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Matrix metalloproteinases (MMPs) are believed to contribute to the complex process of cancer progression. They also exhibit an alpha1-proteinase inhibitor (alphaPI)-degrading activity generating a carboxyl-terminal fragment of approximately 5 kd (alphaPI-C). This study reports that overexpression of alphaPI-C in S2-020, a cloned subline derived from the human pancreas adenocarcinoma cell line SUIT-2, potentiates the growth capability of the cells in nude mice. After stable transfection of a vector containing a chimeric cDNA encoding a signal peptide sequence of tissue inhibitor of metalloproteinase-1 followed by cDNA for alphaPI-C into S2-020 cells, three clones that stably secrete alphaPI-C were obtained. The ectopic expression of alphaPI-C did not alter in vitro cellular growth. However, subcutaneous injection of the alphaPI-C-secreting clones resulted in tumors that were 1.5 to 3-fold larger than those of control clones with an increased tendency to invasiveness and lymph node metastasis. These effects could be a result of modulation of natural killer (NK) cell-mediated control of tumor growth in nude mice, as the growth advantage of alphaPI-C-secreting clones was not observed in NK-depleted mice, and alphaPI-C-secreting clones showed decreased NK sensitivity in vitro. In addition, production of alphaPI and generation of the cleaved form of alphaPI by MMP were observed in various human tumor cell lines and in a highly metastatic subline of SUIT-2 in vitro. These results provide experimental evidence that the alphaPI-degrading activity of MMPs may play a role in tumor progression not only via the inactivation of alphaPI but also via the generation of alphaPI-C.

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By using a combination of the methods of reverse transcription-PCR and rapid amplification of cDNA ends, a cDNA for rat pS2 peptide (rpS2) was successfully cloned and sequenced from rat stomach. By RNA blot analysis, the gene was shown to be expressed abundantly in the stomach and only faintly in the duodenum, but not in other tissues including the distal small and large intestines. rpS2 expression was also examined in the rectum during the course of acetic acid-induced colitis; rpS2 mRNA was detected during the acute phase of colitis but not in normal controls or during the recovery phase. On the other hand, expression of rat intestinal trefoil factor (rITF) was down-regulated during the acute phase of colitis and then up-regulated during the recovery phase, whereas rat spasmolytic peptide was not detectable throughout the course of the induced colitis. These results indicate that the patterns and timing of the expression of these trefoil peptides are different from each other. rpS2 may play an important role in the proliferation of intestinal epithelial cells during the acute phase of mucosal ulceration, whereas rITF may be involved in differentiation of the cells, particularly to form goblet cells, during the recovery phase.

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Expression of inter-alpha-trypsin inhibitor light chain (ITI-LC, also known as bikunin or urinary trypsin inhibitor) was examined in various human tissues. By reverse-transcription polymerase chain reaction, the mRNA was detected not only in the liver, a known site of ITI-LC production, but also in the kidney, heart, lung, and pancreas. By RNA blot analysis, the mRNA was also detected in the pancreas and liver, but not in the kidney, heart, or lung. The ITI-LC protein was immunohistochemically detected along the surface of pancreatic acinar cells. These results indicate the apparent expression of the gene for ITI-LC in the pancreas. ITI-LC protein on the surface of pancreatic acinar cells may play an important role in preventing autodigestion by exocrine enzymes such as trypsinogen and chymotrypsinogen.

To investigate the expression of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in human colorectal carcinomas, Northern blot analysis was performed in a series of human colorectal carcinoma cell lines and in normal or tumoral colorectal tissues. Of 16 human colorectal carcinoma cell lines examined, most expressed TF mRNA, though the levels of expression varied significantly. Considerably higher expression was observed in the cell line CaR‐1, while lines established from metastatic lesions tended to express abundant TF mRNA. By contrast, TFPI mRNA levels were low in these high TF‐expressing cell lines. TFPI was expressed abundantly in WiDr and in a few other cell lines which expressed a very low level of TF mRNA. Immunocytochemically, both proteins were stained predominantly on the cell surface; however, diffuse cytoplasmic staining for TF also was observed in CaR‐1 cells. In addition, the cell surface TF activity was significantly higher in CaR‐1 cells than in WiDr cells, confirming the results of mRNA analysis. The level of TF mRNA in colorectal carcinoma tissue in vivo and its ratio to the normal counterpart also varied significantly among the cases. To search for a possible role of TF/TFPI in metastasis of colorectal carcinoma cells, the expression of these genes was compared between a rectal adenocarcinoma cell line, RCM‐1, and its highly metastatic subline, RCM‐1 L‐10. Compared with the parent line, RCM‐1 L‐10 expressed 7.5‐fold higher levels of TF mRNA, whereas TFPI expression was not altered significantly or even decreased slightly. The higher cellular TF activity was confirmed in the metastatic subline in comparison with the parent line. Int. J. Cancer 72:878–884, 1997. © 1997 Wiley‐Liss, Inc.