Disorderly CD44 gene expression in human cancer cells can be modulated by growth conditions.

Disorderly CD44 gene expression is a well-documented characteristic feature of tumour cells from cancers arising in many different organs of the human body. Molecular pathological studies have established that the pattern of the abnormal expression can differ according to the origin and the stage of the tumour. In this investigation it has been demonstrated that in some but not all tumour cell lines, which are undeniably and irreversibly malignant when inoculated in vivo, CD44 gene expression can still be modulated. In two cell lines, the pattern of CD44v expression was found to be affected by cell-to-cell and cell-to-substrate attachment. Expression was up-regulated by cell-substrate interactions, but only until cell-to-cell contact caused subsequent down-regulation of CD44v transcription. This information provides new opportunities for detailed investigation of the mechanisms of abnormal CD44 gene regulation in cancer and for exploring stage-related changes in the expression of this complex gene.