Detection Of Expression Of P27 Protein And PCNA And Relationship Between Them And Clinical Significance In Oral Squamous Cell Carcinomas

There is a common feature that the control mechanism of cell cycle have disordered and cell begin to out of control in the happening of tumours.The running of cell cycle suffers from a variety of factors to participate in the control. There are CYCLIN, CYCIN DEPENDENT KINASE (CDK), and CYCLIN- DEPENDENT KINASE INHIBITORS (CKI). CYCLIN, CDK and CYCLIN- CDK COMPEX can regulate positively. Instead, CKI does negatively which can inhibit the developing of cell cycle by associating with CYCLIN, CDK or CYCLIN-CDK COMPLEX.As a CKI, P27 was a new discovery. PCNA and CYCLIN are the same material. Therefore, the of P27 and PCNA are more and more attractive in the control of cell cycle. In recent years,people also found that they significantly associate with invasive and prognosis of canser.In the year of 1994, Polyak et al found a new 27KB heat-stable protein in Mv1lu which was treated by TGF-β, named P27kip ,and it was purified by using affinity dialysis.P27 got the seguence by automatic Edman degradation. P27 which localizes in chiromatosome 12p (12.0-13.1), and at least contains two Exons and two Introns.Human's P27cDNA are 594bp long ,which can code 198 a mino acids and also are the highly conservative protein molecules, There are ninty percents homology in the main sequence P27 of mino acids of human, mouse and mink. Their c end all contain a duar sticks nuclear localization signal. Their n end induce and inhibit CDK. Nearly 12 to 87 main sequence mino acids are homologous with p21cip. Its inhibit faction would be weakend, when it losts five mino acids of n end or 15 mino acids of c end.And if it continue to lost 7, the faction will disappear.The expression of P27 protein all decline abnormally in majority tumurs. P27 can inhibit different species the activity of CYCLIN-CDK which have be activated. P27 mediated the cell cycle process and involved in cell growth and differentiation by the way of chemometrics. P27 is a CDK inhibitor that causes cell cycle arrest in G1 to S phase and it was suggested that may play an important role in cell proliferation and carcinogenesis.P27 also is a one of potential mediasin extracellular stimulated signal and among cell cycle status. There would be two results when it was stimulated by extracellular signal. One made cell cycle into G0 phase by stimulate anti-proliferation signal, the other made it form G1 to S phase and then into the next phase by stimulating of mitogen.According to previous studies, the expression of P27protein compared with normal epithelial tissues were declined and lost in squamous cell carcinomas(SCC). P27was also associated with the indicators of poor prognosis of SCC. The relationship among the expression of P27 protein with P53, PCNA and BAX et al in SCC are uncertain, and need to be further studied. Therefore, increasing the expression of P27 protein may have SCC treatment significances.PCNA is nuclear protein. There is little in quiescent cell and begin to increase in late G1 phase, then to the peak in S phase and to decline significantly in G2 -M phase. As PCNA associated with its apparent and cell proliferation,it could be an indicator of cell proliferation.At first,people thought that PCNA and cyclin were different material,whether in subcellular localization,peptide chain composed or biological function.PCNA was digested easily by trypsin protease instead of being damaged by DNA enzyme and RNA enzyme.Waseem et al proved that there were two kinds of PCNA: 1.Soluble PCNA.It was in quiescent prolifering cells and then combinating loose with DNA and drifting away from the nucleus.It contained little change in cell cycle which was eluted easily by detergent. Soluble PCNA would disappear in methanol-treated issue cell.2.Insoluble PCNA.It combinated with specific nucleus DNA,and played an important role in DNA replication.Insluble PCNA occurred significant changes,whether methanl and detergent can damaged.As a non-specific multifunction CKI,P27 control cell cycle negatively with a variety of ways,in order to make it stagnate in G1 phase and then inhibit cell growth and proliferation.PCNA mainly tagged the proliferation nucleus which in late G1 phase and early S phase in cell cycle It associated significantly with cell cycle and cell proliferation then considerated to be a good indicator of evaluating tumor cell proliferation. The expression of P27 protein are not associated with PCNA in some colon cancer research. It was not reported in endometrial cancer whether the expression of P27 protein were associated with PCNA or not at home and abroad. But some scholars found that the expression of P27 protein associated negatively with PCNA in the expression of endometrial. The expression of P27 protein were higher. Insead, the expression of PCNA were lower. This case are consistent with the function that can control negatively cell cycle. It also indicated that the declining of P27 protein stimulated cell overgrowth and proliferation in the way of direct or indirect function. This relevance between P27and PCNA are also not reported in OSCC, and have an urgent need to further our research.Oral squamous cell carcinoma(OSCC) is most common oral cancer,which is a serious threat to human health with a very high incidence and a low survival rate.At present, we don't find any investigation about the relationship between P27 and PCNA. Immunohistochemical analysis was performed on tumor specimens from 55 patients with OSCC, 5 biopsies of normal oral mucosa, 20 hyperplastic tissues. According to the results, we can analysis the relationship among the exression level of P27 and PCNA and oral carcinoma's clinical pathology and lymph node metastasis. We also approach the P27 and PCNA's role in the development of carcinoma and provide a strong theory support for prevention and treatment of OSCC.RESULT: There was no differences of the expression of P27 in normal oral mucosa or hyperplastic tissues (p>0.05). Instead, there were significantly differences between OSCC and them(p<0.01).It was observed significantly lower expression of P27 in OSCC from patients in StageⅢ/Ⅳwith lymph node metastasis as compared to StageⅠ/Ⅱand no lymph node metastasis (p<0.05). There was no differences of the expression of PCNA in normal oral mucosa or hyperplastic tissues(p>0.05). Instead, there were significantly differences between OSCC and them (p<0.01). It was observed significantly higher expression of PCNA in OSCC from patients in StageⅢ/Ⅳwith lymph node metastasis as compared to StageⅠ/Ⅱand no lymph node metastasis (p<0.05). There was no significant correlation about the expression of P27 and PCNA,becaused of different age, sexuality and tumor growth region. We also found that there are an inverse correlations between the expression of p27 and PCNA in OSCC(p=0.001,r=-0.510).CONCLUTION: It was observed significantly lower expression of P27 in OSCC. Instead, PCNA was higher.Their expression in OSCC have a significantly correlation with OSCC's clinical pathology and lymph node metastasis. There was no significant correlation about them becaused of different age, sexuality and tumor growth region(p>0.05). It is hoped that P27 and PCNA could become a new pathway in immune and therapy for OSCC.