The Relationship Between The Expression Of P16 Protein And Biological Behavior In Colorectal Carcinoma

Colorectal cancer is one of comon maliganant tumors in ourcountuy, many people died of it every year, and with the developmentof people living level, Its incidence rate is increasing recent years.Colorectal tumors grow slowly and have no abnormal feeling ortapical syndroms in ealier stages, so patient self and clincal doctorspayed no attention to it. It has been too late stage of colorectal cancerwhen it was found. Thus, it is important to study its mechanism ofcarcinogenesis. There are multiple factors and events involved intumorigenesis. Many endogeneous and exogeneous carcinogenicfactors play the role through its influence on genes.Many tumors suppressor genes are found and help us recognizecarcinogenesis factors, espicially, the role of p16 gene in carcinogensishas attracted considerable attation in recent years. In 1992, Beach andhis comrades studied that CDKs and its integret protein of cell-span incells of melanoma.Through the physicial mapping chromosome andpointing sequence mapping, they studied one hundred melanoma cellsand found that half of tumors cells had one loss of multiple gene andthe other mutation multiple gene in No.9 chromosome in short arm of21 location, and loss of heterozygosity nearby. They predicted thatthere were tumors genes susceptibility in melanome cells. Laterthrough studying serious coloning cells and analysis sequence, namedp16 gene. The protein of p16 gene is oncoprotein of MTS1, the aminoacid sequenator show non-chain multipeptide, the molecule of itsprotein is 15. 845 KD. MTS1 is one of important famliies in CKIS andcan restrain tumor cells from translating span of G1 to S, thus, it canprevent growing of tumor cells. The abnormal changes of p16 generesult in several tumor of beginning and developing. The loss rate ofgene is high in colorectal carcinoma. The alteration of p16 gene i. e.homozygous, deletion, piont mutation and promoter methylation, andtheir consequence, p16 gene inactivation has been found to link to theoccurrence and development of many types tumors. It is small, easy tobe found and strong characters. It is not only diagnosis and prognosishelpful indictation but also an ideal treatment target gene. The study ofrelationship between the expression of p16 protein and biologicalbehavior in colon carcionma seldom is studied. Therefore, lorectal cancers were investigated, hich belonged tomalignant tumors respectivly. Our works was to explore thecorrelation between p16 expression and clinicopathological factors.P16 were examined with immunohistochemical method in 25specimens of normal colon mucous an 70 of colon carcinoma. Thepatients were constucted in 43 men and 27 women, age from 32 to 77,34 specimens under 45 years old and 36 specimens up 45 years old.The clinical classify of Dukes stage: there were 6 specimens in stageof Dukes A; 24 specimens in stage of Dukes B; 36 specimens in stageof Dukes C; 4 specimens in stage of Dukes D. The specimens divided30 specimens with lymph node metastasis and 40 specimens withoutlymph node metastasis. P16 expression was well associated with theclinicopathologic characters of colon carcinoma.The expression ofp16 gene may be an useful tool for showing of biological behavior andprognosis in colorectal carcionma.The expression of p16 protein wasfound in cytoplasm and nucleus of colortctal cancers. Posstive rate ofits expression was 37.1% and significantly lower than 85.0% innormal colon tissue (P<0.005, X2=15.8556) . The results shew theoccurrence frequencies of p16 were 37.5% in 24 specimens of gradeⅠ,50.0% in 14 specimens of gradeⅡ, 40.0% in10 specimens of gradeⅢand 27.3% in 22 specimens of grade Ⅳ. The positive rate of gradeⅣwas significantly lower than that in gradeⅠ(P<0.05) . The expression of p16 protein was 50.0% in Dukes A, 41.7% inDukes B, 30.6% in Dukes C, 50.0% in Dukes D. The postive rate ofsignificantly differentation in Dukes A, B, C, D. (Hc=3.8927,P<0.05) .The expression of p16 protein was 53.2% without lymphnode metastasis and 51.2% in lymph node metastasis (uC=1.8619, P<0.05). The expression of p16 protein have no relation with sex,age,progression and malignant behavior in tumorogenesis. The results of examine shew that there was high loss expressionrate in colorectal carcinoma(62.9%) than in normal colon tissue(16.0%). With the increasing of clinical grade, the rate of expressionof p16 protein was more and more lower (P<0.005,χ2=15.8556). Itis corresponding with civial reports, the loss of expression p16 proteinplayed an important role in the beginning and developing of colorectal...