The impact of proteomics in the understanding of the molecular basis of Paclitaxel-resistance in ovarian tumors

Tephrosin Suppresses the Chemoresistance of Paclitaxel-Resistant Ovarian Cancer via Inhibition of FGFR1 Signaling Pathway

Ovarian cancer is the leading cause of death among gynecologic cancers. Paclitaxel is used as a standard first-line therapeutic agent for ovarian cancer. However, chemotherapeutic resistance and high recurrence rates are major obstacles to treating ovarian cancer. We have found that tephrosin, a natural rotenoid isoflavonoid, can resensitize paclitaxel-resistant ovarian cancer cells to paclitaxel. Cell viability, immunoblotting, and a flow cytometric analysis showed that a combination treatment made up of paclitaxel and tephrosin induced apoptotic death. Tephrosin inhibited the phosphorylation of AKT, STAT3, ERK, and p38 MAPK, all of which simultaneously play important roles in survival signaling pathways. Notably, tephrosin downregulated the phosphorylation of FGFR1 and its specific adapter protein FRS2, but it had no effect on the phosphorylation of the EGFR. Immunoblotting and a fluo-3 acetoxymethyl assay showed that tephrosin did not affect the expression or function of P-glycoprotein. Additionally, treatment with N-acetylcysteine did not restore cell cytotoxicity caused by a treatment combination made up of paclitaxel and tephrosin, showing that tephrosin did not affect the reactive oxygen species scavenging pathway. Interestingly, tephrosin reduced the expression of the anti-apoptotic factor XIAP. This study demonstrates that tephrosin is a potent antitumor agent that can be used in the treatment of paclitaxel-resistant ovarian cancer via the inhibition of the FGFR1 signaling pathway.

The role of tumor-educated platelets in ovarian cancer: A comprehensive review and update

Platelets have recently surfaced as critical players in cancer metastasis and the local and systemic responses to tumor growth. The emerging concept of "Tumor-educated platelets (TEPs)" comprises the exchange of biomolecules between tumor cells and platelets, thereby leading to the "education" of platelets. Increased platelet numbers have long been associated with cancer patients' tumor metastasis and poor clinical prognosis. However, it is very recently that researchers have delved deeper into the tumor-microenvironment and probed the mechanism of interactions between tumor cells and platelets. Designing strategies to target the TEPs and the communications between platelets and tumor cells can prove to be a promising breakthrough in cancer therapy. Through this review, we aim to analyze the recent developments in this field and discuss the characteristics of TEPs, focusing on ovarian cancer-associated TEPs and their characteristics, the interplay between ovarian cancer-associated TEPs and cancer cells, and the purview of TEP-targeted cancer diagnosis and therapy, including platelet biomarkers and inhibitors.

SIAH1-mediated RPS3 ubiquitination contributes to chemosensitivity in epithelial ovarian cancer

The E3 ligase SIAH1 is deregulated in human cancers and correlated with poor prognosis, but its contributions to chemoresistance in epithelial ovarian cancer (EOC) are not evident. Herein we found that SIAH1 was decreased in EOC tumour tissues and cell lines and negatively correlated with the RPS3 levels. SIAH1 overexpression suppressed tumour cell growth, colony formation, invasion, metastasis, and cisplatin resistance in vivo and in vitro. SIAH1 promoted RPS3 ubiquitination and degradation using the RING-finger domain, and these steps were required for RPS3 localization to the cytoplasm, which led to subsequent NF-κB inactivation and thereby conferred chemosensitivity. Moreover, ectopic expression of RPS3 or depletion of RPS3 ubiquitination mediated by SIAH1 via the K214R mutant significantly impaired cisplatin-induced tumour suppression in cells stably expressing SIAH1. Together, our findings reveal a tumour suppressor function of SIAH1 and provide evidence showing that the SIAH1-RPS3-NF-κB axis may act as an appealing strategy for tackling treatment resistance in EOC.

Cisplatin-Resistant Gastric Cancer Cells Promote the Chemoresistance of Cisplatin-Sensitive Cells via the Exosomal RPS3-Mediated PI3K-Akt-Cofilin-1 Signaling Axis

Cisplatin is an important agent in first-line chemotherapy against gastric cancer (GC). However, consequential drug resistance limits its effectiveness for the treatment of GC. In this study, a cisplatin resistant gastric cancer cell line SGC7901R was determined by LC-MS/MS with increased exosomal levels of RPS3 protein. SGC7901R cell-derived exosomes were readily taken up by cisplatin-sensitive SGC7901S cells, thus triggering off a phenotype of chemoresistance in the receptor cells. Subsequently, it was demonstrated that exosomal RPS3 was essential for inducing chemoresistance of receptor cells as shown by the acquisition of this phenotype in SGC7901S cells with enforced expression of RPS3. Further mechanism study demonstrated that cisplatin-resistant gastric cancer cell-derived exosomal RPS3 enhanced the chemoresistance of cisplatin-sensitive gastric cancer cells through the PI3K-Akt-cofilin-1 signaling pathway. All these findings demonstrated that cisplatin-resistant gastric cancer cells communicate with sensitive cells through the intercellular delivery of exosomal RPS3 and activation of the PI3K-Akt-cofilin-1 signaling pathway. Targeting exosomal RPS3 protein in cisplatin-resistant gastric cancer cells may thus be a promising strategy to overcome cisplatin resistance in gastric cancer.

Dishevelled family proteins in serous ovarian carcinomas: a clinicopathologic and molecular study

Dishevelled family proteins (DVL1, DVL2, and DVL3) are cytoplasmic mediators involved in canonical and non-canonical Wnt signaling that are important for embryonic development. Since Wnt signaling promotes cell proliferation and invasion, its increased activation is associated with cancer development as well. To get deeper insight into the behavior of Dishevelled proteins in cancer, we studied their expression in serous ovarian carcinomas [both low- (LGSC) and high-grade (HGSC)], and HGSC cell lines OVCAR5, OVCAR8, and OVSAHO. DVL protein expression in serous ovarian carcinomas tissues was analyzed using immunohistochemistry, while DVL protein and mRNA expressions in HGSC cell lines were analyzed using Western blot and quantitative real-time PCR. DVL1 protein expression was significantly higher in LGSC compared with normal ovarian tissue, while DVL3 was overexpressed in both LGSC and HGSC. DVL2 and DVL3 protein expression was higher in HGSC cell lines when compared with normal control cell line FNE1, while DVL1, DVL2, and DVL3 mRNA expression was significantly increased only in OVSAHO cell line. Survival analysis revealed no significant impact of DVL proteins on patients' outcome. Our data show an active involvement of Dishevelled family proteins in serous ovarian carcinomas. Further studies should confirm the clinical relevance of these observations.

Paclitaxel‑resistant gastric cancer MGC‑803 cells promote epithelial‑to‑mesenchymal transition and chemoresistance in paclitaxel‑sensitive cells via exosomal delivery of miR‑155‑5p

Paclitaxel is a first-line chemotherapeutic agent for gastric cancer; however, resistance limits its effectiveness. Investigation into the underlying mechanisms of paclitaxel resistance is urgently required. In the present study, a paclitaxel-resistant gastric cancer cell line (MGC-803R) was generated with a morphological phenotype of epithelial-to-mesenchymal transition (EMT) and increased expression levels of microRNA (miR)-155-5p. MGC-803R cell-derived exosomes were effectively taken up by paclitaxel-sensitive MGC-803S cells, which exhibited EMT and chemoresistance phenotypes. miR-155-5p was enriched in MGC-803R-exosomes and could be delivered into MGC-803S cells. miR-155-5p overexpression in MGC-803S cells via transfection with mimics resulted in similar phenotypic effects as treatment with MGC-803R exosome and increased miR-155-5p content in MGC-803S exosomes, which then capable of inducing the malignant phenotype in the sensitive cells. GATA binding protein 3 (GATA3) and tumor protein p53-inducible nuclear protein 1 (TP53INP1) were identified as targets of miR-155-5p. Exosomal miR-155-5p inhibited these targets by directly targeting their 3′ untranslated regions. Knockdown of miR-155-5p was observed to reverse the EMT and chemoresistant phenotypes of MGC-803R cells, potentially via GATA3 and TP53INP1 upregulation, which inhibited MGC-803R-exosomes from inducing the malignant phenotype. These results demonstrated that exosomal delivery of miR-155-5p may induce EMT and chemoresistant phenotypes from paclitaxel-resistant gastric cancer cells to the sensitive cells, which may be mediated by GATA3 and TP53INP1 suppression. Targeting miR-155-5p may thus be a promising strategy to overcome paclitaxel resistance in gastric cancer.

Platelet protein biomarker panel for ovarian cancer diagnosis

BACKGROUND

Platelets support cancer growth and spread making platelet proteins candidates in the search for biomarkers.

METHODS

Two-dimensional (2D) gel electrophoresis, Partial Least Squares Discriminant Analysis (PLS-DA), Western blot, DigiWest.

RESULTS

PLS-DA of platelet protein expression in 2D gels suggested differences between the International Federation of Gynaecology and Obstetrics (FIGO) stages III-IV of ovarian cancer, compared to benign adnexal lesions with a sensitivity of 96% and a specificity of 88%. A PLS-DA-based model correctly predicted 7 out of 8 cases of FIGO stages I-II of ovarian cancer after verification by western blot. Receiver-operator curve (ROC) analysis indicated a sensitivity of 83% and specificity of 76% at cut-off >0.5 (area under the curve (AUC) = 0.831, p < 0.0001) for detecting these cases. Validation on an independent set of samples by DigiWest with PLS-DA differentiated benign adnexal lesions and ovarian cancer, FIGO stages III-IV, with a sensitivity of 70% and a specificity of 83%.

CONCLUSION

We identified a group of platelet protein biomarker candidates that can quantify the differential expression between ovarian cancer cases as compared to benign adnexal lesions.

Overcoming tumor cell chemoresistance using nanoparticles: lysosomes are beneficial for (stearoyl) gemcitabine-incorporated solid lipid nanoparticles

Despite recent advances in targeted therapies and immunotherapies, chemotherapy using cytotoxic agents remains an indispensable modality in cancer treatment. Recently, there has been a growing emphasis in using nanomedicine in cancer chemotherapy, and several nanomedicines have already been used clinically to treat cancers. There is evidence that formulating small molecular cancer chemotherapeutic agents into nanomedicines significantly modifies their pharmacokinetics and often improves their efficacy. Importantly, cancer cells often develop resistance to chemotherapy, and formulating anticancer drugs into nanomedicines also helps overcome chemoresistance. In this review, we briefly describe the different classes of cancer chemotherapeutic agents, their mechanisms of action and resistance, and evidence of overcoming the resistance using nanomedicines. We then emphasize on gemcitabine and our experience in discovering the unique (stearoyl) gemcitabine solid lipid nanoparticles that are effective against tumor cells resistant to gemcitabine and elucidate the underlying mechanisms. It seems that lysosomes, which are an obstacle in the delivery of many drugs, are actually beneficial for our (stearoyl) gemcitabine solid lipid nanoparticles to overcome tumor cell resistance to gemcitabine.

G2/M inhibitors as pharmacotherapeutic opportunities for glioblastoma: the old, the new, and the future

Glioblastoma (GBM) is one of the deadliest tumors and has a median survival of 3 months if left untreated. Despite advances in rationally targeted pharmacological approaches, the clinical care of GBM remains palliative in intent. Since the majority of altered signaling cascades involved in cancer establishment and progression eventually affect cell cycle progression, an alternative approach for cancer therapy is to develop innovative compounds that block the activity of crucial molecules needed by tumor cells to complete cell division. In this context, we review promising ongoing and future strategies for GBM therapeutics aimed towards G2/M inhibition such as anti-microtubule agents and targeted therapy against G2/M regulators like cyclin-dependent kinases, Aurora inhibitors, PLK1, BUB, 1, and BUBR1, and survivin. Moreover, we also include investigational agents in the preclinical and early clinical settings. Although several drugs were shown to be gliotoxic, most of them have not yet entered therapeutic trials. The use of either single exposure or a combination with novel compounds may lead to treatment alternatives for GBM patients in the near future.

Docetaxel and its potential in the treatment of refractory esophagogastric adenocarcinoma

Adenocarcinomas of the esophagus and stomach are a major cause of cancer-related morbidity and mortality worldwide. For patients with advanced disease, first-line chemotherapy with platinum-fluoropyrimidine combinations prolongs survival, but inevitably the disease progresses with a median progression-free survival of approximately 6 months. At the time of progression, approximately 40-50% of patients remain fit and eligible for second-line treatment. Docetaxel has been extensively studied in this chemorefractory setting, mostly in small single arm studies, either as a single agent or in combination with platinum agents, fluoropyrimidines or anthracyclines. However, two randomized controlled trials published since 2012 have convincingly shown that treatment with docetaxel modestly prolongs survival compared with best supportive care alone. Moreover, treatment with docetaxel is associated with relief from cancer-related constitutional and gastrointestinal symptoms with manageable, predominantly haematological, toxicity. Therefore, it represents a valuable treatment option for patients with relapsed esophagogastric cancer. Nevertheless, in view of the short survival time for the majority of these patients, further research is necessary to identify, on the one hand, combinations with targeted agents that will further improve outcomes and, on the other, biomarkers that will allow selection of those patients most likely to benefit.

Silencing dishevelled-1 sensitizes paclitaxel-resistant human ovarian cancer cells via AKT/GSK-3β/β-catenin signalling

OBJECTIVES

Expression of dishevelled-1 (DVL1) has recently been linked to cancer progression, however, its role in resistance to cancer therapy is unclear. In this study, we aimed to explore the function of DVL1 in paclitaxel-resistant human ovarian cancer cells.

MATERIALS AND METHODS

The MTT assay was used to assess effects of DVL1 silencing on sensitivity of cells that were otherwise resistant to paclitaxel (Taxol). Western blotting and immunofluorescence staining were used to examine effects of DVL1 on AKT/GSK-3β/β-catenin signalling.

RESULTS

Dishevelled-1 was found to be over-expressed in a paclitaxel-resistant cell line derived from human ovarian cancer cell line A2780 (A2780/Taxol line) as well as parental A2780 cells. Down-regulation of DVL1 (using the inhibitor 3289-8625 or siRNA (siDVL1) against DVL1) sensitized A2780/Taxol cells to paclitaxel. Over-expression of DVL1 in A2780 cells increased protein levels of P-gp, BCRP and Bcl-2, which are known targets of β-catenin. Silencing DVL1 in A2780/Taxol cells also reduced levels of these proteins, and led to accumulation of β-catenin. In addition, DVL1 aberrantly activated AKT/GSK-3β/β-catenin signalling. Inactivation of AKT signalling attenuated DVL1-mediated inhibition of GSK-3β and accumulation of β-catenin, in both A2780 and A2780/Taxol cells.

CONCLUSIONS

Taken together, these results suggest that silencing DVL1 sensitized A2780/Taxol cells to paclitaxel, by down-regulating AKT/GSK-3β/β-catenin signalling, providing a novel strategy for chemosensitization of ovarian cancer to paclitaxel-induced cytotoxicity.

Cluster of Differentiation 44 Targeted Hyaluronic Acid Based Nanoparticles for MDR1 siRNA Delivery to Overcome Drug Resistance in Ovarian Cancer

PURPOSE

Approaches for the synthesis of biomaterials to facilitate the delivery of "biologics" is a major area of research in cancer therapy. Here we designed and characterized a hyaluronic acid (HA) based self-assembling nanoparticles that can target CD44 receptors overexpressed on multidrug resistance (MDR) ovarian cancer. The nanoparticle system is composed of HA-poly(ethyleneimine)/HA-poly(ethylene glycol) (HA-PEI/HA-PEG) designed to deliver MDR1 siRNA for the treatment of MDR in an ovarian cancer model.

METHODS

HA-PEI/HA-PEG nanoparticles were synthesized and characterized, then the cellular uptake and knockdown efficiency of HA-PEI/HA-PEG/MDR1 siRNA nanoparticles was further determined. A human xenograft MDR ovarian cancer model was established to evaluate the effects of the combination of HA-PEI/HA-PEG/MDR1 siRNA nanoparticles and paclitaxel on MDR tumor growth.

RESULTS

Our results demonstrated that HA-PEI/HA-PEG nanoparticles successfully targeted CD44 and delivered MDR1 siRNA into OVCAR8TR (established paclitaxel resistant) tumors. Additionally, HA-PEI/HA-PEG nanoparticles loaded with MDR1 siRNA efficiently down-regulated the expression of MDR1 and P-glycoprotein (Pgp), inhibited the functional activity of Pgp, and subsequently increased cell sensitivity to paclitaxel. HA-PEI/HA-PEG/MDR1 siRNA nanoparticle therapy followed by paclitaxel treatment inhibited tumor growth in MDR ovarian cancer mouse models.

CONCLUSIONS

These findings suggest that this CD44 targeted HA-PEI/HA-PEG nanoparticle platform may be a clinicaly relevant gene delivery system for systemic siRNA-based anticancer therapeutics for the treatment of MDR cancers.