| The small proteoglycan decorin is an extracellular matrix protein which belongs to a growing family of structurally related proteoglycans, grouped as the small leucine-rich proteoglycans (SLRPs). It is involved in the regulation of fundamental biological function such as matrix assembly, cell attachment, migration and proliferation. Decorin has recently become a focus in several areas of cancer research as a novel approach to the treatment of cancer.Different observations have revealed that decorin can inhibit the proliferation of various tumor cells. The inhibitory effects of decorin on tumor cells growth have been demonstrated both in vitro and in vivo. The transfected tumor cells with decorin gene failed to generate tumors in scid mice, the expression of decorin mRNA and protein is various in different tumors tissues.The antiongenic mechanism of decorin has been investigated: (1) Decorin is a natural inhibitor of TGF-β. It reduced the biological activity of TGF-β and inhibited tumor progression and metastasis. (2)Decorin activated the endothelial growth factor receptor (EGFR), thereby triggering a signal cascade that led to a sustained phosphorylation of mitogen-activated protein kinase(MAPK), mobilization of intracellular calcium, induction of the potent cyclin-depent kinase inhibitor p21, and growth suppression. (3) Decorin is also associated with angiogenesis which may retard tumor progression and metastasis .(4) It has been proved that decorin can interact with other proteins and cytokines in the extracellar matrix, which may be associated with tumor progression. The expression of decorin has not been reported on the level of both transcription and translation in the tumor tissues in the domestic research. Relatively little has been reported about the human recombinant decorin expressing in eukaryotic cells in domestic publication, too. The paper investigated the expression of natural decorin on the level of both gene transcription and translation in breast and colorectal cancers. The expression of recombinant decorin both in CHO cells and HCT/8 cells was also studied. 1. The expression of decorin mRNA in breast carcinoma and colorectal cancer tissuesThe expression of decorin mRNA was respectively examined in 25 cases of breast carcinoma, 9 cases of normal breast tissues adjacent to breast carcinoma, 10 cases of colorectal cancer, 9 cases of normal tissues adjacent to colorectal cancer by in situ hybridization. Decorin mRNA was observed in breast carcinoma cells and the positive signal located in the plasma and/or nuclei. The total positive rate of decorin mRNA expression in breast carcinoma was 88% (22/25). We did not observe decorin mRNA in the normal breast tissues adjacent to tumor. Statistical analysis revealed that the decorin mRNA in breast carcinoma significantly increased compared with that in the normal breast tissues adjacent to tumor (P<0.01), but we did not observe any relationship between decorin mRNA and pathological types of breast carcinoma (P>0.05). Decorin mRNA expressed both in colorectal cancer cells and in normal tissues adjacent to tumors. However, the difference of positive rate was not significant (P>0.05). The results suggested that the expression of decorin mRNA was various in different tumor tissues.2. The expression of decorin protein in breast carcinoma and colorectal cancer tissuesImmunohistochemical method was used to investigate the expression of decorin protein in 38 cases of breast carcinoma, 9 cases of normal tissues adjacent to breast carcinoma, 10 cases of colorectal cancer, 9 cases of normal tissues adjacent to colorectal cancer. Decorin protein was observed in breast carcinoma cells but not in normal tissues adjacent to breast tumor. The positive rate of decorin protein expression in breast carcinoma was significantly higher than that in normal tissues adjacent to breast tumor (P<0.01). Statistical analysis also showed that there was no significant difference of positive rate of decorin protein among various pathological types of breast ca... |
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