Acquisition of paclitaxel resistance via PI3K‑dependent epithelial‑mesenchymal transition in A2780 human ovarian cancer cells

Combined PI3K Inhibitor and Eribulin Enhances Anti-Tumor Activity in Preclinical Models of Paclitaxel-Resistant, PIK3CA-Mutated Endometrial Cancer

Endometrial cancer stands as the predominant gynecological malignancy in developed nations. For advanced or recurrent disease, paclitaxel-based chemotherapy is the standard front-line therapy. However, paclitaxel resistance eternally develops. Based on the high prevalence of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutation, reaching 50%, in endometrial cancer, we preclinically investigated the effectiveness of a combination of a phosphatidylinositol 3-kinase (PI3K) inhibitor with eribulin, a post-paclitaxel therapy for breast cancer, in treating paclitaxel-resistant, PIK3CA-mutated endometrial cancer. We generated paclitaxel-resistant cell lines from PIK3CA-mutated endometrial cancer cell lines by gradually increasing the concentration of paclitaxel in cell cultures. We observed that the PI3K/AKT and epithelial-mesenchymal transition (EMT) pathways in paclitaxel-resistant cells were significantly upregulated compared with those in parental cells. Then, we demonstrated that the combination of alpelisib (a PI3K inhibitor) and eribulin more effectively suppressed the cellular growth of paclitaxel-resistant cells in in vitro and in vivo xenograft models. Mechanistically, we demonstrated that the effect of the combination could be enhanced by inhibiting both the PI3K/AKT and EMT pathways. Therefore, we suggest that paclitaxel resistance is associated with the activation of the PIK3/AKT pathway in PIK3CA-mutated endometrial cancer, and the combination of a PI3K inhibitor and eribulin merits further clinical investigation.

Mechanisms of cancer cell death induction by paclitaxel: an updated review

Chemoresistance of cancer cells is a major problem in treating cancer. Knowledge of how cancer cells may die or resist cancer drugs is critical to providing certain strategies to overcome tumour resistance to treatment. Paclitaxel is known as a chemotherapy drug that can suppress the proliferation of cancer cells by inducing cell cycle arrest and induction of mitotic catastrophe. However, today, it is well known that paclitaxel can induce multiple kinds of cell death in cancers. Besides the induction of mitotic catastrophe that occurs during mitosis, paclitaxel has been shown to induce the expression of several pro-apoptosis mediators. It also can modulate the activity of anti-apoptosis mediators. However, certain cell-killing mechanisms such as senescence and autophagy can increase resistance to paclitaxel. This review focuses on the mechanisms of cell death, including apoptosis, mitotic catastrophe, senescence, autophagic cell death, pyroptosis, etc., following paclitaxel treatment. In addition, mechanisms of resistance to cell death due to exposure to paclitaxel and the use of combinations to overcome drug resistance will be discussed.

Investigation of role of CpG methylation in some epithelial mesenchymal transition gene in a chemoresistant ovarian cancer cell line

Ovarian cancer is one of the lethal gynecologic cancers. Chemoresistance is an essential reason for treatment failure and high mortality. Emerging evidence connects epithelial-mesenchymal transition (EMT) like changes and acquisition of chemoresistance in cancers. Including EMT, DNA methylation influences cellular processes. Here, EMT-like changes were investigated in cisplatin-resistant A2780 ovarian cancer cells (A2780cis), wherein role of DNA methylation in some EMT genes regulations was studied. Cell viability assay was carried out to test the sensitivity of A2780, and A2780cis human cancer cell lines to cisplatin. Differential mRNA expression of EMT markers using qPCR was conducted to investigate EMT like changes. CpG methylation role in gene expression regulation was investigated by 5-azacytidine (5-aza) treatment. DNA methylation changes in EMT genes were identified using Methylscreen assay between A2780 and A2780cis cells. In order to evaluate if DNA methylation changes are causally underlying EMT, treatment with 5-aza followed by Cisplatin was done on A2780cis cells. Accordingly, morphological changes were studied under the microscope, whereas EMT marker's gene expression changes were investigated using qPCR. In this respect, A2780cis cell line has maintained its cisplatin tolerance ability and exhibits phenotypic changes congruent with EMT. Methylscreen assay and qPCR study have revealed DNA hypermethylation in promoters of epithelial adhesion molecules CDH1 and EPCAM in A2780cis compared to the cisplatin-sensitive parental cells. These changes were concomitant with gene expression down-regulation. DNA hypomethylation associated with transcription up-regulation of the mesenchymal marker TWIST2 was observed in the resistant cells. Azacytidine treatment confirmed DNA methylation role in regulating gene expression of CDH1, EPCAM and TWIST2 genes. A2780cis cell line undergoes EMT like changes, and EMT genes are regulated by DNA methylation. To that end, a better understanding of the molecular alterations that correlate with chemoresistance may lead to therapeutic benefits such as chemosensitivity restoration.

Comparing the Secretomes of Chemorefractory and Chemoresistant Ovarian Cancer Cell Populations

High-grade serous ovarian cancer (HGSOC) constitutes the majority of all ovarian cancer cases and has staggering rates of both refractory and recurrent disease. While most patients respond to the initial treatment with paclitaxel and platinum-based drugs, up to 25% do not, and of the remaining that do, 75% experience disease recurrence within the subsequent two years. Intrinsic resistance in refractory cases is driven by environmental stressors like tumor hypoxia which alter the tumor microenvironment to promote cancer progression and resistance to anticancer drugs. Recurrent disease describes the acquisition of chemoresistance whereby cancer cells survive the initial exposure to chemotherapy and develop adaptations to enhance their chances of surviving subsequent treatments. Of the environmental stressors cancer cells endure, exposure to hypoxia has been identified as a potent trigger and priming agent for the development of chemoresistance. Both in the presence of the stress of hypoxia or the therapeutic stress of chemotherapy, cancer cells manage to cope and develop adaptations which prime populations to survive in future stress. One adaptation is the modification in the secretome. Chemoresistance is associated with translational reprogramming for increased protein synthesis, ribosome biogenesis, and vesicle trafficking. This leads to increased production of soluble proteins and extracellular vesicles (EVs) involved in autocrine and paracrine signaling processes. Numerous studies have demonstrated that these factors are largely altered between the secretomes of chemosensitive and chemoresistant patients. Such factors include cytokines, growth factors, EVs, and EV-encapsulated microRNAs (miRNAs), which serve to induce invasive molecular, biophysical, and chemoresistant phenotypes in neighboring normal and cancer cells. This review examines the modifications in the secretome of distinct chemoresistant ovarian cancer cell populations and specific secreted factors, which may serve as candidate biomarkers for aggressive and chemoresistant cancers.

Malignant Ascites in Ovarian Cancer: Cellular, Acellular, and Biophysical Determinants of Molecular Characteristics and Therapy Response

Ascites refers to the abnormal accumulation of fluid in the peritoneum resulting from an underlying pathology, such as metastatic cancer. Among all cancers, advanced-stage epithelial ovarian cancer is most frequently associated with the production of malignant ascites and is the leading cause of death from gynecologic malignancies. Despite decades of evidence showing that the accumulation of peritoneal fluid portends the poorest outcomes for cancer patients, the role of malignant ascites in promoting metastasis and therapy resistance remains poorly understood. This review summarizes the current understanding of malignant ascites, with a focus on ovarian cancer. The first section provides an overview of heterogeneity in ovarian cancer and the pathophysiology of malignant ascites. Next, analytical methods used to characterize the cellular and acellular components of malignant ascites, as well the role of these components in modulating cell biology, are discussed. The review then provides a perspective on the pressures and forces that tumors are subjected to in the presence of malignant ascites and the impact of physical stress on therapy resistance. Treatment options for malignant ascites, including surgical, pharmacological and photochemical interventions are then discussed to highlight challenges and opportunities at the interface of drug discovery, device development and physical sciences in oncology.

New insight towards development of paclitaxel and docetaxel resistance in cancer cells: EMT as a novel molecular mechanism and therapeutic possibilities

Epithelial-to-mesenchymal transition (EMT) mechanism is responsible for metastasis and migration of cancer cells to neighboring cells and tissues. Morphologically, epithelial cells are transformed to mesenchymal cells, and at molecular level, E-cadherin undergoes down-regulation, while an increase occurs in N-cadherin and vimentin levels. Increasing evidence demonstrates role of EMT in mediating drug resistance of cancer cells. On the other hand, paclitaxel (PTX) and docetaxel (DTX) are two chemotherapeutic agents belonging to taxene family, capable of inducing cell cycle arrest in cancer cells via preventing microtubule depolymerization. Aggressive behavior of cancer cells resulted from EMT-mediated metastasis can lead to PTX and DTX resistance. Upstream mediators of EMT such as ZEB1/2, TGF-β, microRNAs, and so on are involved in regulating response of cancer cells to PTX and DTX. Tumor-suppressing factors inhibit EMT to promote PTX and DTX sensitivity of cancer cells. Furthermore, three different strategies including using anti-tumor compounds, gene therapy and delivery systems have been developed for suppressing EMT, and enhancing cytotoxicity of PTX and DTX against cancer cells that are mechanistically discussed in the current review.

Combination of Immune-Related Genomic Alterations Reveals Immune Characterization and Prediction of Different Prognostic Risks in Ovarian Cancer

With the highest case-fatality rate among women, the molecular pathological alterations of ovarian cancer (OV) are complex, depending on the diversity of genomic alterations. Increasing evidence supports that immune infiltration in tumors is associated with prognosis. Therefore, we aim to assess infiltration in OV using multiple methods to capture genomic signatures regulating immune events to identify reliable predictions of different outcomes. A dataset of 309 ovarian serous cystadenocarcinoma patients with overall survival >90 days from The Cancer Genome Atlas (TCGA) was analyzed. Multiple estimations and clustering methods identified and verified two immune clusters with component differences. Functional analyses pointed out immune-related alterations underlying internal genomic variables potentially. After extracting immune genes from a public database, the LASSO Cox regression model with 10-fold cross-validation was used for selecting genes associated with overall survival rate significantly, and a risk score model was then constructed. Kaplan-Meier survival and Cox regression analyses among cohorts were performed systematically to evaluate prognostic efficiency among the risk score model and other clinical pathological parameters, establishing a predictive ability independently. Furthermore, this risk score model was compared among identified signatures in previous studies and applied to two external cohorts, showing better prediction performance and generalization ability, and also validated as robust in association with immune cell infiltration in bulk tissues. Besides, a transcription factor regulation network suggested upper regulatory mechanisms in OV. Our immune risk score model may provide gyneco-oncologists with predictive values for the prognosis and treatment management of patients with OV.

GTW inhibits the Epithelial to Mesenchymal Transition of Epithelial Ovarian Cancer via ILK/AKT/GSK3β/Slug Signalling Pathway

Background: Epithelial ovarian cancer (EOC) accounts for the most lethal of all gynaecological cancers which is attributed to metastasis, invasiveness and drug resistance. A crucial link has been found between epithelial-mesenchymal transition (EMT) and cancer metastasis and chemo-resistance. Previous studies have confirmed that one of the main components of tripterygium glycosides (GTW)-triptolide (TPL) has anticancer effects. Methods: The purpose of this study is to determine whether GTW could inhibit EMT in A2780/DPP cells in vitro and in vivo, and explore the underlying mechanism. Results: In vitro results showed that GTW inhibited cell proliferation, invasion and migration, and intensified the sensitivity of A2780/DDP cells to cisplatin (DDP). GTW, especially GTW+DDP, significantly inhibited the expression of N-cadherin, integrin-linked kinase (ILK), phospho-protein kinase B/AKT (PKB/p-AKT), phospho-glycogen synthase kinase (p-GSK3β) and Slug, while it increased E-cadherin levels by inhibiting EMT via the ILK/AKT/GSK3β/Slug signalling pathway. Animal results indicated that GTW, especially GTW+DDP, significantly reduced tumour burden, prolonged the life span of mice, and down-regulated the levels of tumour markers CA125 and HE4 by regulating EMT through the ILK/AKT/GSK3β/Slug signalling pathway. Conclusion: Our results highlighted the significance of EMT in EOC metastasis, invasiveness and resistance to DDP and investigated the potential role of GTW as an adjuvant therapeutic agent in chemo-resistant EOC.

Specific c-Jun N-Terminal Kinase Inhibitor, JNK-IN-8 Suppresses Mesenchymal Profile of PTX-Resistant MCF-7 Cells through Modulating PI3K/Akt, MAPK and Wnt Signaling Pathways

Paclitaxel (PTX) is a widely used chemotherapeutic agent in the treatment of breast cancer, and resistance to PTX is a common failure of breast cancer therapy. Therefore, understanding the effective molecular targets in PTX-resistance gains importance in identifying novel strategies in successful breast cancer therapy approaches. The aim of the study was to investigate the functional role of PTX resistance on MCF-7 cell survival and proliferation related to PI3K/Akt and MAPK pathways. The generated PTX-resistant (PTX-res) MCF-7 cells showed enhanced cell survival, proliferation, and colony formation potential with decreased cell death compared to wt MCF-7 cells. PTX-res MCF-7 cells exhibited increased motility profile with EMT, PI3K/Akt, and MAPK pathway induction. According to the significant SAPK/JNK activation in PTX-res MCF-7 cells, specific c-Jun N-terminal kinase inhibitor, JNK-IN-8 is shown to suppress the migration potential of cells. Treatment of JNK inhibitor suppressed the p38 and SAPK/JNK and Vimentin expression. However, the JNK inhibitor further downregulated Wnt signaling members in PTX-res MCF-7 cells. Therefore, the JNK inhibitor JNK-IN-8 might be used as a potential therapy model to reverse PTX-resistance related to Wnt signaling.

Nanoparticle delivery systems to combat drug resistance in ovarian cancer

Due to the lack of early symptoms and difficulty of accurate diagnosis, ovarian cancer is the most lethal gynecological cancer faced by women. First-line therapy includes a combination of tumor resection surgery and chemotherapy regimen. However, treatment becomes more complex upon recurrence due to development of drug resistance. Drug resistance has been linked to many mechanisms, including efflux transporters, apoptosis dysregulation, autophagy, cancer stem cells, epigenetics, and the epithelial-mesenchymal transition. Thus, developing and choosing effective therapies is exceptionally complex. There is a need for increased specificity and efficacy in therapies for drug-resistant ovarian cancer, and research in targeted nanoparticle delivery systems aims to fulfill this challenge. Although recent research has focused on targeted nanoparticle-based therapies, few of these therapies have been clinically translated. In this review, non-viral nanoparticle delivery systems developed to overcome drug-resistance in ovarian cancer were analyzed, including their structural components, surface modifications, and drug-resistance targeted mechanisms.

EDIL3 promotes epithelial-mesenchymal transition and paclitaxel resistance through its interaction with integrin αVβ3 in cancer cells

Epithelial-mesenchymal transition (EMT) has recently been associated with tumor progression, metastasis, and chemotherapy resistance in several tumor types. We performed a differential gene expression analysis comparing paclitaxel-resistant vs. paclitaxel-sensitive breast cancer cells that showed the upregulation of EDIL3 (EGF Like Repeats and Discoidin I Like Domains Protein 3). This gene codifies an extracellular matrix protein that has been identified as a novel regulator of EMT, so we studied its role in tumor progression and paclitaxel response. Our results demonstrated that EDIL3 expression levels were increased in paclitaxel-resistant breast and prostate cancer cells, and in subsets of high-grade breast and prostate tumors. Moreover, we observed that EDIL3 modulated the expression of EMT markers and this was impaired by cilengitide, which blocks the EDIL3-integrin αVβ3 interaction. EDIL3 knockdown reverted EMT and sensitized cells to paclitaxel. In contrast, EDIL3 overexpression or the culture of cells in the presence of EDIL3-enriched medium induced EMT and paclitaxel resistance. Adding cilengitide resensitized these cells to paclitaxel treatment. In summary, EDIL3 may contribute to EMT and paclitaxel resistance through autocrine or paracrine signaling in cancer cells. Blockade of EDIL3-integrin αVβ3 interaction by cilengitide restores sensitivity to paclitaxel and reverts EMT in paclitaxel-resistant cancer cells. Combinations of cilengitide and taxanes could be beneficial in the treatment of subsets of breast and prostate cancers.

Dual Effects of Non-Coding RNAs (ncRNAs) in Cancer Stem Cell Biology

The identification of cancer stem cells (CSCs) as initiators of carcinogenesis has revolutionized the era of cancer research and our perception for the disease treatment options. Additional CSC features, including self-renewal and migratory and invasive capabilities, have further justified these cells as putative diagnostic, prognostic, and therapeutic targets. Given the CSC plasticity, the identification of CSC-related biomarkers has been a serious burden in CSC characterization and therapeutic targeting. Over the past decades, a compelling amount of evidence has demonstrated critical regulatory functions of non-coding RNAs (ncRNAs) on the exclusive features of CSCs. We now know that ncRNAs may interfere with signaling pathways, vital for CSC phenotype maintenance, such as Notch, Wnt, and Hedgehog. Here, we discuss the multifaceted contribution of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as representative ncRNA classes, in sustaining the CSC-like traits, as well as the underlying molecular mechanisms of their action in various CSC types. We further discuss the use of CSC-related ncRNAs as putative biomarkers of high diagnostic, prognostic, and therapeutic value.

miRNAs: A Promising Target in the Chemoresistance of Bladder Cancer

Chemotherapy is an important cancer treatment method. Tumor chemotherapy resistance is one of the main factors leading to tumor progression. Like other malignancies, bladder cancer, especially muscle-invasive bladder cancer, is prone to chemotherapy resistance. Additionally, only approximately 50% of muscle-invasive bladder cancer responds to cisplatin-based chemotherapy. miRNAs are a class of small, endogenous, noncoding RNAs that regulate gene expression at the posttranscriptional level, which results in the inhibition of translation or the degradation of mRNA. In the study of miRNAs and cancer, including gastric cancer, prostate cancer, liver cancer, and colorectal cancer, it has been found that miRNAs can regulate the expression of genes related to tumor resistance, thereby promoting the progression of tumors. In bladder cancer, miRNAs are also closely related to chemotherapy resistance, suggesting that miRNAs can be a new therapeutic target for the chemotherapy resistance of bladder cancer. Therefore, understanding the mechanisms of miRNAs in the chemotherapy resistance of bladder cancer is an important foundation for restoring the chemotherapy sensitivity of bladder cancer and improving the efficacy of chemotherapy and patient survival. In this article, we review the role of miRNAs in the development of chemotherapy-resistant bladder cancer and the various resistance mechanisms that involve apoptosis, the cell cycle, epithelial-mesenchymal transition (EMT), and cancer stem cells (CSCs).

Sema4C mediates EMT inducing chemotherapeutic resistance of miR-31-3p in cervical cancer cells

Sema4C, the target of many miRNAs, is involved in EMT-mediated chemotherapeutic resistance of many malignant tumors. However, the underlying upstream regulatory mechanisms of Sema4C-induced EMT and Sema4C-mediated drug resistance are still unclear. The aim of this study was to explore the potential role of miR-31-3p/Sema4C in regulating EMT in cisplatin-resistant (CR) cervical cancer cells. High expression levels of Sema4C were more frequently found in cervical cancer tissues and were associated with poor prognosis, whereas miR-31-3p was significantly downregulated in cervical cancer tissues, which was associated with shorter disease-free and overall survival. Overexpression of miR-31-3p inhibited malignant behaviors and EMT of cervical cancer cells in vitro. Furthermore, miR-31-3p was identified to directly target Sema4C, and upregulation of miR-31-3p reversed EMT-mediated biological functions, including cisplatin resistance of Sema4C in cervical cancer cells. These results suggest that Sema4C promoted EMT-mediated cisplatin resistance in cervical cancer cells and that this effect was inhibited by overexpression of miR-31-3p. Thus, silencing Sema4C or overexpression of miR-31-3p could be a novel approach to treat drug resistance to chemotherapy in cervical cancers.

Inhibition of Phosphatidylinositol 3-kinase (PI3K) Signaling Synergistically Potentiates Antitumor Efficacy of Paclitaxel and Overcomes Paclitaxel-Mediated Resistance in Cervical Cancer

Acquired paclitaxel (PTX) resistance limits its effectiveness and results in advanced cancer progression. This review investigated whether the inhibition of phosphatidylinositol 3-kinase (PI3K) signaling overcomes paclitaxel resistance in cervical cancer. It was established paclitaxel-resistant cell lines (PTX-R ME180/PTX-R HeLa) and determined the combination index for paclitaxel and PI3K inhibitors (BYL-719/ LY294002) by tetrazolium dye assay. Flow cytometry was used to detect the cell cycle and apoptosis. Migration and invasion were explored by wound healing and transwell assays. Genes related to multiple pathways were assessed by a western blot. It was found that the PI3K pathway was significantly activated in paclitaxel-resistant HeLa and ME180 cells compared to parental cells. PTX + PI3K inhibitor combined therapy showed a synergistic effect by strengthening paclitaxel-induced S and G2M arrest in PTX-R cell sublines by the inactivation of cyclin A1, cyclin B1, cyclin E, and Cdc2 expression. Moreover, combination therapy significantly enhanced drug sensitivity and apoptosis through the activation of Bax, and cleavage of poly-(ADP-ribose) polymerase compared with paclitaxel alone. In addition, PI3K inhibition also suppressed tumor migration and invasion by targeting β-catenin and matrix metalloproteinase-2/9. The authors suggest that the combination of a PI3K inhibitor with paclitaxel may enhance antitumor activity through a cascade of PI3K signaling events.

All-trans retinoic acid reverses epithelial-mesenchymal transition in paclitaxel-resistant cells by inhibiting nuclear factor kappa B and upregulating gap junctions

Paclitaxel is a widely used chemotherapy drug, but development of resistance leads to treatment failure. Tumor cells that are treated with a sublethal dose of paclitaxel for a long period of time show the epithelial‐mesenchymal transition (EMT) phenotype, which leads to metastasis and resistance. All‐trans retinoic acid (ATRA) is always used in combination with paclitaxel and can reverse EMT in many types of cancer cells. The ability of ATRA to reverse EMT in chemoresistant cells is still unknown. In the present study, the ability of ATRA to reverse EMT in paclitaxel‐resistant cells was investigated. Three colorectal cancer cell lines, HCT116, LoVo and CT26, were treated with sublethal doses of paclitaxel to create resistant cell lines. Western blotting, immunocytochemistry, and “parachute” dye‐coupling assays showed that ATRA reverses EMT, inhibits nuclear factor kappa B (NF‐κΒ), and upregulates gap junctions in paclitaxel‐resistant cells. Scratch wound‐healing and Transwell assays showed that ATRA decreases the migration and invasion abilities of paclitaxel‐resistant cells. In addition, the CT26 cell line was used in the Balb/c pulmonary metastasis model to show that ATRA reduces metastasis of paclitaxel‐resistant cells in vivo. Given these data, ATRA may reverse EMT by inhibiting NF‐κΒ and upregulating gap junctions in paclitaxel‐resistant cells.

A Phase Ib, open-label, dose-finding study of alpelisib in combination with paclitaxel in patients with advanced solid tumors

Phosphatidylinositol 3-kinase (PI3K) pathway activation is associated with resistance to paclitaxel in solid tumors. We assessed the safety and activity of alpelisib, an oral, selective PI3K p110α inhibitor, plus paclitaxel in patients with advanced solid tumors. This Phase Ib, multicenter, open-label, dose-finding study, with a planned dose-expansion phase of alpelisib once daily (QD) plus fixed-dose paclitaxel, recruited patients with advanced solid tumors. For the dose-finding phase, the primary objective was determination of maximum tolerated and/or recommended Phase II dose of alpelisib plus paclitaxel, and the secondary objectives included the assessment of safety for this combination. From March 2014 to August 2016, 19 patients with advanced solid tumors were treated with alpelisib QD (300 mg, n=6; 250 mg, n=4; 150 mg, n=9) plus paclitaxel (80 mg/m², per standard of care). During dose finding, five of 12 (41.7%) evaluable patients for MTD determination experienced dose-limiting toxicities: alpelisib 300 mg, Grade 2 hyperglycemia (n=1); alpelisib 250 mg, Grade 2 hyperglycemia (n=1), Grade 4 hyperglycemia and Grade 3 acute kidney injury (n=1); and alpelisib 150 mg, Grade 2 hyperglycemia (n=1) and Grade 4 leukopenia (n=1). The MTD of alpelisib when administered with paclitaxel was 150 mg QD. Most frequent all-grade AEs were diarrhea (73.7%; Grade 3/4 10.5%) and hyperglycemia (57.9%; Grade 3/4 31.6%). The planned dose-expansion phase was not initiated. Alpelisib plus paclitaxel has a challenging safety profile in patients with advanced solid tumors. This study was closed following the completion of the dose-finding phase. Clinical trial registration: ClinicalTrials.gov NCT02051751.

Molecular Alterations and Buparlisib Efficacy in Patients with Squamous Cell Carcinoma of the Head and Neck: Biomarker Analysis from BERIL-1

Purpose: The preplanned exploratory analysis of the BERIL-1 trial presented here aimed to identify biomarkers of response to the combination of buparlisib and paclitaxel.Patients and Methods: BERIL-1 was a multicenter, randomized, double-blind, placebo-controlled phase II study. Patients with recurrent or metastatic squamous cell carcinoma of the head and neck (SCCHN) progressing on/after one previous platinum-based chemotherapy regimen in the recurrent or metastatic setting were treated with either buparlisib plus paclitaxel or placebo plus paclitaxel. Archival tumor tissue and ctDNA samples were analyzed for molecular alterations and immune infiltration using next-generation sequencing or immunohistochemistry.Results: Biomarker analyses were performed in randomized patients (n = 158) with available biomarker data. The most frequently (>5%) mutated genes were TP53, FAT1, TET2, KMT2D, PIK3CA, NOTCH1, NFE2L2, NOTCH2, CCND1, and CDKN2A Patients with SCCHN tumors (from various primary sites) having HPV-negative status (HR = 0.51), TP53 alterations (HR = 0.55) or low mutational load (HR = 0.57) derived overall survival (OS) benefit with the combination of buparlisib and paclitaxel. OS benefit with this combination was also increased in patients with presence of intratumoral TILs ≥10% (HR = 0.51), stromal TILs ≥15% (HR = 0.53), intratumoral CD8-positive cells ≥5% (HR = 0.45), stromal CD8-positive cells ≥10% (HR = 0.47), or CD8-positive cells in invasive margins >25% (HR = 0.37). A trend for improved progression-free survival with the combination of buparlisib and paclitaxel was also observed in these patients.Conclusions: The BERIL-1 biomarker analyses showed that patients with TP53 alterations, HPV-negative status, low mutational load, or high infiltration of TILs or CD8-positive cells derived survival benefit with the combination of buparlisib and paclitaxel. Clin Cancer Res; 24(11); 2505-16. ©2018 AACR.

Targeting epithelial-mesenchymal transition and cancer stem cells for chemoresistant ovarian cancer

Chemoresistance is the main challenge for the recurrent ovarian cancer therapy and responsible for treatment failure and unfavorable clinical outcome. Understanding mechanisms of chemoresistance in ovarian cancer would help to predict disease progression, develop new therapies and personalize systemic therapy. In the last decade, accumulating evidence demonstrates that epithelial-mesenchymal transition and cancer stem cells play important roles in ovarian cancer chemoresistance and metastasis. Treatment of epithelial-mesenchymal transition and cancer stem cells holds promise for improving current ovarian cancer therapies and prolonging the survival of recurrent ovarian cancer patients in the future. In this review, we focus on the role of epithelial-mesenchymal transition and cancer stem cells in ovarian cancer chemoresistance and explore the therapeutic implications for developing epithelial-mesenchymal transition and cancer stem cells associated therapies for future ovarian cancer treatment.

LncRNAs and their role in cancer stem cells

Cancer stem cells (CSCs) play a vital role in the formation of tumors and have been studied as a target of anticancer therapy. Long non-coding RNAs (lncRNAs) are important in the genesis and progression of cancer. Various lncRNAs, such as ROR, HOTAIR, H19, UCA1, and ARSR, are involved in cancer stemness. These lncRNAs could regulate the expression of CSC-related transcriptional factors, such as SOX2, OCT4, and NANOG, in colorectal, prostate, bladder, breast, liver, and other cancer types. In this work, we review the progress of lncRNAs and cancer stem cells and discuss the potential signal pathways of lncRNAs in cancer stemness.

The N-terminal polypeptide derived from viral macrophage inflammatory protein II reverses breast cancer epithelial-to-mesenchymal transition via a PDGFRα-dependent mechanism

NT21MP, a 21-residue peptide derived from the viral macrophage inflammatory protein II, competed effectively with the natural ligand of CXC chemokine receptor 4 (CXCR4), stromal cell-derived factor 1-alpha, to induce apoptosis and inhibit growth in breast cancer. Its role in tumor epithelial-to-mesenchymal transition (EMT) regulation remains unknown. In this study, we evaluated the reversal of EMT upon NT21MP treatment and examined its role in the inhibition of EMT in breast cancer. The parental cells of breast cancer (SKBR-3 and MCF-7) and paclitaxel-resistant (SKBR-3 PR and MCF-7 PR) cells were studied in vitro and in combined immunodeficient mice. The mice injected with SKBR-3 PR cells were treated with NT21MP through the tail vein or intraperitoneally with paclitaxel or saline. Sections from tumors were evaluated for tumor weight and EMT markers based on Western blot. In vitro, the effects of NT21MP, CXCR4 and PDGFRα on tumor EMT were assessed by relative quantitative real-time reverse transcription-polymerase chain reaction, western blot and biological activity in breast cancer cell lines expressing high or low levels of CXCR4. Our results illustrated that NT21MP could reverse the phenotype of EMT in paclitaxel-resistant cells. Furthermore, we found that NT21MP governed PR-mediated EMT partly due to controlling platelet-derived growth factors A and B (PDGFA and PDGFB) and their receptor (PDGFRα). More importantly, NT21MP down-regulated AKT and ERK1/2 activity, which were activated by PDGFRα, and eventually reversed the EMT. Together, these results indicated that CXCR4 overexpression drives acquired paclitaxel resistance, partly by activating the PDGFA and PDGFB/PDGFRα autocrine signaling loops that activate AKT and ERK1/2. Inhibition of the oncogenic EMT process by targeting CXCR4/PDGFRα-mediated pathways using NT21MP may provide a novel therapeutic approach towards breast cancer.

Akt Activation Mediates Acquired Resistance to Fibroblast Growth Factor Receptor Inhibitor BGJ398

Activation of FGFR signaling through mutations, amplifications, or fusions involving FGFR1, 2, 3, or 4 is seen in multiple tumors, including lung, bladder, and cholangiocarcinoma. Currently, several clinical trials are evaluating the role of novel FGFR inhibitors in solid tumors. As we move forward with FGFR inhibitors clinically, we anticipate the emergence of resistance with treatment. Consequently, we sought to study the mechanism(s) of acquired resistance to FGFR inhibitors using annotated cancer cell lines. We identified cancer cell lines that have activating mutations in FGFR1, 2, or 3 and treated them chronically with the selective FGFR inhibitor, BGJ398. We observed resistance to chronic BGJ398 exposure in DMS114 (small-cell lung cancer, FGFR1 amplification) and RT112 (urothelial carcinoma, FGFR3 fusion/amplification) cell lines based on viability assays. Reverse-phase protein array (RPPA) analysis showed increased phosphorylation of Akt (T308 and S473) and its downstream target GSK3 (S9 and S21) in both the resistant cell lines when compared with matching controls. Results of RPPA were confirmed using immunoblots. Consequently, the addition of an Akt inhibitor (GSK2141795) or siRNA was able to restore sensitivity to BGJ398 in resistant cell lines. These data suggest a role for Akt pathway in mediating acquired resistance to FGFR inhibition. Mol Cancer Ther; 16(4); 614-24. ©2017 AACR.

miR-25-3p reverses epithelial-mesenchymal transition via targeting Sema4C in cisplatin-resistance cervical cancer cells

Acquisition of epithelial-mesenchymal transition (EMT) has recently been proposed as an important contributor of drug resistance in cervical cancer cells. However, the underlying mechanisms are still unclear. MicroRNAs play a crucial role in regulating EMT. The aim of this study was to explore the potential role of miR-25-3p in regulating EMT in cisplatin-resistant (CR) cervical cancer cells. To this end, we established stable CR cervical cancer cells, HeLa-CR and CaSki-CR, and investigated the function of miR-25-3p in regulating EMT. It is found that CR cervical cancer cells possessed more EMT characteristics and demonstrated higher migratory abilities and invasiveness. miR-25-3p downregulation was also seen in HeLa-CR and CaSki-CR cells. Of note, ectopic expression of miR-25-3p reversed the EMT phenotype and sensitized CR cells to cisplatin via targeting Sema4C. Furthermore, stable overexpression of miR-25-3p in HeLa-CR cells suppressed tumor growth in mice, downregulated Sema4C and Snail, and upregulated E-cadherin compared with the control group. These results suggest that miR-25-3p is an important regulator of cervical cancer EMT and chemoresistance. Thus, upregulation of miR-25-3p could be a novel approach to treat cervical cancers that are resistant to chemotherapy.

Epithelial-to-Mesenchymal Transition in Paclitaxel-Resistant Ovarian Cancer Cells Is Downregulated by Luteolin

Ovarian cancer (OVCA) is the deadliest of all gynecological cancers which is attributed to late presentation, persistence, and development of chemoresistance. The objectives were to evaluate the association between OVCA paclitaxel-resistance and epithelial-to-mesenchymal transition (EMT) and to determine the capability of luteolin to chemosensitize OVCA cells. X10 and X22 cells were 11.8-25.3-fold and 7.8-8.6-fold resistant to paclitaxel than 1AP cells. X10 and X22 cells exhibited a mesenchymal phenotype, while 1AP has an epithelial characteristics. Furthermore, the expression of the epithelial marker E-cadherin was downregulated, while mesenchymal markers Vimentin and N-cadherin were upregulated in X10 and X22 cells when compared to 1AP cells. Transcription factors Snail, Slug, and Twist1 were upregulated in X10 cells, while Twist1 was highly expressed in X22 cells. Luteolin treatment caused cytotoxicity being most potent to X10 OVCA cells. Treatment of non-cytotoxic dose of luteolin at 15.625 μM chemosensitized X10 and X22 OVCA cells to paclitaxel as evidenced by reduced ED₅₀ values from 11.8 to 0.2 μM and 8.6 to 3.6 μM for X10 and X22 cells, respectively. Moreover, luteolin treatment led to a more epithelial phenotype of X10 and X22 cells and modification of EMT markers indicating reversal of EMT. The mechanism involved is through reduction of phosphorylation of FAK and ERK leading to reduced nuclear translocation of p65. Our results highlight the significance of EMT in OVCA resistance to paclitaxel and warrant the investigation of luteolin as a potential therapeutic agent in chemoresistant OVCA. J. Cell. Physiol. 232: 391-401, 2017. © 2016 Wiley Periodicals, Inc.

Paclitaxel-loaded polymeric depots as injectable drug delivery system for cancer chemotherapy of hepatocellular carcinoma

In this work, paclitaxel-encapsulated polymeric depots were prepared and characterized as drug delivery system for cancer chemotherapy against hepatocellular carcinoma. Effects of different parameters, including drug-loading content, polymer concentration and depot weight on depot formation, percentage of sustained-release taxol and drug release profile were evaluated. Paclitaxel-loaded depots were successfully formed at the polymer concentration above 25% w/v. For all formulations, paclitaxel could be encapsulated with very high percentage of sustained-release taxol (>90%). The release rate of paclitaxel from depots could be controlled by the amount of drug-loading content, polymer concentration and depot weight. Cytotoxicity against liver cancer cell line, HepG2, was evaluated by medium extraction method. Paclitaxel releasing from depots showed cytotoxic effect against HepG2 at different incubation times, whereas blank depots exhibited no cytotoxicity.

MiR-125b regulates epithelial-mesenchymal transition via targeting Sema4C in paclitaxel-resistant breast cancer cells

Emerging evidence has demonstrated that microRNAs (miRNA) play a critical role in chemotherapy-induced epithelial-mesenchymal transition (EMT) in breast cancer. However, the underlying mechanism of chemotherapy-mediated EMT has not been fully understood. To address this concern, we explored the role of miR-125b in regulation of EMT in stable paclitaxel-resistant (PR) breast cancer cells, namely MCF-7 PR and SKBR3 PR, which have displayed mesenchymal features. Our results illustrated that miR-125b was significantly downregulated in PR cells. Moreover, ectopic expression of miR-125b by its mimics reversed the phenotype of EMT in PR cells. Furthermore, we found that miR-125b governed PR-mediate EMT partly due to governing its target Sema4C. More importantly, overexpression of miR-125b or depletion of Sema4C sensitized PR cells to paclitaxel. These findings suggest that up-regulation of miR-125b or targeting Sema4C could serve as novel approaches to reverse chemotherapy resistance in breast cancers.

Skp2 Regulates the Expression of MMP-2 and MMP-9, and Enhances the Invasion Potential of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the head and neck regions and accounts for more than 90 % of cancers in the oral cavity. S-phase kinase-associated protein-2 (Skp2) is a member of the F-box protein family and the substrate recognition subunit of the Skp1-Cullin-F box protein E3 ubiquitin ligase complex. Skp2 is oncogenic and overexpressed in human cancers. The aims of the present study were to determine the clinicopathological significance of Skp2 in OSCC and clarify its function in OSCC cell lines in vitro. Multiple methods including immunohistochemical staining, RT-PCR, western blotting, migration and invasion assays, and siRNA transfection were employed in order to investigate the clinicopathological significance and molecular function of Skp2 in OSCC. The overexpression of Skp2 was more frequent in OSCC than in the normal oral epithelium. It was also more frequently detected in cancers with higher grades according to the T classification, N classification, and pattern of invasion. The high-Skp2 expression group had a significantly poorer prognosis, at 30.1 %, than that of the low-expression group, at 63.0 %. The downregulation of Skp2 decreased migration and invasion potentials in HSC3 cells. Moreover, the suppression of Skp2 reduced the enzyme activities of MMP-2 and MMP-9 via Sp1. Skp2 may be a prognostic factor in OSCC patients, and may also play crucial roles in the migration and invasion potentials of OSCC cells.

The role of photodynamic therapy in overcoming cancer drug resistance

Many modalities of cancer therapy induce mechanisms of treatment resistance and escape pathways during chronic treatments, including photodynamic therapy (PDT). It is conceivable that resistance induced by one treatment might be overcome by another treatment. Emerging evidence suggests that the unique mechanisms of tumor cell and microenvironment damage produced by PDT could be utilized to overcome cancer drug resistance, to mitigate the compensatory induction of survival pathways and even to re-sensitize resistant cells to standard therapies. Approaches that capture the unique features of PDT, therefore, offer promising factors for increasing the efficacy of a broad range of therapeutic modalities. Here, we highlight key preclinical findings utilizing PDT to overcome classical drug resistance or escape pathways and thus enhance the efficacy of many pharmaceuticals, possibly explaining the clinical observations of the PDT response to otherwise treatment-resistant diseases. With the development of nanotechnology, it is possible that light activation may be used not only to damage and sensitize tumors but also to enable controlled drug release to inhibit escape pathways that may lead to resistance or cell proliferation.

Epithelial-mesenchymal status renders differential responses to cisplatin in ovarian cancer

Chemoresistance to platinums, such as cisplatin, is of critical concern in the treatment of ovarian cancer. Recent evidence has linked epithelial-mesenchymal transition (EMT) as a contributing mechanism. The current study explored the connection between cellular responses to cisplatin and EMT in ovarian cancer. Expression microarrays were utilized to estimate the EMT status as a binary phenotype, and the transcriptional responses of 46 ovarian cancer cell lines to cisplatin were measured at dosages equivalent to 50% growth inhibition. Phenotypic responses to cisplatin were quantified with respect to cell number, proliferation rate and apoptosis, and then compared with the epithelial or mesenchymal status. Ovarian cancer cell lines with an epithelial status exhibited higher resistance to cisplatin treatment in the MTS assay than those with a mesenchymal status. Pathway analyses revealed the induction of G1/S- and S-phase genes (P=0.001) and the activation of multiple NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) downstream genes (P=0.0016) by cisplatin selectively in epithelial-like cell lines. BrdU incorporation and Caspase-3/7 release assays confirmed impaired apoptosis in epithelial-like ovarian cancer cells. In clinical samples, we observed resistance to single platinum treatment and the selective activation of the NF-κB pathway by platinum in ovarian cancers with an epithelial status. Overall, our results suggest that, in epithelial-like ovarian cancer cells, NF-κB activation by cisplatin may lead to defective apoptosis, preferential proliferation arrest and a consequential decreased sensitivity to cisplatin.

β-Catenin expression is regulated by an IRES-dependent mechanism and stimulated by paclitaxel in human ovarian cancer cells

Paclitaxel (PTX) is commonly used in the chemotherapy of ovarian cancer, but resistance occurs in most cases, allowing cancer progression. The Wnt/β-catenin pathway has been associated with this resistance, but there are no reports on the regulation of β-catenin expression at the translational level. In the present study, we found that PTX induced different transcription and translation levels of β-catenin in the human ovarian cancer cell lines A2780 and SKOV3. We also demonstrated that β-catenin mRNA contained an internal ribosome entry segment (IRES) that regulated its translation. Using gene transfection and reporter assays, we revealed that the entire CTNNB1 5'-untranslated region (UTR) contributed to IRES activity. Interestingly, we found that c-myc and cyclin D1 increased significantly in transfected cells with increasing PTX concentration, and cell-survival rates remained at 60% while the PTX concentration increased. Suppressing β-catenin resulted in decreased expression of c-myc and cyclin D1 and made these cells less resistant. These results indicate that β-catenin translation is initiated via the IRES and this is regulated by PTX, suggesting that regulation of the IRES-dependent translation of β-catenin may be involved in the cancer cell response to PTX treatment.

Microvesicles mediate transfer of P-glycoprotein to paclitaxel-sensitive A2780 human ovarian cancer cells, conferring paclitaxel-resistance

The overexpression of P-glycoprotein (P-gp) causes resistance to chemotherapy in human ovarian cancer. However, the underlying mechanism remains unclear. In the present study, we showed that, at membrane-bound protein level, P-gp was 'shared' between human ovarian cancer cells by the intercellular transfer of microvesicles (MVs). Paclitaxel-resistant human ovarian cancer cells (A2780/PTX) readily formed and released P-gp-containing MVs into the extracellular space compared with the wild-type parental line (A2780/WT). Shedding MVs bound to the chemosensitive A2780/WT cells in a time- and dose-dependent manner, transferring P-gp via the microenvironment. MV-mediated transfer of P-gp led to redistribution of the chemotherapeutic drug adriamycin in recipient cells (A2780/WT), which displayed 5- and 5-fold higher resistance to adriamycin and paclitaxel, respectively. Thus, these findings demonstrate a new mechanism of drug-resistance acquisition via MVs.

Epithelial-mesenchymal status renders differential responses to cisplatin in ovarian cancer

Chemoresistance to platinums, such as cisplatin, is of critical concern in the treatment of ovarian cancer. Recent evidence has linked epithelial-mesenchymal transition (EMT) as a contributing mechanism. The current study explored the connection between cellular responses to cisplatin and EMT in ovarian cancer. Expression microarrays were utilized to estimate the EMT status as a binary phenotype, and the transcriptional responses of 46 ovarian cancer cell lines to cisplatin were measured at dosages equivalent to 50% growth inhibition. Phenotypic responses to cisplatin were quantified with respect to cell number, proliferation rate and apoptosis, and then compared with the epithelial or mesenchymal status. Ovarian cancer cell lines with an epithelial status exhibited higher resistance to cisplatin treatment in the MTS assay than those with a mesenchymal status. Pathway analyses revealed the induction of G1/S- and S-phase genes (P=0.001) and the activation of multiple NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) downstream genes (P=0.0016) by cisplatin selectively in epithelial-like cell lines. BrdU incorporation and Caspase-3/7 release assays confirmed impaired apoptosis in epithelial-like ovarian cancer cells. In clinical samples, we observed resistance to single platinum treatment and the selective activation of the NF-κB pathway by platinum in ovarian cancers with an epithelial status. Overall, our results suggest that, in epithelial-like ovarian cancer cells, NF-κB activation by cisplatin may lead to defective apoptosis, preferential proliferation arrest and a consequential decreased sensitivity to cisplatin.

MicroRNAs and drug resistance in prostate cancers

Prostate cancer is the second leading cause of cancer related death in American men. Androgen deprivation therapy (ADT) is used to treat patients with aggressive prostate cancers. After androgen deprivation therapy, prostate cancers slowly progress to an androgen-independent status. Taxanes (e.g., docetaxel) are used as standard treatments for androgen-independent prostate cancers. However, these chemotherapeutic agents will eventually become ineffective due to the development of drug resistance. A microRNA (miRNA) is a small noncoding RNA molecule, which can regulate gene expression at the post-transcription level. miRNAs elicit their effects by binding to the 3'-untranslated region (3'-UTR) of their target mRNAs, leading to the inhibition of translation or the degradation of the mRNAs. miRNAs have received increasing attention as targets for cancer therapy, as they can target multiple signaling pathways related to tumor progression, metastasis, invasion, and chemoresistance. Emerging evidence suggests that aberrant expression of miRNAs can lead to the development of resistant prostate cancers. Here, we discuss the roles of miRNAs in the development of resistant prostate cancers and their involvement in various drug resistant mechanisms including androgen signaling, apoptosis avoidance, multiple drug resistance (MDR) transporters, epithelialmesenchymal transition (EMT), and cancer stem cells (CSCs). In addition, we also discuss strategies for treating resistant prostate cancers by targeting specific miRNAs. Different delivery strategies are also discussed with focus on those that have been successfully used in human clinical trials.

The therapeutic potential of targeting the epithelial-mesenchymal transition in cancer

INTRODUCTION

The process of epithelial-to-mesenchymal transition (EMT) has long been advocated as a process during tumor progression and the acquisition of metastatic potential of human cancers. EMT has also been linked with resistance to cancer therapies.

AREAS COVERED

Basic research has provided evidence connecting EMT to increased invasion, angiogenesis and metastasis of cancer cells. A number of signaling pathways such as notch, wnt, hedgehog and PI3K-AKT, and various other individual factors therein, have been intricately connected to the onset of EMT. Here, we provide latest updates on the evidences that further highlight an association between various signaling pathways and EMT, with a focus on therapeutic targets that may have the potential to reverse EMT.

EXPERT OPINION

Our understanding of EMT and its underlying causes is rapidly evolving and a number of putative targets have been identified. It is crucial, now than ever before, to design novel translational and clinical studies for the benefit of advanced stage cancer patients with metastatic disease.

Acquisition of epithelial-mesenchymal transition is associated with Skp2 expression in paclitaxel-resistant breast cancer cells

Background:

Breast cancer is the most common female malignant disease, and the second leading cause of cancer-related death in the United States. Acquired resistance to chemotherapeutic drugs is a pivotal reason that leads to worse treatment outcome of breast cancer. Therefore, it is urgent to elucidate the mechanism of drug resistance in breast cancer.

Methods:

To investigate the underlying molecular basis of the acquired resistant cells to paclitaxel in breast cancer, we used multiple methods including real-time RT–PCR, western blotting analysis, migration and invasion assays, wound healing assay, and transfection.

Results:

We found that epithelial–mesenchymal transition (EMT) is involved in paclitaxel-resistant (PR) breast cancer cells. The resistant cells with EMT features exhibit increased migration and invasion activities. Mechanistically, high expression of Skp2 was found to be associated with EMT in PR cells. Notably, depletion of Skp2 in PR cells led to partial reversal of EMT phenotype.

Conclusions:

These findings suggest that Skp2 was critically involved in PR-mediated EMT. Skp2 could be a potential therapeutic target for breast cancer.

Resveratrol inhibits cisplatin-induced epithelial-to-mesenchymal transition in ovarian cancer cell lines

Background

Many patients diagnosed with ovarian cancer experience recurrence and metastasis, two aspects that will often cause their demise. Epithelial-to-mesenchymal transition (EMT) is a key process involved in cancer progression. With increasing evidence linking Cisplatin and EMT, we wanted to identify a compound able to counter EMT progression when cancer cells are treated with Cisplatin.

Methodology/Principal Findings

Cell death was evaluated by cytometry with Annexin V/PI staining in A2780 and A2780CP cells. Ovarian cancer cell lines were treated with Cisplatin (24 h, 10 µM) and different concentrations of Resveratrol to evaluate its effect on Cisplatin-induced EMT using Western Blot and RT-PCR analysis. Morphological studies and wound healing assay to evaluate cell motility were performed using 72 h Cisplatin treatment with A2780 and A2780CP cells. Densitometry was done on Western Blot and PCR results, and statistical significance was determined using One-Way ANOVA followed by Tukey post-hoc test. Our results show that Cisplatin induced EMT-associated morphological changes in the A2780 ovarian cancer cell line and to a lesser extent in its Cisplatin-resistant counterpart A2780CP. Resveratrol caused cell death in A2780 and A2780CP cell lines in an apoptotic-independent manner. Resveratrol inhibited Cisplatin-induced Snail expression by reducing the Erk pathway activation, reverted morphological changes induced by Cisplatin and decreased cell migration.

Conclusions

These results indicate that Resveratrol has interesting potential to prevent Cisplatin-induced EMT in ovarian cancer cells. By increasing cell death, it also represents an inviting approach as adjuvant therapy to be used with chemotherapy. Using Erk pathway inhibitors could also prove helpful in ovarian cancer treatment to reduce the risk of metastasis.

miR-34a regulates cisplatin-induce gastric cancer cell death by modulating PI3K/AKT/survivin pathway

The purposes of this study were to determine the expression profiles of microRNA-34a (miR-34a) in human gastric cancer cell line (SGC-7901) and cisplatin-resistant cell lines (SGC-7901/DDP), and to establish the correlation between miR-34a expression profile and the sensitivity of human gastric cancer cell to cisplatin-based pattern, thereby providing new methods and strategies for treating gastric cancer. Gastric cancer cell line (SGC-7901) and cisplatin-resistant cell line (SGC-7901/DDP) were cultivated in vitro, respectively. Quantitative real-time PCR (qRT-PCR) and Western blot were utilized to determine the expression profiles of miR-34a and survivin in both gastric cancer cell lines. With miR-34a mimic and miR-34a inhibitor transfected into SGC-7901 and SGC-7901/DDP for 48 h, post-transfection changes of miR-34a expression was determined; the effects of miR-34a ectopic expression on the viability of cisplatin-induce gastric cancer cell were assayed by the MTT method. The effects of miR-34a ectopic expression on apoptosis of cisplatin-induce gastric cancer cell were determined by Annexin V/propidium iodide (PI) double staining method and flow cytometry. The effects of miR-34a ectopic expression on the AKT and p-AKT expression of cisplatin-induce gastric cancer cells were determined by Western blot and flow cytometry with the PI3K pathway inhibitor Wortmannin. As shown by qRT-PCR and Western blot analyses, the expression of miR-34a in cisplatin-resistant cell lines decreased significantly in comparison to that of SGC-7901 cell line (p < 0.05), while significant up-regulation of survivin expression was also observed (p < 0.05). Compared with the control group, the expression of miR-34a increased significantly in SGC-7901 cells transfected with miR-34a mimic for 48 h (p < 0.01). After miR-34a inhibitor transfection, the expression of miR-34a decreased significantly (p < 0.05). The viability of cisplatin-induce gastric cancer cells increased significantly (p < 0.05) with significant decrease of apoptosis after miR-34a expression inhibition, as demonstrated by MTT and flow cytometry with miR-34a over-expression, the viability of cisplatin-induce gastric cancer cells decreased significantly (p < 0.05), with significant apoptosis increase (p < 0.05). As shown by Western blot and flow cytometry, in comparison to the control group, Wortmannin could inhibit miR-34a inhibitor and DDP induced up-regulation of p-AKT significantly (p < 0.05) and stimulated apoptosis. In conclusion, miR-34a expression was down-regulated in cisplatin-resistant cell lines. miR-34a over-expression could improve the sensitivity of gastric cancer cells against cisplatin-based chemotherapies, with PI3K/AKT/survivin signaling pathway possibly involved in the mechanism.