Dynamic modulation of phosphoprotein expression in ovarian cancer xenograft models

Evaluation of the dual mTOR/PI3K inhibitors Gedatolisib (PF-05212384) and PF-04691502 against ovarian cancer xenograft models

This study investigated the antitumour effects of two dual mTOR/PI3K inhibitors, gedatolisib (WYE-129587/PKI-587/PF-05212384) and PF-04691502 against a panel of six human patient derived ovarian cancer xenograft models. Both dual mTOR/PI3K inhibitors demonstrated antitumour activity against all xenografts tested. The compounds produced tumour stasis during the treatment period and upon cessation of treatment, tumours re-grew. In several models, there was an initial rapid reduction of tumour volume over the first week of treatment before tumour stasis. No toxicity was observed during treatment. Biomarker studies were conducted in two xenograft models; phospho-S6 (Ser235/236) expression (as a readout of mTOR activity) was reduced over the treatment period in the responding xenograft but expression increased to control (no treatment) levels on cessation of treatment. Phospho-AKT (Ser473) expression (as a readout of PI3K) was inhibited by both drugs but less markedly so than phospho-S6 expression. Initial tumour volume reduction on treatment and regrowth rate after treatment cessation was associated with phospho-S6/total S6 expression ratio. Both drugs produced apoptosis but minimally influenced markers of proliferation (Ki67, phospho-histone H3). These results indicate that mTOR/PI3K inhibition can produce broad spectrum tumour growth stasis in ovarian cancer xenograft models during continuous chronic treatment and this is associated with apoptosis.

LINC01127 promotes the development of ovarian tumors by regulating the cell cycle

BACKGROUND

Ovarian cancer is characterized by the high mortality rate and poor prognosis. Nevertheless, the oncogenesis mechanisms of ovarian cancer remain unclear. In our study, we focused on the potential role of lncRNA LINC01127 in the pathogenesis of ovarian cancer and its underlying mechanism.

METHODS

LINC01127, which may participate in the development of ovarian cancer, was screened out by bioinformatics analysis. GSEA was used to analyze the function of LINC01127. QRT-PCR was used to analyze the LINC01127 level in 72 cases of ovarian cancer tissues and 53 cases of normal ovarian tissues. LINC01127 level in ovarian cancer cell lines was also determined by qRT-PCR. Subsequently, the selected ovarian tumor cells were transfected with LINC01127 siRNA by Lipofectamine 2000, followed by cell cycle detection using flow cytometry. The regulatory effects of LINC01127 on tumor growth and cell cycle in nude mice were verified by tumor formation assay. The mechanism of LINC01127 involving in cell cycle regulation was further explored by Western Blot.

RESULTS

LINC01127 expression in ovarian cancer tissues was significantly higher than that in normal ovary tissues. The expression level of LINC01127 was negatively correlated with the prognosis of patients with ovarian cancer. GSEA analysis showed that LINC01127 was mainly enriched in the regulation of cell cycle. After transfection with LINC01127 siRNA, the proliferative abilities of SKOV3 and HO8910 cells were inhibited and cell cycle was arrested at G1/G0 phase. Tumorigenicity assay in nude mice showed that low expression of LINC01127 inhibited the growth of ovarian tumors. Further study found that LINC01127 knockdown upregulated expression levels of Cyclin D, Cyclin E and CDK4, but dramatically upregulated expression levels of P16 and P21. Meanwhile, the AKT and ERK pathways were inhibited by LINC01127 knockdown.

CONCLUSIONS

LINC01127 was up-regulated in ovarian cancer tissues. LINC01127 may be involved in the development of ovarian cancer by accelerating cell cycle progression through promoting the phosphorylation of ERK and AKT.

Molecular Response to Neoadjuvant Chemotherapy in High-Grade Serous Ovarian Carcinoma

While high-grade serous ovarian carcinoma (HGSOC) is the most common histologic subtype of ovarian cancer, significant tumor heterogeneity exists. In addition, chemotherapy induces changes in gene expression and alters the mutational profile. To evaluate the notion that patients with HGSOC could be better classified for optimal treatment based on gene expression, we compared genetic variants [by DNA next-generation sequencing (NGS) using a 50 gene Ion Torrent panel] and gene expression (using the NanoString PanCancer 770 gene Panel) in the tumor from 20 patients with HGSOC before and after neoadjuvant chemotherapy (NACT). NGS was performed on plasma cell free DNA (cfDNA) on a select group of patients (n = 14) to assess the utility of using cfDNA to monitor these changes. A total of 86 genes had significant changes in RNA expression after NACT. Thirty-eight genetic variants (including SNPs) from 6 genes were identified in tumors pre-NACT, while 59 variants from 19 genes were detected in the cfDNA. The number of DNA variants were similar after NACT. Of the 59 variants in the plasma pre-NACT, only 6 persisted, whereas 33 of 38 specific variants in the tumor DNA remained unchanged. Pathway analysis showed the most significant alterations in the cell cycle and DNA damage pathways.Implications: Gene expression profiles at the time of interval debulking provide additional genetic information that could help impact treatment decisions after NACT; although, continued collection and analysis of matched tumor and cfDNA from multiple time points are needed to determine the role of cfDNA in the management of HGSOC. Mol Cancer Res; 16(5); 813-24. ©2018 AACR.

Evaluation of the combination of the dual m-TORC1/2 inhibitor vistusertib (AZD2014) and paclitaxel in ovarian cancer models

Activation of the PI3K/mTOR pathway has been shown to be correlated with resistance to chemotherapy in ovarian cancer. We aimed to investigate the effects of combining inhibition of mTORC1 and 2 using the mTOR kinase inhibitor vistusertib (AZD2014) with paclitaxel in in vitro and in vivo ovarian cancer models. The combination of vistusertib and paclitaxel on cell growth was additive in a majority of cell lines in the panel (n = 12) studied. A cisplatin- resistant model (A2780Cis) was studied in vitro and in vivo. We demonstrated inhibition of mTORC1 and mTORC2 by vistusertib and the combination by showing reduction in p-S6 and p-AKT levels, respectively. In the A2780CisR xenograft model compared to control, there was a significant reduction in tumor volumes (p = 0.03) caused by the combination and not paclitaxel or vistusertib alone. In vivo, we observed a significant increase in apoptosis (cleaved PARP measured by immunohistochemistry; p = 0.0003). Decreases in phospholipid and bioenergetic metabolites were studied using magnetic resonance spectroscopy and significant changes in phosphocholine (p = 0.01), and ATP (p = 0.04) were seen in tumors treated with the combination when compared to vehicle-control. Based on this data, a clinical trial evaluating the combination of paclitaxel and vistusertib has been initiated (NCT02193633). Interestingly, treatment of ovarian cancer patients with paclitaxel caused an increase in p-AKT levels in platelet-rich plasma and it was possible to abrogate this increase with the co-treatment with vistusertib in 4/5 patients: we believe this combination will benefit patients with ovarian cancer.