Hypoxic Inflammation, a Deadly Bridge to Malignant Transformation and a Fertile Soil for Cancer Prevention

Abstract

The interplay of the inflammatory microenvironment with its hypoxic niche and the potential mechanism by which they lead to malignant transformation has long been the subject of great controversy and continues to be an area of great interest today. In our previous studies we have examined this subject by using Gia2 knock out mice as the focus of our research. These mice are well known for their tendency to develop chronic inflammation in the sub mucosa of their gut, with gradual worsening and development of colon adenocarcinoma in most as they age. It has also attracted our attention that they develop a significant increase in the number of hypoxic niches in their sub mucosa, proven by EF5 staining.In contradistinction to MSI-high colon adenocarcinomas, we have also shown that histone deacetylation rather than MLH1 promoter methylation is the main mechanism of MLH1 and MSH2 deactivation in these mice. Here we show that hypoxic niches evolve under massive selective pressure of the inflammatory microenvironment as a protective shield offering survival advantage by the up regulation of NFKb and its downstream pathways, which indeed independent of true hypoxia leads to stabilization of HIF as well, securing a dual mechanism for perpetuation and expansion of hypoxic niches. We incorporated western blot and Luciferase assay of cells exposed to hypoxia+/-inflammatory cytokines to acquire data.