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MITOSTATIN, a putative tumor suppressor on chromosome 12q24.1, is downregulated in human bladder and breast cancer.

Vecchione A, Fassan M, Anesti V, Morrione A, Goldoni S, Baldassarre G, Byrne D, D'Arca D, Palazzo JP, Lloyd J, Scorrano L, Gomella LG, Iozzo RV, Baffa R - Oncogene (2008)

Bottom Line: Human MITOSTATIN was found within a 3.2-kb transcript, which encoded a approximately 62 kDa, ubiquitously expressed protein with little homology to any known protein.We found homozygous deletions and mutations of MITOSTATIN gene in approximately 5 and approximately 11% of various cancer-derived cells and solid tumors, respectively.Finally, MITOSTATIN expression was significantly reduced in primary bladder and breast tumors, and its reduction was associated with advanced tumor stages.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.

ABSTRACT
Allelic deletions on human chromosome 12q24 are frequently reported in a variety of malignant neoplasms, indicating the presence of a tumor suppressor gene(s) in this chromosomal region. However, no reasonable candidate has been identified so far. In this study, we report the cloning and functional characterization of a novel mitochondrial protein with tumor suppressor activity, henceforth designated MITOSTATIN. Human MITOSTATIN was found within a 3.2-kb transcript, which encoded a approximately 62 kDa, ubiquitously expressed protein with little homology to any known protein. We found homozygous deletions and mutations of MITOSTATIN gene in approximately 5 and approximately 11% of various cancer-derived cells and solid tumors, respectively. When transiently overexpressed, MITOSTATIN inhibited colony formation, tumor cell growth and was proapoptotic, all features shared by established tumor suppressor genes. We discovered a specific link between MITOSTATIN overexpression and downregulation of Hsp27. Conversely, MITOSTATIN knockdown cells showed an increase in cell growth and cell survival rates. Finally, MITOSTATIN expression was significantly reduced in primary bladder and breast tumors, and its reduction was associated with advanced tumor stages. Our findings support the hypothesis that MITOSTATIN has many hallmarks of a classical tumor suppressor in solid tumors and may play an important role in cancer development and progression.

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MITOSTATIN inhibits cell growth in bladder and prostate cancer cells by a down-regulation of Hsp27Endogenous and ectopic MITOSTATIN protein is detected in prostate (a) and bladder (b, left panel) stable MITOSTATIN-transfectants cells. (b) A significant reduction of MITOSTATIN protein is detected in PC3 M2 and DU145 M2 cells stably transfected with a MITOSTATIN antisense-vector. Reduced Hsp27 is shown in cells over-expressing MITOSTATIN (a). Conversely, an increased level of Hsp27 is observed in cells with lower expression of MITOSTATIN (b, right panel). 5637 bladder cancer cells do not express Hsp27 (b). (c) Growth curves show significant decrease in cells over-expressing MITOSTATIN when compared with parental cells and cells transfected with the MITOSTATIN-antisense plasmid. Data show the mean of three independent experiments ±SEM. * P<0.05 ** P<0.01.
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Figure 6: MITOSTATIN inhibits cell growth in bladder and prostate cancer cells by a down-regulation of Hsp27Endogenous and ectopic MITOSTATIN protein is detected in prostate (a) and bladder (b, left panel) stable MITOSTATIN-transfectants cells. (b) A significant reduction of MITOSTATIN protein is detected in PC3 M2 and DU145 M2 cells stably transfected with a MITOSTATIN antisense-vector. Reduced Hsp27 is shown in cells over-expressing MITOSTATIN (a). Conversely, an increased level of Hsp27 is observed in cells with lower expression of MITOSTATIN (b, right panel). 5637 bladder cancer cells do not express Hsp27 (b). (c) Growth curves show significant decrease in cells over-expressing MITOSTATIN when compared with parental cells and cells transfected with the MITOSTATIN-antisense plasmid. Data show the mean of three independent experiments ±SEM. * P<0.05 ** P<0.01.

Mentions: To further investigate the MITOSTATIN effects on tumor cell growth, we transfected PC3, LNCaP, and 5637 cells with a MITOSTATIN-V5 fusion expression construct, and PC3 and DU145 cells with an anti-sense cDNA construct. Moreover, we placed MITOSTATIN in a self-inactivating retroviral vector under the control of an inducible Drosophila HSP70 promoter, that we used to transfect DU145 cells. We obtained five clones stably over-expressing MITOSTATIN and two clones which showed a decreased level of endogenous MITOSTATIN (Figure 6a and b). Clones showed different levels of the protein over-expression: in PC3 cells, PC3 B2 had a 2.0 fold increase over parental cells; DU145-MITOSTATIN showed a 4.2 fold increase; in LNCaP clones, LNCaP B1A, LNCaP B3A and LNCaP A3A had a 1.6, 2.1 and 2.6 fold increase, respectively; 5637 B3 MITOSTATIN expression was 2.9 times over the parental cells expression.


MITOSTATIN, a putative tumor suppressor on chromosome 12q24.1, is downregulated in human bladder and breast cancer.

Vecchione A, Fassan M, Anesti V, Morrione A, Goldoni S, Baldassarre G, Byrne D, D'Arca D, Palazzo JP, Lloyd J, Scorrano L, Gomella LG, Iozzo RV, Baffa R - Oncogene (2008)

MITOSTATIN inhibits cell growth in bladder and prostate cancer cells by a down-regulation of Hsp27Endogenous and ectopic MITOSTATIN protein is detected in prostate (a) and bladder (b, left panel) stable MITOSTATIN-transfectants cells. (b) A significant reduction of MITOSTATIN protein is detected in PC3 M2 and DU145 M2 cells stably transfected with a MITOSTATIN antisense-vector. Reduced Hsp27 is shown in cells over-expressing MITOSTATIN (a). Conversely, an increased level of Hsp27 is observed in cells with lower expression of MITOSTATIN (b, right panel). 5637 bladder cancer cells do not express Hsp27 (b). (c) Growth curves show significant decrease in cells over-expressing MITOSTATIN when compared with parental cells and cells transfected with the MITOSTATIN-antisense plasmid. Data show the mean of three independent experiments ±SEM. * P<0.05 ** P<0.01.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2628456&req=5

Figure 6: MITOSTATIN inhibits cell growth in bladder and prostate cancer cells by a down-regulation of Hsp27Endogenous and ectopic MITOSTATIN protein is detected in prostate (a) and bladder (b, left panel) stable MITOSTATIN-transfectants cells. (b) A significant reduction of MITOSTATIN protein is detected in PC3 M2 and DU145 M2 cells stably transfected with a MITOSTATIN antisense-vector. Reduced Hsp27 is shown in cells over-expressing MITOSTATIN (a). Conversely, an increased level of Hsp27 is observed in cells with lower expression of MITOSTATIN (b, right panel). 5637 bladder cancer cells do not express Hsp27 (b). (c) Growth curves show significant decrease in cells over-expressing MITOSTATIN when compared with parental cells and cells transfected with the MITOSTATIN-antisense plasmid. Data show the mean of three independent experiments ±SEM. * P<0.05 ** P<0.01.
Mentions: To further investigate the MITOSTATIN effects on tumor cell growth, we transfected PC3, LNCaP, and 5637 cells with a MITOSTATIN-V5 fusion expression construct, and PC3 and DU145 cells with an anti-sense cDNA construct. Moreover, we placed MITOSTATIN in a self-inactivating retroviral vector under the control of an inducible Drosophila HSP70 promoter, that we used to transfect DU145 cells. We obtained five clones stably over-expressing MITOSTATIN and two clones which showed a decreased level of endogenous MITOSTATIN (Figure 6a and b). Clones showed different levels of the protein over-expression: in PC3 cells, PC3 B2 had a 2.0 fold increase over parental cells; DU145-MITOSTATIN showed a 4.2 fold increase; in LNCaP clones, LNCaP B1A, LNCaP B3A and LNCaP A3A had a 1.6, 2.1 and 2.6 fold increase, respectively; 5637 B3 MITOSTATIN expression was 2.9 times over the parental cells expression.

Bottom Line: Human MITOSTATIN was found within a 3.2-kb transcript, which encoded a approximately 62 kDa, ubiquitously expressed protein with little homology to any known protein.We found homozygous deletions and mutations of MITOSTATIN gene in approximately 5 and approximately 11% of various cancer-derived cells and solid tumors, respectively.Finally, MITOSTATIN expression was significantly reduced in primary bladder and breast tumors, and its reduction was associated with advanced tumor stages.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.

ABSTRACT
Allelic deletions on human chromosome 12q24 are frequently reported in a variety of malignant neoplasms, indicating the presence of a tumor suppressor gene(s) in this chromosomal region. However, no reasonable candidate has been identified so far. In this study, we report the cloning and functional characterization of a novel mitochondrial protein with tumor suppressor activity, henceforth designated MITOSTATIN. Human MITOSTATIN was found within a 3.2-kb transcript, which encoded a approximately 62 kDa, ubiquitously expressed protein with little homology to any known protein. We found homozygous deletions and mutations of MITOSTATIN gene in approximately 5 and approximately 11% of various cancer-derived cells and solid tumors, respectively. When transiently overexpressed, MITOSTATIN inhibited colony formation, tumor cell growth and was proapoptotic, all features shared by established tumor suppressor genes. We discovered a specific link between MITOSTATIN overexpression and downregulation of Hsp27. Conversely, MITOSTATIN knockdown cells showed an increase in cell growth and cell survival rates. Finally, MITOSTATIN expression was significantly reduced in primary bladder and breast tumors, and its reduction was associated with advanced tumor stages. Our findings support the hypothesis that MITOSTATIN has many hallmarks of a classical tumor suppressor in solid tumors and may play an important role in cancer development and progression.

Show MeSH
Related in: MedlinePlus