Bárbara Simas Chagas

Susceptibility to cervical cancer: an overview.

Cervical cancer is the second most common cancer in females worldwide. It is well-established that Human Papillomavirus (HPV) infections play a critical role in the development of cervical cancer. However, a large number of women infected with oncogenic HPV types will never develop cervical cancer. Thus, there are several external environment and genetic factors involved in the progression of a precancerous lesion to invasive cancer. In this review article, we addressed possible susceptible phenotypes to cervical cancer, focusing on host genome and HPV DNA variability, multiple HPV infections, co-infection with other agents, circulating HPV DNA and lifestyle.

An interleukin-10 gene polymorphism associated with the development of cervical lesions in women infected with Human Papillomavirus and using oral contraceptives.

Human Papillomavirus (HPV) infection plays a crucial role in the development of cervical lesions and tumors, however most lesions containing high-risk HPVs do not progress to cervical tumors. Some studies suggest that the use of oral contraceptives may increase the risk of cervical carcinogenesis, but this has not been confirmed by all the studies. Cytokines are important molecules that act in the defense of an organism against viral infections. Several genetic studies have attempted to correlate cytokine polymorphisms with human diseases, including cancer. The significance of IL10 polymorphisms for cancer is that they have both immunosuppressive and antiangiogenic properties. We aimed to investigate the role of promoter polymorphisms in the IL10 gene in women with cervical lesions associated with HPV infection, in the presence of the use of oral contraceptives. Using High Resolution Melt analysis (HRM), we analyzed an SNP -1082A/G and -819C/T in interleukin-10 promoter region in 364 Brazilian women: 171 with cervical lesions and HPV infection, and 193 with normal cytological results and HPV-negative. We observed no significant differences in genotype and allele frequencies in the two loci between patients and healthy controls. Furthermore, in the haplotype analysis of IL10, we found that CA haplotype was significantly more frequent in patients infected with HPV than in the control group (p = 0.0188). We did not find any genotype and allelic association of the IL10 gene polymorphisms between cases and controls. However, in this study, when the HPV-positive patients were stratified according to their use of contraceptives, we found a significant association between the -1082G allele (p = 0.0162) and -1082GG genotype (p = 0.0332) among HPV-infected patients who used oral contraceptives. Our findings suggest that -1082A/G gene polymorphism represents a greater susceptibility to progressive cervical lesions in HPV- infected women who use oral contraceptives.

New variants of E6 and E7 oncogenes of human papillomavirus type 31 identified in Northeastern Brazil

OBJECTIVE We sought to characterize E6 and E7 oncogenes genetic variability of HPV-31 isolated from cervical scraping samples of Northeastern Brazilian women. METHODS E6 and E7 were amplified with specific primers, cloned and sequenced. The sequences obtained were aligned with the GenBank reference sequences with the aim of evaluating the possible genetic variants. RESULTS We identified several genetic variants in E6 and E7 sequences from HPV-31 positive women. Three nucleotide changes in E6 were described for the first time in this study. Some nucleotide changes were non-synonymous substitutions. CONCLUSION The knowledge of region/country HPV specific genetic variations is relevant to understand the epidemiology and the development of effective vaccines.

Association Study between Cervical Lesions and Single or Multiple Vaccine-Target and Non-Vaccine Target Human Papillomavirus (HPV) Types in Women from Northeastern Brazil.

We performed an association between high-grade squamous intraepithelial lesions (HSIL), low-grade squamous intraepithelial lesions (LSIL) and single or multiple vaccine-target as well as non-vaccine target Human papillomavirus (HPV) types. Using bead-based HPV genotyping, 594 gynecological samples were genotyped. An association between squamous intraepithelial lesion (SIL) and presence of HPV16, 18, 31, 58 and 56 types were calculated. The risk was estimated by using odds ratio (OR) and 95% of confidence intervals (CI). A total of 370 (62.3%) women were HPV positive. Among these, 157 (42.7%) presented a single HPV infection, and 212 (57.3%) were infected by more than one HPV type. HPV31 was the most prevalent genotype, regardless single and multiple HPV infections. Single infection with HPV31 was associated with LSIL (OR=2.32; 95%CI: 1.01 to 5.32; p=0.04); HPV31 was also associated with LSIL (OR=3.28; 95%CI: 1.74 to 6.19; p= 0.0002) and HSIL (OR=3.82; 95%CI: 2.10 to 6.97; p<0.001) in multiple HPV infections. Risk to harbor cervical lesions was observed in multiple HPV infections with regard to the HPV56 (OR=5.39; 95%CI: 2.44 to 11.90; p<0.001for LSIL; OR=5.37; 95%CI: 2.71 to 10.69; p<0.001) and HPV58 (OR=3.29; 95%CI: 1.34 to 8.09; p=0.0091 for LSIL; OR=3.55; 95%CI: 1.56 to 8.11; p=0.0026) genotypes. In addition, women coinfected with HPV16/31/56 types had 6 and 5-fold increased risk of HSIL (OR=6.46; 95%CI: 1.89 to 22.09; p=0.002) and LSIL (OR=5.22; 95%CI: 1.10 to 24.70; p=0.03), respectively. Multiple HPV infections without HPV16/18 has 2-fold increased risk of HSIL (OR=2.57; 95%CI: 1.41 to 4.70; p=0.002) and LSIL OR=2.03; 95%CI: 1.08 to 3.79; p=0.02). The results of this study suggest that single and multiple vaccine target as well as non-vaccine target HPV types are associated with LSIL and HSIL. These finding should be taken into consideration in the design of HPV vaccination strategies.

Prevalence and Genetic Variability in Capsid L1 Gene of Rare Human Papillomaviruses (HPV) Found in Cervical Lesions of Women from North-East Brazil

The aim of this study was to examine the prevalence and genetic variability of the capsid L1 gene of rare HPV genotypes that were found in the cervical lesions of women from North-East Brazil. A total number of 263 patients were included in this study. HPV detection was performed using PCR followed by direct sequencing of MY09/11, as well as type-specific PCR to detect the Alpha-9 species. Epitope prediction was performed to determine whether or not the genetic variants are inserted in B-cell and T-cell epitopes. The prevalence of rare HPV types in cervical lesions was found to be 9.47%. The rare HPV genotypes that were detected were HPV-53, 54, 56, 61, 62, 66, 70, and 81. The genetic variability in the L1 gene of rare HPV types involved thirty nucleotide changes, eight of which were detected for the first time in this study. Moreover, some of these variants are embedded in B-cell or T-cell epitope regions. The results of this research suggest that rare HPV types might be involved in cervical lesions and some of these variants can be found in B-cell and T-cell epitopes. Data on the prevalence and variability of rare HPV types will assist in clarifying the role of these viruses in carcinogenesis.

MDM2 polymorphism associated with the development of cervical lesions in women infected with Human papillomavirus and using of oral contraceptives

BackgroundThe MDM2 gene is the major negative regulator of p53, a tumor suppressor protein. Single nucleotide polymorphism in promoter region of MDM2 gene leads to increased expression resulting in higher levels of MDM2 protein. This event increases the attenuation of the p53 pathway. Polymorphisms in this gene can interfere in the regulation of cellular proliferation. We evaluated whether MDM2 SNP309 (rs2278744) associated or not with the use of oral contraceptive can heighten susceptibility to development of cervical lesions in women HPV infected.MethodsMDM2 SNP309 (rs2278744) was genotyped in a total of 287 patients using the PCR-RFLP technique. The results were analyzed by UNPHASED v.3.121 and SNPStats programs.ResultsThe three groups (SIL, LSIL and HSIL) showed no significant differences in either genotype or allelic frequencies for MDM2 polymorphisms, except when HSIL was compared with LSIL (p = 0.037; OR = 1.81). Furthermore, in the analysis of contraceptives, a significant association was found between the use of contraceptives and the MDM2 variant in the development of high-grade cervical lesions for the TG genotype (p = 0.019; OR = 2.21) when HSIL was compared with control. When HSIL was compared with LSIL (p = 0.006; OR = 2.27).ConclusionThe results of this study suggest that MDM2 SNP309 might be a good marker for assessing the progression of LSIL to HSIL. In addition, they also show that oral contraceptives alone, did not have any effect on the progression or development of cervical lesions. However, they may act synergistically with MDM2 SNP309 (rs2278744) and HPV infection in the development of cervical lesions.

Novel E6 and E7 oncogenes variants of human papillomavirus type 31 in Brazilian women with abnormal cervical cytology.

HPV-31 has been widely described as an important oncogenic type, showing high incidence in worldwide and especially in Northeastern Brazil. We sought to identify the presence of specific mutations in HPV-31 E6 and E7 oncogenes in women with abnormal cervical smear. We enrolled 150 gynecological patients from Sergipe State, Northeastern Brazil. HPV screening was carried out by polymerase chain reaction (MY09/11). E6 and E7 oncogenes were amplified with specific primers and sequenced. The sequences obtained were aligned with the GenBank reference sequences in order to search for genetic variants. We identified genetic variants in E6 and E7 sequences from HPV-31. Two new nucleotide changes in E6 and E7 were described for the first time in this study. A novel mutation in E6 resulted in amino acid change in a site belonging to T-cell epitope with MHC II binding activity. There was no significant difference in the distribution of HPV-31 E6 and E7 variants when compared to all selected clinical/epidemiological characteristics. HPV-31 isolates have been clustered into three main groups called lineages A, B and C. We describe new HPV-31 variants in Brazil, contributing to better understand the genomic diversity of these viruses.

Prevalence of Human Papillomavirus Variants and Genetic Diversity in the L1 Gene and Long Control Region of HPV16, HPV31, and HPV58 Found in North-East Brazil

This study showed the prevalence of human papillomavirus (HPV) variants as well as nucleotide changes within L1 gene and LCR of the HPV16, HPV31, and HPV58 found in cervical lesions of women from North-East Brazil.

DEFB1 polymorphisms are involved in susceptibility to human papillomavirus infection in Brazilian gynaecological patients

The human beta defensin 1 (hBD-1) antimicrobial peptide is a member of the innate immune system known to act in the first line of defence against microorganisms, including viruses such as human papillomavirus (HPV). In this study, five functional polymorphisms (namely g-52G>A, g-44C>G and g-20G>A in the 5’UTR and c.*5G>A and c.*87A>G in the 3’UTR) in the DEFB1 gene encoding for hBD-1 were analysed to investigate the possible involvement of these genetic variants in susceptibility to HPV infection and in the development of HPV-associated lesions in a population of Brazilian women. The DEFB1 g-52G>A and c.*5G>A single-nucleotide polymorphisms (SNPs) and the GCAAA haplotype showed associations with HPV-negative status; in particular, the c.*5G>A SNP was significantly associated after multiple test corrections. These findings suggest a possible role for the constitutively expressed beta defensin-1 peptide as a natural defence against HPV in the genital tract mucosa.

Human Papillomavirus-Related Cancers

Cancer is a public health problem occupying the first and second place in number of deaths in developed and developing countries, respectively. Since the last century, the relationship between infection and cancer has been established in animals and more recently in several human cancers. Currently known that 15–20 % of cancers in the world of infectious origin, many of them related to viral infections. The human papillomavirus (HPV) stands out for its association with confirmed cervical cancer and the large volume of evidence that relate to the head and neck cancer. In addition, there is evidence of their relationship with breast cancers, lung and prostate. However, they are still required more detailed research that aim to clarify the possible mechanisms involved in these processes related to carcinogenic HPV.This chapter discusses the main molecular characteristics of HPV and its relationship with cancers using for this the infective models described by recent studies, the mechanisms of tumor progression, forms of diagnosis and therapy.