Current treatment for ovarian cancer

Engineering and Validation of a Peptide-Stabilized Poly(lactic-co-glycolic) Acid Nanoparticle for Targeted Delivery of a Vascular Disruptive Agent in Cancer Therapy

Developing a biocompatible and biodegradable nanoparticle (NP) carrier that integrates drug-loading capability, active targeting, and imaging modality is extremely challenging. Herein, we report an NP with a core of poly(lactic-co-glycolic) acid (PLGA) chemically modified with the drug combretastatin A4 (CA4), a vascular disrupting agent (VDA) in clinical development for ovarian cancer (OvCA) therapy. The NP is stabilized with a short arginine-glycine-aspartic acid-phenylalanine x3 (RGDFFF) peptide via self-assembly of the peptide on the PLGA surface. Importantly, the use of our RGDFFF coating replaces the commonly used polyethylene glycol (PEG) polymer that itself often induces an unwanted immunogenic response. In addition, the RGD motif of the peptide is well-known to preferentially bind to αvβ3 integrin that is implicated in tumor angiogenesis and is exploited as the NP's targeting component. The NP is enhanced with an optical imaging fluorophore label via chemical modification of the PLGA. The RGDFFF-CA4 NPs are synthesized using a nanoprecipitation method and are ∼75 ± 3.7 nm in diameter, where a peptide coating comprises a 2-3 nm outer layer. The NPs are serum stable for 72 h. In vitro studies using human umbilical cord vascular endothelial cells (HUVEC) confirmed the high uptake and biological activity of the RGDFFF-CA4 NP. NP uptake and viability reduction were demonstrated in OvCA cells grown in culture, and the NPs efficiently accumulated in tumors in a preclinical OvCA mouse model. The RGDFFF NP did not induce an inflammatory response when cultured with immune cells. Finally, the NP was efficiently taken up by patient-derived OvCA cells, suggesting a potential for future clinical applications.

The emerging roles of E3 ubiquitin ligases in ovarian cancer chemoresistance

Epithelial cancer of the ovary exhibits the highest mortality rate of all gynecological malignancies in women today, since the disease is often diagnosed in advanced stages. While the treatment of cancer with specific chemical agents or drugs is the favored treatment regimen, chemotherapy resistance greatly impedes successful ovarian cancer chemotherapy. Thus, chemoresistance becomes one of the most critical clinical issues confronted when treating patients with ovarian cancer. Convincing evidence hints that dysregulation of E3 ubiquitin ligases is a key factor in the development and maintenance of ovarian cancer chemoresistance. This review outlines recent advancement in our understanding of the emerging roles of E3 ubiquitin ligases in ovarian cancer chemoresistance. We also highlight currently available inhibitors targeting E3 ligase activities and discuss their potential for clinical applications in treating chemoresistant ovarian cancer patients.

Effect of Sepatronium Bromide (YM-155) on DNA Double-Strand Breaks Repair in Cancer Cells

Survivin, as an antiapoptotic protein often overexpressed in cancer cells, is a logical target for potential cancer treatment. By overexpressing survivin, cancer cells can avoid apoptotic cell death and often become resistant to treatments, representing a significant obstacle in modern oncology. A survivin suppressor, an imidazolium-based compound known as YM-155, is nowadays studied as an attractive anticancer agent. Although survivin suppression by YM-155 is evident, researchers started to report that YM-155 is also an inducer of DNA damage introducing yet another anticancer mechanism of this drug. Moreover, the concentrations of YM-155 for DNA damage induction seems to be far lower than those needed for survivin inhibition. Understanding the molecular mechanism of action of YM-155 is of vital importance for modern personalized medicine involving the selection of responsive patients and possible treatment combinations. This review focuses mainly on the documented effects of YM-155 on DNA damage signaling pathways. It summarizes up to date literature, and it outlines the molecular mechanism of YM-155 action in the context of the DNA damage field.

Diphenhydramine increases the therapeutic window for platinum drugs by simultaneously sensitizing tumor cells and protecting normal cells

Platinum-based compounds remain a well-established chemotherapy for cancer treatment despite their adverse effects which substantially restrict the therapeutic windows of the drugs. Both the cell type-specific toxicity and the clinical responsiveness of tumors have been associated with mechanisms that alter drug entry and export. We sought to identify pharmacological agents that promote cisplatin (CP) efficacy by augmenting the levels of drug-induced DNA lesions in malignant cells and simultaneously protecting normal tissues from accumulating such damage and from functional loss. Formation and persistence of platination products in the DNA of individual nuclei were measured in drug-exposed cell lines, in primary human tumor cells and in tissue sections using an immunocytochemical method. Using a mouse model of CP-induced toxicity, the antihistaminic drug diphenhydramine (DIPH) and two methylated derivatives decreased DNA platination in normal tissues and also ameliorated nephrotoxicity, ototoxicity, and neurotoxicity. In addition, DIPH sensitized multiple cancer cell types, particularly ovarian cancer cells, to CP by increasing intracellular uptake, DNA platination, and/or apoptosis in cell lines and in patient-derived primary tumor cells. Mechanistically, DIPH diminished transport capacity of CP efflux pumps MRP2, MRP3, and MRP5 particularly in its C2+C6 bimethylated form. Overall, we demonstrate that DIPH reduces side effects of platinum-based chemotherapy and simultaneously inhibits key mechanisms of platinum resistance. We propose that measuring DNA platination after ex vivo exposure may predict the responsiveness of individual tumors to DIPH-like modulators.

Elevated expression of pancreatic adenocarcinoma upregulated factor (PAUF) is associated with poor prognosis and chemoresistance in epithelial ovarian cancer

Pancreatic adenocarcinoma upregulated factor (PAUF) is a ligand of toll-like receptors (TLRs) and has been reported to be involved in pancreatic tumor development. However, the significance of PAUF expression in epithelial ovarian cancer remains unclear. We aimed to investigate the possible clinical significance of PAUF in epithelial ovarian cancer. We examined the link between PAUF and TLR4 in ovarian cancer cell lines. Recombinant PAUF induced cell activation and proliferation in ovarian cancer cell lines, whereas PAUF knockdown inhibited these properties. Subsequently, we assessed PAUF and TLR4 expression by immunohistochemistry on tissue microarray of 408 ovarian samples ranging from normal to metastatic. PAUF expression positively correlated with TLR4 expression. Overexpression of PAUF was associated with high-grade tumor (p = 0.014) and chemoresistant tumor (p = 0.017). Similarly, high expression of TLR4 correlated with advanced tumor stage (p = 0.002) and chemoresistant tumor (p = 0.001). Multivariate analysis indicated that PAUF^high, TLR4^high, and PAUF^high/TLR4^high expression are independent prognostic factor for progression-free survival, while TLR4^high and PAUF^high/TLR4^high expression were independent prognostic factors for overall survival. Our results suggest that PAUF has a role in ovarian cancer progression and is a potential prognostic marker and novel chemotherapeutic target for ovarian cancer.

Expression of V-domain immunoglobulin suppressor of T cell activation is associated with the advanced stage and presence of lymph node metastasis in ovarian cancer

V-domain immunoglobulin suppressor of T cell activation (VISTA) is a novel negative immune checkpoint that belongs to the B7 family. VISTA is primarily expressed on hematopoietic cells and inhibits T cell proliferation and cytokine production. The blockade of VISTA has demonstrated promising results in certain murine tumor models. In the present study, an immunohistochemical analysis of VISTA expression on tumor cells, intratumoral immune cells and vascular endothelial cells was performed in a cohort of 65 patients with ovarian cancer (OC). The associations between VISTA expression and different clinicopathological characteristics were evaluated using Fisher's exact test, and the analysis of overall survival in different groups was performed by the construction of Kaplan-Meier curves. The results indicated that high expression of VISTA on tumor cells or ICs was significantly associated with advanced tumor stage and the presence of lymph node metastasis (LNM). However, the percentage of cases with high expression of VISTA on tumor cells (24.6%) was decreased compared with those with high expression on ICs (44.6%). There was no association between VISTA expression and the 5-year overall survival rate, and advanced-stage disease was the only independent predictor of poor prognosis based on multivariate Cox regression analysis. In general, VISTA expression increased with advanced disease stage and LNM, indicating that VISTA expression is involved in the progression of OC. More importantly, these data implicate VISTA as a candidate immunotherapeutic target in OC.

Effects of isoliquiritigenin on ovarian cancer cells

Background

Ovarian cancer is one of the most fatal gynecologic malignancies, with most patients diagnosed at the late stage due to insidious onset and lack of early onset specific symptoms. Previous studies have implied that isoliquiritigenin (ILQ) is a promising chemopreventive agent against oral cancer.

Aim

This study aimed to investigate effects of ILQ and elucidate the related mechanism.

Materials and methods

Ovarian cancer cell lines, SKOV3 and OVCAR3, were treated with various concentrations of ILQ to detect the dose-dependent effects of ILQ and select the suitable concentration. CCK8 assay and clone formation efficiency assays were used to detect viability and proliferation. The cell migration, invasion, and apoptosis were evaluated by wound healing assays, transwell, and flow cytometry assays. The expression of apoptosis-related proteins (Caspase-3, Caspase3-p17, Bcl-2, Bax, and Bim) and related-signaling pathway proteins were also detected by Western blot.

Results

It was observed that the treatment of ILQ inhibited the survival and proliferation of SKOV3 and OVCAR3 cells. ILQ treatment inhibited migration and invasion, and induced apoptosis in SKOV3 and OVCAR3 cells. Also, the ILQ treatment increased the Bax/Bcl-2 ratio in SKOV3 and OVCAR3 cells, suggesting that a mitochondrial apoptotic pathway was triggered. It was also observed that, after treated with ILQ, the phosphorylated form of Akt and mTOR decreased and the expression of GSK3β increased, while P70/S6K decreased. ILQ treatment also decreased the expression of Wnt3a and, therefore, caused the decrease of phosphorylated ERK. ILQ also suppressed the PI3K/Akt/mTOR pathway by reduced the expression level of p-Akt, p-mTOR, P70/S6K and Cyclin D1 in Ishikawa and ES-2 cells.

Conclusion

The data suggested that ILQ inhibited viability, proliferation, and invasion, and induced apoptosis of SKOV3 and OVCAR3 cells through the PI3K/Akt/mTOR pathway. Together, the data revealed that ILQ treatment may be used as a novel strategy for ovarian cancer therapy.

MicroRNA-136 inhibits cancer stem cell activity and enhances the anti-tumor effect of paclitaxel against chemoresistant ovarian cancer cells by targeting Notch3

To identify microRNAs (miRNAs) regulating Notch3 expression in association with paclitaxel resistance, candidate miRNAs targeting Notch3 were predicted using TargetScan. We found that miR-136 directly targets Notch3, and miR-136 was significantly downregulated in OSC tissues relative to normal control tissues, and low expression of miR-136 correlated with poor overall in ovarian cancer patients. Artificial miR-136 overexpression significantly reduced cell viability, proliferation, Cancer stem cell (CSC) spheroid formation, and angiogenesis, and increased apoptosis in paclitaxel-resistant SKpac cells compared with the effects of paclitaxel alone. miR-136 overexpression downregulated cell survival- (survivin, DNA-PK, pS6, S6) and cell cycle- (Cyclin D1, NF-κB) related proteins, and anti-apoptotic proteins (BCL2, and BCL-XL), and upregulated pro-apoptotic proteins (Bim, Bid, and Bax). Taken together, miR-136 targets the Notch3 oncogene and functions as a tumor suppressor. miR-136 overexpression resensitized paclitaxel-resistant ovarian cancer cells and reduced CSC activities, suggesting a promising new target for the treatment of chemoresistant ovarian cancers.

Selective inhibition of tumor cell associated Vacuolar-ATPase 'a2' isoform overcomes cisplatin resistance in ovarian cancer cells

Development of resistance to platinum compounds significantly hinders successful ovarian cancer (OVCA) treatment. In tumor cells, dysregulated pH gradient across cell membranes is a key physiological mechanism of metastasis/chemo-resistance. These pH alterations are mediated by aberrant activation of key multi-subunit proton pumps, Vacuolar-ATPases (V-ATPases). In tumor cells, its 'a2' isoform (V-ATPase-V0a2) is a component of functional plasma-membrane complex and promotes tumor invasion through tumor-acidification and immuno-modulation. Its involvement in chemo-resistance has not been studied. Here, we show that V-ATPase-V0a2 is over-expressed in acquired-cisplatin resistant OVCA cells (cis-A2780/cis-TOV112D). Of all the 'a' subunit isoforms, V-ATPase-V0a2 exhibited an elevated expression on plasma membrane of cisplatin-resistant cells compared to sensitive counterparts. Immuno-histochemistry revealed V-ATPase-V0a2 expression in both low grade (highly drug-resistant) and high grade (highly recurrent) human OVCA tissues indicating its role in a centralized mechanism of tumor resistance. In cisplatin resistant cells, shRNA mediated inhibition of V-ATPase-V0a2 enhanced sensitivity towards both cisplatin and carboplatin. This improved cytotoxicity was mediated by enhanced cisplatin-DNA-adduct formation and suppressed DNA-repair pathway, leading to enhanced apoptosis. Suppression of V0a2 activity strongly reduced cytosolic pH in resistant tumor cells, which is known to enhance platinum-associated DNA-damage. As an indicator of reduced metastasis and chemo-resistance, in contrast to plasma membrane localization, a diffused cytoplasmic localization of acidic vacuoles was observed in V0a2-knockdown resistant cells. Interestingly, pre-treatment with monoclonal V0a2-inhibitory antibody enhanced cisplatin cytotoxicity in resistant cells. Taken together, our findings suggest that the isoform specific inhibition of V-ATPase-V0a2 could serve as a therapeutic strategy for chemo-resistant ovarian carcinoma and improve efficacy of platinum drugs.

EVALUATION THE EXPRESSION OF THREE GENES TO EPITHELIAL OVARIAN CANCER RISK IN CHINESE POPULATION

BACKGROUND

Ovarian cancer is associated with poor survival, because patients are diagnosed at an advanced stage of the disease, and in addition, tumors develop chemoresistance, which carries a poor prognosis for the patient.

MATERIAL AND METHODS

We hypothesize that high expression of SDF-1, survivin and smac is associated with ovarian cancers development and could be used as a biomarker to identify this disease. The expressions of SDF-1, survivin and smac in normal ovarian (NO) tissue, benign tumor (BT) tissue and epithelial ovarian cancer (EOC) tissue were immunohistochemically analysed.

RESULTS

Positive expressions of SDF-1, survivin and smac were significantly higher in EOC tissue than those in NO and BT tissues. SDF-1 expressions were significantly more weaker in advanced ovarian carcinomas (FIGO stage III-IV), and in high-grade carcinomas. There was a positive correlation between EOC patients with lymph node metastasis and with ascites and SDF-1 positivity (P < 0.05). Survivin expressions were significantly more stronger in advanced ovarian carcinomas (FIGO stage III-IV), and in high-grade carcinomas. There was a positive correlation between EOC patients with lymph node metastasis and with ascites and surviving positivity (P < 0.05). Smac expressions were significantly more stronger in advanced ovarian carcinomas (FIGO stage III-IV), and in high-grade carcinomas. There was a positive correlation between EOC patients with lymph node metastasis and with ascites and smac positivity (P < 0.05).

CONCLUSION

These results indicate that SDF-1, surviving and smac are closely associated with EOC metastasis.

Fatty acid synthase overexpression: target for therapy and reversal of chemoresistance in ovarian cancer

Background

Fatty acid synthase (FASN) is crucial to de novo long-chain fatty acid synthesis, needed to meet cancer cells’ increased demands for membrane, energy, and protein production.

Methods

We investigated FASN overexpression as a therapeutic and chemosensitization target in ovarian cancer tissue, cell lines, and primary cell cultures. FASN expression at mRNA and protein levels was determined by quantitative real-time polymerase chain reaction and immunoblotting and immunohistochemistry, respectively. FASN inhibition’s impact on cell viability, apoptosis, and fatty acid metabolism was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide assay, cell death detection enzyme-linked immunosorbent assay, immunoblotting, and ¹⁸ F-fluoromethylcholine uptake measurement, respectively.

Results

Relative to that in healthy fallopian tube tissue, tumor tissues had 1.8-fold average FASN protein overexpression; cell lines and primary cultures had 11-fold–100-fold mRNA and protein overexpression. In most samples, the FASN inhibitor cerulenin markedly decreased FASN expression and cell viability and induced apoptosis. Unlike concomitant administration, sequential cerulenin/cisplatin treatment reduced cisplatin’s half maximal inhibitory concentration profoundly (up to 54%) in a cisplatin-resistant cell line, suggesting platinum (re)sensitization. Cisplatin-resistant cells displayed lower ¹⁸ F-fluoro-methylcholine uptake than did cisplatin-sensitive cells, suggesting that metabolic imaging might help guide therapy.

Conclusions

FASN inhibition induced apoptosis in chemosensitive and platinum-resistant ovarian cancer cells and may reverse cisplatin resistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0511-3) contains supplementary material, which is available to authorized users.

Epigenetic silencing of microRNA-199b-5p is associated with acquired chemoresistance via activation of JAG1-Notch1 signaling in ovarian cancer

Epithelial ovarian cancer is a highly lethal and aggressive gynecological malignancy. The high mortality rate is due in part to the fact that many advanced cancer patients become refractory to current chemotherapeutic agents, leading to tumor recurrence and death. However, the underlying mechanisms leading to chemoresistance remain obscure. Here, we report that the loss of miR-199b-5p due to progressive epigenetic silencing leads to the activation of the JAG1-mediated Notch1 signaling cascade, thereby leading to the development of acquired chemoresistance in ovarian cancer. Using miRCURY LNA™ microRNA array and Q-PCR analyses of two pairs of cisplatin-sensitive and –resistant ovarian cancer cell lines, we identified miR-199b-5p as significantly down-regulated in cisplatin-resistant ovarian cancer cells and confirmed that miR-199b-5p is clinically associated with advanced and poor survival ovarian cancers. Interestingly, the loss of miR-199b-5p could be restored by 5-Aza-dC-mediated demethylation, and methylated specific PCR (MS-PCR), bisulfite-sequencing and pyrosequencing revealed that the promoter region of miR-199b-5p was hypermethylated. Computational and mechanistic analyses identified JAG1 as a primary target of miR-199b-5p. Notably, the reduced expression of miR-199b-5p was found to be inversely correlated with the increased expression of JAG1 using an ovarian cancer tissue array. Enforced expression of miR-199b-5p sensitized ovarian cancer cells to cisplatin-induced cytotoxicity both in vitro and in vivo. Conversely, re-expression of miR-199b-5p and siRNA-mediated JAG1 knockdown or treatment with Notch specific inhibitor γ-secretase (GSI) attenuated JAG1-Notch1 signaling activity, thereby enhancing cisplatin-mediated cell cytotoxicity. Taken together, our study suggests that the epigenetic silencing of miR-199b-5p during tumor progression is significantly associated with acquired chemoresistance in ovarian cancer through the activation of JAG1-Notch1 signaling.

Annexin A11 in disease

Ubiquitously expressed in many cell types, annexin A11 (Anxa11) is a member of the multigene family of Ca(2+)-regulated phospholipid-dependent and membrane-binding annexin proteins. Studies have shown that Anxa11 plays an important role in cell division, Ca(2+) signaling, vesicle trafficking and apoptosis. The deregulation and mutation of Anxa11 are involved in systemic autoimmune diseases, sarcoidosis and the development, chemoresistance and recurrence of cancers. Malfunction of Anxa11 may lead to or enhance the metastasis, invasion and drug resistance of cancers through the platelet-derived growth factor receptor (PDGFR) pathway and/or the mitogen-activated protein kinase (MAPK)/p53 pathway. In a variety of diseases, Anxa11 is most commonly reported to function through interactions with apoptosis-linked gene-2 protein (ALG-2) and/or calcyclin (S100A6). Although it has been little studied, Anxa11 is a promising biomarker for the diagnosis, treatment and prognosis of certain diseases. In this review, the associations of Anxa11 with Ca(2+)-regulated exocytosis, cytokinesis, sex differentiation, autoimmune diseases, thrombolysis and cancers are summarized and interpreted.

YM155 sensitizes ovarian cancer cells to cisplatin inducing apoptosis and tumor regression

OBJECTIVE

The objective of this study is to chemosensitize ovarian cancer (OVCa) cells to cisplatin (CDDP) using an inhibitor of Survivin, YM155. The efficacy of YM155 in combination with CDDP was determined in vitro, ex vivo and in vivo.

METHODS

Human OVCa cell lines A2780p and their cisplatin-resistant derivative A2780cis, were treated with CDDP, YM155, and the combined treatment (YM155+CDDP), and cell viability, mRNA and protein expression levels, cell-cycle distribution, and DNA damage were then evaluated. Furthermore, the efficacy of YM155 combined with CDDP was further examined in established primary cell cultures and xenograft models.

RESULTS

The combination of YM155 with CDDP induced G2/M cell cycle arrest and apoptosis, increased DNA damage, and decreased Survivin levels, especially in A2780cis CDDP-resistant cells. Additionally, YM155 in combination with CDDP sensitized primary cell cultures to CDDP. Studies in vivo showed how this combination significantly decreased the tumor size of OVCa xenografts.

CONCLUSIONS

Our results demonstrate that in OVCa cells the expression of Survivin did not affect their sensitivity to YM155, suggesting that Survivin was not the only target of YM155. The combination of YM155 with CDDP could be a good option for therapy of CDDP-resistant OVCa, independently of p53 status.

TOFA suppresses ovarian cancer cell growth in vitro and in vivo

A characteristic feature of cancer cells is the activation of de novo fatty acid synthesis. Acetyl‑CoA carboxylase (ACC) is a key enzyme in fatty acid synthesis, accelerating the reaction that carboxylates cytosolic acetyl‑CoA to form malonyl‑CoA. ACC is highly expressed in several types of human cancer and is important in breast and prostate cancer cell growth. The aim of the present study was to investigate the effects of 5‑tetradecyloxy‑2‑furoic acid (TOFA), an allosteric inhibitor of ACC, on the proliferation and cell cycle progression of the ovarian cancer cell lines COC1 and COC1/DDP. TOFA was found to be cytotoxic to COC1 and COC1/DDP cells with a 50% inhibitory concentration (IC50) of ~26.1 and 11.6 µg/ml, respectively. TOFA inhibited the proliferation of the cancer cells examined in a time‑ and dose‑dependent manner, arrested the cells in the G0/G1 cell cycle phase and induced apoptosis. The expression of the cell cycle regulating proteins cyclin D1 and cyclin-dependent kinase (CDK) 4, as well as the expression of the apoptosis‑related proteins caspase‑3 and Bcl‑2, were detected by western blot analysis. Cyclin D1, CDK4 and Bcl‑2 protein expression was inhibited by TOFA, while caspase‑3 was cleaved and activated. To the best of our knowledge, the present study demonstrated for the first time that TOFA inhibits COC1/DDP cell growth in ovarian tumor mouse xenografts. By inhibiting ACC, TOFA may be a promising small molecule agent for ovarian cancer therapy.

Knockdown of survivin contributes to antitumor activity in cisplatin-resistant ovarian cancer cells

Survivin (SVV) is an important member of the inhibitor of apoptosis family. It is overexpressed in a number of cancer types, including human ovarian carcinomas. SVV promotes invasion, metastasis, growth and survival of malignant cells and confers resistance to specific chemotherapeutic drugs. The present study aimed to elucidate the role and possible mechanisms of SVV in cisplatin-resistant ovarian cancer cells (A2780/CP). Using a loss-of-function approach, we investigated the effects of adenovirus-mediated knockdown of SVV by small hairpin RNA (ad5-SVV) on the expression of pro-caspase-3, cleaved caspase-3, proliferating cell nuclear antigen (PCNA) and matrix metalloproteinase-2 (MMP-2) in A2780/CP cells by real-time PCR and western blot analysis. Proliferation was measured by MTT assay, invasive potential by Transwell, and cell apoptosis by FITC-Annexin V and propidium iodide for the functional analysis of A2780/CP cells following infection with ad5-SVV. As a result, knockdown of SVV downregulated the expression of PCNA and MMP-2 and upregulated the expression of pro-caspase-3 and cleaved caspase-3. In addition, knockdown of SVV enhanced cisplatin-induced proliferative activities, induced cell apoptosis and inhibited the invasive potential in A2780/CP cells. The present findings demonstrate that knockdown of SVV contributes to antitumor activity in cisplatin-resistant ovarian cancer cells via the downregulation of PCNA and MMP-2 expression and the upregulation of caspase-3 expression and indicate that SVV is a potential target for therapeutic anticancer drugs.

Regulation of survival and chemoresistance by HSP90AA1 in ovarian cancer SKOV3 cells

Previous researches have showed that HSP90AA is important in ovarian cancer, but the mechanism of HSP90AA is still unknown. This study aimed to investigate the role of the potential therapy target protein HSP90AA1 in ovarian cancer. The level of HSP90AA1 in ovarian cancer SKOV3 cell line was altered by RNAi and overexpression. Survival of these cell lines was investigated by tetrazolium-based assay and fluorescence-activated cell sorter (FACS). The chemosensitivity to cisplatin of the cell was also tested by FACS when HSP90AA1 was overexpressed. HSP90AA1 RNAi inhibited the proliferation of ovarian cancer SKOV3 cell line and increased the apoptosis. Furthermore, overexpression of HSP90AA1 decreased the chemosensitivity to cisplatin of SKOV3 cells and overexpression of HSP90AA1 could partially rescue the survival rate of SKOV3 cells which were treated with cisplatin. HSP90AA1 is required for the survival and proliferation of SKOV3 cells. High level of HSP90AA1 can increase chemoresistance to cisplatin of SKOV3 cells.

P73 regulates cisplatin-induced apoptosis in ovarian cancer cells via a calcium/calpain-dependent mechanism

P73 is important in drug-induced apoptosis in some cancer cells, yet its role in the regulation of chemosensitivity in ovarian cancer (OVCA) is poorly understood. Furthermore, if and how the deregulation of p73-mediated apoptosis confers resistance to cisplatin (CDDP) treatment is unclear. Here we demonstrate that TAp73α over-expression enhanced CDDP-induced PARP cleavage and apoptosis in both chemosensitive (OV2008 and A2780s) and their resistant counterparts (C13* and A2780cp) and another chemoresistant OVCA cells (Hey); in contrast, the effect of ΔNp73α over-expression was variable. P73α downregulation attenuated CDDP-induced PUMA and NOXA upregulation and apoptosis in OV2008 cells. CDDP decreased p73α steady-state protein levels in OV2008, but not in C13*, although the mRNA expression was identical. CDDP-induced p73α downregulation was mediated by a calpain-dependent pathway. CDDP induced calpain activation and enhanced its cytoplasmic interaction and co-localization with p73α in OV2008, but not C13* cells. CDDP increased the intracellular calcium concentration ([Ca(2+)](i)) in OV2008 but not C13* whereas cyclopiazonic acid (CPA), a Ca(2+)-ATPase inhibitor, caused this response and calpain activation, p73α processing and apoptosis in both cell types. CDDP-induced [Ca(2+)](i) increase in OV2008 cells was not effected by the elimination of extracellular Ca(2+), but this was attenuated by the depletion of internal Ca(2+) store, indicating that mobilization of intracellular Ca(2+]) stores was potentially involved. These findings demonstrate that p73α and its regulation by the Ca(2+)-mediated calpain pathway are involved in CDDP-induced apoptosis in OVCA cells and that dysregulation of Ca(2+)/calpain/p73 signaling may in part be the pathophysiology of CDDP resistance. Understanding the cellular and molecular mechanisms of chemoresistance will direct the development of effective strategies for the treatment of chemoresistant OVCA.

An integrative approach to identifying cancer chemoresistance-associated pathways

Background

Resistance to chemotherapy severely limits the effectiveness of chemotherapy drugs in treating cancer. Still, the mechanisms and critical pathways that contribute to chemotherapy resistance are relatively unknown. This study elucidates the chemoresistance-associated pathways retrieved from the integrated biological interaction networks and identifies signature genes relevant for chemotherapy resistance.

Methods

An integrated network was constructed by collecting multiple metabolic interactions from public databases and the k-shortest path algorithm was implemented to identify chemoresistant related pathways. The identified pathways were then scored using differential expression values from microarray data in chemosensitive and chemoresistant ovarian and lung cancers. Finally, another pathway database, Reactome, was used to evaluate the significance of genes within each filtered pathway based on topological characteristics.

Results

By this method, we discovered pathways specific to chemoresistance. Many of these pathways were consistent with or supported by known involvement in chemotherapy. Experimental results also indicated that integration of pathway structure information with gene differential expression analysis can identify dissimilar modes of gene reactions between chemosensitivity and chemoresistance. Several identified pathways can increase the development of chemotherapeutic resistance and the predicted signature genes are involved in drug resistant during chemotherapy. In particular, we observed that some genes were key factors for joining two or more metabolic pathways and passing down signals, which may be potential key targets for treatment.

Conclusions

This study is expected to identify targets for chemoresistant issues and highlights the interconnectivity of chemoresistant mechanisms. The experimental results not only offer insights into the mode of biological action of drug resistance but also provide information on potential key targets (new biological hypothesis) for further drug-development efforts.

Proteomic identification of paclitaxel-resistance associated hnRNP A2 and GDI 2 proteins in human ovarian cancer cells

Ovarian cancer is a gynecological malignancy with the highest mortality. Chemoresistance is an important subject for the treatment of ovarian cancer, because obtaining significant drug resistance to the first line chemotherapy, paclitaxel, causes major therapeutic obstacles. It is essential to improve the survival rate of ovarian cancer patients by mining the biomarkers indicating the drug resistance and prognosis, and by further understanding underlying mechanisms of drug resistance. In the present study, we established paclitaxel-resistant subline (SKpac) from human epithelial ovarian cancer cell line, SKOV3, and performed comparative analysis of whole proteomes between paclitaxel-resistant SKpac sublines and paclitaxel-sensitive parental SKOV3 cells to identify differentially expressed proteins and useful biomarkers indicating chemoresistance. Proteins related to chemoresistant process were identified by two-dimensional gel electrophoresis (2DE) with mass spectrometry (MALDI-TOF and LC-MS/MS). Eighteen spots were differentially expressed and were identified in SKpac chemoresistant cells compared to SKOV3. The expressions of ALDH 1A1, annexin A1, hnRNP A2, and GDI 2 proteins were validated by Western blot, which was consistent with proteomic analysis. Among the selected proteins, downregulation of hnRNP A2 and GDI 2 was found to be the most significant finding in SKpac cells and chemoresistant ovarian cancer tissues. Our results suggest that hnRNP A2 and GDI 2 may represent potential biomarkers of the paclitaxel-resistant ovarian cancers for tailored cancer therapy.

BRCA1-IRIS overexpression promotes cisplatin resistance in ovarian cancer cells

Evasion of apoptosis plays a key role in cancer development, drug resistance, and recurrence. The BRCA1 locus product protein BRCA1-IRIS is overexpressed in several cisplatin-resistant ovarian cancer cell lines, but its relationship to resistance is uncertain. Here, we show that in human ovarian surface epithelial (HOSE) cells, overexpression of BRCA1-IRIS triggers expression of the antiapoptotic protein survivin. Negative modulation of phosphatidylinositol 3-kinase (PI3K) signaling or AKT silencing reduced survivin expression in this setting. Conversely, silencing BRCA1-IRIS in ovarian cancer cell lines derepressed PTEN expression along with the antiapoptotic AKT targets FOXO1 and FOXO3a, suppressing survivin expression. Cisplatin (≤50 μmol/L) exposure was sufficient to activate expression of the BRCA1-IRIS-AKT-survivin cascade in HOSE cells, whereas under similar conditions cisplatin failed to induce apoptosis in ovarian cancer cell lines expressing this regulatory cascade. Mechanistic investigations indicated that BRCA1-IRIS triggers survivin expression through a PI3K/AKT-dependent pathway involving NF-κB, but also through a PI3K/AKT-independent pathway involving PTEN, FOXO1, and FOXO3a. Our findings indicate how BRCA1-IRIS overexpression prevents chemotherapy-induced cell death by upregulating expression of survivin, and they highlight this regulatory cascade as a candidate focus to improve treatment of advanced drug-resistant ovarian cancers.

Downregulation of Epidermal Growth Factor Receptor Expression Contributes to alpha-TEA's Proapoptotic Effects in Human Ovarian Cancer Cell Lines

RRR-α-tocopherol derivative α-TEA (RRR-α-tocopherol ether-linked acetic acid analog) has been shown to be a potent antitumor agent both in vivo and in vitro. In this study, we investigated the effects of α-TEA on the expression of epidermal growth factor receptor (EGFR) family members, ErbB1, 2 and 3, and the role of ErbB 2 and 3 in α-TEA-induced apoptosis and suppression of Akt, FLIP and survivin in the cisplatin-sensitive (A2780S) and -resistant (A2780/CP70R) human ovarian cancer cell lines. Data show that α-TEA's ability to induced apoptosis was associated with reduced expression of ErbB1 (cisplatin-resistant cells), 2 and 3 (both cell types) and reduced levels of the phosphorylated (active) form of Akt; as well as, reduced levels of FLIP and survivin proteins in both cell types. Ectopic overexpression and siRNA knockdown studies showed that ErbB2, ErbB3, Akt, FLIP and survivin are involved in α-TEA-induce apoptosis and that α-TEA downregulates FLIP and survivin via suppression of pAkt, which is mediated by ErbB2 and ErB3. Thus, α-TEA is a potent pro-apoptotic agent for both cisplatin-sensitive and -resistant ovarian cancer cell lines in cell culture and it produces cell death, at least in part, by downregulation of members of the EGFR family.

Cancer antigen 125 in ovarian cancer surveillance: a decision analysis model

We used decision analysis techniques with Markov cohort modeling to examine the role of cancer antigen 125 (CA-125) in follow-up surveillance strategies among patients with advanced ovarian cancer. Utilities were derived from a societal perspective.

Using quality-adjusted life years (qalys) as the outcome variable, the value of CA-125 monitoring for asymptomatic women with ovarian cancer was found to be reduced as compared with a strategy that includes CA-125 testing. Decisions to include CA-125 in surveillance strategies for ovarian cancer patients should be made after discussion with full disclosure of the preference-sensitive nature of CA-125. The model demonstrates that preferences and perspective can influence decisions in cancer care.

Bortezomib treatment of ovarian cancer cells mediates endoplasmic reticulum stress, cell cycle arrest, and apoptosis

Bortezomib, an approved drug for the treatment of certain haematological neoplasms, is currently being tested in clinical trials as a potential therapeutic agent against several types of solid cancer, including ovarian cancer. We have analyzed the effect of bortezomib on ovarian cancer cells and tissue explants either as a single agent or in combination with carboplatin, taxol, or TRAIL (tumor necrosis factor-related apoptosis-inducing ligand). Bortezomib alone efficiently induced apoptosis in ovarian cancer cells. Apoptosis was preceded by an upregulation of the endoplasmic reticulum stress sensor ATF3, and increased the expression of cytoplasmic heat shock proteins. Bortezomib enhanced the sensitivity of ovarian cancer cells and tissue explants to an apoptosis-inducing TRAIL receptor antibody by upregulating the TRAIL receptor DR5. In contrast to the synergistic effect observed for TRAIL, the efficacy of the taxol treatment was reduced by bortezomib, and bortezomib inhibited the G2/M phase accumulation of ovarian cancer cells treated with taxol. Bortezomib alone or in combination with taxol induced a cell cycle arrest within the S phase, and downregulation of cdk1, a cyclin-dependent kinase that is necessary for the entry into the M phase. Thus, bortezomib can be regarded as a promising agent for the treatment of ovarian cancer and could either be administered as a single agent or in combination with TRAIL. However, a combination treatment with taxanes may not be beneficial and may even be less effective.

DNA damage induces two distinct modes of cell death in ovarian carcinomas

Activation of p53 by cellular stress may lead to either cell cycle arrest or apoptotic cell death. Restrictions in a cell's ability to halt the cell cycle might, in turn, cause mitotic catastrophe, a delayed type of cell death with distinct morphological features. Here, we have investigated the contribution of p53 and caspase-2 to apoptotic cell death and mitotic catastrophe in cisplatin-treated ovarian carcinoma cell lines. We report that both functional p53 and caspase-2 were required for the apoptotic response, which was preceded by translocation of nuclear caspase-2 to the cytoplasm. In the absence of functional p53, cisplatin treatment resulted in caspase-2-independent mitotic catastrophe followed by necrosis. In these cells, apoptotic functions could be restored by transient expression of wt p53. Hence, p53 appeared to act as a switch between apoptosis and mitotic catastrophe followed by necrosis-like lysis in this experimental model. Further, we show that inhibition of Chk2, and/or 14-3-3sigma deficiency, sensitized cells to undergo mitotic catastrophe upon treatment with DNA-damaging agents. However, apoptotic cell death seemed to be the final outcome of this process. Thus, we hypothesize that the final mode of cell death triggered by DNA damage in ovarian carcinoma cells is determined by the profile of proteins involved in the regulation of the cell cycle, such as p53- and Chk2-related proteins.

Risk of developing ovarian cancer among women with ovarian endometrioma: a cohort study in Shizuoka, Japan

Although some studies have indicated that endometriosis may increase the risk of developing ovarian cancer, there are no data from epidemiologic studies in Japan. We prospectively analyzed all cases of ovarian endometrioma enrolled in the prefecture-wide Shizuoka Cohort Study on Endometriosis and Ovarian Cancer Programme, which was initiated in 1985. To evaluate the risk of ovarian cancer by time periods subsequent to ovarian endometrioma diagnosis, a cohort of 6,398 women with a clinically documented ovarian endometrioma in Shizuoka between 1985 and 1995 was identified from the Shizuoka Cancer Registry (SCR), with follow-up through 2002. Ovarian cancer incidence among cohort members was ascertained by linkage to the SCR using a unique person-identification number. Standardized incidence ratios (SIR) and their 95% confidence intervals (CI) were computed by a use of prefecture-wide rates of ovarian cancer, adjusted for age and calendar year. During follow-up of up to 17 years of the ovarian endometrioma cohort, 46 incident ovarian cancers were identified, yielding that the ovarian cancer risk was elevated significantly among patients with ovarian endometrioma (SIR = 8.95, 95% CI = 4.12-15.3). The SIR did not increase with increasing follow-up duration. The risk increased with increasing age at ovarian endometrioma diagnosis, with a SIR equal to 13.2 (95% CI = 6.90-20.9) in women above 50 years of age. Our findings for the first time support the hypothesis that ovarian endometrioma increases the subsequent risk of developing ovarian cancer in Shizuoka, Japan.

Use of anti-thrombotic agents during chemotherapy for epithelial ovarian cancer

The association between malignancy and venous thrombotic events is well established. However, arterial thrombosis among cancer patients is extremely rarely reported. There are several mechanisms of arterial thrombosis or embolism in malignancy. Important mechanisms in arterial thrombogenesis are shear stress-induced platelet aggregation and platelet-derived microparticles. Both of these are induced by major abdominal surgery. A major abdominopelvic surgery followed by adjuvant platinum-based combined chemotherapy is routinely performed for epithelial ovarian cancer which is the leading cause of death among all gynecologic malignancies. These patients have a greater risk of arterial thrombosis at the postoperative period. If the affected arteries are relatively larger, clinical findings will be evident due to limb ischemia or fatal organ infarctions. However, thrombosis of the small arteries disturbs the tissue circulation which is extremely important for the chemotherapeutic agents to reach the residual tumor cells. When the thrombosis of small arteries is prevented, these drugs will reach all of the residual macroscopic or microscopic tumoral tissues and so the prognosis of the patients may be improved. Therefore, we hypothesize that anti-platelet therapy with aspirin is needed to be initiated during the postoperative period of epithelial ovarian cancer patients and be continued as long as chemotherapy goes on. Such an approach might have a role in optimizing the oncological prognosis of these patients via increasing the effectiveness of cytotoxic therapy since some of the recurrences may be caused by some microscopic tumor foci which were not affected by cytotoxic drugs because of subclinical small arterial thromboses.

Gene therapy progress and prospects: transcription regulatory systems

The clinical efficacy and safety as well as the application range of gene therapy will be broadened by developing systems capable of finely modulating the expression of therapeutic genes. Transgene regulation will be crucial for maintaining appropriate levels of a gene product within the therapeutic range, thus preventing toxicity. Moreover, the possibility to modulate, stop or resume transgene expression in response to disease evolution would facilitate the combination of gene therapy with more conventional therapeutic modalities. The development of ligand-dependent transcription regulatory systems is thus of great importance. Here, we summarize the most recent progress in the field.

Chemotherapy resistant ovarian cancer in carriers of an hMSH2 mutation?

Hereditary Non-Polyposis Colorectal Cancer (HNPCC, Lynch syndrome) is an autosomal dominant condition of cancer susceptibility with high penetrance, characterised by early onset of colon tumours as well as a variety of extracolonic tumours including ovarian cancer and, in particular, cancer of the endometrium. Germline mutations in one of five DNA-mismatch repair (MMR) genes (hMLH1, hMSH2, hMSH6, PMS1, PMS2) are known to cause HNPCC. To date, mutations in two of these genes (hMSH2 and hMLH1) are found in the majority of mutation positive families. Recent literature suggests that especially hMSH2 mutations are associated with extracolonic tumours. We describe two women from an HNPCC family carrying an hMSH2 mutation (deletion of exon 6 of this gene) who developed ovarian cancer. In these patients (full cousins) the ovarian cancers were noted for their aggressive development and rapid recurrence after surgical debulking and during regular multichemotherapy including Cisplatin. This report strengthens recent in vitro studies suggesting an involvement of MMR-gene mutations in ovarian cancer cell biology with decreased susceptibility to Cisplatin therapy. The possible implications for the therapy of ovarian cancer, the screening and genetic counselling of family members are discussed.

Chemoresistance in human ovarian cancer: the role of apoptotic regulators

Ovarian cancer is among the most lethal of all malignancies in women. While chemotherapy is the preferred treatment modality, chemoresistance severely limits treatment success. Recent evidence suggests that deregulation of key pro- and anti-apoptotic pathways is a key factor in the onset and maintenance of chemoresistance. Furthermore, the discovery of novel interactions between these pathways suggests that chemoresistance may be multi-factorial. Ultimately, the decision of the cancer cell to live or die in response to a chemotherapeutic agent is a consequence of the overall apoptotic capacity of that cell. In this review, we discuss the biochemical pathways believed to promote cell survival and how they modulate chemosensitivity. We then conclude with some new research directions by which the fundamental mechanisms of chemoresistance can be elucidated.

Advanced age and adjuvant tamoxifen prescription in early-stage breast carcinoma patients

BACKGROUND

Adjuvant tamoxifen is recommended for all women with estrogen receptor-positive breast carcinoma without regard for age. We investigated age-dependent variations in adjuvant tamoxifen prescription patterns in a cohort of women 80 years of age and older.

METHODS

We studied 92 women diagnosed at four U.S. sites with primary, early-stage breast carcinoma. Each woman consented to a medical record review and participated in two telephone interviews. We compared the proportion of tamoxifen prescriptions received by women 85-92 years of age with those received by women 80-84 years of age. Relative risks (RR) and 95% confidence intervals (95% CI) were generated using generalized estimating equations. Confounding by demographic, disease, and treatment characteristics was assessed.

RESULTS

Before adjustment, patients 85-92 years of age were 28% less likely to receive a tamoxifen prescription compared with patients 80-84 years of age (RR = 0.72, 95% CI 0.57-0.91). In this sample, patients not prescribed tamoxifen had substantially more comorbidity. After adjusting the crude finding for comorbidity, the RR was 0.74 (95% CI 0.58-0.93). In addition, the oldest patients and those not prescribed tamoxifen were significantly less likely to be married or have living children. After adjusting the crude finding for these two factors, the RR was 0.75 (95% CI 0.59-0.95). There was no confounding by the other demographic, disease, or treatment covariates assessed.

CONCLUSION

Given the increasing longevity of the oldest old, undertreatment with adjuvant tamoxifen may put older breast carcinoma patients at an increased risk of disease recurrence and breast carcinoma mortality.

Role of X-linked inhibitor of apoptosis protein in chemoresistance in ovarian cancer: possible involvement of the phosphoinositide-3 kinase/Akt pathway

Although cisplatin derivatives are first-line chemotherapeutic agents for the treatment of epithelial ovarian cancer, chemoresistance remains a major hurdle to successful therapy and the molecular mechanisms involved are poorly understood. Apoptosis is the cellular underpinning of cisplatin-induced cell death, which is associated with expression of specific "death" genes and down-regulation of "survival" counterparts. The X-linked inhibitor of apoptosis proteins (Xiap), an intracellular anti-apoptotic protein, plays a key role in cell survival by modulating death signaling pathways and is a determinant of cisplatin resistance in ovarian cancer cells in vitro. This review focuses on the role of Xiap and its interactions with the phosphoinositide-3 kinase (PI3K)/Akt cell survival pathway in conferring resistance of ovarian cancer cells to chemotherapeutic agents and discusses potential therapeutic strategies in overcoming chemoresistant ovarian cancer.