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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

PER 2 expression increases P53 but decreases cyclin D1 expression in MCF-7 cells. (A) MCF-7 cells were transiently transfected with and empty vector (pcDNA 3.1) [U] or vector expressing PER 2 [T]. After 48 hours, total cell extracts were prepared and subjected to Western blot analysis using an antibodies directed against the P53 and PER 2 proteins. (B) Densitometric analysis of P53 protein expression. * p < 0.05. (C) Western blot analysis using an antibodies directed against the cyclin D1(cD1) and PER 2 proteins. (D) Densitometric analysis of cD1 protein expression. * p < 0.05.
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Figure 5: PER 2 expression increases P53 but decreases cyclin D1 expression in MCF-7 cells. (A) MCF-7 cells were transiently transfected with and empty vector (pcDNA 3.1) [U] or vector expressing PER 2 [T]. After 48 hours, total cell extracts were prepared and subjected to Western blot analysis using an antibodies directed against the P53 and PER 2 proteins. (B) Densitometric analysis of P53 protein expression. * p < 0.05. (C) Western blot analysis using an antibodies directed against the cyclin D1(cD1) and PER 2 proteins. (D) Densitometric analysis of cD1 protein expression. * p < 0.05.

Mentions: Given that expression of PER 2 and PER 2 plus CRY 2 in MCF-7 cells results in decreased cell proliferation, alters the cell cycle, and induces apoptosis, we asked if there were associated changes in the expression of the cyclin D1 cell cycle associated gene and the DNA repair/apoptosis associated p53 protein. Seventy two hours following transfection with an empty vector (pcDNA 3.1) or the Per 2 expression construct, total cellular protein was extracted, prepared and subjected to Western blot analysis using antibodies directed against human p53 and cyclin D1 (Figure 5). Compared to vector transfected control cells, PER 2 expressing cells displayed significantly elevated levels (157% of controls) of p53 protein but significantly decreased levels (56% reduced vs. controls) of cyclin D1 protein.


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)

PER 2 expression increases P53 but decreases cyclin D1 expression in MCF-7 cells. (A) MCF-7 cells were transiently transfected with and empty vector (pcDNA 3.1) [U] or vector expressing PER 2 [T]. After 48 hours, total cell extracts were prepared and subjected to Western blot analysis using an antibodies directed against the P53 and PER 2 proteins. (B) Densitometric analysis of P53 protein expression. * p < 0.05. (C) Western blot analysis using an antibodies directed against the cyclin D1(cD1) and PER 2 proteins. (D) Densitometric analysis of cD1 protein expression. * p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2365929&req=5

Figure 5: PER 2 expression increases P53 but decreases cyclin D1 expression in MCF-7 cells. (A) MCF-7 cells were transiently transfected with and empty vector (pcDNA 3.1) [U] or vector expressing PER 2 [T]. After 48 hours, total cell extracts were prepared and subjected to Western blot analysis using an antibodies directed against the P53 and PER 2 proteins. (B) Densitometric analysis of P53 protein expression. * p < 0.05. (C) Western blot analysis using an antibodies directed against the cyclin D1(cD1) and PER 2 proteins. (D) Densitometric analysis of cD1 protein expression. * p < 0.05.
Mentions: Given that expression of PER 2 and PER 2 plus CRY 2 in MCF-7 cells results in decreased cell proliferation, alters the cell cycle, and induces apoptosis, we asked if there were associated changes in the expression of the cyclin D1 cell cycle associated gene and the DNA repair/apoptosis associated p53 protein. Seventy two hours following transfection with an empty vector (pcDNA 3.1) or the Per 2 expression construct, total cellular protein was extracted, prepared and subjected to Western blot analysis using antibodies directed against human p53 and cyclin D1 (Figure 5). Compared to vector transfected control cells, PER 2 expressing cells displayed significantly elevated levels (157% of controls) of p53 protein but significantly decreased levels (56% reduced vs. controls) of cyclin D1 protein.

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