Tumor promotion

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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]

In order for a tumor cell to survive, it must decrease its expression of tumor suppressor genes such as p53, BRCA1, BRCA2, RB1, or the fas receptor. [4] [5] 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, which promote or cause downstream activation of growth factors and cell survival signals such as RAS, [6] Mitogen-activated protein kinase kinase, VEGF, or Akt. [7]

See also

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Oncogene Gene that has the potential to cause cancer

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.

Tumor suppressor gene Gene that inhibits expression of the tumorigenic phenotype

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 reduction in its function. In combination with other genetic mutations, this could allow the cell to grow abnormally. The loss of function for these genes may be even more significant in the development of human cancers, compared to the activation of oncogenes.

A mitogen is a small bioactive protein or peptide that induces a cell to begin cell division, or enhances the rate of division (mitosis). Mitogenesis is the induction (triggering) of mitosis, typically via a mitogen. The mechanism of action of a mitogen is that it triggers signal transduction pathways involving mitogen-activated protein kinase (MAPK), leading to mitosis.

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. Cell division is a physiological process that occurs in almost all tissues and under a variety of circumstances. Normally, the balance between proliferation and programmed cell death, in the form of apoptosis, is maintained to ensure the integrity of tissues and organs. According to the prevailing accepted theory of carcinogenesis, the somatic mutation theory, mutations in DNA and epimutations that lead to cancer disrupt these orderly processes by interfering with the programming regulating the processes, upsetting the normal balance between proliferation and cell death. This results in uncontrolled cell division and the evolution of those cells by natural selection in the body. Only certain mutations lead to cancer whereas the majority of mutations do not.

C-Met Mammalian protein found in Homo sapiens

c-Met, also called tyrosine-protein kinase Met or hepatocyte growth factor receptor (HGFR), is a protein that in humans is encoded by the MET gene. The protein possesses tyrosine kinase activity. The primary single chain precursor protein is post-translationally cleaved to produce the alpha and beta subunits, which are disulfide linked to form the mature receptor.

HRAS

GTPase HRas, from "Harvey Rat sarcoma virus", also known as transforming protein p21 is an enzyme that in humans is encoded by the HRAS gene. The HRAS gene is located on the short (p) arm of chromosome 11 at position 15.5, from base pair 522,241 to base pair 525,549. HRas is a small G protein in the Ras subfamily of the Ras superfamily of small GTPases. Once bound to Guanosine triphosphate, H-Ras will activate a Raf kinase like c-Raf, the next step in the MAPK/ERK pathway.

KRAS Protein-coding gene in the species Homo sapiens

KRAS is a gene that provides instructions for making a protein called K-Ras, a part of the RAS/MAPK pathway. The protein relays signals from outside the cell to the cell's nucleus. These signals instruct the cell to grow and divide (proliferate) or to mature and take on specialized functions (differentiate). It is called KRAS because it was first identified as a viral oncogene in the KirstenRAt Sarcoma virus. The oncogene identified was derived from a cellular genome, so KRAS, when found in a cellular genome, is called a proto-oncogene.

Cyclin D

Cyclin D is a member of the cyclin protein family that is involved in regulating cell cycle progression. The synthesis of cyclin D is initiated during G1 and drives the G1/S phase transition. Cyclin D protein is anywhere from 155 to 477 amino acids in length.

Transcription factor Jun Mammalian protein found in Homo sapiens

Transcription factor Jun is a protein that in humans is encoded by the JUN gene. c-Jun, in combination with protein c-Fos, forms the AP-1 early response transcription factor. It was first identified as the Fos-binding protein p39 and only later rediscovered as the product of the JUN gene. c-jun was the first oncogenic transcription factor discovered. The proto-oncogene c-Jun is the cellular homolog of the viral oncoprotein v-jun. The viral homolog v-jun was discovered in avian sarcoma virus 17 and was named for ju-nana, the Japanese word for 17. The human JUN encodes a protein that is highly similar to the viral protein, which interacts directly with specific target DNA sequences to regulate gene expression. This gene is intronless and is mapped to 1p32-p31, a chromosomal region involved in both translocations and deletions in human malignancies.

CHEK2

CHEK2 is a tumor suppressor gene that encodes the protein CHK2, a serine-threonine kinase. CHK2 is involved in DNA repair, cell cycle arrest or apoptosis in response to DNA damage. Mutations to the CHEK2 gene have been linked to a wide range of cancers.

PLK1

Serine/threonine-protein kinase PLK1, also known as polo-like kinase 1 (PLK-1) or serine/threonine-protein kinase 13 (STPK13), is an enzyme that in humans is encoded by the PLK1 gene.

ELK1 Protein-coding gene in the species Homo sapiens

ETS Like-1 protein Elk-1 is a protein that in humans is encoded by the ELK1. Elk-1 functions as a transcription activator. It is classified as a ternary complex factor (TCF), a subclass of the ETS family, which is characterized by a common protein domain that regulates DNA binding to target sequences. Elk1 plays important roles in various contexts, including long-term memory formation, drug addiction, Alzheimer's disease, Down syndrome, breast cancer, and depression.

Proto-oncogene tyrosine-protein kinase Src Mammalian protein found in Homo sapiens

Proto-oncogene tyrosine-protein kinase Src, also known as proto-oncogene c-Src, or simply c-Src, is a non-receptor tyrosine kinase protein that in humans is encoded by the SRC gene. It belongs to a family of Src family kinases and is similar to the v-Src gene of Rous sarcoma virus. It includes an SH2 domain, an SH3 domain and a tyrosine kinase domain. Two transcript variants encoding the same protein have been found for this gene.

CDKN2B Protein-coding gene in the species Homo sapiens

Cyclin-dependent kinase 4 inhibitor B also known as multiple tumor suppressor 2 (MTS-2) or p15INK4b is a protein that is encoded by the CDKN2B gene in humans.

ELK4 Protein-coding gene in the species Homo sapiens

ETS domain-containing protein Elk-4 is a protein that in humans is encoded by the ELK4 gene.

MRAS Protein

Ras-related protein M-Ras, also known as muscle RAS oncogene homolog and R-Ras3, is a protein that in humans is encoded by the MRAS gene on chromosome 3. It is ubiquitously expressed in many tissues and cell types. This protein functions as a signal transducer for a wide variety of signaling pathways, including those promoting neural and bone formation as well as tumor growth. The MRAS gene also contains one of 27 SNPs associated with increased risk of coronary artery disease.

Retinoblastoma protein Mammalian protein found in Homo sapiens

The retinoblastoma protein is a tumor suppressor protein that is dysfunctional in several major cancers. One function of pRb is to prevent excessive cell growth by inhibiting cell cycle progression until a cell is ready to divide. When the cell is ready to divide, pRb is phosphorylated, inactivating it, and the cell cycle is allowed to progress. It is also a recruiter of several chromatin remodeling enzymes such as methylases and acetylases.

Julian Downward

(David) Julian (Harry) Downward FRS FMedSci is Associate Research Director at the Francis Crick Institute and Senior Group Leader at the Institute of Cancer Research. He was formerly head of the Signal transduction Laboratory at the London Research Institute. He is a member of the Editorial Board for Cell.

Antineoplastic resistance, often used interchangeably with chemotherapy resistance, is the resistance of neoplastic (cancerous) cells, or the ability of cancer cells to survive and grow despite anti-cancer therapies. In some cases, cancers can evolve resistance to multiple drugs, called multiple drug resistance.

DIRAS3 (gene) Mammalian protein found in Homo sapiens

GTP-binding protein Di-Ras3 (DIRAS3) also known as aplysia ras homology member I (ARHI) is a protein that in humans is encoded by the DIRAS3 gene.

References

  1. Compton C (2020). "Cancer initiation, promotion, and progression and the acquisition of key behavioral traits.". Cancer: The Enemy from Within. Cham: Springer. pp. 25–48. doi:10.1007/978-3-030-40651-6_2.
  2. Rakoff-Nahoum S (December 2006). "Why cancer and inflammation?". The Yale Journal of Biology and Medicine. 79 (3–4): 123–130. PMC   1994795 . PMID   17940622.
  3. "NCI Dictionary of Cancer Terms:Tumor promotion". National Cancer Institute. Retrieved 10 Nov 2012.
  4. Cooper GM (2000). "Tumor Suppressor Genes". The Cell: A Molecular Approach (2nd ed.).
  5. "Oncogenes, Tumor Suppressor Genes, and Cancer" (PDF). American Cancer Society.
  6. Cancer Genes: RAS
  7. "Oncogenes, Tumor Suppressor Genes, and Cancer" (PDF). American Cancer Society.