Despite numerous human papillomavirus (HPV) frequency studies in women with cervical cancer (CC), little is known of HPV frequency trends according to patient age. In this work, we compare the mean age and frequency distribution by age of CC patients positive for different HPVs. This study included 462 CC patients. HPVs were detected by PCR and typed using DNA sequencing. A total of 456 patients (98.7%) were positive for HPV: 418 (90.5%) had single and 38 (8.2%) had double HPV infections. HPV16 (46.5%), HPV18 (10.4%), HPV45 (6.7%), and HPV31 (4.1%) were the most frequent viral types in single-infected patients. The mean ages of single-infected patients with HPV16 (49.2±13.3), HPV18 (47.9±12.2), HPV45 (47.9±11.7), or HPV39 (42.6±8.9) were significantly lower than the mean ages of patients singly (53.9±12.7; p<0.001, t-test) or doubly (55.4±12.7; p<0.05, t-test) infected with the remaining HPVs. Three different trends were identified: one for HPV16, another for HPVs18/45/39, and a third for the rest of HPVs. The frequency trend of HPV16 shows two peaks. The first (63.2%) was found in the youngest women (≤35 years), followed by a decreasing trend until the age of 55–60 years (31.1%). The second peak arose at 61–65 years (52.5%), followed by a decreasing trend. The trend for HPVs18/45/39 declined from the youngest (19.3%) to the oldest (>70 years; 12.8%) women. In contrast, the trend for the remaining HPVs increased from the youngest (15.8%) to the oldest (46.2%) women. Unlike other life-style factors, low-risk sexual behavior was associated with late onset of CC independent of low-oncogenic HPV types (p<0.05, Wald chi-square statistic). The data indicate that most CCs in young women depend on the presence of high-oncogenic HPVs. In contrast, almost half of CCs in older patients had low-oncogenic HPVs, suggesting they could depend on the presence of other factors.

We investigated the role of tumor copy number (CN)–altered genome (CN-AG) in the carcinogenesis of cervical cancer (CC), especially its effect on gene expression, biological processes, and patient survival. Fifty-nine human papillomavirus 16 (HPV16)-positive CCs were investigated with microarrays–31 for mapping CN-AG and 55 for global gene expression, with 27 CCs in common. Five-year survival was investigated in 55 patients. Deletions and amplifications >2.5 Mb were defined as CN alterations. The %CN-AG varied from 0 to 32.2% (mean = 8.1±8.9). Tumors were classified as low (mean = 0.5±0.6, n = 11), medium (mean = 5.4±2.4, n = 10), or high (mean = 19.2±6.6, n = 10) CN. The highest %CN-AG was found in 3q, which contributed an average of 55% of all CN alterations. Genome-wide, only 5.3% of CN-altered genes were deregulated directly by gene dosage. In contrast, the rate in fully duplicated 3q was twice as high. Amplification of 3q explained 23.2% of deregulated genes in whole tumors (r2 = 0.232, p = 0.006; analysis of variance), including genes located in 3q and other chromosomes. A total of 862 genes were deregulated exclusively in high-CN tumors, but only 22.9% were CN altered. This suggests that the remaining genes are not deregulated directly by gene dosage, but by mechanisms induced in trans by CN-altered genes. Anaphase-promoting complex/cyclosome (APC/C)-dependent proteasome proteolysis, glycolysis, and apoptosis were upregulated, whereas cell adhesion and angiogenesis were downregulated exclusively in high-CN tumors. The high %CN-AG and upregulated gene expression profile of APC/C-dependent proteasome proteolysis were associated with poor patient survival (p<0.05, log-rank test). Along with glycolysis, they were linearly associated with FIGO stage (r>0.38, p<0.01, Spearman test). Therefore, inhibition of APC/C-dependent proteasome proteolysis and glycolysis could be useful for CC treatment. However, whether they are indispensable for tumor growth remains to be demonstrated.

There are limited data on mitochondrial DNA (mtDNA) variation in the Mexican mestizo population. To examine the genetic diversity and matrilineal ancestry, the full mtDNA hypervariable regions I and II were sequenced in 270 unrelated mestizos from different regions of Mexico. A total of 202 different haplotypes were identified and the haplotype diversity was 0.9945. Amerindian haplotypes predominated in the sample with a proportion of 93.3%, followed by European (6.0%) and African haplotypes (0.7%). The frequency of the Amerindian haplogroups A2, B2, C1 and D1 was 51.1, 17.8, 18.5 and 5.9%, respectively. The frequency of Amerindian haplogroups was higher in the central region than in Mexico City, whereas it was the contrary for European haplogroups. This difference was accounted principally by the high frequency of B2 haplotypes in the central region. The minimum spanning network, the mismatch distribution and Tajima's D neutrality test suggest a population expansion for each Amerindian haplogroup, which could be initiated more recently for haplogroups A2 and D1. The present knowledge combined with other nuclear genetic markers will be essential in future association studies to correct for genetic substructure in mestizo populations.

Although human papillomavirus (HPV) infection is the main causal factor for cervical cancer (CC), there are data suggesting that genetic factors could modulate the risk for CC. Sibling studies suggest that maternally inherited factors could be involved in CC. To assess whether mitochondrial DNA (mtDNA) polymorphisms are associated to CC, HPV infection and HPV types, a case-control study was performed in the Mexican population. Polymorphism of mtDNA D-loop was investigated in 187 CC patients and 270 healthy controls. HPV was detected and typed in cervical scrapes. 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 (odds ratio (OR)=1.6; 95% confidence interval (CI): 1.05-2.58) and enhanced 36% (OR=208; 95% CI: 25.2-1735.5) the risk conferred by the HPV alone (OR=152.9; 95% CI: 65.4-357.5). In cases, the distribution of HPV types was similar in all haplogroups but one (D1), in which is remarkable the absence of HPV18, a very low frequency of HPV16 and high frequencies of HPV45, HPV31 and other HPV types. Two mtDNA genes (mitochondrial aspartic acid tRNA (MT-TD), mitochondrial lysine tRNA (MT-TK)) could be involved in the increased risk conferred by the haplogroup B2, as they were upregulated exclusively in B2 tumors (P<0.01, t-test). Although the association of mtDNA with CC and HPV infection is clear, other studies with higher sample size will be needed to elucidate the role of mtDNA in cervical carcinogenesis.

The cyclin-dependent kinase inhibitor 3 (CDKN3) gene, involved in mitosis, is upregulated in cervical cancer (CC). We investigated CDKN3 mRNA as a survival biomarker and potential therapeutic target for CC. CDKN3 mRNA was measured in 134 CC and 25 controls by quantitative PCR. A 5-year survival study was conducted in 121 of these CC patients. Furthermore, CDKN3-specific siRNAs were used to investigate whether CDKN3 is involved in proliferation, migration, and invasion in CC-derived cell lines (SiHa, CaSki, HeLa). CDKN3 mRNA was on average 6.4-fold higher in tumors than in controls (p = 8 x 10−6, Mann-Whitney). A total of 68.2% of CC patients over expressing CDKN3 gene (fold change ≥ 17) died within two years of diagnosis, independent of the clinical stage and HPV type (Hazard Ratio = 5.0, 95% CI: 2.5–10, p = 3.3 x 10−6, Cox proportional-hazards regression). In contrast, only 19.2% of the patients with lower CDKN3 expression died in the same period. In vitro inactivation of CDKN3 decreased cell proliferation on average 67%, although it had no effect on cell migration and invasion. CDKN3 mRNA may be a good survival biomarker and potential therapeutic target in CC.