| Objectives: Matrix metalloproteinases (MMPs) are a family of Zinc-dependent proteinase, which hydrolyze extracellur matrix and play an essential role in both physiological and pathological condition , such as embryonic development, organ morphogenesis, tissues destruction, angiogenesis, and tumor invasion or metastasis. MMP-7 is the smallest member of the MMP gene family after being activated, having a proteolysis activity against a variety of extracellular matrix component , including collagen, proteoglycan, laminin, fibronectin and elastin. It exists in several normal tissue , such as endometrium, bronchial mucosa ,monocytes, and is also produced by some malignant tumor cells. MMP-7 is over-expressed in colorectal , prostate, gastric, breast, pancreatic carcinoma, and may contribute directly to cancer cells in invasion and metastasis. The length of invasion of rectal carcinoma is relational with the selection of surgical operation, extent of distal intramural spread deciding the distal resection when performing sphincter-preserving operation . It is reported that length of intramural spread of the tumor is less than 2cm. But some writers insist that the length is more than 2cm,2-3cm distal margin of resection is not safe for sphincter-saving procedure for rectal carcinoma. Cancer cells remaining in the rectal wall lead to recurrence at the sit of anastomosis . In this study , we wanted to find out the relationship between expression of MMP-7 and clinic-pathologic stage in rectal carcinoma and its connection with distal spread and lymph node metastasis, to evaluate the frequency of microscopic distal intramural spread in the carcinoma and ascertain the length of distal spread, provide the evidence for the anal-preserving operation.Material and methods: Thirty-two patients with rectal carcinoma included in this study and all patients had undergone radical resection in the Second Hospital Hebei Medical University between July 2000 and November 2001. There were 14 males and 18 females, aged from twenty eight to eighty years old, mean age of fifty-seven. None of patients received chemotherapy or radiotherapy. All were diagnosed with adenocarcinoma by pathology, 11 were well differentiated, 9 were moderately differentiated, 12were poorly differentiated. Not distant metastasis was found by clinical examination. All the patients were in Duke's'stage A 8 B1K C 12. Fresh specimens (0.5 X 0.5cm) were obtained in operating room, which distal edge of resection distant from the tumor more than 3cm . Other specimens of entire intestinal wall were transversely taken at intervals of 0.5cm along the longitudinal axis of tumor toward the distalresection line from inferior edge of the tumor. The specimens were fixed in 70% alcohol for detecting MMP-7 by flowcytometry and immunoflurescence staining. Corresponding normal colon bowel wall specimens distant at 15cm away from the superior edge were also obtained. The specimens were placed in 10% formalin and embedded in paraffin wax for hematoxylin and eosin staining and immunohistochemistry respectively. Pathologic slices were used to study the length of distal intramural spread of rectal cancers and the location of MMP-7 in cancer tissue was observed by immunostaining with an anti-matrilysin monoclon antibody.Results: 1. FCM shows: 1.1 The expression of MMP-7 in tumor was 6.82+1.77, and was negative in normal bowel tissue(P<0.01). 1.2 expression of MMP-7 was 6.27 + 0.47, 6.74 + 0.70, 7.23 + 0.94 respectively in well, moderate, poorly differentiation(P>0.05). 1.3 The expression of MMP-7 was 7.92 + 1.14in rectal cancer with lymph node metastasis and 6.21 + 0.96 in those without lymph node metastasis(P<0.05). 1.4 There was difference in Duke's'stage A, B, C (5.76 + 0.71, 6.58+1.01, 7.92+1.14 respectively P<0.05). 1.5 MMP-7 was 6.14+1.07 and 7.47+1.26 respectively in the group with and without distal intramural spread(P<0.05). 1.6 There was no relationship between MMP-7 and the length of distal intramural spread (Spearman analysis, r=0.117, P>0.05). 1.7 The expression...
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