Expression Of HAX-1 In Colorectal Cancer Tissues And Its Effect In Cell Proliferation, And Cell Apoptosis Of Human Carcinoma Of Colon Cell Line

Colorectal cancer is one of the most common human digestive malignancy, whose incidence is increasing year by year.From the year of 2020,900 million people worldwide will suffer from this disease each year. Hence, more and more attention will be paid on colorectal research. Excessive cell proliferation and too little apoptosis has been figured to be an important reason of tumor development, thus how to inhibit over-proliferation and promote apoptosis of tumor cells is a hot and focus of cancer research. HAX-1 [HS1 (Haematopoietic cell specific protein l)-associated protein X-1] is first found when studing hematopoietic cell signaling protein HSl (Haematopoietic cell specific protein1) as its partner.It was expressed in various tissues, and located in the mitochondria in the sub-cellular level. Reasches imply that HAX-1 has sequence similarity with Nip3, and so its homology-BCL-2 in the BH1, BH2 sequence; it interacts with viral protein, caspase-9, PLN and many other cellular proteins; it has an immportant role in the endoplasmic reticulum calcium cycle,and also tumor cell proliferation and apoptosis. However, there is no relevant reports about the gene in colorectal cancer.We used RT-PCR, Western Blot and immunohistochemistry to detect the expressions of HAX-1 in human colorectal cancer tissue and normal tissue. We constructed both eukaryotic expression vector and replication-defective adenovirus expression vector of full HAX-1 gene, transfected them into colon cancer cell line SW480, and observe the effect of exogenous HAX-1 gene on the cell line proliferation and apoptosis; we used RNA interference technology to silence of endogenous expression of HAX-1 in colon cancer cells SW480, and observed cell proliferation, apoptosis, and explored its mechanism. The results indicated that:(1) the protein and mRNA expression level of HAX-1 in colorectal tumor tissue was significantly higher than that in adjacent normal tissue. (2) We successfully constructed a pEGFP-N1-HAX-1, pFLAG-CMV4-HAX-1 eukaryotic expression vector and replication-defective adenovirus vector Ad-HAX1-GFP.(3) The colon cells that overexpressed HAX-1 were apparently antagonizing apoptosis, and increasing proliferation; RNA interference silenced endogenous HAX-1 expression in colorectal cancer cells an reduced the cell ability to antagonize apoptosis and slowed cell proliferation; (4) by yeast two-hybrid technology and IP technology, we confirmed that hSavl (the core components of SWH pathway) directly interacted with HAX-1, indicating that HAX-1 involved in SWH pathway which is an important pathway of cell proliferation and apoptosis; (5) HAX-1 involved in mitochondria caspase-9 apoptosis pathway of colon cancer SW480 cells. (6) the changes of HAX-1 expression in SW480 colon cancer cells induced the changes of cyclin A, cyclin B1 and cyclin E. Hence, we conclude that:HAX-1 gene is closely related with the development of colorectal cancer; HAX-1 gene take part in rectal cancer cell proliferation and apoptosis activities;HAX-1 is likely a connecting sub of SWH signal pathway and mitochondrial caspase-9 pathway.This study was designed to reveal the relevance of HAX-1 and colorectal cancer,by detecting the expression of it in human colorectal tumor tissues; to further reveale the importance of HAX-1 in colorectal tumor occurrence and development, by observing the HAX-1 on human colorectal cancer cell proliferation and apoptosis;and to provides a theoretical basis for the treatment of colorectal cancer.