Saghar rasouli,1,*
1. Malair National University , IR , IRAN
Introduction: Cancer ranks as the first or second leading cause of death before the age of 70 in more than half of the world's countries, according to a (WHO) report .
It is estimated that infectious agents cause of all human cancers, with viruses accounting for 10–15% of all cases.
The main viruses that cause cancer in humans include hepatitis B and C , human herpes (HHV-8), human T lymphotrophic type 1 (HTLV-1), Epstein–Barr (EBV), and human papillomavirus (HPV)
Methods: HPV is linked to nearly 5% of all cancers worldwide . associated with a variety of serious cancers, such as gastrointestinal ( Colorectal,Anal,Gasteric,Esophageal,Liver cancer) , cervical, urinary bladder, and head, and neck cancers(Oral squamous cell carcinoma, Hypopharygeal and Laryngeal cancer).
Results: Over 100 HPV types have been described,
papillomaviruses are classified into low-risk (LR) and high-risk (HR) HPV types. LR-HPV types, including types 1, 2, 6, and 11, are non-carcinogenic types and they do not induce cancerous lesions. They can benign lesions (warts, condylomas, or recurrent respiratory papillomatosis) or, in rare cases, precancerous lesions . HR types, including 16, 18, 31, 33, .., because they induce 99.7% of cervical cancers and other anogenital cancers.
HPV infection concerns both women and men, but cervix an ideal tissue to complete the viral lifecycle it is transmitted through sexual contact by all contact points. Epidemiological and clinical data also inform about various non-sexual modes of transmission especially at the time of birth and by close contact.
HPV is small and non-enveloped virus with double-stranded circular DNA . HPV genome is divided into three regions: 1. The non-coding region, which affects the replication and transcription 2. The early region, which encodes E1, E2, E4, E5, E6, and E7 proteins 3. The late region, which encodes L1 and L2 as capsid proteins.
E6 and E7 proteins of the early region have an essential role in the oncogenic properties of HPV . they promote excessive cell cycle proliferation by interfering with regulatory proteins such as p53 and pRb.
The virus entry to be achieved via binding to heparin sulfate proteoglycans in the epithelial basement membrane via L1. The virus capsid then undergoes a conformational change allowing the exposure of L2, This newly exposed site on L2 binds to surface molecules on the wound keratinocyte, and that there the capsid undergoes a further conformational change and that the cellular receptor binding site on L1 is exposed. The virus binds via L1 to the cellular receptor, and cell entry is accomplished.
Cervical cancer is the fourth most common female malignancy worldwide .
Squamous cell carcinoma and adenocarcinoma account for nearly 70% and 25% of all cervix cancers caused by HPV infection, respectively.
HPV 16 and 18 are associated with two-thirds of cervical cancer and subsets of cancers of the vulva, vaginal, penis, anus, oropharynx, and skin.
Cervical cancer relieves further copies of the chromosome arm 3q, which contains the hTERC gene in the 3q26 location. This gene is considered to be a template for telomerase RNA, which are responsible for the repeat sequence, which enhances tandem to the ends of chromosomes to maintain the telomere length. As a result, abnormal hTERC amplification leads to increased proliferation, resulting in cervical tumors.
expression of the hTERC has the potential to act as a biomarker for the diagnosis and prognosis of cervical neoplasia.
Conclusion: Detecting markers that existence of cancers help to improve the treatment and control of cancer before the final stages of the tumor. One of these factors is the p16 protein, one of the inhibitory proteins of cyclin-dependent kinases. Overexpression of this factor in HPV is due to the inhibitory effect of E7 on Rb. Another factor is the level of expression of P53, which may be mutated or inhibited. In many cancers, detecting antibodies against P53 can help in the early diagnosis of cancer.
Currently, what is considered a cancer-tracking agent is HPV ctDNA. This factor is released into the blood due to the destruction of cancer cells, and they believe that identifying this marker can help initiate cancer treatment.