Human papilloma virus infection and expression of p16 protein in laryngeal papilloma and laryngeal carcinoma]

OBJECTIVE: To evaluate the role of human papilloma virus (HPV) infection and inactivation of p16 gene in laryngeal papilloma (LP) and laryngeal squamous cell carcinoma (LC). METHODS: HPV consensus primers direct in situ polymerase chain reaction (ISPCR) and immunohistochemical method were applied to detect the presence of HPV genomes (1, 6, 8, 11, 13, 16, 18, 30, 31, 32, 33, 45, 51) and the expression of p16 protein respectively in 93 cases of formalin-fixed, paraffin-imbedded specimens, which contained 46 cases of LPs adult-onset laryngeal papilloma (ALP) 21, juvenile-onset laryngeal papilloma (JLP)25], 26 cases of LCs, 6 cases of normal tissues adjacent to carcinoma, and 15 cases of vocal noduli. RESULTS: (1) The difference of positive rates of HPV-DNA in JLP group (84%, 21/25) and other groups were statistically significant (chi 2 test, P < 0.05). The difference of positive rates of HPV-DNA in ALPs(38.1%, 8/21), in LCs(19.2%, 5/26), in vocal noduli(0%, 0/15), and in normal tissues adjacent to carcinoma(0%, 0/6) were not significant statistically (chi 2 test or Fisher's exact probability test, P > 0.05). (2) The positive rates of expression of p16 protein in ALP group(57.1%, 12/21) and LC group(38.5%, 10/26) were significantly lower than that in vocal nodule group(93.3%, 14/15), in JLP group(88%, 22/25), and in normal tissues adjacent to carcinoma group (100%, 6/6) (chi 2 test or Fisher's exact probability test, P > 0.05). There were no significant differences of positive rates of expression of p16 protein between ALP group and LC group, and between JLP group and vocal nodule group (chi 2 test, P > 0.05). (3) In LPs, the difference of positive rates of p16 protein expression between HPV positive cases and HPV negative cases was significant statistically (chi 2 test, P < 0.05). In LCs, there was no difference in p16 protein expression rate between the two teams(Fisher exact probability test, P > 0.05). CONCLUSION: The pathogenesis of JLP is closely associated with HPV infection and not associated with the inactivation of p16 gene. Conversely, the pathogenesis of ALP and LC is associated with the inactivation of p16 gene and not associated with the HPV infection.