Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43146 (tumour suppressor)
 5,935 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Breast cancer patients usually do not die of their primary cancers; they die of metastatic disease. Thus understanding the progression of breast cancer to the metastatic state and the changes that take place in highly malignant breast cells are important goals that could eventually result in new therapeutic approaches to highly progressive breast disease. Changes in the expression of certain genes or alterations in gene structures and encoded products can result in benign tumour cells progressing to the metastatic state. Experimentally, this has been performed by transferring dominantly acting oncogenes into susceptible cells and then testing the malignant properties of these cells in suitable animal models, but such rapid qualitative changes occur in vivo only rarely, and the natural progression of mammary cells to the metastatic state is thought to occur through a slow stepwise process that can take several years. Some of the slow stepwise changes in mammary cancer progression can be reversible and need not involve dominantly acting oncogenes or tumour suppressor genes, consistent with clinical observations. An important element of the natural progression of mammary tumours to malignancy may be their ability to circumvent microenvironmental controls that regulate growth and cellular diversity, a process that appears to involve mainly quantitative changes in gene expression, resulting in loss of normal cellular regulation. One of the important mechanisms of cellular regulation in epithelial tissues, such as those found in the breast, is mediated by intercellular junctional communication. Alterations in gene expression can result in loss of gap-junctional communication, concomitant with cellular diversification and progression. It is thought that the highly malignant cancer cells that have slowly evolved in vivo with only a few qualitative changes in gene structure have undergone extensive cycles of diversification and the accumulation of several quantitative changes in the expression of various genes that encode products related to malignancy. We have identified some of the genes that are related to progression and metastasis in breast cancer. For example, one of these genes, a novel gene called mta1 (in rodents) or MTA1 (in humans) appears to be involved in mammary cell motility and growth regulation. Thus highly malignant cellular phenotypes can arise rapidly due to specific qualitative changes in critical controlling genes, or more slowly via less critical qualitative genetic changes coupled with other cellular changes, such as loss of intercellular communication, and changes in gene expression, such as in the MTA1 gene, resulting in cellular diversification and ultimately tumour progression to the metastatic state.
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PMID:Breast cancer metastasis-associated genes: role in tumour progression to the metastatic state. 951 27

Dysregulation of microRNAs is involved in the initiation and progression of several human cancers, including breast cancer, as strong evidence of miRNAs acting as oncogenes or tumour suppressor genes has been found. This study was performed to investigate the biological functions of microRNA-421 (miR-421) in breast cancer and the underlying mechanisms. The expression level of miR-421 was detected in 50 pairs of surgical specimens and human breast cancer cell lines. The results showed that miR-421 is downregulated in breast cancer tissues and metastatic cell lines. In addition, the decrease in miR-421 levels was significantly associated with lymph node metastasis, recurrence/metastasis, or pTNM stage. Functions of miR-421 in cell migration and invasion were assessed through its silencing and overexpression. The results showed that miR-421 knockdown promotes invasion and metastasis in MCF-7 cells and its overexpression suppresses invasion and metastasis in MDA-MB-231 cells. The specific target genes of miR-421 were predicted by TargetScan algorithm and determined by dual luciferase reporter assay, quantitative reverse transcriptase PCR, and western blot analysis. miR-421 could suppress luciferase activity of the reporter containing 3'-untranslated region of metastasis associated 1 (MTA1), a potent oncogene. miR-421 overexpression or knockdown had no effect on the mRNA expression of MTA1, but it could modulate MTA1 protein level. Furthermore, MTA1 knockdown receded the effect of miR-421 inhibitor on invasion and metastasis of MCF-7 cells, and its overexpression receded the effect of miR-421 on invasion and metastasis of MDA-MB-231 cells. Our findings clearly demonstrate that miR-421 suppresses breast cancer metastasis by directly inhibiting MTA1 expression. The present study provides a new insight into the tumour suppressor roles of miR-421 and suggests that miR-421/MTA1 pathway is a putative therapeutic target in breast cancer.
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PMID:MicroRNA-421 inhibits breast cancer metastasis by targeting metastasis associated 1. 2758 80