Análise da expressão das proteínas MCM7 e L1 do HPV como biomarcadores de diagnóstico de ASC-US e lesões escamosas intraepiteliais cervicais por meio de técnica de citologia em meio líquido

Abstract

Word-wide, cervical cancer (CC) is the third most commonly diagnosed cancer in women resulting in 280,000 deaths annually. The frequency of CC has decreased markedly in developed countries which mostly results from early diagnosis through effective screening programs and management of precursor lesions. However, cytological screening remains to be hampered by imperfect sensitivity and less-than-ideal inter-observer reproducibility, especially for some diagnostic categories. Immunocytochemical (ICC) detection of molecular alterations caused by HPV in host cells could potentially be used as an adjunct to cytological screening to improve sensitivity without compromising specificity. The aim of our study was to evaluate the expression of two proteins, MCM7, which is involved in the DNA replication regulation, and the L1-HPV capsid, as possible markers of cervical lesions diagnosis and HPV infection. The expression patterns of both proteins were evaluated by ICC analysis of smears prepared from 213 cervical samples collected by LBC (Liquid-base cytology) from women presenting distinct classes of cytological diagnosis ASCUS (36,1%), LSIL (55,8%) and HSIL (3,3%), or without any cervical abnormalities. It was observed that 39/213 (18.3%) from the cervical samples exhibited nuclear positivity to MCM7, with absence of the protein expression in cases without abnormalities. It was verified an increasing number of positive samples according to the lesion severity (7.3% of the ASCUS cases, 65.3% of LSIL and 100% of HSIL). An interesting association between the MCM7 expression and the DNA/HPV detection was also observed. Concerning the L1-HPV expression, 82/162 (62.6%) from the samples showed immuno-labeling to L1, with an important association among the expression of this protein, and the low-grade lesions and the HPV detection. The analysis of the four distinct expression patterns of MCM7 and L1, among the different cervical lesions categories, clearly showed that the cervical samples were distributed in two main groups, with the majority of them (ASC-US and LSIL) localized within the group whose samples did not express MCM7 (profiles MCM7-/L1- and MCM7-/L1+). In addition, almost 20% from the ASCUS and LSIL samples, and the totality of the HSIL smears, exhibited the MCM7+/L1+ and MCM7+/L1- immuno-labeling patterns, which were possibly more related to more severe cervical lesions. In conclusion, our data suggest that the single or combined analysis of the MCM7 and L1-HPV expression, can be considered as useful biomarkers of cervical lesion progression, in addition to the HPV infectio