The Expression of Type IV Collagen α6 Chain Is Related to the Prognosis in Patients with Esophageal Squamous Cell Carcinoma.

The destruction of the basement membrane (BM) is the first step in cancer cell invasion and metastasis. Type IV collagen is a major component of the BM, and is composed of six genetically distinct α(IV) chains: α1(IV) to α6(IV). The loss of α5/α6(IV) chains from the epithelial BM at the early stage of cancer cell invasion has been reported in several cancers. However, the expression of α5/α6(IV) chains in esophageal squamous cell carcinoma (ESCC) remains unclear. The expression of α(IV) chains in 116 resected ESCC specimens was immunohistochemically examined. The role of α6(IV) chain was assessed in ESCC cell lines by short interfering RNA (siRNA). In intraepithelial carcinoma, the α5/α6(IV) chains were stained in a continuous linear pattern in the BM. In some cases of ESCC with the invasion beyond the lamina propria, the α5/α6(IV) chains were lost in the BM zone surrounding the cancer cell nests, but in other cases they remained. In the former, the disease-free survival and overall survival were significantly better than in those with the latter. The down-regulation of α6(IV) chain expression by siRNA revealed a slight increase of cancer cell invasiveness. The evaluation of α5/α6(IV) chains may be a useful marker for determining tumor cell properties, as a prognostic factor, in patients with ESCC. [ABSTRACT FROM AUTHOR]