Immunohistochemical Expression of Human Papillomavirus and MCM2 in Ameloblastoma and Keratocystic Odontogenic Tumor

Abstract

Human papillomavirus is a small, non-enveloped, double-stranded DNA virus, known for its epitheliotropism. It is an oncogenic virus, whose role in tumorigenesis of various epithelial neoplasms has been unequivocally proven. HPV relevance to odontogenic tumors has been questioned since 1989, when Kahn, for the first time, detected HPV presence in AB, using IHC and this made him believe that HPV might play an important role in etiopathogenesis of AB. After that, a plethora of studies on HPV presence in the odontogenic tumors, especially AB and KCOT, utilizing different modalities were conducted, but the results were inconsistent, varying between obvious expression of HPV in some tumors, to total absence of the virus in others. Moreover, some authors regarded the presence of HPV in the tumors as a secondary infection or a contamination from the surface mucosal epithelium during the surgical procedure. The minichromosome maintenance protein MCM2 is a member of MCMs family which consists of ten factors essential for the initiation of genome replication in eukaryotes. Six major isoforms, MCM2–7, are biochemically related to each other, forming a complex, that acts as a licensing factor for replication of DNA, ensuring that the entire genome is replicated once and only once per cell cycle. MCM proteins are expressed throughout the four phases of cell cycle and their activity is lost in quiescent and senescent cells. Remarkable expression of MCM2 in various body neoplasms and correlation of its level with the clinical behavior of the tumors made it a sensitive proliferation marker as well as a diagnostic and prognosti