Omega-3 DHA- and EPA-dopamine conjugates induce PPARγ-dependent breast cancer cell death through autophagy and apoptosis.

BACKGROUND: The omega-3 docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) may form conjugates with amines that have potential health benefits against common diseases including cancers. Here we synthesized DHA-dopamine (DHADA) and EPA-dopamine (EPADA) conjugates and studied their biological effects on different breast cancer cell lines. METHODS AND RESULTS: MTT assays indicated that increasing concentrations of DHADA and EPADA significantly affected viability in MCF-7, SKBR3 and MDA-MB-231 breast cancer cells, whereas no effect was observed in MCF-10A non-tumorigenic epithelial breast cells. DHADA and EPADA enhanced Beclin-1 expression, as evidenced by immunoblotting, real-time-PCR and functional analyses. Chromatin Immunoprecipitation (ChIP) and Re-ChIP assays revealed that both compounds induced recruitment of Peroxisome-Proliferator-Activated-Receptor gamma (PPARγ) and RNA Polymerase-II at the Retinoic-X-Receptor binding region on Beclin-1 promoter. Moreover, both compounds enhanced autophagosome formation, evaluated by LC-3 and monodansylcadaverine labeling, that was prevented by the PPARγ antagonist GW9662, addressing the direct involvement of PPARγ. Noteworthy, long-term treatment with DHADA and EPADA caused the blockade of autophagic flux followed by apoptotic cell death as evidenced by PARP cleavage and DNA fragmentation in all breast cancer cells. CONCLUSIONS: We have provided new insights into the molecular mechanism through which PPARγ, as a central molecule in the cross talk between autophagy and apoptosis, mediates DHADA- and EPADA-induced cell death in breast cancer cells. GENERAL SIGNIFICANCE: Our findings suggest that omega-3 DHADA- and EPADA activation of PPARγ may assume biological relevance in setting novel adjuvant therapeutic interventions in breast carcinoma.

Identification of bioactive constituents of Ziziphus jujube fruit extracts exerting antiproliferative and apoptotic effects in human breast cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Ziziphus extracts have been used in Traditional Chinese Medicine for the treatment of cancer. AIM OF THE STUDY: In the present study we have investigated the effects of Ziziphus jujube extracts (ZEs) on breast cancer. MATERIALS AND METHODS: We evaluated the effects of increasing concentrations of ZEs on ERα positive MCF-7 and ERα negative SKBR3 breast cancer cell proliferation using MTT assays. Apoptosis was analyzed by evaluating the involvement of some pro-apoptotic proteins, including Bax, Bad, Bid and PARP cleavage by immunoblotting analysis. Moreover, the effects of ZEs treatment on apoptosis were tested by both DNA fragmentation and terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) staining. By using chromatographic techniques, we identified the constituents of the effective extracts. RESULTS: ZE1, ZE2, and ZE4 exerted significant antiproliferative effects on estrogen receptor alpha (ERα) positive MCF-7 (IC(50) values of 14.42, 7.64, 1.69µg/mL) and ERα negative SKBR3 (IC(50) values of 14.06, 6.21, 3.70µg/mL) human breast cancer cells. Remarkably, ZEs did not affect cell viability of both normal human fibroblasts BJ1-hTERT and nonmalignant breast epithelial MCF-10A cells. Treatment with ZEs induced cell death by apoptosis in both malignant breast cells. We found that the most effective extracts ZE2 and ZE4 shared a number of triterpenic acids, already known for their anticancer activities. CONCLUSIONS: Our data provide a rational base for the use of Ziziphus extracts in the treatment of breast cancer in Traditional Chinese Medicine.