The mtDNA Amerindian Haplogroup B2 enhances the risk for Cervical Cancer of HPV: de-regulation of mitochondrial genes may be involved.

Although Human papillomavirus infection is the main causal factor for cervical cancer (CC), there is data suggesting genetic factors could modulate the risk and progression of CC. Sibling studies suggest that maternally inherited factors could be involved in CC. To assess whether mitochondrial DNA (mtDNA) polymorphisms are associated to cervical cancer, HPV infection and HPV types, a case-control study was performed in the Mexican mestizo population. The polymorphism of mtDNA D-Loop was investigated in 187 cervical cancer patients and 270 healthy controls. D-loop was amplified from a blood DNA sample and analyzed by sequencing. HPV was detected and typed in cervical scrapes from both groups. mtDNA polymorphisms were compared in the whole samples and stratified by HPV types. The expression of 29 mitochondrial genes was analyzed in a subset of 45 tumor biopsies using the expression microarray ST1.0. The Amerindian haplogroup B2 increased the risk for CC (OR=1.6, 95% CI: 1.05-2.58) and showed an additive effect of 36% over the risk conferred by the HPV (OR=153, 95% CI: 65.4-357.5). The frequency of HPV 16, 18, 31 and 45 in cancer samples was similar in all haplogroups but one (D1). It showed a very low frequency of HPV16, any HPV18 and high frequency of HPVs 31, 45 and other types. Two mtDNA genes (MT-TD, MTTK) could be involved in the increased risk conferred by the haplogroup B2, since they were up-regulated exclusively in B2 tumors (p<0.05, t-test). These findings will contribute to clarify the importance of genetic factors in CC.

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Guardado-Estrada M, Medina-Martínez I, Juárez-Torres E, Roman-Bassaure E, Macías L, Alfaro A, Alcántara-Vázquez A, Alonso P, Gomez G, Cruz-Talonia F, Serna L, Muñoz-Cortez S, Borges-Ibañez M, Espinosa A, Kofman S, Berumen J