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Stem cell activation types transforming normal stem cells into cancerous stem cells |
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| Stem cell activation type |
Target tissue/organ |
Cancer type |
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| Naturally activated stem cell: Inactivation of RB1 gene |
Retinoblasts |
Retinoblastoma |
| Loss of tumor suppressor genes (p53) |
Breast |
Breast |
| Expression of oncogenes (ras, myc) |
Brain |
Brain |
| Hormonal stimulation: estrogen |
Breast |
Breast |
| Inflammation: Crohn disease, inflammatory bowl disease, result in activated cell growth |
Colon |
Colon |
| Viral infection: Hepatitis B and C cause inflammation and extensive cirrhosis |
Liver |
Liver |
| Exposure to irritants like tobacco, asbestos cause inflammation |
Lung |
Lung |
| Bacterial infection: Helicobacter pylori and metal dust exposure cause inflammation |
Stomach |
Stomach |
| Loss of miRNA genes (miR15 and miR16) which act as tumor suppressors |
Bone marrow |
Chronic lymphoid leukemia |
| Enforced expression of miR17-92 cluster which acts as oncogenes |
Bone marrow |
B cell lymphoma |
| DNA methylation at 5-position at cytosine residue within CpGs by Dnmt1 (maintenance methyltranferase), Dnmt3a, 3b (initiate de novo methylation), Dnmt2 |
Colon |
Colorectal |
| Methylation dependent repression of transcription by binding of methyl CpG binding proteins- MECP2, MBD1-4, Kaiso to DNA |
Colon |
Colorectal |
| Histone methylation by H3K4 Mtases, H3K9 Mtases, Suv39h1/Suv39h2, G9a, Eu-H Matse1, ESET/SETDB1 |
Prostate |
Prostate |
| Histone acetylation via histone acetyltransferases (HAT) include Gcn5 family proteins, MYST protein, p300/CBP, TAF250, ACTR/SRC1 nuclear receptor cofactors mediate transcriptional activation |
Breast |
Breast |
| Histone deacetylation silences gene expression via HDAC I family, HDAC II family, Sirtuin family (Sir2) |
Bone marrow |
Acute myeloid leukemia |
| Blockage of DNA accessibility to transcription factors by polycomb group proteins which include Polycomb repressive complexes – PRC1 contains Cbx, Mph, Ring, Bmi-1, Mel18 and PRC2 contains Ezh2, Suz12 and Eed |
Bone marrow |
B and T cell lymphoma |
| Alteration in chromatin accessibility to proteins and restriction endonucleases by the disruption of association of histones with DNA using the energy by ATP hydrolysis via ATP dependent remodeling complexes (SWI2/SNF2 protein, ISWI enzymes, Mi-2/NuRD proteins |
Bone marrow |
Acute myeloid leukemia |
Vaish Molecular Cancer 2007 6:26 doi:10.1186/1476-4598-6-26 |
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