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BRCA1 regulates PIG3-mediated apoptosis in a p53-dependent manner.

Zhang W, Luo J, Chen F, Yang F, Song W, Zhu A, Guan X - Oncotarget (2015)

Bottom Line: Moreover, we reveal that overexpression of BRCA1 significantly increased expression of PIG3 in cells with intact p53, whereas no increase in PIG3 was observed in p53- MDA-MB-157 cells and p53-depleted HCT116p53-/- cells.Meanwhile, ectopic expression of BRCA1 could not lead to an increase expression level of prohibitin (PHB), which we have previously identified to induce PIG3-mediated apoptosis.Finally, ChIP analysis revealed that PHB can bind to the PIG3 promoter and activate PIG3 transcription independent of p53, although p53 presence did enhance this process.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China.

ABSTRACT
BRCA1 plays a key role in the regulation of p53-dependent target gene transcription activation. Meanwhile, the p53 inducible gene 3 (PIG3) is a downstream target of p53 and is involved in p53-initiated apoptosis. However, little is known about whether BRCA1 can regulate PIG3-mediated apoptosis. Using a tissue microarray containing 149 breast cancer patient samples, we found that BRCA1 and PIG3 expression status were significantly positively correlated (r = 0.678, P < 0.001) and identified a significant positive correlation between high expression of BRCA1 and/or PIG3 and overall survival (OS). Moreover, we reveal that overexpression of BRCA1 significantly increased expression of PIG3 in cells with intact p53, whereas no increase in PIG3 was observed in p53- MDA-MB-157 cells and p53-depleted HCT116p53-/- cells. Meanwhile, ectopic expression of BRCA1 could not lead to an increase expression level of prohibitin (PHB), which we have previously identified to induce PIG3-mediated apoptosis. Finally, ChIP analysis revealed that PHB can bind to the PIG3 promoter and activate PIG3 transcription independent of p53, although p53 presence did enhance this process. Taken together, our findings suggest that BRCA1 regulates PIG3-mediated apoptosis in a p53-dependent manner, and that PIG3 expression is associated with a better OS in breast cancer patients.

No MeSH data available.


Related in: MedlinePlus

BRCA1 induces PIG3 expression independent of PHB(A) PHB protein levels were determined by western blotting following transfection of plasmid encoding BRCA1 into MCF-7, T47D, SK-BR-3, and MDA-MB-157 cells, and normalized to GAPDH expression. (B) PHB mRNA expression levels were determined by RT-PCR following transfection of plasmid encoding BRCA1 into HCT116p53+/+ and HCT116p53−/− cells, and normalized to GAPDH expression. Data are the mean of three independent experiments. *P < 0.05, as compared with untreated cells. (C) Localization and expression of PHB were determined by fluorescence microscopy following the same treatment as (B), with DMSO treatment as a control. Nuclei were stained with DAPI. The high magnification (200×) regions were shown above.
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Figure 3: BRCA1 induces PIG3 expression independent of PHB(A) PHB protein levels were determined by western blotting following transfection of plasmid encoding BRCA1 into MCF-7, T47D, SK-BR-3, and MDA-MB-157 cells, and normalized to GAPDH expression. (B) PHB mRNA expression levels were determined by RT-PCR following transfection of plasmid encoding BRCA1 into HCT116p53+/+ and HCT116p53−/− cells, and normalized to GAPDH expression. Data are the mean of three independent experiments. *P < 0.05, as compared with untreated cells. (C) Localization and expression of PHB were determined by fluorescence microscopy following the same treatment as (B), with DMSO treatment as a control. Nuclei were stained with DAPI. The high magnification (200×) regions were shown above.

Mentions: Our previous studies have identified that prohibitin (PHB) could also contribute to PIG3-mediated apoptosis [17]. Based on our findings, we postulated that BRCA1 could induce PIG3 expression in a PHB-dependent manner. To test it, we detected the effect of BRCA1 on the expression of PHB in both p53 wild-type and p53- cells. However, the protein level and mRNA level of PHB were both unchanged after BRCA1 vector transfection (Figure 3A and 3B; Supplementary Figure S2). The immunofluorescent staining also showed no change of the expression and subcellular localization of the protein (Figure 3C). Taken together, these data suggest that BRCA1 induces PIG3 expression independent of PHB.


BRCA1 regulates PIG3-mediated apoptosis in a p53-dependent manner.

Zhang W, Luo J, Chen F, Yang F, Song W, Zhu A, Guan X - Oncotarget (2015)

BRCA1 induces PIG3 expression independent of PHB(A) PHB protein levels were determined by western blotting following transfection of plasmid encoding BRCA1 into MCF-7, T47D, SK-BR-3, and MDA-MB-157 cells, and normalized to GAPDH expression. (B) PHB mRNA expression levels were determined by RT-PCR following transfection of plasmid encoding BRCA1 into HCT116p53+/+ and HCT116p53−/− cells, and normalized to GAPDH expression. Data are the mean of three independent experiments. *P < 0.05, as compared with untreated cells. (C) Localization and expression of PHB were determined by fluorescence microscopy following the same treatment as (B), with DMSO treatment as a control. Nuclei were stained with DAPI. The high magnification (200×) regions were shown above.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4480703&req=5

Figure 3: BRCA1 induces PIG3 expression independent of PHB(A) PHB protein levels were determined by western blotting following transfection of plasmid encoding BRCA1 into MCF-7, T47D, SK-BR-3, and MDA-MB-157 cells, and normalized to GAPDH expression. (B) PHB mRNA expression levels were determined by RT-PCR following transfection of plasmid encoding BRCA1 into HCT116p53+/+ and HCT116p53−/− cells, and normalized to GAPDH expression. Data are the mean of three independent experiments. *P < 0.05, as compared with untreated cells. (C) Localization and expression of PHB were determined by fluorescence microscopy following the same treatment as (B), with DMSO treatment as a control. Nuclei were stained with DAPI. The high magnification (200×) regions were shown above.
Mentions: Our previous studies have identified that prohibitin (PHB) could also contribute to PIG3-mediated apoptosis [17]. Based on our findings, we postulated that BRCA1 could induce PIG3 expression in a PHB-dependent manner. To test it, we detected the effect of BRCA1 on the expression of PHB in both p53 wild-type and p53- cells. However, the protein level and mRNA level of PHB were both unchanged after BRCA1 vector transfection (Figure 3A and 3B; Supplementary Figure S2). The immunofluorescent staining also showed no change of the expression and subcellular localization of the protein (Figure 3C). Taken together, these data suggest that BRCA1 induces PIG3 expression independent of PHB.

Bottom Line: Moreover, we reveal that overexpression of BRCA1 significantly increased expression of PIG3 in cells with intact p53, whereas no increase in PIG3 was observed in p53- MDA-MB-157 cells and p53-depleted HCT116p53-/- cells.Meanwhile, ectopic expression of BRCA1 could not lead to an increase expression level of prohibitin (PHB), which we have previously identified to induce PIG3-mediated apoptosis.Finally, ChIP analysis revealed that PHB can bind to the PIG3 promoter and activate PIG3 transcription independent of p53, although p53 presence did enhance this process.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, Nanjing 210002, China.

ABSTRACT
BRCA1 plays a key role in the regulation of p53-dependent target gene transcription activation. Meanwhile, the p53 inducible gene 3 (PIG3) is a downstream target of p53 and is involved in p53-initiated apoptosis. However, little is known about whether BRCA1 can regulate PIG3-mediated apoptosis. Using a tissue microarray containing 149 breast cancer patient samples, we found that BRCA1 and PIG3 expression status were significantly positively correlated (r = 0.678, P < 0.001) and identified a significant positive correlation between high expression of BRCA1 and/or PIG3 and overall survival (OS). Moreover, we reveal that overexpression of BRCA1 significantly increased expression of PIG3 in cells with intact p53, whereas no increase in PIG3 was observed in p53- MDA-MB-157 cells and p53-depleted HCT116p53-/- cells. Meanwhile, ectopic expression of BRCA1 could not lead to an increase expression level of prohibitin (PHB), which we have previously identified to induce PIG3-mediated apoptosis. Finally, ChIP analysis revealed that PHB can bind to the PIG3 promoter and activate PIG3 transcription independent of p53, although p53 presence did enhance this process. Taken together, our findings suggest that BRCA1 regulates PIG3-mediated apoptosis in a p53-dependent manner, and that PIG3 expression is associated with a better OS in breast cancer patients.

No MeSH data available.


Related in: MedlinePlus