expression, and suppressed both Wnt activation and viral replication.Conclusion: DDX5 is a negative regulator of Wnt signaling and hepatocyte reprogramming in HCCs. Restoration of DDX5 levels by miR17~92 / miR106b~25 antagomirs in HBV-infected patients can be explored as both antitumor and antiviral strategy.

PDTM-37. GALECTIN-3 PROMOTES CXCR2 EXPRESSION IN MEDULLOBLASTOMA

Abstract Brain tumors are the leading cause of childhood cancer mortality, with medulloblastoma (MB) representing the most frequent malignant tumor. The identification of cancer stem cell (CSC) populations in MB has play a vital role in drug resistance, and cancer relapse. Galectin-3 (Gal-3) a multifunctional β-galactoside-binding protein is known to participate in tumor progression and drug resistance. However, the exact role of Gal-3 in medulloblastoma tumor pathophysiology is yet unknown. In this study, we observed higher levels of stem/progenitor cell markers, such as Oct4, Sox2, CD133 and Nanog in MB slices. Among the Gal family, Gal-3 in particular was highly expressed in MB tumor slices. To further investigate Gal-3’s role in the pathophysiology of MB, we used either small interfering RNA (siRNA) to knock down Gal-3 expression or Gal-3 inhibitor, TD139 to suppress Gal-3 expression in ex vivo slice culture model. Upon suppressing Gal-3 in parental MB slices, drug resistance (MDR1and MPR1) and stem cell related gene expression were all significantly decreased. Furthermore, CXCL6, CXCL7 and CXCR2 were down-regulated in Gal-3-knockdown or Gal-3 inhibitor treated MB tumor slices, while CXCR2 overexpression in Gal-3-knockdown or Gal-3 inhibitor treated MB slices restored their viability. These results indicate that highly expressed Gal-3 may up-regulate CXCR2 to augment MB invasiveness and progression. Gal-3 may be a prognostic and innovative target for the treatment of MB.

MiR-153 inhibits the resistance of lung cancer to gefitinib via modulating expression of ABCE1.

Gefitinib-resistance in lung cancers has become an intractable clinical problem. However, the mechanisms underlying this resistance are not fully understood. Present study aims to investigate the roles and underlying mechanism of miR-153 in modulating gefitinib resistance in lung cancers. In the present study, genes expression of miR-153, MDR-1 and ABCE1 were detected by qRT-PCR and western blot. The cell viability was examined by MTT assays. The regulation of miR-153 on ABCE1 was examined by luciferase reporter gene assays. The interaction of miR-153 and ABCE1 was detected by gene over-expression and siRNA interference technology. The mRNA level of miR-153 was significantly down-regulated in gefitinib-resistance (GR) tissues and HCC827 cells, while the protein level of ABCE1 was up-regulated in GR tissues and HCC827 cells. Besides, miR-153 over-expression evidently increased miR-153 level and suppressed cell viability and multi drug resistance gene (MDR-1) expression in HCC827/Gef cells, while silence of miR-153 caused adverse alterations in HCC827 cells. Luciferase reporter assay results showed that miR-153 directly targeted ABCE1. Further studies showed that ABCE1 over-expression improved the expression of ABCE1 and MDR-1 and increased cell viability in HCC827/Gef cells, while ABCE1 silencing resulted in contrary trends in HCC827 cells. What's more, miR-153 over-expression inhibited tumorigenesis and ABCE1 expression, while increased miR-153 level in tumor tissues. MiR-153 regulates gefitinib resistance by modulating expression of ABCE1 in lung cancers. Our findings may provide a worthwhile therapeutic target to reverse gefitinib resistance in lung cancers in the future.

Abstract 5135: Genome-wide CRISPR-based screening reveals ABCG2 as a novel drug resistance gene in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most deadly cancers and incidence is increasing due to the increase in risk factors such as diabetes and obesity. One reason for the high mortality rate associated with this cancer is the high rate of resistance to commonly used chemotherapies. Our previous work showed a link between patient survival and expression of drug resistance genes, thus we undertook genome-wide CRISPR knockout and activation screens to identify genes conferring resistance to cytotoxic chemotherapies in two pancreatic cancer cell lines. Our screen revealed hundreds of genes with potential roles in drug resistance, many of which have expression levels that correlate with patient survival. We have validated our top candidates by stably expressing individual guide RNAs in each of three pancreatic cell lines, Panc-1, BxPC-3 and MiaPaCa-2 and screening for viability following treatment with three chemotherapeutic agents, oxaliplatin, gemcitabine, and irinotecan. ABCG2, an ABC transporter, was revealed as our top hit, conferring resistance to multiple drugs in multiple cell lines. Our results would suggest that repression of ABCG2 might improve sensitivity to cytotoxic chemotherapies. We test this hypothesis using an ABCG2 inhibitor and demonstrate the effect of this inhibitor on cell viability, drug sensitivity and transcriptomic profiles in the context of cell lines with variable ABCG2 expression. Note: This abstract was not presented at the meeting. Citation Format: Ryne C. Ramaker, Andrew A. Hardigan, Emily R. Gordon, Richard M. Myers, Sara J. Cooper. Genome-wide CRISPR-based screening reveals ABCG2 as a novel drug resistance gene in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5135.

A survey of adaptive cell population dynamics models of emergence of drug resistance in cancer, and open questions about evolution and cancer

This article is a proceeding survey (deepening a talk given by the first author at the Biomath 2019 International Conference on Mathematical Models and Methods, held in Bedlewo, Poland) of mathematical models of cancer and healthy cell population adaptive dynamics exposed to anticancer drugs, to describe how cancer cell populations evolve toward drug resistance.Such mathematical models consist of partial differential equations (PDEs) structured in continuous phenotypes coding for the expression of drug resistance genes; they involve different functions representing targets for different drugs, cytotoxic and cytostatic, with complementary effects in limiting tumour growth. These phenotypes evolve continuously under drug exposure, and their fate governs the evolution of the cell population under treatment. Methods of optimal control are used, taking inevitable emergence of drug resistance into account, to achieve the best strategies to contain the expansion of a tumour.This evolutionary point of view, which relies on biological observations and resulting modelling assumptions, naturally extends to questioning the very nature of cancer as evolutionary disease, seen not only at the short time scale of a human life, but also at the billion year-long time scale of Darwinian evolution, from unicellular organisms to evolved multicellular organs such as animals and man. Such questioning, not so recent, but recently revived, in cancer studies, may have consequences for understanding and treating cancer.Some open and challenging questions may thus be (non exhaustively) listed as:- May cancer be defined as a spatially localised loss of coherence between tissues in the sameВ multicellular organism, `spatially localised' meaning initially starting from a given organ in the body, butВ also possibly due to flaws in an individual's rms of evolution towards drug resistance governed by the phenotypes which determine landscape such as imperfect epigenetic control of differentiation genes?- If one assumes that ''The genes of cellular cooperation that evolved with multicellularity about a billion years ago arethe same genes that malfunction in cancer.'', how can these genes besystematically investigated, looking for zones of fragility - that depend on individuals - in the 'tinkering' evolution is made of, tracking local defaults of coherence?- What is such coherence made of and to what extent is the immune system responsible for it (the self and differentiation within the self)?Related to this question of self, what parallelism can be established between the developmentВ of multicellularity in different species proceeding from the same origin and the development of theВ immune system in these different species?

Reversal effect of ginsenoside Rh2 on oxaliplatin-resistant colon cancer cells and its mechanism.

Chemotherapy is an important treatment modality for colon cancer, however, drug resistance is the main factor leading to treatment failure. Ginsenoside Rh2 (G-Rh2), the main bioactive metabolite of ginseng, is known to possess the ability to potently induce cell apoptosis, inhibit cell proliferation and reverse multidrug resistance in a variety of cancer cells. The present study examined the effect of G-Rh2 on oxaliplatin (L-OHP)-resistant colon cancer cells and its potential mechanism. L-OHP-resistant colon cancer cells (LoVo/L-OHP) and LoVo cells were used in the present study. The effect of G-Rh2 on LoVo/L-OHP and LoVo cell proliferation was measured using a 3-(4,5 dimethylthiazol-z-yl)-3,5-diphenyltetrazolium bromide assay. The effects of G-Rh2 on LoVo/L-OHP and LoVo cell apoptosis were detected by flow cytometry. The mRNA and protein expression of apoptosis-related genes Bax, Bcl-2 and caspase-3, drug resistance-related genes P-glycoprotein (P-gp) and Smad4, were determined in LoVo/L-OHP and LoVo cells treated with G-Rh2 by reverse transcription-quantitative polymerase chain reaction and western blot analyses. G-Rh2 treatment significantly inhibited the proliferation and induced the apoptosis of LoVo/L-OHP and LoVo cells. In addition, G-Rh2 treatment resulted in a significant increase in pro-apoptotic factors, Bax and caspase-3, and decrease in anti-apoptotic factor Bcl-2 in the LoVo/L-OHP and LoVo cells. Furthermore, G-Rh2 treatment significantly decreased the levels of P-gp and increased the levels of Smad4 in the LoVo/L-OHP and LoVo cells. It was found that L-OHP had no significant effects on LoVo/L-OHP cell proliferation or apoptosis, whereas G-Rh2 + L-OHP treatment significantly inhibited LoVo/L-OHP cell proliferation and induced apoptosis. L-OHP had no significant effects on the expression of P-gp, Smad4, Bcl-2, Bax or caspase-3 in LoVo/L-OHP cells. Treatment with G-Rh2 + L-OHP significantly reduced the expression of P-gp and Bcl-2, and enhanced the expression levels of Smad4, Bax and caspase-3. These findings demonstrated that G-Rh2 reversed the drug resistance of LoVo/L-OHP cells to L-OHP, and this may be mediated by inhibiting cell proliferation and promoting apoptosis and regulating the expression of drug resistance genes. These results suggest that G-Rh2 may function as a potent anticancer drug for drug resistance in colon cancer treatment.

In vitro Effect of Recombinant Feline Interferon-Ω (rFeIFN-Ω) on the Primary CanineTransmissible Venereal Tumor Culture.

Background: Interferons (IFNs), signaling proteins produced by host cells, are secreted in response to pathogen activity as well as to tumor cells, and display antiviral, antiproliferative, and immunomodulatory effects. Recombinant feline interferon omega (rFeIFN-ω) has in vitro growth inhibition activities on various canine and feline tumor cell lines. Canine transmissible venereal tumor (CTVT) is used as an animal model for immunotherapy due to its specific growth phase. Previous studies have usually focused on the interaction between tumor infiltrating lymphocytes (TILs) and CTVT cells. However, the specific effects of rFeIFN-ω on CTVT cells remains poorly defined.Aims: The aims of this study, therefore, were to evaluate the in vitro effect of rFeIFN-ω on primary CTVT cells and to study the mRNA expression of apoptotic genes and drug resistance genes.Materials and Methods: Purified CTVT cells were treated with various concentrations of rFeIFN-ω and the viability of the cultured cells was ascertained at 24, 48, and 72 h post treatment (hpt) and a dose-response curve plotted. The mRNA expression of apoptotic (BAX and BCL-2) and drug resistance (ABCB1 and ABCG2) genes was performed by reverse transcription quantitative real-time PCR at 72 hpt.Results: rFeIFN-ω displayed an effect against CTVT cell viability, which decreasing viability in a dose-dependent manner within 72 hpt. The relative mRNA expression of BCL-2 was upregulated only at a rFeIFN-ω concentration of 104 IU/100 μl. However, higher concentrations of rFeIFN-ω gave a higher level of relative mRNA expression of ABCB1 transporter gene.Conclusion: This study provided the information of in vitro effect of rFeIFN-ω on CTVT cell viability in a dose dependent manner, as well as, the alteration of BCL-2 and ABCB1 gene expression after treatment. These results encourage future in vivo studies to evaluate the potential efficacy of this treatment in CTVT cases.

Utilization of optically induced dielectrophoresis in a microfluidic system for sorting and isolation of cells with varied degree of viability: Demonstration of the sorting and isolation of drug-treated cancer cells with various degrees of anti-cancer drug resistance gene expression

The heterogeneity of the drug resistance of cancer cells in a tumor is regarded as an important cause of therapeutic resistance and thus treatment failure. An understanding of the heterogeneity of cancer cells in a tumor in terms of their anti-cancer drug resistance is of great value for clinical applications or fundamental studies. To achieve this goal, a combination of cell-based drug testing and optically induced dielectrophoresis (ODEP)-based cell manipulation for sorting, separation, and isolation of drug-treated cells with various degrees of cell viability is proposed. For the latter, the key working principle is based on the difference in the ODEP force generated on the cells with various degrees of viability. To test the proposed idea, an ODEP microfluidic system was designed and fabricated in which two types of ODEP-based cell manipulation schemes were tested. The results successfully demonstrated that the proof-of-concept and practical application schemes were capable of effectively sorting, separating, and isolating doxorubicin-treated Dx5 (i.e., cells with drug resistance) and MES-SA (i.e., cells without drug resistance) cells that exhibited various degrees of viability and levels of anti-cancer drug resistance gene (i.e., ABCB1) expression. Moreover, the results also demonstrated that the proposed technique was capable of sorting and separating cell of the same type (i.e., drug-treated Dx5 cells) but different degrees of viability and anti-cancer drug resistance gene expression levels. Overall, this study presents a technique that is able to effectively sort, separate, and isolate drug-treated cancer cells with phenotypic heterogeneity for subsequent clinical applications or fundamental studies.

Emodin Enhances the Chemosensitivity of Endometrial Cancer by Inhibiting ROS-Mediated Cisplatin-resistance.

Endometrial cancer is a common cause of death in gynecological malignancies. Cisplatin is a clinically chemotherapeutic agent. However, drug-resistance is the primary cause of treatment failure. Emodin is commonly used clinically to increase the sensitivity of chemotherapeutic agents, yet whether Emodin promotes the role of Cisplatin in the treatment of endometrial cancer has not been studied. CCK-8 kit was utilized to determine the growth of two endometrial cancer cell lines, Ishikawa and HEC-IB. The apoptosis level of Ishikawa and HEC-IB cells was detected by Annexin V / propidium iodide double-staining assay. ROS level was detected by DCFH-DA and NADPH oxidase expression. Expressions of drug-resistant genes were examined by real-time PCR and Western blotting. Emodin combined with Cisplatin reduced cell growth and increased the apoptosis of endometrial cancer cells. Co-treatment of Emodin and Cisplatin increased chemosensitivity by inhibiting the expression of drugresistant genes through reducing the ROS levels in endometrial cancer cells. In an endometrial cancer xenograft murine model, the tumor size was reduced and animal survival time was increased by co-treatment of Emodin and Cisplatin. This study demonstrates that Emodin enhances the chemosensitivity of Cisplatin on endometrial cancer by inhibiting ROS-mediated expression of drug-resistance genes.

Effect of resveratrol on proliferation of telmozolamine resistant glioblastoma and mechanism

Objective To investigate the effect of resveratrol on the proliferation of glioblastoma resistant to temozolamine (TMZ) and the relationship between cell cycle and drug resistance genes expression. Methods U87 cell line was adopted to induce TMZ glioma model (U87-TMZ) by increasing the concentration of temozolomide. Methyl thiazol tetrazolium (MTT) assay was used to detect the proliferation of drug-resistant cell lines. Flow cytometry was used to detect the change of U87-TMZ cell cycle by resveratrol. Western blotting was used to detect the expression of Cyclin D1, topoisomerase (TOPOⅡ)α, glutathione-s-transferase (GST)-π, O6-methylguanine-DNA-methyltransferase (MGMT), and P-glycoprotein (P-gp). Results U87 glioma cells were stably stimulated with 20 μg/ml temozolamine for 6 months, and the U87-TMZ model was successfully constructed. Compared with the control group (DMSO group) and the blank group, the inhibition of proliferation of glioma cells was significantly decreased in 24 h in U87-TMZ model treated with 40 μg/ml resveratrol (experimental group) (P=0.014). Resveratrol inhibited the U87-TMZ cell cycle in a different period as compared with the control group, resulting in prolongation of the G1 phase and a decrease in the division phase. Western blotting analysis showed that resveratrol had different expression of drug resistance genes. The expression of Cyclin D1, TOPOⅡα, GST-π and MGMT proteins was significantly decreased in U87-TMZ group (experimental group) as compared with U87 group (P=0.002, 0.007, 0.031). Before and after treatment with resveratrol in the U87-TMZ group (experimental group), the expression of P-gp gene was not significantly different (P=1.043). The content of Cyclin D protein in U87-TMZ group was related to the change of resveratrol resistance genes. After up-regulating the expression of Cyclin D, the expression of TOPOⅡα, GST-π, MGMT and P-gp was statistically significantly increased (P= 0.001). Conclusion Resveratrol inhibits tumor cell proliferation by affecting the expression of Cyclin D protein and regulating U87-TMZ cell cycle. The mechanism may be related to the reduction of the sensitivity of the drug resistance of TOPO Ⅱ α, GST-π and MGMT gene expression. Key words: Resveratrol; Glioblastoma; Temozolamide; Drug resistance

Expression of resistance gene and prognosis of chemotherapy in primary epithelial ovarian cancer

The sensitivity of tumor cells to chemotherapy drugs may become attenuated accounts for various reasons. Reduced drug sensitivity may cause the failure of chemotherapy and affect the prognosis of patients with cancer. This study investigates the relationship between the expression levels of lung resistance protein (LRP) and placental glutathione S-transferase-P1 (GSTP1), the resistance of primary epithelial ovarian cancer (PEOC) to chemotherapy, and the prognosis of patients with platinum drug-resistant PEOC.Quantitative PCR (QT-PCR) was used to detect the mRNA level of the resistance genes LRP, GSTP1 in all tissue and cell lines.The expression levels of resistance gene (LRP, GSTP1) in PEOC were the highest, followed by borderline adenoma tissues, and the lowest levels found in benign tumor tissues, the difference of genes expression between different tissues was statistically significant; the difference between the expression rates and relative expression level of drug resistance genes was statistically significant in platinum sensitive group compare with the platinum resistant group. The difference between resistant gene negative-expression and positive-expression of chemotherapy efficiency, disease free survival time, and recurrence time were statistically significant. The resistant genes expression in the PEOC patients of the negative-group survival curves was higher than that in the positive group. With ascites non-cellular component (ANCC) stimulated SKOV3 cells, the cell proliferation inhibition rate (CPIR) increased, and with ANCC stimulated SKOV3/DDP, the expression of LRP and GSTP1 also increased.ANCC may promote the expression of drug resistance genes, and the expression of genes may predict the poorly prognosis of epithelial ovarian cancer.

DIFFERENT MORPHOLOGICAL STRUCTURES OF BREAST TUMORS DEMONSTRATE INDIVIDUAL DRUG RESISTANCE GENE EXPRESSION PROFILES

To identify gene expression profiles involved in drug resistance of different morphological structures (tubular, alveolar, solid, trabecular, and discrete) presented in breast cancer. Ten patients with luminal breast cancer have been included. A laser microdissection-assisted microarrays and qRT-PCR were used to perform whole-transcriptome profiling of different morphological structures, to select differentially expressed drug response genes, and to validate their expression. We found 27differentially expressed genes (p < 0.05) encoding drug uptake (SLC1A3, SLC23A2, etc.) and efflux (ABCC1, ABCG1, etc.) transporters, drug targets (TOP2A, TYMS, and Tubb3), and proteins that are involved in drug detoxification (NAT1and ALDH1B1), cell cycle progression (CCND1, AKT1, etc.), apoptosis (CASP3, TXN2, etc.), and DNA repair (BRCA1and USP11). Each type of structures showed an individual gene expression profile related to resistance and sensitivity to anticancer drugs. However, most of the genes (19/27; p < 0.05) were expressed in alveolar structures. Functional enrichment analysis showed that drug resistance is significantly associated with alveolar structures. Other structures demonstrated the similar number (10-13out of 27) of expressed genes; however, the spectrum of resistance and sensitivity to different anticancer drugs varied. Different morphological structures of breast cancer show individual expression of drug resistance genes.

Significant Role of MUC1 in Development of Resistance to Currently Existing Anti-cancer Therapeutic Agents.

As an extensively glycosylated transmembrane protein of epithelium, Mucin1 (MUC1) mostly protects cells from tensions induced by external milieu. Physiologically, during stress condition, MUC1 separates into MUC1-N and MUC1-C moieties, resulting in transduction of inward survival signals, essential for maintaining cell's functionality. Recent studies have proposed a significant correlation between MUC1 overexpression and amplification of cancer cell's proliferation and metastasis through modulation of multiple signaling pathways and cell-cell and cell-matrix interactions. It has been shown that MUC1- Cytoplasmic Domain (MUC1-CD) accelerates development of resistance to several anti-cancer therapeutic agents including bortezomib, trastuzumab and tamoxifen. Furthermore, MUC1-CD is also involved in promoting expression of multi drug resistance (MDR) genes and finally, silencing MUC1 expression was together with resensitization of human epidermal growth factor receptor 2 positive (HER2+) and/or estrogen receptor (ER+) positive breast cancer cells to bortezomib, trastuzumab and tamoxifen respectively. In this review, we briefly describe the role of MUC1 proto-oncogene in cancer cell's survival, tumor progression and metastasis and then continue with mentioning the mechanisms through which MUC1 induce resistance to various currently existing therapeutic agents in market including bortezomib, trastuzumab and tamoxifen.

Low-frequency ultrasound enhances chemotherapy sensitivity and induces autophagy in PTX-resistant PC-3 cells via the endoplasmic reticulum stress-mediated PI3K/Akt/mTOR signaling pathway.

BackgroundSonodynamic therapy (SDT) is an emerging tumor-inhibiting method that has gained attention in cancer therapy in the last several years. Although autophagy has been observed in SDT-treated cancer cells, its role and mechanism of action remain unclear. This study aimed to investigate the effects of low-frequency ultrasound on autophagy and drug-resistance of paclitaxel (PTX)-resistant PC-3 cells via the endoplasmic reticulum stress (ERs)-mediated PI3K/AT/mTOR signaling pathway.MethodsCCK-8 assay was conducted to select the appropriate exposure time for PTX-resistant PC-3 cells under low-frequency ultrasound. PTX-resistant PC-3 cells were divided into a control group, PTX group, ultrasound group, ultrasound + PTX group, ultrasound + PTX + autophagy-related gene 5 (Atg5) siRNA group, and ultrasound + 4-PBA (an ERs inhibitor) group. Autophagy was observed by transmission electron microscopy (TEM) and fluorescence microscopy. Cell proliferation was evaluated using CCK-8 assay; apoptosis was detected by flow cytometry. Expression of multiple drug-resistance genes was detected by qRT-PCR. Western blotting was used to detect the expression of ERS-related proteins, autophagy-related proteins, apoptosis-related proteins, and PI3K/AKT/mTOR pathway-related proteins.ResultsTen-second exposure was selected as optimal for all experiments. Compared to the PTX group, the level of autophagy, inhibition rate, apoptosis rate, and expression of ERS-related proteins (GRP78) increased, whereas the expression of multiple drug-resistance genes (MRP3, MRP7, and P-glycoprotein), PI3K/AKT/mTOR pathway-related proteins (PI3K, p-AKT, mTORC1), and apoptosis-related proteins (Bcl-2, NF-κB) decreased in PTX-resistant PC-3 cells after low-frequency ultrasound and PTX treatment for 24 h. These trends were more obvious after treatment with Atg5 siRNA, excluding the autophagy level. Post 4-PBA-treatment, the expression of GRP78 and LC3II proteins decreased, whereas that of PI3K, p-AKT, and mTORC1 increased.ConclusionResults indicated that ultrasound induces autophagy by ERs-mediated PI3K/AKT/mTOR signaling pathway in PTX-resistant PC-3 cells; this autophagy acts as a cytoprotector during low-frequency ultrasound-mediated reversal of drug resistance.

Abstract LB-049: Cancer stem cell-produced lysophosphatidic acid reprograms surrounding tumor cells to a stem-like state

Abstract Within a tumor, cancer stem cells (CSCs) represent a small yet highly aggressive, metastatic population that enhances the progression of the surrounding non-CSCs. Here we define lysophosphatidic acid (LPA) as a primary factor produced by pancreatic CSCs that converts non-CSCs to a stem-like fate. LPA promotes increased anchorage independence, drug resistance, self-renewal and stem gene expression including Oct4 and Nanog. Cancer stem cells were found to express high levels of the LPA producing enzyme cPLA2 explaining their production of LPA. Pancreatic cancer cells exposed to the drug Gemcitabine showed a dramatic upregulation of the LPA receptor 4 enabling the cells to become drug resistant and tolerant to a range of microenvironmental stresses. These finding indicate that LPA is a bioactive lipid produced by CSCs that converts surround pancreatic tumor cells to a highly aggressive state. Therapeutic intervention and/or microenvironmental stress will induce non-CSCs to express LPA Receptor 4, thereby making them stress tolerant and drug resistant. Evidence is provided that targeting the LPA receptor pathway may reverse this paracrine effect and thereby reverse cancer progression and drug resistance. Citation Format: Taha Rakhshandehroo, Jiali Tan, Brandon Grosshart, David Cheresh. Cancer stem cell-produced lysophosphatidic acid reprograms surrounding tumor cells to a stem-like state [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-049.

Fabrication and Characterization of Chitosan-Hyaluronic Acid Scaffolds with Varying Stiffness for Glioblastoma Cell Culture.

The invasive and recurrent nature of glioblastoma multiforme (GBM) is linked to a small subpopulation of cancer cells, which are self-renewing, resistant to standard treatment regimens, and induce formation of new tumors. Matrix stiffness is implicated in the regulation of cell proliferation, drug resistance, and reversion to a more invasive phenotype. Therefore, understanding the relationship between matrix stiffness and tumor cell behavior is vital to develop appropriate in vitro tumor models. Here, chitosan-hyaluronic acid (CHA) polyelectrolyte complex scaffolds are fabricated with statistically significant stiffness variances to characterize the effect of scaffold stiffness on morphology, proliferation, drug resistance, and gene expression in human glioblastoma cells (U-87 MG). All scaffolds support GBM proliferation over a 12-day culture period, yet larger spheroids are observed in scaffolds with higher stiffness. Additionally, GBM cells cultured in stiffer CHA scaffolds prove significantly more resistant to the common chemotherapeutic temozolomide. Moreover, the stiffer 8% CHA scaffolds exhibit an increase in expression of drug resistance and invasion related genes compared to 2D culture. CHA scaffolds present a tunable microenvironment for enhanced tumor cell malignancy and may provide a valuable in vitro microenvironment for studying tumor progression and screening anticancer therapies.

Down-regulation of MDR1 by Ad-DKK3 via Akt/NFκB pathways augments the anti-tumor effect of temozolomide in glioblastoma cells and a murine xenograft model.

Glioblastoma multiforme (GBM) is the most malignant of brain tumors. Acquired drug resistance is a major obstacle for successful treatment. Earlier studies reported that expression of the multiple drug resistance gene (MDR1) is regulated by YB-1 or NFκB via the JNK/c-Jun or Akt pathway. Over-expression of the Dickkopf (DKK) family member DKK3 by an adenovirus vector carrying DKK3 (Ad-DKK3) exerted anti-tumor effects and led to the activation of the JNK/c-Jun pathway. We investigated whether Ad-DKK3 augments the anti-tumor effect of temozolomide (TMZ) via the regulation of MDR1. GBM cells (U87MG and U251MG), primary TGB105 cells, and mice xenografted with U87MG cells were treated with Ad-DKK3 or TMZ alone or in combination. Ad-DKK3 augmentation of the anti-tumor effects of TMZ was associated with reduced MDR1 expression in both in vivo and in vitro studies. The survival of Ad-DKK3-treated U87MG cells was inhibited and the expression of MDR1 was reduced. This was associated with the inhibition of Akt/NFκB but not of YB-1 via the JNK/c-Jun- or Akt pathway. Our results suggest that Ad-DKK3 regulates the expression of MDR1 via Akt/NFκB pathways and that it augments the anti-tumor effects of TMZ in GBM cells.