What are the roles of initiators and promoters in carcinogenesis?
Initiators and Promoters Initiation is the first step in the two-stage model of cancer development. Initiators cause irreversible changes (mutations) to DNA that increase cancer risk. Promotion is the second step in the two-stage model of cancer development.
What is an initiator in carcinogenesis?
Initiation. Initiators are mutagens that act either directly or indirectly by forming electrophilic species that interact with and modify DNA structure, or otherwise damage the DNA sequence, but do not by themselves induce tumor formation.
What are the 3 stages of carcinogenesis?
The three-stage theory of carcinogenesis is one of the most common explanations for the development of cancer. This theory divides cancer development into three stages: initiation, promo- tion, and progression.
How many stages of carcinogenesis are there?
Most types of cancer have four stages: stage I (1) to IV (4). Some cancers also have a stage 0 (zero). Here is a general description of cancer stage groupings. (Please see the guide for a specific type of cancer for details about its detailed staging system.)
What is multistep carcinogenesis?
The multistep theory of carcinogenesis predicts that the cumulative effect of the loss of key tumour suppressor genes and overexpression of important oncogenes in an individual cell will cause a normal cell to become a cancer cell.
What are oncogenes and proto-oncogenes?
An oncogene is a mutated gene that has the potential to cause cancer. Before an oncogene becomes mutated, it is called a proto-oncogene, and it plays a role in regulating normal cell division.
What are the initiators and triggers of abnormal cells?
Initiators act as triggers which lead to a cell becoming abnormal. This involves damage to the cell DNA or genes. Thus, ionizing radiation for example, leads to DNA damage and this would be an initiator or a trigger. It creates the abnormal cells in the first place.
Are oncogenes the initiators of cancer?
Oncogenes (meaning the genes that start a tumour mass) have been described and they are said to transform normal cells into cancer cells. Hence, they are initiators. Conventional cancer research tends to treat the oncogene as the primary causal unit in cancer. However, this is not correct.
What are promoters of cancer?
Promoters are things that do not damage genetic material but they facilitate or support the growth of the abnormal cells in any of the three stages ( hyperplasia, neoplastic or cancerous ). So when the cancer process has been triggered by an initiator or more, it will lie undetected because it is only very small at this stage.
What is the difference between an initiator and trigger?
Initiators act as triggers which lead to a cell becoming abnormal. This involves damage to the cell DNA or genes. Thus, ionizing for example, leads to DNA damage and this would be an initiator or a trigger. It creates the abnormal cells in the first place.