Background: The presence of hypoxic cells in solid tumors has been suggested to contribute to the malignant progression of various tumors. Recently, we reported an activation of heat shock transcription factor (HSF) and expression of heat shock proteins (Hsp) in murine tumor cells by hypoxia.
Methods: To search for a possible role of Hsp in the malignant progression of human tumors, we analyzed the expression profiles of Hsp family proteins in weakly and highly metastatic human colorectal cancer (CRC) cell lines. We also analyzed the expression profiles of Bcl-2 family proteins because the altered expression of these proteins has been demonstrated in various solid tumors.
Results: In the present paper we showed among various Hsp and Bcl-2 family proteins that the expression of Hsp70 and Hsp110 was elevated in highly metastatic CX-1 and HT-29 cells, while the expression of Bcl-2 was elevated in weakly metastatic MIP-101 and Clone A cells. Subsequent immunohistochemical analysis of 81 primary human CRC tissues demonstrated that the expression of Hsp70 and Hsp110 was highly correlated with the advanced clinical stages and positive lymph node involvement. The expression of Bcl-2, in contrast, was correlated to the early clinical stage and negative lymphovascular invasion.
Conclusion: Taken together, our study demonstrated for the first time a differential, stage-dependent expression of Hsp70, Hsp110 and Bcl-2 in CRC. We suggest that the molecular mechanisms underlying the differential expression of Hsp and Bcl-2 family members deserves a more rigorous future study, the results of which might offer novel modes of rationale and strategy to predict and manipulate the malignant progression of colorectal cancers.