The Relationship Of P16INK4a With HPV And The Value Of P16INK4a And L1 Expression In Cervical Lesions

BACKGROUND:High risk human papillomavirus (HR-HPV) infection is known to be the most important etiology of invasive cervical cancer (ICC) and cervical intraepithelial neoplasia (CIN).It is reported that the expression of p16INK4a were positively associated with CIN grade and mainly expressed in the later proliferative phase. HPV-L1(L1) is a capsid protein that is expressed in the early, productive phase of cervical carcinogenesis and is progressively lost in the later proliferative phase. Whether expression of p16 INK4a is associated with HR-HPV or HPV subtype and the value of p16INK4a in combination with L1 expression in predicting the behaviour of CIN are still unknown.PURPOSE:To study the relationship of p16INK4a with HPV and the prognostic value of p16INK4a and L1 expression in cervical lesions.METHOD:To determine expression of p16INK4a and its relationship with HR-HPV, p16INK4a staining was performed on 97 CIN1,32 CIN2,30 CIN3,4 invasive cervical cancer (ICC) and 161 randomly selected normal tissues. Vaginal and cervical exfoliated cells were used in hybrid capture 2 (HC2). To evaluate p16INK4a and L1 expression models of CIN and its relation with HPV subtypes,a sandwich technique was used to cut paraffin sections for Haematoxylin and Eosin (H&E),immunohistochemistry staining and paraffin sections for HPV DNA analysis from each cervical specimen. A total number of 188 women were enrolled into study (including 45 CIN1,31 CIN2,64 CIN3,48 ICC).After confirmation of histological diagnosis, SPF10 PCR was applied to amplify HPV DNA and then the genetic amplification products were detected by DNA enzyme immunoassay (DEIA). HPV-positive specimens were typed by reverse hybridization line probe assay SPF10 LiPA25. p16INK4a and L1 staining were performed.To evaluate p16INK4a and L1 as immunohistochemical markers of the biologic potentiality of CIN1.Women with CIN1 of part 2 were enrolled in follow up for 6 years.RESULT:Expression rates of p16INK4a were 69.5%and 10.5%in HR-HPV DNA positive and negative group,with a significant difference(x2=40.40, P=0.000). OR value of HR-HPV and p16INK4a was 19.36(6.39,58.61).15 type of HPV were detected, including high-risk subtype HPV 16,18,31,33,39,51,52,53,56,58 and 66,low-risk subtype HPV 6,11,68,74. HPV 16 was the most common type of HPV and HPV 58,33 were the second and third most common type of HPV detected in CIN2/CIN3 patients while HPV 18,31 were the second and third most common type of HPV detected in ICC. The expression level of p16INK4a was higher in patients with HPV16(93.8%) than in patients without HPV16 (41.8%) (p＜0.001) while the expression level of L1 was lower in patients with HPV16(12.4%) than in patients without HPV16 (41.8%) (34.2%)(p<0.001).HPV33,HPV18,HPV31,HPV58 was not associated with the expression levels of p16INK4a or L1 (p＞0.05). The results of p16INK4a and L1 expressions were summarized in 4 different categories:1) L1(+)/p16INK4a (-):24 cases,mostly in CIN1,without CIN3 or ICC.2)L1(+)/p16INK4a (+):19 cases, this pattern appears in 31.6%CIN1,26.3% CIN2,31.6% CIN3,10.5% ICC.3)L1(-)/p16INK4a(-): 31 cases,48.4% is CIN1,25.8% is CIN2,16.1% is CIN3 and 9.7% is ICC.4) L1(-)/p16INK4a (+):114 cases, mostly in CIN3 or ICC(83.2%),few in CIN1. Follow-up showed difference in CIN1 progression between 4 different categories:no patient of CIN1 in L1(-)/p16INK4a (-) group progress, the risk of CIN1 progression in L1(-)/p16INK4a (+) group is 66.7%(2/3);L1(+)/p16INK4a (-) group is 9.5%(2/21)while the risk of CIN1 progression in the risk of CIN1 progression in L1(+)/p16INK4a (+) is 33.3%(2/6).CONCLUSION:p16INK4a expressions increased significantly with high-risk HPV infection, especially HPV 16. p16INK4a together with L1 immunohistochemistry can be helpful for estimating the biologic potentiality of CIN1.