The high immunohistochemical expression for both p16 and pRb in VC is quite different compared with SCC, which may indicate a possible relationship between VC and human papillomavirus (HPV) infection.
Our main findings are as follows: (a) methylation was completely absent in control tissues; (b) the frequencies of methylation for all of the genes except hMLH1 were >20% in cervical cancers; (c) aberrant methylation commenced early during multistage pathogenesis and methylation of at least one gene was noted in 30% of the nondysplasia/low-grade CIN group; (d) an increasing trend for methylation was seen with increasing pathological change; (e) methylation of RARbeta and GSTP1 were early events, p16 and MGMT methylation were intermediate events, and FHIT methylation was a late, tumor-associated event; and (f) methylation occurred independently of other risk factors including papillomavirus infection, smoking history, or hormone use.
The diffuse distribution of p16 immunostaining in HPV16/18-positive glandular neoplasms supports a strong association with HPV infection and indicates that this biomarker may discriminate ACIS from its benign mimics.
Unlike the cervix, p16 and cyclin E will not consistently distinguish VSKs from HPV-negative lesions due to underexpression in low-risk HPV infections (p16) and less-restricted expression in vulvar lesions (cyclin E).
These observations indicate that overexpression of p16 and loss of Rb nuclear staining are commonly associated with high-risk HPV infection, which may serve as useful surrogate biomarkers for identifying squamous cell carcinomas harboring HPV DNA.
We can conclude that high-risk HPV types are associated with p16 overexpression, and p16 may serve as a biomarker in oral cancer related to high-risk HPV infection.
These observations indicate that different mechanisms are involved in the pathogenesis of small cell carcinomas of the uterine cervix and support the notion that nuclear p16 overexpression serves as an indication of Rb defunctioning in tumor cells, which may or may not result from high-risk HPV infection.
In conclusion, our case, which is the first case of VSAC with polymerase chain reaction analysis and immunohistochemical expression of p16 protein, suggested that this neoplasm could be related to human papillomavirus infection.
Our recent report indicated that HPV infection may be associated with an increased frequency of p16INK4a promoter hypermethylation to cause p16 inactivation.
In addition, p16 overexpression consistently showed elevated sensitivity (84%) and specificity (98%) in detecting HR-HPV infection with a high positive predictive value (97%) and negative predictive value (86%).
These results suggest that high-risk HPV types promote inducible nitric oxide synthase-dependent DNA damage, which leads to dysplastic changes and carcinogenesis; in contrast, p16 appears to be merely a marker of HPV infection.
We performed p16 immunocytochemical analysis and the Hybrid Capture 2 (HC2) test (Digene, Gaithersburg, MD) for HR-HPV infection in 471 ThinPrep-processed (Cytyc, Boxborough, MA) cervicovaginal samples and correlated the results with histologic findings.
Immunohistochemical p16ink4a expression is associated with HPV infection in HSIL and cervical cancer, suggesting a role of p16 as a biomarker of HPV-associated cervical lesions.
Our results indicate that p16 immunostaining is a much better useful marker for HR-HPV infection and detection of SIL in ASC-H categorized smears compared to those defined as ASC-US.
Strong and diffuse cytoplasmic and nuclear expression of p16 in squamous cell carcinomas (SCC) of the female genital tract is strongly associated with high-risk human papilloma virus infection and neoplasms of cervical origin.
In HPV infection, the oncoprotein E7 inactivates the tumor suppressor Rb, leading to p16 upregulation; however, in small cell carcinomas, the Rb pathway is often blocked by other mechanisms; thus, increased p16 may not indicateHPV infection.
There was no correlation between p16 expression and the presence of HPV infection in squamous cell carcinoma of the bladder or urothelial carcinoma with squamous differentiation.
Epidermal growth factor receptor (EGFR) and p16 (a surrogate marker of human papillomavirus [HPV] infection) expression are strong prognostic factors in patients with head and neck squamous cell carcinoma (HNSCC).
Moreover, the lack of aberrant methylation of p16, which is in accordance with over-expression of p16 immunoreactivity, in the absence of HPV infection may be related to other unknown genetic alterations.