Frances L. Byrne

Investigation of Transcriptome Patterns in Endometrial Cancers from Obese and Lean Women

Endometrial cancer is the most common gynaecological malignancy in developed countries. One of the largest risk factors for endometrial cancer is obesity. The aim of this study was to determine whether there are differences in the transcriptome of endometrial cancers from obese vs. lean women. Here we investigate the transcriptome of endometrial cancer between obese and lean postmenopausal women using rRNA-depleted RNA-Seq data from endometrial cancer tissues and matched adjacent non-cancerous endometrial tissues. Differential expression analysis identified 12,484 genes (6370 up-regulated and 6114 down-regulated) in endometrial cancer tissues from obese women, and 6219 genes (3196 up-regulated and 3023 down-regulated) in endometrial cancer tissues from lean women (adjusted p-value < 0.1). A gene ontology enrichment analysis revealed that the top 1000 up-regulated genes (by adjusted p-value) were enriched for growth and proliferation pathways while the top 1000 down-regulated genes were enriched for cytoskeleton restructure networks in both obese and lean endometrial cancer tissues. In this study, we also show perturbations in the expression of protein coding genes (HIST1H2BL, HIST1H3F, HIST1H2BH, HIST1H1B, TTK, PTCHD1, ASPN, PRELP, and CDH13) and the lncRNA MBNL1-AS1 in endometrial cancer tissues. Overall, this study has identified gene expression changes that are similar and also unique to endometrial cancers from obese vs. lean women. Furthermore, some of these genes may serve as prognostic biomarkers or, possibly, therapeutic targets for endometrial cancer.

The NF-κB signalling pathway regulates GLUT6 expression in endometrial cancer

Gene and protein expression of the glucose transporter GLUT6 are elevated in multiple cancers, including endometrial cancer. However, the extrinsic and intrinsic mechanisms that regulate GLUT6 expression in this malignancy are unknown. Herein we investigate the potential mechanisms regulating GLUT6 expression in endometrial cancer. Data mining of the GLUT6 gene (SLC2A6) in The Cancer Genome Atlas (TCGA) PanCan datasets was performed in cBioPortal. A transcriptome PCR array was used to identify regulators of GLUT6 expression. The role of RELA in regulating GLUT6 gene and protein expression was investigated by overexpressing constitutively active and dominant-negative RELA in endometrial cells. Endometrial cells were treated with the pro-inflammatory cytokine TNFα and the expression of RELA, IκBα, TNFα, and GLUT6 were examined by Western blotting and RT-qPCR. GLUT6 is altered in 1% of all cancer samples (157 of 10, 967 samples) within TCGA datasets including 4.7% of uterine (endometrial) cancers. GLUT6 expression was positively co-expressed with multiple members of the NF-κB signalling pathway including NFKB2, RELB, NFKBIE, and TNF in endometrial cancer samples. A transcriptome PCR array identified RELA as the top potential transcriptional regulator of GLUT6 expression. Overexpression of constitutively active RELA increased GLUT6 gene expression in normal endometrial epithelial cells (hUE-Ts), while overexpression of dominant-negative RELA decreased GLUT6 expression in cancerous RL95-2 endometrial cells. TNFα treatment activated canonical NF-κB signalling and increased the expression of GLUT6, but not that of other glucose transporters (GLUTs 1, 3, 4, 8, 10, or 12) in endometrial cells. TNFα is a cytokine that is commonly increased in obesity-related endometrial cancer and the findings herein support a potential mechanism whereby TNFα may contribute to endometrial cancer initiation or progression by increasing GLUT6 expression. Furthermore, we identified RELA, an important downstream mediator of the TNFα signalling cascade, as a regulator of GLUT6 expression in endometrial cells. Future studies are warranted to determine how GLUT6 expression affects endometrial tumourigenesis or cancer progression.