Oxidative metabolism drives inflammation-induced platinum resistance in human ovarian cancer.

Tumour cells have long been considered defective in mitochondrial respiration and mostly dependent on glycolytic metabolism. However, this assumption is currently challenged by several lines of evidence in a growing number of tumours. Ovarian cancer (OC) is one of the most lethal cancers worldwide, but it continues to be a poorly understood disease and its metabolic features are far to be elucidated. In this context, we investigated the role of tumour necrosis factor receptor-associated protein 1 (TRAP1), which is found upregulated in several cancer types and is a key modulator of tumour cell metabolism. Surprisingly, we found that TRAP1 expression inversely correlated with grade, stage and lower survival in a large cohort of OC patients. Accordingly, TRAP1 silencing induced resistance to cisplatin, resistant cells showed increased oxidative metabolism compared with their sensitive counterpart, and the bioenergetics cellular index of higher grade tumours indicated increased mitochondrial respiration. Strikingly, cisplatin resistance was reversible upon pharmacological inhibition of mitochondrial oxidative phosphorylation by metformin/oligomycin. At molecular level, increased oxidative metabolism in low TRAP1-expressing OC cells and tissues enhanced production of inflammatory mediators such as interleukin (IL)-6 and IL-8. Mechanistically, we identified members of the multidrug resistance complex (MDR) as key mediators of such metabolism-driven, inflammation-induced process. Indeed, treatment of OC cell lines with TNFα and IL6 induced a selective increase in the expression of TAP1 and multidrug resistance protein 1, whereas TAP1 silencing sensitized cells to cisplatin-induced apoptosis. Our results unveil a novel role for TRAP1 and oxidative metabolism in cancer progression and suggest the targeting of mitochondrial bioenergetics to increase cisplatin efficacy in human OC.

Differential expression of IL-8 and IL-8 receptors in benign, borderline and malignant ovarian epithelial tumours.

INTRODUCTION: Ovarian Cancer is the leading cause of death from gynecological malignancy. The poor prognosis is mainly due to presentation at a late stage and poor response to therapy. Much research is needed to identify diagnostic and prognostic biomarkers as well as therapeutic targets for ovarian cancer. Interleukin-8 is expressed by many tumour types and is known to have mitogenic, motogenic and angiogenic effects on tumour cells. AIMS: The aim of this study was to investigate the expression of IL-8 and IL-8 receptors (IL-8RA and IL-8RB) in different histological subtypes of ovarian tumours, as potential prognostic biomarkers in ovarian tumours. MATERIALS AND METHODS: Immunohitochemistry was used to study the expression of IL-8 and IL-8 receptors in 115 ovarian tumours including 21 benign tumours, 25 borderline tumours and 69 carcinomas of serous, clear cell, endometrioid and mucinous types. The correlation of expression profile, tumour type, stage, and progression free survival and overall survival was statistically analysed. RESULTS: IL-8 and IL-8 receptors were expressed in all types of tumours with variable intensity and subcellular distribution. There was a statistically significant correlation between levels of expression and tumour stage and tumour type, being mostly significant in serous tumours. No correlation with patient progression free survival or overall survival was found. CONCLUSION: This is the first study investigating the expression of IL-8 and IL-8 receptors using immunohistochemistry in different types of ovarian tumours, including benign and borderline tumours. IL-8 and IL-8RA are potential prognostic biomarkers and therapeutic targets in ovarian cancer, particularly in ovarian serous carcinoma.

Chromatin H3K27me3/H3K4me3 histone marks define gene sets in high-grade serous ovarian cancer that distinguish malignant, tumour-sustaining and chemo-resistant ovarian tumour cells.

In embryonic stem (ES) cells, bivalent chromatin domains containing H3K4me3 and H3K27me3 marks silence developmental genes, while keeping them poised for activation following differentiation. We have identified gene sets associated with H3K27me3 and H3K4me3 marks at transcription start sites in a high-grade ovarian serous tumour and examined their association with epigenetic silencing and malignant progression. This revealed novel silenced bivalent marked genes, not described previously for ES cells, which are significantly enriched for the PI3K (P<10(-7)) and TGF-ß signalling pathways (P<10(-5)). We matched histone marked gene sets to gene expression sets of eight normal fallopian tubes and 499 high-grade serous malignant ovarian samples. This revealed a significant decrease in gene expression for the H3K27me3 and bivalent gene sets in malignant tissue. We then correlated H3K27me3 and bivalent gene sets to gene expression data of ovarian tumour 'stem cell-like' sustaining cells versus non-sustaining cells. This showed a significantly lower expression for the H3K27me3 and bivalent gene sets in the tumour-sustaining cells. Similarly, comparison of matched chemo-sensitive and chemo-resistant ovarian cell lines showed a significantly lower expression of H3K27me3/bivalent marked genes in the chemo-resistant compared with the chemo-sensitive cell line. Our analysis supports the hypothesis that bivalent marks are associated with epigenetic silencing in ovarian cancer. However it also suggests that additional tumour specific bivalent marks, to those known in ES cells, are present in tumours and may potentially influence the subsequent development of drug resistance and tumour progression.

Microarray coupled to quantitative RT-PCR analysis of androgen-regulated genes in human LNCaP prostate cancer cells.

The androgen receptor (AR) mediates the growth-stimulatory effects of androgens in prostate cancer cells. Identification of androgen-regulated genes in prostate cancer cells is therefore of considerable importance for defining the mechanisms of prostate-cancer development and progression. Although several studies have used microarrays to identify AR-regulated genes in prostate cancer cell lines and in prostate tumours, we present here the results of gene expression microarray profiling of the androgen-responsive LNCaP prostate-cancer cell line treated with R1881 for the identification of androgen-regulated genes. We show that the expression of 319 genes is stimulated by 24 h after R1881 addition, with a similar number (300) of genes being significantly repressed. Expression of the upregulated genes, as well as of 60 of the most robustly downregulated genes, was carried out using quantitative RT-PCR (Q-RT-PCR) over a time-course of R1881 treatment from 0 to 72 h. Q-RT-PCR was also carried out following treatment with other AR agonists (dihydrotestosterone, estradiol and medroxyprogesterone) and antagonists (cyproterone acetate, hydroxyflutamide and bicalutamide). This study provides a comprehensive analysis of androgen-regulated gene expression in the LNCaP prostate cancer cell line, and identifies a number of androgen-regulated genes, not described previously, as candidates for mediating androgen responses in prostate cancer cells.

BARX2 induces cadherin 6 expression and is a functional suppressor of ovarian cancer progression.

The human homeobox BARX2 is located at 11q24-q25, within a minimal region associated with frequent loss of heterozygosity and adverse survival in epithelial ovarian cancer. BARX2 is a transcription factor that regulates transcription of specific cell adhesion molecules in the mouse. We show that BARX2 and cadherin 6 are expressed in normal human ovarian surface epithelium. BARX2 and cadherin 6 both have significantly lower expression in a clinical sample of endometrioid and clear cell ovarian cancers, as compared with serous or mixed mesodermal tumors. In a series of ovarian cancer cell lines, BARX2 expression showed a significant direct correlation with cadherin 6 expression. In OAW42, an ovarian cancer cell line that does not endogenously express BARX2, in vitro transfection of human BARX2 cDNA induced cadherin 6 expression. Transfection of BARX2 into OAW42 inhibited Matrigel invasion, haptotactic cellular migration to a collagen IV signal, and adhesion to collagen IV-coated plates. Our data demonstrate that BARX2 is expressed in the ovarian surface epithelium and has functional suppressor properties in ovarian cancer cells.

Novel PCR-based diagnostic tools for Charcot-Marie-Tooth type 1A and hereditary neuropathy with liability to pressure palsies.

The majority of cases of Charcot-Marie-Tooth type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP) are the result of DNA duplications and deletions respectively of a 1.5 Mb region on 17p11.2. The region contains the peripheral myelin protein 22 gene (PMP-22) and is flanked by homologous proximal and distal CMT1A-REP elements. The majority of duplications and deletions arise during meiotic recombination following misalignment and unequal crossing-over between the proximal and distal CMT1A-REP elements. The cross-over breakpoints are most frequently located within a 1.7 Kb hotspot of recombination and produce novel duplication or deletion junctional CMT1A-REPs with unique restriction patterns. Here we describe the use of PCR based tests, which amplify a 3.6 Kb region including the 1.7 Kb hotspot from specific CMT1A-REPs, for the rapid diagnosis of CMT1A and HNPP patients. In an analysis of 96 CMT1A and 30 HNPP patients, duplication and deletion events were detected in all samples with cross-over breakpoints known to be within the region amplified by PCR.