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MicroRNA and cancer--focus on apoptosis.

Wang Y, Lee CG - J. Cell. Mol. Med. (2009)

Bottom Line: A significant observation is that greater than one-quarter of all known human miRs were reported to be deregulated in at least one cancer type.Several miRs were implicated to play roles in cell proliferation and apoptosis.In conclusion, although our current understanding of the functions of miRs is still fragmentary, taken together, this review highlights the complex and intricate roles that miRs play in the regulation of cellular processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, National University of Singapore, Singapore.

ABSTRACT
MicroRNAs (miRs) are small non-coding RNAs regulating gene expression at the post-transcriptional and/or translational levels. miRs play important roles in diverse biological processes, including development, cell differentiation, proliferation and apoptosis. Recent evidence has shown that miR loci frequently map to cancer-associated genomic regions and deregulated miR expression profiles are associated with many cancer types, implicating miRs in crucial processes that lead to tumourigenesis. Here, we review the current findings about miRs and tumourigenesis, focusing on their involvement in the apoptosis pathway. A significant observation is that greater than one-quarter of all known human miRs were reported to be deregulated in at least one cancer type. The expression of a subset of miRs (e.g. miR-21 and miR-155) was found to be consistently up-regulated, whereas another subset of miRs (e.g.miR-143 and miR-145) was consistently down-regulated across different cancer types suggesting their involvement in regulating common cellular processes whose deregulation may lead to tumourigenesis. Several miRs were implicated to play roles in cell proliferation and apoptosis. Some miRs, such as miR-29b and miR-15-16, influence only the apoptotic pathway, whereas others including let-7/miR-98 and miR-17-92 may play roles in both the apoptotic and cell-proliferation pathways. In conclusion, although our current understanding of the functions of miRs is still fragmentary, taken together, this review highlights the complex and intricate roles that miRs play in the regulation of cellular processes. Perturbation of the expression of miRs may thus lead to tumourigenesis.

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Related in: MedlinePlus

Diagrammatic representation of the roles of miRs in the regulation of cell proliferation and apoptosis. Red colour indicates a general up-regulation of miRs in cancers and green colour indicates a general down-regulation of miRs in cancer.
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fig01: Diagrammatic representation of the roles of miRs in the regulation of cell proliferation and apoptosis. Red colour indicates a general up-regulation of miRs in cancers and green colour indicates a general down-regulation of miRs in cancer.

Mentions: Apoptosis is the intrinsic cellular mechanism to eliminate cells that are damaged or transformed. Deregulation of apoptosis is an important step in cancer as it allows the genetically unstable cells to survive and accumulate further mutations that eventually lead to tumourigenesis. As cancer cells are mostly characterized by increased cell proliferation and decreased cell death, cancer-implicated genes have conventionally been classified into two groups. One group, the oncogenes, up-regulates proliferation and down-regulates apoptosis, whereas the other group, the tumour suppressor genes, performs just the opposite function. Indeed, pro-apoptotic genes such as p53 are frequently inactivated whilst anti-apoptotic genes such as B-cell CLL/lymphoma 2 (BCL2) are frequently over-activated in cancer progression. However, recent evidence has shown that up-regulation of MYC and E2F onco-genes can increase both cell proliferation and apoptosis [113, 114], suggesting the classification of cancer-related genes into oncogenes or tumour suppressors may be an over-simplification. Figure 1 summarizes our current knowledge of miRs implicated in cell-proliferation and apoptosis, revealing that the miR-regulatory network is just as complicated as its protein-coding counterparts. Some miRs, such as miR-29b and miR-15–16, were found to affect only the apoptotic pathway, whereas others including let-7/miR-98 and miR-17–92 play roles in both the apoptotic and cell-proliferation pathways (see review [114, 115]). In the following discussion, we will discuss some pro-apoptotic miRs, anti-apoptotic miRs and miRs that regulate both proliferation and apoptosis.


MicroRNA and cancer--focus on apoptosis.

Wang Y, Lee CG - J. Cell. Mol. Med. (2009)

Diagrammatic representation of the roles of miRs in the regulation of cell proliferation and apoptosis. Red colour indicates a general up-regulation of miRs in cancers and green colour indicates a general down-regulation of miRs in cancer.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3823033&req=5

fig01: Diagrammatic representation of the roles of miRs in the regulation of cell proliferation and apoptosis. Red colour indicates a general up-regulation of miRs in cancers and green colour indicates a general down-regulation of miRs in cancer.
Mentions: Apoptosis is the intrinsic cellular mechanism to eliminate cells that are damaged or transformed. Deregulation of apoptosis is an important step in cancer as it allows the genetically unstable cells to survive and accumulate further mutations that eventually lead to tumourigenesis. As cancer cells are mostly characterized by increased cell proliferation and decreased cell death, cancer-implicated genes have conventionally been classified into two groups. One group, the oncogenes, up-regulates proliferation and down-regulates apoptosis, whereas the other group, the tumour suppressor genes, performs just the opposite function. Indeed, pro-apoptotic genes such as p53 are frequently inactivated whilst anti-apoptotic genes such as B-cell CLL/lymphoma 2 (BCL2) are frequently over-activated in cancer progression. However, recent evidence has shown that up-regulation of MYC and E2F onco-genes can increase both cell proliferation and apoptosis [113, 114], suggesting the classification of cancer-related genes into oncogenes or tumour suppressors may be an over-simplification. Figure 1 summarizes our current knowledge of miRs implicated in cell-proliferation and apoptosis, revealing that the miR-regulatory network is just as complicated as its protein-coding counterparts. Some miRs, such as miR-29b and miR-15–16, were found to affect only the apoptotic pathway, whereas others including let-7/miR-98 and miR-17–92 play roles in both the apoptotic and cell-proliferation pathways (see review [114, 115]). In the following discussion, we will discuss some pro-apoptotic miRs, anti-apoptotic miRs and miRs that regulate both proliferation and apoptosis.

Bottom Line: A significant observation is that greater than one-quarter of all known human miRs were reported to be deregulated in at least one cancer type.Several miRs were implicated to play roles in cell proliferation and apoptosis.In conclusion, although our current understanding of the functions of miRs is still fragmentary, taken together, this review highlights the complex and intricate roles that miRs play in the regulation of cellular processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, National University of Singapore, Singapore.

ABSTRACT
MicroRNAs (miRs) are small non-coding RNAs regulating gene expression at the post-transcriptional and/or translational levels. miRs play important roles in diverse biological processes, including development, cell differentiation, proliferation and apoptosis. Recent evidence has shown that miR loci frequently map to cancer-associated genomic regions and deregulated miR expression profiles are associated with many cancer types, implicating miRs in crucial processes that lead to tumourigenesis. Here, we review the current findings about miRs and tumourigenesis, focusing on their involvement in the apoptosis pathway. A significant observation is that greater than one-quarter of all known human miRs were reported to be deregulated in at least one cancer type. The expression of a subset of miRs (e.g. miR-21 and miR-155) was found to be consistently up-regulated, whereas another subset of miRs (e.g.miR-143 and miR-145) was consistently down-regulated across different cancer types suggesting their involvement in regulating common cellular processes whose deregulation may lead to tumourigenesis. Several miRs were implicated to play roles in cell proliferation and apoptosis. Some miRs, such as miR-29b and miR-15-16, influence only the apoptotic pathway, whereas others including let-7/miR-98 and miR-17-92 may play roles in both the apoptotic and cell-proliferation pathways. In conclusion, although our current understanding of the functions of miRs is still fragmentary, taken together, this review highlights the complex and intricate roles that miRs play in the regulation of cellular processes. Perturbation of the expression of miRs may thus lead to tumourigenesis.

Show MeSH
Related in: MedlinePlus