Aberrant regulation of mitotic cell cycle due to RB1 defects

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Homo sapiens
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RB1 was the first tumor suppressor gene discovered. Bi-allelic loss of function of the RB1 gene, located at the chromosomal band 13q14, is the underlying cause of both familial and sporadic retinoblastoma, a pediatric eye cancer (reviewed by Lohmann and Gallie 2000, Knudson 2001, Corson and Gallie 2007). Besides retinoblastoma, carriers of germline RB1 mutations are predisposed to an array of other cancers, called second primary tumors, such as pinealoblastoma, osteosarcoma, leiomyosarcoma, rhabdomyosarcoma and melanoma (reviewed by Lohmann and Gallie 2000).

Inactivating somatic mutations in the RB1 gene are frequent in bladder cancer (Cancer Genome Atlas Research Network 2014), osteosarcoma (Ren and Gu 2017), ovarian cancer (Liu et al. 1994, Kuo et al. 2009, Cancer Genome Atlas Research Network 2011), small-cell lung carcinoma (reviewed by Gazdar et al. 2017), liver cancer (Ahn et al. 2014, Bayard et al. 2018) and esophageal cancer (Gao et al. 2014, Kishino et al. 2016, Salem et al. 2018).

The vast majority of RB1 mutations in cancer represent complete genomic deletions or nonsense and frameshift mutations that are predicted to result in null alleles. Missense mutations are rare and usually result in partially active RB1 mutants. Functionally characterized RB1 missense mutations and inframe deletions mostly affect pocket domains A and B and the nuclear localization signal (NLS). RB1 missense mutations reported in cancer are, however, scattered over the entire RB1 coding sequence and the molecular consequences of the vast majority of these mutations have not been studied (reviewed by Dick 2007).

The RB1 protein product, also known as pRB or retinoblastoma protein, is a nuclear protein that plays a major role in the regulation of the G1/S transition during mitotic cell cycle in multicellular eukaryotes. RB1 performs this function by binding to activating E2Fs (E2F1, E2F2 and E2F3), and preventing transcriptional activation of E2F1/2/3 target genes, which include a number of genes involved in DNA synthesis (reviewed by Classon and Harlow 2002, Dick 2007). RB1 also regulates mitotic exit by acting on SKP2, a component of the SCF E3 ubiquitin ligase complex. RB1 facilitates degradation of SKP2 by the anaphase promoting complex/cyclosome (APC/C), thus preventing SKP2-mediated degradation of the cyclin-dependent kinase inhibitor CDKN1B (p27Kip1). RB1-dependent accumulation of p27Kip1 plays an important role in mitotic exit and RB1-mediated tumor suppression (reviewed by Dyson 2016).

In addition to its role in regulation of the G1/S transition and mitotic exit, RB1 also performs other, non-canonical, functions, such as its role in the maintenance of genomic stability, which is linked to its role in chromosome condensation during mitotic prophase. The impact of RB1 mutations on these E2F-independent functions, which are still important for RB1-mediated tumor suppression, has been poorly studied (reviewed by Chau and Wang 2003, Burkhart and Sage 2008, Manning and Dyson 2012, Dyson 2016, Dick et al. 2018).

Literature References
PubMed ID Title Journal Year
17437278 One hit, two hits, three hits, more? Genomic changes in the development of retinoblastoma

Corson, TW, Gallie, BL

Genes Chromosomes Cancer 2007
21720365 Integrated genomic analyses of ovarian carcinoma

Cancer Genome Atlas Research Network, -

Nature 2011
24476821 Comprehensive molecular characterization of urothelial bladder carcinoma

Cancer Genome Atlas Research Network, -

Nature 2014
20301625 Retinoblastoma

Lohmann, DR, Gallie, BL

29692417 Non-canonical functions of the RB protein in cancer

Dick, FA, Goodrich, DW, Sage, J, Dyson, NJ

Nat. Rev. Cancer 2018
17854503 Structure-function analysis of the retinoblastoma tumor suppressor protein - is the whole a sum of its parts?

Dick, FA

Cell Div 2007
12459729 The retinoblastoma tumour suppressor in development and cancer

Classon, M, Harlow, E

Nat. Rev. Cancer 2002
19383911 Analysis of DNA copy number alterations in ovarian serous tumors identifies new molecular genetic changes in low-grade and high-grade carcinomas

Kuo, KT, Guan, B, Feng, Y, Mao, TL, Chen, X, Jinawath, N, Wang, Y, Kurman, RJ, Shih, IeM, Wang, TL

Cancer Res. 2009
12563312 Coordinated regulation of life and death by RB

Chau, BN, Wang, JY

Nat. Rev. Cancer 2003
8077050 Molecular analysis of the retinoblastoma gene in primary ovarian cancer cells

Liu, Y, Heyman, M, Wang, Y, Falkmer, U, Hising, C, Székely, L, Einhorn, S

Int J Cancer 1994
18650841 Cellular mechanisms of tumour suppression by the retinoblastoma gene

Burkhart, DL, Sage, J

Nat. Rev. Cancer 2008
22318235 RB: mitotic implications of a tumour suppressor

Manning, AL, Dyson, NJ

Nat. Rev. Cancer 2012
27401552 RB1: a prototype tumor suppressor and an enigma

Dyson, NJ

Genes Dev. 2016
11905807 Two genetic hits (more or less) to cancer

Knudson, AG

Nat. Rev. Cancer 2001
Participant Of
Name Identifier Synonyms
cancer 162 malignant tumor, malignant neoplasm, primary cancer
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