Beyene, Dereje (PhD)Gebrehiwot, Yirgu (Msc)Seifu, Daniel (PhD)Lorincz, Attila T. (PhD)Kumbi, Birhanu2020-10-132023-11-082020-10-132023-11-082020-07-07http://etd.aau.edu.et/handle/123456789/22695Cervical cancer is the second most common among cancers in Ethiopia with an incidence of more than 6000 cases and around 5000 deaths per year. Infection by high risk human papillomavirus (hrHPV) is the major risk factor for cervical cancer with almost all cases being infected. HPV infection is a very common sexually transmitted infection that majority of sexually active women acquire. Most of the infected women however clear the infection spontaneously in short time while it persists and causes cervical cancer in only small portion of the infected women. Various factors are known to determine the outcome of the infection but with scarce information on the mechanisms. DNA methylation changes in both human genes and HPV genes are among the biological events associated with cervical cancer progression. This study was aimed at determining prevalence of hrHPV, socio-demographic risk factors for cervical cancer and epigenetic changes associated with cervical cancer and evaluate their potential as diagnostic markers. The study was conducted as an observational case-control study by taking records of various risk factors and clinical information along with cervical cell samples for hrHPV testing and DNA methylation analysis. The human EPB41L3 gene promoter region and HPV L1 and L2 regions were PCR amplified from bisulphite converted DNA. The PCR amplicons were then pyrosequenced and proportion of converted cytosine is measured and means of the targeted CpG sites methylation were recorded. Prevalence of both hrHPV and demographic risk factors were compared among women with cervical lesions (cases) and women with normal cytology (controls) to determine associations with various stages of cervical cancer. The DNA methylation assays were evaluated and compared for their performance using Reciever Operating Characteristics (ROC) curve analysis. From a total of 135 women, 96 had cervical cell lesions ranging from CIN1 to invasive cancer (cases) and 39 had no lesion (controls). Parity was higher in cases 5.44(±3.01) than in controls 2.03(±2.04). Cases started sexual intercourse earlier, at mean age of 16.57(±4.04) years, than the controls 20.18(±4.24) years. Hormonal contraceptive use showed no significant difference among cases and controls. HPV DNA was detected in 79(82.3%) of cases and 7(17.9%) of controls from which 77(80.2%) of cases and 6(15.4%) of controls were hrHPV. HPV16 was the most prevalent virus constituting 84% of all hrHPV positive cases and 33.3% of hrHPV positive controls. HPV45, HPV18 and HPV31 were detected in 17.7%, 5.2% and 3.8% respectively of the hrHPV positive cases. Level of methylation in both human and hrHPV DNA was found to be higher in higher grade lesions than in low grade lesions (CIN1) and normal cervical cells. Methylation assays, both EPB41L3 promoter methylation and S5 score discriminated normal and CIN1 from CIN3 or worse lesions with sensitivity and specificity of greater than 95%. In conclusion, higher parity and earlier age at first sexual intercourse are among the factors that put women at higher risk of cervical cancer in addition to hrHPV infection. HPV16 is the most prevalent (69.8%) hrHPV type followed by HPV45 (14.6%) in Ethiopian women with cervical lesions. Methylation levels of the human EPB41L3 promoter region and HPV L1 and L2 regions are potential biomarker to improve precision of diagnosing the cancer and targeting for therapy. EBP41L3 methylation alone discriminated normal and CIN1 cells from CIN3 or worse lesions with 95% sensitivity and 96% specificity while S5 detected with 96% sensitivity and 95% specifienCervical cancerCINDNA methylationHPV GenotypehrHPVRisk FactorThesis