Expression of the matrix Gla protein in urogenital malignancies

Matrix Gla protein (MGP), is a vitamin‐K‐dependent protein which is synthesized in a variety of tissues such as lung, heart, kidney, cartilage and bone. The function of MGP in these tissues is unclear. We have previously reported elevated MGP mRNA levels in a breast‐cancer cell line, 600PEI, as compared to normal breast epithelium. Here we describe high MGP expression in primary renal‐cell carcinomas, prostate carcinomas and testicular germ‐cell tumors, as determined by Northern analysis. MGP was over‐expressed in 21 out of 28 patients with renal‐cell carcinoma, and in 16 out of 29 patients with testicular germ‐cell tumors, as compared to matched normal tissues. For the renal‐cell carcinomas, a statistically significant inverse correlation was observed between the level of MGP expression and tumor size, lymph‐node metastasis and tumor grade. MGP was also highly expressed in 13 primary prostatic carcinomas as compared to prostate cell lines derived from metastatic tumors, and to lymph‐node metastasis. Our findings indicate that the loss of MGP expression may be associated with tumor progression and metastasis. © 1992 Wiley‐Liss, Inc.