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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 reduces MCF-7 cell growth in soft agar. Soft agar clonogenic assays were performed with MCF-7 cells. MCF-7 cell were transfected with pTracer™-CMV2 or pTracer™-CMV2-hPer 2 and sorted. Two thousand five hundred cells per well were seeded in 12-well plates (3.8 cm2) in culture medium containing 0.35% low-melting agarose over a 0.7% agarose base layer and incubated for 12 days. Colonies larger than 100 μm in diameter were counted.
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Figure 3: PER 2 expression reduces MCF-7 cell growth in soft agar. Soft agar clonogenic assays were performed with MCF-7 cells. MCF-7 cell were transfected with pTracer™-CMV2 or pTracer™-CMV2-hPer 2 and sorted. Two thousand five hundred cells per well were seeded in 12-well plates (3.8 cm2) in culture medium containing 0.35% low-melting agarose over a 0.7% agarose base layer and incubated for 12 days. Colonies larger than 100 μm in diameter were counted.

Mentions: To assess the effect of PER 2 on in vitro tumorigenicity, soft agar clonogenic assays were performed with MCF-7 cells (Figure 3). After 12 days in culture, control cells transfected with the pTracer™-CMV2 displayed a clonogenic efficiency of 27% (25.00 ± 1.86 colonies), whereas MCF-7 cells transfected with and expressing PER 2 demonstrated a significantly reduced efficiency to 1.6% (4.11 ± 0.86 colonies). The difference in clonogenic efficiency between these two cell groups was determined to be highly significant (P < 0.001). In addition to clonogenic efficiency, the size of colonies formed by pTracer™-CMV2 vector transfected cells (376 ± 37 μm) was significantly larger (p < 0.05) than those formed by Per 2 transfected cells (163 ± 18 μm).


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 reduces MCF-7 cell growth in soft agar. Soft agar clonogenic assays were performed with MCF-7 cells. MCF-7 cell were transfected with pTracer™-CMV2 or pTracer™-CMV2-hPer 2 and sorted. Two thousand five hundred cells per well were seeded in 12-well plates (3.8 cm2) in culture medium containing 0.35% low-melting agarose over a 0.7% agarose base layer and incubated for 12 days. Colonies larger than 100 μm in diameter were counted.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: PER 2 expression reduces MCF-7 cell growth in soft agar. Soft agar clonogenic assays were performed with MCF-7 cells. MCF-7 cell were transfected with pTracer™-CMV2 or pTracer™-CMV2-hPer 2 and sorted. Two thousand five hundred cells per well were seeded in 12-well plates (3.8 cm2) in culture medium containing 0.35% low-melting agarose over a 0.7% agarose base layer and incubated for 12 days. Colonies larger than 100 μm in diameter were counted.
Mentions: To assess the effect of PER 2 on in vitro tumorigenicity, soft agar clonogenic assays were performed with MCF-7 cells (Figure 3). After 12 days in culture, control cells transfected with the pTracer™-CMV2 displayed a clonogenic efficiency of 27% (25.00 ± 1.86 colonies), whereas MCF-7 cells transfected with and expressing PER 2 demonstrated a significantly reduced efficiency to 1.6% (4.11 ± 0.86 colonies). The difference in clonogenic efficiency between these two cell groups was determined to be highly significant (P < 0.001). In addition to clonogenic efficiency, the size of colonies formed by pTracer™-CMV2 vector transfected cells (376 ± 37 μm) was significantly larger (p < 0.05) than those formed by Per 2 transfected cells (163 ± 18 μm).

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