Tumorigenicity and Metastatic Behavior in Nude Mice of Two Human Squamous Cell Carcinoma Lines that Differ in Production of the Cytokine ETAF/IL-1

Abstract

The purpose of these studies was to determine whether the production of the cytokine epidermal cell thymocyte-activating factor (ETAF) by human squamous cell carcinoma (SCC) cells correlated with their tumorigenicity and metastatic potential in athymic nude mice. Cells of the human SCC line A431 produced rapidly growing subcutaneous tumors, few experimental lung metastases, and low levels of ETAF activity in vitro. In contrast, cells of the SCC Colo-16 line produced slower growing subcutaneous tumors, high numbers of experimental lung metastases, and a high level of ETAF activity in culture supernatants. The apparent relationship between production of ETAF and experimental metastasis formation was not consistent. Clonal populations of the SCC A431 and Colo-16 were isolated in vitro. The clones of Colo-16 varied in their ability to produce experimental metastases and in production of ETAF in vitro. However, the levels of ETAF production did not correlate with the propensity of the SCC cells to produce experimental metastases. We conclude that while the growth and metastasis of human SCC in nude mice may benefit from production of the cytokine ETAF, the ETAF production per se is not invariably linked with the capability of the SCC cells to metastasize.