SIRT1 displays important epigenetic regulation of the Surivivn promoter. (A) Diagram of the 2kb region of the mouse Survivin promoter, showing the NF-κB and CEBP binding sites. (B) Loss of SIRT1 increases the acetylation level of histone H3 lysine 9 on two fragments of the Survivin promoter, 1033-1700 bp and 475-1052 bp, revealed by ChIP assay. (C) SIRT1 binds to the Survivin promoter on fragment 475-1052bp strongly, and on 1033-1700 weakly as revealed by ChIP. SIRT1 does not bind to the fragment 186–595 in Survivin promoter, and the promoter of the Gapdh gene, which was used as negative controls.

Brca1^Co/Co;MMTV-Cre;p53^+/− tumors show increased Survivin expression. (A–C) Brca1^Co/Co;MMTV-Cre;p53^+/− primary tumors (A,B) and tumor cell lines (C) express higher Survivin as revealed by Western blot and mRNA level. (D) Western blot analysis showing knockdown efficiency of two mouse Survivin specific siRNA oligos. (E) Transfection with mouse Survivin siRNA oligos induced apoptosis in Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cells. (F–H) Survivin shRNA significantly inhibited tumor formation of Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cells in nude mice allograft as reflected by volume (F) and weight (G), but did not reduce tumor formation of MMTV-cNeu;p53^+/− tumor cells (H) in nude mice. The RT-PCR on the bottom shows Survivin expression (upper panel) from 2 individual tumors of each treatment. Lower panel is Gapdh level as internal control. From (E) to (H), data are presented as average ± SD.

Resveratrol down-regulates Survivin through SIRT1 at the transcriptional level. (A) Resveratrol treatment significantly inhibited expression of Survivin and also reduced expression of Bcl2 and XIAP in 69 cells. “*” represents p < 0.05 by Student T-test. Data is average±SD.(B) Resveratrol treatment reduced Survivin protein level but did not change SIRT1 level in Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cells three days after the treatment. (C) Resveratrol inhibits Survivin expression from mRNA level in Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cells (69 and 780) as assessed by RT-PCR. (D) In Sirt1^−/− cells, resveratrol cannot reduce Survivin mRNA level. (E) In Sirt1^−/− MEFs, Survivin expression was increased. Data from MEFs of different passages (P) are shown. (F) Reconstituting SIRT1 in Sirt1^−/− cells was able to reduce Survivin mRNA expression. (G) SIRT1 down-regulates Survivin promoter activity. Insert shows the levels of SIRT1 after transfection with increasing amount of DNA. Data is average±SD. (H) Deacetylase activity of SIRT1 is required for inhibition of Survivin mRNA expression by SIRT1. SIRT1 knockout MEFs were transfected with plasmids either carrying wildtype SIRT1 (SIRT1) or catalytic site mutated SIRT1 (SIRT1-HY).

BRCA1 regulates Survivin through SIRT1. (A–C) BRCA1 negatively regulates Survivin expression. Over-expression of BRCA1 decreases the level of Survivin (A), while down-regulation of BRCA1 by siRNA up-regulates Survivin as revealed by Realtime PCR (B). (C) Down-regulation of BRCA1 results in about a 5 fold increase in Survivin promoter activity, while over-expression of SIRT1 on top of siBRCA1 significantly reduced the activity. Two BRCA1 siRNA exhibited similar results and data from one siRNA was shown. (D, E) Over-expression of BRCA1 only reduces Survivin in SIRT1 wild type cells, but not in SIRT1^−/− cells as revealed by RT-PCR (D), and by Realtime RT-PCR (E). (F) Resveratrol treatment reduced Survivin expression in Brca1^Co/Co;MMTV-Cre;p53^+/− allografted tumors in nude mice. Tumors from 3 pairs of individual nude mice were analyzed. (G) Ectopic overexpression of Survivin significantly reversed the lethality caused by resveratrol. (H) A model showing a BRCA1-SIRT1-Survivin axis signaling pathway involved in tumor cell survival and proliferation. Our data indicates that resveratrol treatment induces deacetylase activity of SIRT1, which inhibits Survivin and potentially other factors leading to reduced cell proliferation and increased apoptosis. Data in (A–B), (C), (E–G) are average ± SD.

Over-expression of SIRT1 inhibits growth of Brca1^Co/Co; MMTV-Cre;p53^+/− tumor cells. (A, B) Over-expression of SIRT1 inhibits the allografted tumor growth of Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cells (cell line: 69) compared with GFP transfected cells as reflected by average tumor volume (mm³) ±SE (A) and average weight (mg) ±SE (B). The tumor size was measured daily starting one week post transplantation, and the tumor weight was recorded when animals were sacrificed. P is a student t-test value and represents the comparison between the GFP and SIRT1 tranfected tumors. (C–E) Over-expression of SIRT1 reduced growth of 69 cells (C) and induced cell death at the same time. Cell death at day 6 is shown. (E). (D) Western blot to measure the expression level of SIRT1 in SIRT1 transfected 69 cells at 1 to 12 days after sorting. (F, G) Over-expression of SIRT1 did not inhibit the allografted tumor growth of MMTV-Neu;p53^+/−tumor cells (cell line: Neu) compared with GFP transfected cells by volume (F) and weight (G). (H–J) Over-expression of SIRT1 did not affect the growth (H) and cell death of Neu cells. Cell death at day 6 is shown. (J). (I) Western blot analysis to monitor the expression of SIRT1 in SIRT1 transfected Neu tumor cells at 1 to 12 days after sorting. For the nude mice study, each group of data was collected from 10 individual mice, bearing 2 inoculated tumors each. Data is presented as average±SD if it is not specifically mentioned.

Resveratrol inhibits Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cell growth in vitro and in allograft tumors. (A, B) Resveratrol reduces Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cell colony formation in soft agar in both size (A) and number (B). (C, D) Resveratrol does not affect MMTV-Neu;p53^+/− tumor cell colony formation in soft agar in both size (C) and number (D). In (B) and (D), data are average ± SD. (E) Nude mice were pretreated with carrier (control), 5μg, or 10μg revesveratrol per 30g body weight daily by IP injection for 10 days. The Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cells were implanted subcutaneously and resveratrol treatment was provided daily. The tumor size was measured daily starting 1-week post transplantation (E). Data shown is mean ±SE. The tumor weight was recorded when animals were sacrificed (F). Data is Mean±SE. P is a Student t-test value and represents the comparison between the control and two treated groups. (G, H) Resveratrol treatment did not inhibit allografted MMTV-Neu;p53^+/− tumor cells in volume (G) and weight (H). In (G) and (H), data are Mean±SE. (I) Brca1^Co/Co;MMTV-Cre;p53^+/− tumor cells were innoculated subcutaneously into nude mice and resveratrol treatment started at 5μg/30g either next day (Day1+Res) or until the tumor was visible (Tumor+Res). For all in vivo resveratrol treatment, data for each group of allografted tumors was collected from 10 individual nude mice, bearing 2 tumors each. The data is presented as Mean±SE.

BRCA1 positively regulates SIRT1 expression. (A, B) Levels of SIRT1 in mouse mammary tumor cells lines, Neu and Ras, derived from BRCA1 wild type (MMTV-cNeu and MMTV-ras transgenic mice, respectively), and 69 and 780, derived from BRCA1 mutant (Brca1^Co/Co;MMTV-Cre;p53^+/−) mice measured using 3 pairs of SIRT1 primers by Reatime RT-PCR (A) and Western blot (B). The intensity of bands was measured by Quantity One Software (Bio-Rad) and normalized using intensity of β-actin. The quantified numbers are shown at the bottom of the picture. (C) Western blot showing SIRT1 levels in normal mammary glands of wild type mouse, and primary mammary tumors derived in MMTV-cNeu;p53^+/− and Brca1^Co/Co;MMTV-Cre;p53^+/− mice. (D) Expression of SIRT1 in vector and wild type BRCA1 reconstituted HCC-1937 cell lines by Western blot and Realtime RT-PCR. (E) Increased BRCA1 in UBR60 cells (by tetracycline withdrawal, −Tet) up-regulates endogenous SIRT1 as revealed by Realtime RT-PCR. (F) Acute knockdown of BRCA1 in UBR60 cells by BRCA1 specific, but not scrambled, siRNA decreased SIRT1 expression, revealed by Realtime RT-PCR. (G,H) BRCA1 positively regulates the SIRT1 promoter. UBR60 cells were transfected with a SIRT1 luciferase reporter (S-2852) and SIRT1 promoter activity was measured 24 hours post transfection in the presence (+Tet), absence (−Tet) of over-expressed BRCA1 (G), or acute knockdown of endogenous BRCA1 (H). Two sets of scrambled siRNA and BRCA1 siRNA were used, and BRCA1 protein levels were shown below the panels. (I) ChIP assay by Realtime PCR showing that BRCA1 binds to SIRT1 promoter from position 1354-1770 bp. Data in D–I are presented as average±SD.