The PI3K/Akt pathway in colitis associated colon cancer and its chemoprevention with celecoxib, a Cox-2 selective inhibitor

Abstract

Oncogenesis and angiogenesis are the two major pathways involved in tumorigenesis. Oncogenesis involves the PI3K/Akt and Wnt/β-catenin pathways, both of which are upregulated in several types of cancers. We established animal model of ulcerative colitis, colon cancer and colitis associated colon cancer by the incorporation of dextran sufate sodium (DSS) and dimethyl hydrazine (DMH), alone as well as in combination. Apart from the gross morphological analysis, we presently explored the role of various components of the oncogenic pathways, including PI3K, p-Akt, PTEN, PDK1, mTOR, GSK-3β, Wnt and β-catenin and found the elevated levels of these proteins, except the tumor suppressors PTEN and GSK-3β, whose levels were downregulated in both inflammatory and carcinogenic conditions. We also studied the protein expression of some major angiogenic agents, such as Vegf, MMP-2, MMP-9 and iNOS. The angiogenic pathway was also upregulated presently in the DSS, DMH and DSS+DMH groups. Also, the reactive oxygen and nitrogen species, which lead to oxidative stress, were found to be elevated in these groups. All these effects were brought towards normal by the co-administration of celecoxib, a second generation non-steroidal anti-inflammatory drug (NSAID), with DSS, DMH and their combinatorial group.