POSSIBLE ROLE OF DIFFERENTIAL METALLOPROTEENASE 1 EXPRESSION IN SIGNET RING CELL AND INTESTINAL COLORECTAL CARCINOMA HISTOTYPES

Background: Signet ring cell colorectal carcinoma (SRCC) pure is an infrequent and highly malignant variant of colorectal cancer, while this histological component is present in 30% of all colorectal carcinomas. In our previous studies, we compared the E-cadherin, beta -catenin, fibronectin, Ki-67 and thymidylate synthase (TS) expression of SRCC with those of the intestinal type of colorectal carcinoma (ICRC) to try to show the pathogenesis, aggressiveness and low 5-fluorouracil (5-FU) responsiveness of these tumours. We found that all SRCCs had very low levels of all markers and were in the post-mitotic phase of the cell cycle. To understand their high metastatic capability we assessed the SRCC expression of matrix metalloproteinase-1 (MMP1), a proteolytic enzyme, suspected to play an important role in the progression of various types of cancer and compared it to the ICRC one. Materials and Methods: We tested MMP1 expression immunohistochemically on formalin-fixed, paraffin-embedded samples of 32 SRCC and 70 ICRC. Differences in the distribution of the study variables, and associations between variables were assessed by means of the chi super(2) test. Results: SRCC showed a high expression of MMP1 over all the invasion front of the tumour and in the neoplastic embolus, rather than the ICRC (p