The Genetics of Small cell Lung Cancer
What are genes?
Genes are sequences of DNA (Deoxyribose Nucleic Acid) located in chromosomes which code to make particular proteins. DNA is made up partly of pairs of corresponding nitrogen bases. A set of three of these nitrogen bases form a codon which codes for a certain amino acid. A gene is a chain of codons all coding for complementary amino acids which when strung together make a protein. There are about 30,000 different genes in the human genome. There are three types of genes that have to with cancer:
________________________________________________________________________ Here are the genes most commonly associated with Small cell lung cancer.
(oncogene) Behavior: The Ras gene produces the Ras protein which attaches to the molecule GTP and turns "on" a path way which controls the transcription of genes and in turn regulates cell growth. The entire set of changes in a cell caused by a receptor activating is called a pathway. Mutations in the Ras gene sometimes make it so the protein can not detach from the GTP molecule causing cell growth and proliferation which leads to Cancer. Also, because cell division is regulated by a balance of positive and negative signals, When the transcription of the RAS gene is increased the excess of RAS proteins causes an excess of positive signals, leading to unchecked cell division and cancer.
Location: On chromosome 17 Behavior: P53 gene creates a protein that attaches to DNA at promoters and helps with transcription into RNA. The protein is also capable of triggering cell death if mistakes or damage is detected in the DNA. The way the protein does this is by provoking the transcription of the p21 gene which regulates the production of an enzyme that is crucial in cell growth and division. By prompting the p21 gene, P53 prevents cell advancement and reproduction. Often times when P53 undergoes a mutation it results in the protein not being able to signal cell death, which leads to proliferation of cells with damaged DNA and often cancer. This gene is found to be defective in about 50% of all cancer cases.
Behavior: The EGFR Gene codes for a tyrosine kinase which is critical in cell division. The EGFR protein under the right conditions can trigger cell division in epithelial cells, which are the cells in your skin and linings of hollow or tubule organs. Mutations in the gene that result in the overproduction of the EGFR protein or the over transcription of the gene can lead to unregulated cell division and cancer. ________________________________________________________________________ Other genes related to lung cancer:
| The location of the RAS gene:
_(on chromosome 11)
The location of the P53 gene
_(on chromosome 17)
_EGFR (epidermal growth factor receptor) Gene_(on chromosome 4)
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