Tumor Cell Kinetics and Expression of Type IV Collagen and E-cadherin in a Human Gingival Carcinoma Xenograft Line in Nude Mice

Abstract

In order to elucidate the relationship of tumor invasion with the expression of E-cadherin and type IV collagen, I carried out immunohistochemical studies on a human gingival carcinoma xenograft line, GK-1, in nude mice. The transplanted tumors were divided into four stages of progression for examination at 5, 7, 10 and l5 weeks after transplantation based on the value of the labeling index for BrdU.
The labeling index for BrdU showed its greatest value at seven weeks after transplantation. There was a marked decrease of E-cadherin expression in the tumors at seven weeks after transplantation, and the amount of expression negatively correlated with the labeling index. In addition, the expression of type IV collagen decreased, having a positive correlation with the expression of E-cadherin, and it became discontinuous and unstable.
From the above findings, both the decreased expression of E-cadherin and the discontinuous expression of type IV collagen suggest that the tumor cells maintain high invasiveness.