Upregulation of HO-1 is accompanied by activation of p38MAPK and mTOR in human oesophageal squamous carcinoma cells.

Induction of HO-1 protein can have both beneficial and detrimental effects for cells, including regulating proliferation and apoptosis of several tumours. We have investigated the regulation of HO-1, p38MAPK and mTOR in the context of proliferation, cell cycle events and apoptosis of oesophageal squamous cell carcinoma cells. Real-time PCR and Western blots were used to determine the expression levels of HO-1, p38MAPK, p-p38MAPK and p-mTOR. MTT assays were used to measure proliferation, FACS for cell cycle events and Annexin V staining for apoptosis. Proliferation of Eca109 cells was inhibited and apoptosis was induced in the presence of p38MAPK inhibitor (SB203580) and mTOR inhibitor (Rapamycin, RAPA). HO-1 expression was downregulated in cells treated with SB203580 and RAPA. HO-1 overexpression inhibited apoptosis and induced G2/M arrest in SB203580 and RAPA-treated cells. HO-1 expression was upregulated in the presence of ethanol, and was accompanied by activation of p38MAPK and mTOR. However, ethanol-treated cells exposed to HO-1 inhibitor showed no effect on p38MAPK and mTOR activation. The data suggest that ethanol-induced upregulation of HO-1 in oesophageal squamous cell carcinoma is accompanied by the activation of the p38MAPK and mTOR pathways.