Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined the epidermal growth factor (EGF) receptor gene for structural alterations in fresh human tumors. DNA samples from 92 patients with solid tumors (lung cancer, 37; breast cancer, 24; head and neck cancer, 17; other tumors, 14) were analyzed and compared with those from 22 leukemia patients and 14 individuals without malignant neoplasms. When DNA samples were digested with HindIII restriction endonuclease, Southern blot analysis demonstrated 3 distinct polymorphic bands (9.8, 11, and 12 kilobases) after hybridization to the HER-A64-1 probe and another 2 distinct polymorphic bands (4.9 and 5.2 kilobases) after hybridization to the HER-A64-3 probe. Pedigree analysis of 43 members of a single family and comparative analysis of tumor and normal DNA samples from the same patients demonstrated that the variations in fragment size observed were due to 2 independent restriction fragment length polymorphisms in the region of the EGF receptor gene. Amplification of the EGF receptor gene was detected in 3 cases of breast cancer, but not in other tumors studied. We conclude that the human EGF receptor gene has multiple restriction fragment length polymorphisms and that in fresh human tumor samples rearrangement and amplification of the gene occur infrequently, if ever, within the region encompassed by the 2 complementary DNA probes used.
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PMID:Multiple restriction fragment length polymorphisms of the human epidermal growth factor receptor gene. 289 88

The presence of high-risk types of human papillomavirus (HPV) 16, 18 and 33 in cell lines established from several malignancies including 5 of cervical cancer and 6 of head and neck cancer was studied. HPV DNA, either type 16 or 18, was detected by polymerase chain reaction, and by Southern blot hybridization in all of the cell lines derived from cervical cancers. The hybridization patterns of HPV DNA after endonuclease digestion differed among cell lines, suggesting that all of these cell lines were independent isolates. Accordingly, high-risk types of HPV DNA seem to be ubiquitous in cervical cancer. HPV DNA was not detected in the cell lines derived from head and neck cancers or from any other malignancies besides cervical cancer in this study.
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PMID:Human papillomavirus DNA in cell lines derived from malignancies. 767 43

Oxidative DNA damage and DNA repair mediate the development of several human pathologies, including cancer. The major pathway for oxidative DNA damage repair is base excision repair (BER). Functional assays performed in blood leukocytes of cancer patients and matched controls show that specific BER pathways are decreased in cancer patients, and may be risk factors. These include 8-oxoguanine (8-oxoG) repair in lung and head and neck cancer patients and repair of lipid peroxidation (LPO) induced 1,N(6)-ethenoadenine (epsilonA) in lung cancer patients. Decrease of excision of LPO-induced DNA damage, epsilonA and 3,N(4)-ethenocytosine (epsilonC) was observed in blood leukocytes of patients developing lung adenocarcinoma, specific histological type of cancer related to inflammation and healing of scars. BER proteins activity depends on gene polymorphism, interactions between BER system partners and post-translational modifications. Polymorphisms of DNA glycosylases may change their enzymatic activities, and some polymorphisms increase the risk of inflammation-related cancers, colorectal, lung and other types. Polymorphisms of BER platform protein, XRCC1 are connected with increased risk of tobacco-related cancers. BER efficiency may also be changed by reactive oxygen species and some diet components, which induce transcription of several glycosylases as well as a major human AP-endonuclease, APE1. BER is also changed in tumors in comparison to unaffected surrounding tissues, and this change may be due to transcription stimulation, post-translational modification of BER enzymes as well as protein-protein interactions. Modulation of BER enzymes activities may be, then, an important factor determining the risk of cancer and also may participate in cancer development.
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PMID:Base excision repair modulation as a risk factor for human cancers. 1762 57

The aetiology of head and neck cancer (HNC) has been shown to be associated with genetic and certain environmental factors that produce DNA damage. Base excision repair (BER) genes are responsible for repair of DNA damage caused by reactive oxygen species and other electrophiles and therefore are good candidate susceptibility genes for HNC. Apurinic/apyrimidinic endonuclease-1 (APEX1) proteins have important functions in the BER pathway. In this case-control study, all exons of the APEX1 gene and its exon/intron boundaries were amplified in 300 HNC cases and 300 matched healthy controls and then analysed by single-stranded conformational polymorphism. Amplified products showing altered mobility patterns were sequenced and analysed. To confirm our observations, we examined APEX1 expression at mRNA level on 50 head and neck squamous cell carcinoma (HNSCC) and 50 normal control samples by quantitative real-time polymerase chain reaction. At germ line level, three novel mutations (13T > G, Ser129Arg and Val131Gly) of APEX1 were observed. The homozygous and heterozygous genotypes of APEX1 13T > G, Ser129Arg and Val131Gly appear to be significantly involved in the development of HNC. In the case of expressional level, APEX1 mRNA expression was positively correlated with tumour size, clinical stage and positive lymph node metastasis. Statistical analysis showed a significantly higher APEX1 mRNA level in HNC tumour tissue than in control samples. Our study demonstrated that APEX1 mutations and deregulation of APEX1 are associated with increased risk of HNC in the Pakistani population.
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PMID:Genetic and expressional variations of APEX1 are associated with increased risk of head and neck cancer. 2340 43