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Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic , and epigenetic levels and abnormal cell division .
A carcinogen (/ k ɑːr ˈ s ɪ n ə dʒ ən /) is any agent that promotes the development of cancer. [1] Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. [2]
The central role of DNA damage and epigenetic defects in DNA repair genes in carcinogenesis. The classical view of cancer is a set of diseases driven by progressive genetic abnormalities that include mutations in tumor-suppressor genes and oncogenes, and in chromosomal abnormalities.
Carcinogenesis is caused by mutation and epimutation of the genetic material of normal cells, which upsets the normal balance between proliferation and cell death. This results in uncontrolled cell division in the body. The uncontrolled and often rapid proliferation of cells can lead to benign or malignant tumours (cancer).
Insulin-like growth factors and their binding proteins play a key role in cancer cell growth, differentiation and apoptosis, suggesting possible involvement in carcinogenesis. [59] Hormones are important agents in sex-related cancers such as cancer of the breast, endometrium, prostate, ovary, and testis, and also of thyroid cancer and bone ...
Tumor promotion is a process in carcinogenesis by which various factors permit the descendants of a single initiated cell to survive and expand in number, i.e. to resist apoptosis and to undergo clonal growth. [1] This is a step toward tumor progression. [2] [3]
The involvement of TGF-β in carcinogenesis is twofold. TGF-β, which acts in the epithelial cells of the mammary gland as a potent tumor suppressor at the early stages of cancer, can affect tumor development via interaction with oncogenic cytokines. Increased expression of TGF-β has been associated with the progression of tumors, which has ...
It was later found that carcinogenesis (the development of cancer) depended both on the mutation of proto-oncogenes (genes that stimulate cell proliferation) and on the inactivation of tumor suppressor genes, which are genes that keep proliferation in check. Knudson's hypothesis refers specifically, however, to the heterozygosity of tumor ...