Tumor promotion is a process in

carcinogenesis 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 abno ...

by which various factors permit the descendants of a single

initiated Initiation is a rite of passage marking entrance or acceptance into a group or society. It could also be a formal admission to adulthood in a community or one of its formal components. In an extended sense, it can also signify a transformation ...

cell to survive and expand in number, i.e. to resist apoptosis and to undergo clonal growth. This is a step toward

tumor progression Tumor progression is the third and last phase in tumor development. This phase is characterised by increased growth speed and invasiveness of the tumor cells. As a result of the progression, phenotypical changes occur and the tumor becomes more agg ...

. In order for a tumor cell to survive, it must decrease its expression of

tumor suppressor genes A tumor suppressor gene (TSG), or anti-oncogene, is a gene that regulates a cell during cell division and replication. If the cell grows uncontrollably, it will result in cancer. When a tumor suppressor gene is mutated, it results in a loss or red ...

such as

p53 p53, also known as Tumor protein P53, cellular tumor antigen p53 (UniProt name), or transformation-related protein 53 (TRP53) is a regulatory protein that is often mutated in human cancers. The p53 proteins (originally thought to be, and often s ...

BRCA1 Breast cancer type 1 susceptibility protein is a protein that in humans is encoded by the ''BRCA1'' () gene. Orthologs are common in other vertebrate species, whereas invertebrate genomes may encode a more distantly related gene. ''BRCA1'' is a ...

, BRCA2, RB1, or the

fas receptor The Fas receptor, also known as Fas, FasR, apoptosis antigen 1 (APO-1 or APT), cluster of differentiation 95 (CD95) or tumor necrosis factor receptor superfamily member 6 (TNFRSF6), is a protein that in humans is encoded by the ''FAS'' gene. Fas ...

. A tumor suppressor would trigger an apoptotic pathway in a cancer cell if there were DNA damage, polyploidy, or uncontrolled cell growth. Simultaneously, tumor cells need to upregulate

oncogenes An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels.

, which promote or cause downstream activation of growth factors and cell survival signals such as RAS,

Mitogen-activated protein kinase kinase Mitogen-activated protein kinase kinase (also known as MAP2K, MEK, MAPKK) is a dual-specificity kinase enzyme which phosphorylates mitogen-activated protein kinase (MAPK). MAP2K is classified as . There are seven genes: * (a.k.a. MEK1) * ( ...

VEGF Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors ...

, or

Akt Protein kinase B (PKB), also known as Akt, is the collective name of a set of three serine/threonine-specific protein kinases that play key roles in multiple cellular processes such as glucose metabolism, apoptosis, cell proliferation, tran ...

References

Carcinogenesis {{Oncology-stub

See also

References