Laminin and fibronectin increase the steady state level of the 67 kD high affinity metastasis-associated laminin receptor mRNA in human cancer cells.

Among the various known laminin binding proteins, the 67 kD high affinity laminin receptor (LR) is intimately involved during tumor invasion and metastasis. In this study, we report that laminin and fibronectin, two attachment glycoproteins, significantly increased the total cellular level of 67 kD LR mRNA in two human cancer cell lines, T47D breast carcinoma cells and A2058 melanoma cells. Neither GRGDS nor YIGSR synthetic peptides induced such a stimulatory effect. Since the steady state level of LR mRNA has been shown to control the number of receptors expressed at the cell surface, these results suggest that contact of the cancer cells with laminin and fibronectin in the host matrix may be an important regulatory mechanism by which cancer cells maintain a high number of LR at their cell surface as they progress through the several steps of tumoral invasion and metastasis.