We studied by indirect immunofluorescence microscopy the distribution of integrins and laminins in four human renal cell carcinoma cell lines (CAKI-2, A498, CAKI-1, and ACHN) in vitro and in s.c. xenografts in nude mice. In vitro, all four cell lines expressed the alpha 1, alpha 3, alpha v, beta 1, beta 3, and beta 5 subunits and three expressed the alpha 6 subunit; all cell lines expressed laminin A, B1, and B2 chains. Histologically, the CAKI-2 and A498 cells formed differentiated grade 1

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... and G2 tumors, respectively, while the CAKI-1 and ACHN cells formed poorly differentiated G3 tumors. The described integrin profile was largely retained upon xenografting. Basal polarization of the alpha 3 and alpha 6 integrin subunits was found in the differentiated tumors, and human laminins were detected as discrete linear structures surrounding tumor cell clusters in these tumors, suggesting that the cells have retained a polarized cell-laminin interaction characteristic of normal tubular epithelial cells. A disorganized distribution of integrins and laminins was noted in the G3 tumors. We conclude that these renal carcinoma cell lines displayed an integrin repertoire similar to that of clinical renal carcinomas and retained it upon xenografting. Furthermore, the organization of integrins and laminins in the xenografts correlated with histological grade.