Differential effects of rapalogues, dual kinase inhibitors on human ovarian carcinoma cells in vitro

Differential Regulation of Genes by the Glucogenic Hormone Asprosin in Ovarian Cancer

Background: Ovarian cancer (OvCa) is one of the most lethal forms of gynaecological malignancy. Altered energy metabolism and increased aerobic glycolysis in OvCa are hallmarks that demand attention. The glucogenic hormone asprosin is often dysregulated in metabolic disorders such as insulin resistance, diabetes (type 2 and gestational), and preeclampsia. Despite association with metabolic disorders, its role in energy metabolism within the tumour microenvironment is yet to be explored. Here, we study the role of asprosin in OvCa using transcriptomics and expand on functional studies with clinical samples. Methods: RNA sequencing, functional gene enrichment analysis, Western blotting and ImageStream. Results: Following treatment with 100 nM of asprosin, the serous OvCa cell line, SKOV-3, displayed 160 and 173 gene regulatory changes, at 4 and 12 h respectively, when compared with control samples (p < 0.05 and Log2FC > 1). In addition to energy metabolism and glucose-related pathways, asprosin was shown to alter pathways associated with cell communication, TGF-β signalling, and cell proliferation. Moreover, asprosin was shown to induce phosphorylation of ERK1/2 in the same in vitro model. Using liquid biopsies, we also report for novel expression of asprosin’s predicted receptors OR4M1 and TLR4 in cancer-associated circulating cells; with significant reduction seen between pre-chemotherapy and end of first line chemotherapy, in addition to patients under maintenance with bevacizumab +/− olaparib for OR4M1. Conclusions: In relation to OvCa, asprosin appears to regulate numerous signalling pathways in-vitro. The prognostic potential of OR4M1 in liquid biopsies should also be explored further.

Identification of Potential Bisphenol A (BPA) Exposure Biomarkers in Ovarian Cancer

Endocrine-disrupting chemicals (EDCs) can exert multiple deleterious effects and have been implicated in carcinogenesis. The xenoestrogen Bisphenol A (BPA) that is found in various consumer products has been involved in the dysregulation of numerous signalling pathways. In this paper, we present the analysis of a set of 94 genes that have been shown to be dysregulated in presence of BPA in ovarian cancer cell lines since we hypothesised that these genes might be of biomarker potential. This study sought to identify biomarkers of disease and biomarkers of disease-associated exposure. In silico analyses took place using gene expression data extracted from The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) databases. Differential expression was further validated at protein level using immunohistochemistry on an ovarian cancer tissue microarray. We found that 14 out of 94 genes are solely dysregulated in the presence of BPA, while the remaining 80 genes are already dysregulated (p-value < 0.05) in their expression pattern as a consequence of the disease. We also found that seven genes have prognostic power for the overall survival in OC in relation to their expression levels. Out of these seven genes, Keratin 4 (KRT4) appears to be a biomarker of exposure-associated ovarian cancer, whereas Guanylate Binding Protein 5 (GBP5), long intergenic non-protein coding RNA 707 (LINC00707) and Solute Carrier Family 4 Member 11 (SLC4A11) are biomarkers of disease. BPA can exert a plethora of effects that can be tissue- or cancer-specific. Our in silico findings generate a hypothesis around biomarkers of disease and exposure that could potentially inform regulation and policy making.

H2A Histone Family Member X (H2AX) Is Upregulated in Ovarian Cancer and Demonstrates Utility as a Prognostic Biomarker in Terms of Overall Survival

Background: H2AX can be of prognostic value in breast cancer, since in advanced stage patients with high levels, there was an association with worse overall survival (OS). However, the clinical relevance of H2AX in ovarian cancer (OC) remains to be elucidated. Methods: OC H2AX expression studied using the TCGA/GTEX datasets. Subsequently, patients were classified as either high or low in terms of H2AX expression to compare OS and perform gene set enrichment. qRT-PCR validated in-silico H2AX findings followed by immunohistochemistry on a tissue microarray. The association between single nucleotide polymorphisms in the area of H2AX; prevalence and five-year OC survival was tested in samples from the UK Biobank. Results: H2AX was significantly overexpressed in OCs compared to normal tissues, with higher expression associated with better OS (p = 0.010). Gene Set Enrichment Analysis demonstrated gene sets involved in G2/M checkpoint, DNA repair mTORC1 signalling were enriched in the H2AX highly expressing OCs. Polymorphisms in the area around the gene were associated with both OC prevalence (rs72997349-C, p = 0.005) and worse OS (rs10790282-G, p = 0.011). Finally, we demonstrated that H2AX gene expression correlated with γ-H2AX staining in vitro. Conclusions: Our findings suggest that H2AX can be a novel prognostic biomarker for OC.

[MicroRNA-671-3p suppresses proliferation and invasion of breast cancer cells by targeting DEPTOR]

OBJECTIVE

To investigate the effects of miR-671-3p on the proliferation and invasion of breast cancer cells and explore the possible mechanism.

METHODS

We examined the expressions of miR-671-3p in human normal epithelial cells (MCF-10A) and breast cancer cell lines (MCF-7, MDA-MB-231, and SK-BR3) using RT-PCR. The effects of transfection with a miR-671-3p mimic or inhibitor on the proliferation, migration and invasion of MCF-7 cells were evaluated using CCK-8 assay and Transwell chamber assay. The target gene of miR-671-3p was predicated with Targetscan and validated by a dual luciferase reporter system and Western blotting.

RESULTS

The expression of miR-671-3p was significantly lower in breast cancer cells than in normal breast epithelial cells. Compared with negative control group, MCF-7 cells with miR-671-3p overexpression exhibited significantly reduced proliferation and invasion, whereas inhibition of miR-671-3p obviously promoted the cell proliferation and invasion. Luciferase reporter assay demonstrated that DEPTOR was the target gene of miR-671-3p, and miR-671-3p overexpression caused significant down-regulation of the protein expression of DEPTOR.

CONCLUSIONS

MiR-671-3p suppresses the proliferation and invasion of breast cancer cell line MCF-7 by directly targeting DEPTOR protein.

Kinase Inhibitors and Ovarian Cancer

Ovarian cancer is fifth in the rankings of cancer deaths among women, and accounts for more deaths than any other gynecological malignancy. Despite some improvement in overall-(OS) and progression-free survival (PFS) following surgery and first-line chemotherapy, there is a need for development of novel and more effective therapeutic strategies. In this mini review, we provide a summary of the current landscape of the clinical use of tyrosine kinase inhibitors (TKIs) and mechanistic target of rapamycin (mTOR) inhibitors in ovarian cancer. Emerging data from phase I and II trials reveals that a combinatorial treatment that includes TKIs and chemotherapy agents seems promising in terms of PFS despite some adverse effects recorded; whereas the use of mTOR inhibitors seems less effective. There is a need for further research into the inhibition of multiple signaling pathways in ovarian cancer and progression to phase III trials for drugs that seem most promising.

Surfactant Protein D as a Potential Biomarker and Therapeutic Target in Ovarian Cancer

Surfactant protein D (SP-D) is an important innate immune molecule that is involved in clearing pathogens and regulating inflammation at pulmonary as well as extra-pulmonary sites. Recent studies have established the role of SP-D as an innate immune surveillance molecule against lung and pancreatic cancer, but little is known about its involvement in signaling pathways it can potentially activate in ovarian cancer. We focused our study on ovarian cancer by performing bioinformatics analysis (Oncomine) of datasets and survival analysis (Kaplan-Meier plotter), followed by immunohistochemistry using ovarian cancer tissue microarrays. SP-D mRNA was found to be expressed widely in different types of ovarian cancer irrespective of stage or grade. These in silico data were further validated by immunohistochemistry of clinical tissues. High transcriptional levels of SP-D were associated with unfavorable prognosis (overall and progression-free survival). We also detected SP-D protein in Circulating Tumor Cells of three ovarian cancer patients, suggesting that SP-D can also be used as a potential biomarker. Previous studies have shown that a recombinant fragment of human SP-D (rfhSP-D) induced apoptosis in pancreatic cancer cells via Fas-mediated pathway. In this study, we report that treatment of SKOV3 cells (an ovarian cancer cell line) with rfhSP-D led to a decrease in cell motility and cell proliferation. This was followed by an inhibition of the mTOR pathway activity, increase in caspase 3 cleavage, and induction of pro-apoptotic genes Fas and TNF-α. These data, suggesting a likely protective role of rfhSP-D against ovarian cancer, together with the observation that the ovarian cancer microenvironment overexperesses SP-D leading to poor prognosis, seems to suggest that the tumor microenvironment components manipulate the protective effect of SP-D in vivo.

Differential expression of mTOR components in endometriosis and ovarian cancer: Effects of rapalogues and dual kinase inhibitors on mTORC1 and mTORC2 stoichiometry

Endometriosis is a well‑known risk factor for ovarian cancer. The genetic changes that characterise endometriosis are poorly understood; however, the mechanistic target of rapamycin (mTOR) pathway is involved. In this study, we investigated the expression of key mTOR components in endometriosis and the effects of rapalogues using an endometrioid ovarian carcinoma cell line (MDAH 2774) as an in vitro model. Gene expression of mTOR, DEPTOR, Rictor and Raptor was assessed by qPCR in 24 endometriosis patients and in silico in ovarian cancer patients. Furthermore, the effects of Rapamycin, Everolimus, Deforolimus, Temsirolimus, Resveratrol, and BEZ235 (Dactolisib, a dual kinase inhibitor) on mTOR signalling components was assessed. mTOR showed a significant increase in the expression in endometriosis and ovarian endometrioid adenocarcinoma patients compared to non‑affected controls. DEPTOR, an inhibitor of mTOR, was downregulated in the advanced stages of ovarian cancer (III and IV) compared to earlier stages (I and II). Treatment of MDAH‑2774 cells with the mTOR inhibitors resulted in the significant upregulation of DEPTOR mRNA, whereas treatment with rapamycin and BEZ‑235 (100 nM) resulted in downregulation of the mTOR protein expression after 48 h of treatment. None of the treatments resulted in translocation of mTOR from cytoplasm to nucleus. Upregulation of DEPTOR is a positive prognostic marker in ovarian cancer and is increased in response to mTOR pathway inhibition suggesting that it functions as a tumour suppressor gene in endometrioid ovarian carcinoma. Collectively, our data suggest the mTOR pathway as a potential connection between endometriosis and ovarian cancer and may be a potential target in the treatment of both conditions.

Identification of cancer biomarkers of prognostic value using specific gene regulatory networks (GRN): a novel role of RAD51AP1 for ovarian and lung cancers

To date, microarray analyses have led to the discovery of numerous individual ‘molecular signatures’ associated with specific cancers. However, there are serious limitations for the adoption of these multi-gene signatures in the clinical environment for diagnostic or prognostic testing as studies with more power need to be carried out. This may involve larger richer cohorts and more advanced analyses. In this study, we conduct analyses—based on gene regulatory network—to reveal distinct and common biomarkers across cancer types. Using microarray data of triple-negative and medullary breast, ovarian and lung cancers applied to a combination of glasso and Bayesian networks (BNs), we derived a unique network-containing genes that are uniquely involved: small proline-rich protein 1A (SPRR1A), follistatin like 1 (FSTL1), collagen type XII alpha 1 (COL12A1) and RAD51 associated protein 1 (RAD51AP1). RAD51AP1 and FSTL1 are significantly overexpressed in ovarian cancer patients but only RAD51AP1 is upregulated in lung cancer patients compared with healthy controls. The upregulation of RAD51AP1 was mirrored in the bloods of both ovarian and lung cancer patients, and Kaplan–Meier (KM) plots predicted poorer overall survival (OS) in patients with high expression of RAD51AP1. Suppression of RAD51AP1 by RNA interference reduced cell proliferation in vitro in ovarian (SKOV3) and lung (A549) cancer cells. This effect appears to be modulated by a decrease in the expression of mTOR-related genes and pro-metastatic candidate genes. Our data describe how an initial in silico approach can generate novel biomarkers that could potentially support current clinical practice and improve long-term outcomes.

mTORC1/2 inhibition re-sensitizes platinum-resistant ovarian cancer by disrupting selective translation of DNA damage and survival mRNAs

Platinum resistance is a major cause of treatment failure and mortality in epithelial ovarian cancer. mTORC1/2 inhibitors, which impair mRNA translation, can re-sensitize resistant ovarian cancer cells to platinum chemotherapy but the mechanism remains poorly described. Using platinum-resistant OVCAR-3 cells treated with the selective mTORC1/2 inhibitor INK128/MLN128, we conducted genome-wide transcription and translation studies and analyzed the effect on cell proliferation, AKT-mTOR signaling and cell survival, to determine whether carboplatin resistance involves selective mRNA translational reprogramming, and whether it is sensitive to mTORC1/2 inhibition. Gene ontology and Ingenuity Pathway Analysis (IPA) were used to categorize gene expression changes into experimentally authenticated biochemical and molecular networks. We show that carboplatin resistance involves increased mTORC1/2 signaling, resulting in selective translation of mRNAs involved in DNA damage and repair responses (DDR), cell cycle and anti-apoptosis (survival) pathways. Re-sensitization of ovarian cancer cell killing by carboplatin required only modest mTORC1/2 inhibition, with downregulation of protein synthesis by only 20-30%. Genome-wide transcriptomic and translatomic analyses in OVCAR-3 cells revealed that the modest downregulation of global protein synthesis by dual mTORC1/2 inhibition is associated with greater selective inhibition of DDR, cell cycle and survival mRNA translation, which was confirmed in platinum-resistant SKOV-3 cells. These data suggest a clinical path to re-sensitize platinum resistant ovarian cancer to platinum chemotherapy through partial inhibition of mTORC1/2, resulting in selective translation inhibition of DDR and anti-apoptosis protective mRNAs.

Prognostic and clinicopathological significance of DEPTOR expression in cancer patients: a meta-analysis

Background

DEP domain containing mammalian target of rapamycin (mTOR)-interacting protein (DEPTOR), a recently discovered endogenous inhibitor of mTOR, has been found to be abnormally expressed in various tumors. Recent studies have demonstrated that DEPTOR could serve as a potential prognostic biomarker in several kinds of cancer. However, the prognostic value of DEPTOR is still controversial so far.

Patients and methods

PubMed, Embase and Web of Science were systematically searched to obtain all relevant articles about the prognostic value of DEPTOR in cancer patients. ORs or HRs with corresponding 95% CIs were pooled to estimate the association between DEP-TOR expression and the clinicopathological characteristics or survival of cancer patients.

Results

A total of nine eligible studies with 974 cancer patients were included in our meta-analysis. Our results demonstrated that the expression of DEPTOR was not associated with the overall survival (OS) (pooled HR=0.795, 95% CI=0.252-2.509) and event-free survival (EFS) (pooled HR=1.244, 95% CI=0.543-2.848) in cancer patients. Furthermore, subgroup analysis divided by sample size, type of cancer, Newcastle-Ottawa Scale (NOS) score and evaluation of DEPTOR expression showed identical prognostic value. In addition, our analysis also revealed that there was no significant association between expression level of DEPTOR and clinicopathological characteristics, such as tumor stage, lymph node metastasis, differentiation grade and gender.

Conclusion

Our meta-analysis suggested that despite the fact that DEPTOR could be overexpressed or downregulated in cancer patients, it might not be a potential marker to predict the prognosis of cancer patients.

Downregulation of DEPTOR inhibits the proliferation, migration, and survival of osteosarcoma through PI3K/Akt/mTOR pathway

Accumulating evidence reveals that DEP-domain containing mTOR-interacting protein (DEPTOR) plays pivotal roles in the pathogenesis and progression of many tumors. However, the expression level of DEPTOR and its function in the tumorigenesis of osteosarcoma (OS) remain unknown. In this study, we conducted quantitative real-time polymerase chain reaction, Western blot, and immunohistochemistry to detect DEPTOR expression level in human OS tissues and cell lines. To assess DEPTOR function, DEPTOR siRNA was designed and transfected into OS cells, which were then used in a series of in vitro assays. Our results indicated that DEPTOR was highly expressed in some OS tissues and cell lines. DEPTOR knockdown by siRNA dramatically inhibited cell proliferation, migration, invasion, and the formation of vasculogenic mimicry in OS cells. In addition, DEPTOR knockdown induced cell cycle arrest in the G0/G1 phase and apoptosis in the OS cell lines, MG63 and MNNG/HOS. Furthermore, we found that DEPTOR knockdown notably activated mTOR and inhibited the PI3K/Akt pathway. Taken together, these results suggest that DEPTOR overexpression is necessary for the proliferation, migration, invasion, formation of vasculogenic mimicry, and survival of OS cells and may be a potential target for the treatment of OS.