A Study On Expressions Of Bax,PCNA And CDK₄ In Human Oral Lichen Planus And Oral Squamous Cell Carcinoma

Background and objectivesOral squamous cell carcinoma (OSCC) is the commonest malignancy in the oral cavity. Oral lichen planus (OLP) is pathologically classified as precancerous condition. It is of great clinical significance to study for the early diagnosis of OSCC and for the assessment of malignant potential of OLP.The carcinogenesis is considered as a multi-step process in which many cell genetic alterations are involved. Irregulation of both cell apoptosis and cell proliferation can result in malignancy. Bax gene is an important apoptogenic gene. It is associated with carcinogenesis of a wide variety of human tissues. PCNA has been found as a very important factor to promote cell proliferation and it can assess the cell proliferating condition. CDK₄ has the role to promote the replication of DNA. The more expression of CDK4, the more production of DNA. So CDK₄ can improve cell proliferation, then induce malignant transition of oralprecancerous condition.Investigation into the sequent expression of Bax and CDK₄ in precancerous and cancerous lesions of the oral mucosa have rarely been reported in China and foreign researches, and the possible roles of Bax and CDF₄ in oral carcinogenesis remain unknow.This paper immunohistochemically studied the expression of Bax PCNA and CDK4 protein in oral mucosa lesions, including oral normal mucosa OLP and OSCC of varying grades, to investigate their possible roles in carcinogenesis of oral mucosa and their possible clinical significances.MethodsSeventy cases of formalin-fixed Paraffin-embedded specimens from oral mucosa lesions were obtained from the pathology archive files of the Department of Pathology of ZhengZhou University. These specimens included 30 cases of OLP and 30 of OSCC. The specimens of OSCC were pathologically classified as 10 of grade I 10 of grade II , and 10 of grade III. 10 cases of specimens from oral normal mucosa were taken as control. Immunohistochemical detection for Bax PCNA and CDK₄ protein were carried out for all specimens. The positive cell countings of Bax PCNA and CDK₄ were calculated. All data were statistically analysed. Results1. Expression of Bax protein in oral normal mucosa and various oral mucosa lesions: The positive rates of Bax protein in oral normal mucosa OLP OSCC I . OSCC II and OSCC III were 90.00%(9/10) 96.67%(29/30) 90.00%(9/10),20.00%(2/10) and 10.00%(1/10). By statistical analysis, the positive expression of Bax protein decreased with the malignant progression of oral mucosa lesions2. Expression of PCNA in oral normal mucosa and various oral mucosalesions: The proliferating index(PI) of PCNA in oral normal mucosa, OLP, OSCCI OSCC II and OSCCIII were 9.80±1.16, 25.98 + 2.34, 45.25 + 2. IK 62.53± 1 .80 and 82.26 ± 1 .78. There were significant difference between any two groups3. Expression of CDK4 protein in oral normal mucosa and various oral mucosa lesions:The CDK.4 positive rates in oral normal mucosa, OLP and OSCC were 60.00%(6/10), 80.00%(24/30) and 93.33%(28/30). The positive expression of CDK4 protein increased with the malignant progression of oral mucosa lesions (P<0.01). But, the positive rates in OSCC I , OSCC II and OSCCIII were 90.00%(9/10) 90.00%(9/10) and 100%(10/10), there were no significant difference between any two groups(P>0.05).4. Relationships of PCNA positive expression with the expression of Bax protein and CDK4 protein: All specimens from oral mucosa lesions were classified as Bax-positive, Bax-negative and CDK₄-positive, CDK4-negative according to stainting. (1)The proliferating index in Bax negative specimens was significantly higher than it in Bax positive specimens (P<0.01). (2)The proliferating index in CDK₄-positive specimens was significantly higher than it in CDK₄-negative specimens (P<0.01).5. Correlation of Bax protein with CDK₄ protein: NO correlation between Bax protein expression and CDK₄ protein expression was found in OLP (rs=0.05...