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Period-2: a tumor suppressor gene in breast cancer.

Xiang S, Coffelt SB, Mao L, Yuan L, Cheng Q, Hill SM - J Circadian Rhythms (2008)

Bottom Line: The inhibitory effect of PER 2 on breast cancer cells was also demonstrated by its suppression of the anchorage-independent growth of MCF-7 cells as evidenced by the reduced number and size of colonies.A corresponding blockade of MCF-7 cells in the G1 phase of the cell cycle was also observed in response to the expression of PER 2 alone or in combination with CRY 2.Finally, our studies demonstrate that PER 2 expression in MCF-7 breast cancer cells is associated with a significant decrease in the expression of cyclin D1 and an up-regulation of p53 levels.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Structural and Cellular Biology, Tulane University Health Sciences Center, New Orleans, LA 70112, USA. smhill@tulane.edu.

ABSTRACT
Previous reports have suggested that the ablation of the Period 2 gene (Per 2) leads to enhanced development of lymphoma and leukemia in mice. Employing immunoblot analyses, we have demonstrated that PER 2 is endogenously expressed in human breast epithelial cell lines but is not expressed or is expressed at significantly reduced level in human breast cancer cell lines. Expression of PER 2 in MCF-7 breast cancer cells significantly inhibited the growth of MCF-7 human breast cancer cells, and, when PER 2 was co-expressed with the Crytochrome 2 (Cry 2) gene, an even greater growth-inhibitory effect was observed. The inhibitory effect of PER 2 on breast cancer cells was also demonstrated by its suppression of the anchorage-independent growth of MCF-7 cells as evidenced by the reduced number and size of colonies. A corresponding blockade of MCF-7 cells in the G1 phase of the cell cycle was also observed in response to the expression of PER 2 alone or in combination with CRY 2. Expression of PER 2 also induced apoptosis of MCF-7 breast cancer cells as demonstrated by an increase in PARP [poly (ADP-ribose) polymerase] cleavage. Finally, our studies demonstrate that PER 2 expression in MCF-7 breast cancer cells is associated with a significant decrease in the expression of cyclin D1 and an up-regulation of p53 levels.

No MeSH data available.


Related in: MedlinePlus

Effect of PER 2 and CRY 2 on the growth of MCF-7 cells. Cell proliferation assays were conducted on parental, vector-transfected, PER 2 overexpressing MCF-7 cells, CRY 2 overexpressing MCF-7 cells, and cells over expressing both PER 2 and CRY 2. Cells were counted on a hemacytometer using the trypan blue stain every day for four days. N = 3 independent experiments in triplicate. *a = p < 0.05 vs. pCS2+pCDNA3.1, *b = p < 0.05 vs. Per2, *c = p < 0.05 vs. pCS2
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Figure 2: Effect of PER 2 and CRY 2 on the growth of MCF-7 cells. Cell proliferation assays were conducted on parental, vector-transfected, PER 2 overexpressing MCF-7 cells, CRY 2 overexpressing MCF-7 cells, and cells over expressing both PER 2 and CRY 2. Cells were counted on a hemacytometer using the trypan blue stain every day for four days. N = 3 independent experiments in triplicate. *a = p < 0.05 vs. pCS2+pCDNA3.1, *b = p < 0.05 vs. Per2, *c = p < 0.05 vs. pCS2

Mentions: Cell proliferation assays were conducted on parental, vector-transfected, Per 2 transfected and expressing MCF-7 cells, Cry 2 transfected and expressing MCF-7 cells, and MCF-7 cells transfected with and expressing both Per 2 and Cry 2. Following transfection, cell number and cell viability were assessed by hemacytometer cell counts and trypan blue staining (Figure 2). A significant 31.6% decrease in cell number was seen in cells expressing PER 2 on day 4, but not in cells expressing CRY 2. However, when both PER 2 and CRY 2 were expressed in the same cells a significant 44.6% and 61.81% suppression of cell proliferation was noted as compared to control cells on day 2 and day 4 respectively.


Period-2: a tumor suppressor gene in breast cancer.

Xiang S, Coffelt SB, Mao L, Yuan L, Cheng Q, Hill SM - J Circadian Rhythms (2008)

Effect of PER 2 and CRY 2 on the growth of MCF-7 cells. Cell proliferation assays were conducted on parental, vector-transfected, PER 2 overexpressing MCF-7 cells, CRY 2 overexpressing MCF-7 cells, and cells over expressing both PER 2 and CRY 2. Cells were counted on a hemacytometer using the trypan blue stain every day for four days. N = 3 independent experiments in triplicate. *a = p < 0.05 vs. pCS2+pCDNA3.1, *b = p < 0.05 vs. Per2, *c = p < 0.05 vs. pCS2
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2365929&req=5

Figure 2: Effect of PER 2 and CRY 2 on the growth of MCF-7 cells. Cell proliferation assays were conducted on parental, vector-transfected, PER 2 overexpressing MCF-7 cells, CRY 2 overexpressing MCF-7 cells, and cells over expressing both PER 2 and CRY 2. Cells were counted on a hemacytometer using the trypan blue stain every day for four days. N = 3 independent experiments in triplicate. *a = p < 0.05 vs. pCS2+pCDNA3.1, *b = p < 0.05 vs. Per2, *c = p < 0.05 vs. pCS2
Mentions: Cell proliferation assays were conducted on parental, vector-transfected, Per 2 transfected and expressing MCF-7 cells, Cry 2 transfected and expressing MCF-7 cells, and MCF-7 cells transfected with and expressing both Per 2 and Cry 2. Following transfection, cell number and cell viability were assessed by hemacytometer cell counts and trypan blue staining (Figure 2). A significant 31.6% decrease in cell number was seen in cells expressing PER 2 on day 4, but not in cells expressing CRY 2. However, when both PER 2 and CRY 2 were expressed in the same cells a significant 44.6% and 61.81% suppression of cell proliferation was noted as compared to control cells on day 2 and day 4 respectively.

Bottom Line: The inhibitory effect of PER 2 on breast cancer cells was also demonstrated by its suppression of the anchorage-independent growth of MCF-7 cells as evidenced by the reduced number and size of colonies.A corresponding blockade of MCF-7 cells in the G1 phase of the cell cycle was also observed in response to the expression of PER 2 alone or in combination with CRY 2.Finally, our studies demonstrate that PER 2 expression in MCF-7 breast cancer cells is associated with a significant decrease in the expression of cyclin D1 and an up-regulation of p53 levels.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Structural and Cellular Biology, Tulane University Health Sciences Center, New Orleans, LA 70112, USA. smhill@tulane.edu.

ABSTRACT
Previous reports have suggested that the ablation of the Period 2 gene (Per 2) leads to enhanced development of lymphoma and leukemia in mice. Employing immunoblot analyses, we have demonstrated that PER 2 is endogenously expressed in human breast epithelial cell lines but is not expressed or is expressed at significantly reduced level in human breast cancer cell lines. Expression of PER 2 in MCF-7 breast cancer cells significantly inhibited the growth of MCF-7 human breast cancer cells, and, when PER 2 was co-expressed with the Crytochrome 2 (Cry 2) gene, an even greater growth-inhibitory effect was observed. The inhibitory effect of PER 2 on breast cancer cells was also demonstrated by its suppression of the anchorage-independent growth of MCF-7 cells as evidenced by the reduced number and size of colonies. A corresponding blockade of MCF-7 cells in the G1 phase of the cell cycle was also observed in response to the expression of PER 2 alone or in combination with CRY 2. Expression of PER 2 also induced apoptosis of MCF-7 breast cancer cells as demonstrated by an increase in PARP [poly (ADP-ribose) polymerase] cleavage. Finally, our studies demonstrate that PER 2 expression in MCF-7 breast cancer cells is associated with a significant decrease in the expression of cyclin D1 and an up-regulation of p53 levels.

No MeSH data available.


Related in: MedlinePlus