Tannic acid ameliorates doxorubicin-induced cardiotoxicity and potentiates its anti-cancer activity: potential role of tannins in cancer chemotherapy

Doxorubicin, an anthracycline antibiotic, is widely used in the treatment of various solid tumors including breast cancer. However, its use is limited due to a variety of toxicities including cardiotoxicity. The present study aimed to evaluate the effect of tannic acid, a PARG/PARP inhibitor and an antioxidant, on doxorubicin-induced cardiotoxicity in H9c2 embryonic rat heart myoblasts and its anti-cancer activity in MDA-MB-231 human breast cancer cells as well as in DMBA-induced mammary tumor animals. Doxorubicin-induced cardiotoxicity was assessed by measurement of heart weight, plasma LDH level and histopathology. Bcl-2, Bax, PARP-1 and p53 expression were examined by western blotting. Our results show that tannic acid prevents activation of PARP-1, reduces Bax and increases Bcl-2 expression in H9c2 cells, thus, preventing doxorubicin-induced cell death. Further, it reduces the cell viability of MDA-MB-231 breast cancer cells, increases p53 expression in mammary tumors and shows maximum tumor volume reduction, suggesting that tannic acid potentiates the anti-cancer activity of doxorubicin. To the best of our knowledge, this is the first report which shows that tannic acid ameliorates doxorubicin-induced cardiotoxicity and potentiates its anti-cancer activity both in vitro (H9c2 and MDA-MB-231 cells) as well as in in vivo model of DMBA-induced mammary tumor animals.     

Differential effects of doxorubicin treatment on cell cycle arrest and Skp2 expression in breast cancer cells

Overexpression of Skp2, the ubiquitin ligase subunit that targets p27 for degradation, is often observed in cancers, and is associated with aggressive tumor proliferation and poor prognosis. As there is no drug at present that specifically targets Skp2, studies were undertaken to examine the effects of commonly used drugs on Skp2 regulation. Doxorubicin is among the most effective antitumor agents used for the management of breast cancer, but its effect on Skp2 expression is unknown. The objective of this study was to examine the effect of doxorubicin on Skp2 expression regulation in breast cancer cell lines. The expression of Skp2 mRNA and the protein levels of Skp2, p27, p21 and cyclin B were examined in doxorubicin-treated MCF-7 and MDA-MB-231 breast cancer cells. The effect of doxorubicin on the cell cycle profile was assessed by fluorescence-activated cell sorting analysis. Doxorubicin decreased Skp2 mRNA and protein levels in MCF-7 cells, but had the opposite effect in MDA-MB-231 cells. p27 levels were slightly decreased, whereas p53 and p21 levels were significantly upregulated in doxorubicin-treated MCF-7 cells. In contrast, p27 levels were unaffected by doxorubicin treatment in MDA-MB-231 cells, but cyclin B levels were markedly increased. Doxorubicin arrested MCF-7 cells at G1/S and G2/M checkpoints, whereas MDA-MB-231 cells were arrested at G2/M only. The differential effects of doxorubicin on Skp2 expression in breast cancer cells depend upon the specific cell cycle checkpoints activated by the drug. These changes induced by doxorubicin, however, do not significantly affect p27 expression in these cell lines, suggesting that the potential of a given drug to alter p27 expression through Skp2 modulation might depend on its specific action on cell cycle arrest.     

Undecylprodigiosin selectively induces apoptosis in human breast carcinoma cells independent of p53

Undecylprodigiosin (UP) is a bacterial bioactive metabolite produced by Streptomyces and Serratia. In this study, we explored the anticancer effect of UP. Human breast carcinoma cell lines BT-20, MCF-7, MDA-MB-231 and T47D and one nonmalignant human breast epithelial cell line, MCF-10A, were tested in this study. We found that UP exerted a potent cytotoxicity against all breast carcinoma cell lines in a dose- and time-dependent manner. In contrast, UP showed limited toxicity to MCF-10A cells, indicating UP's cytotoxic effect is selective for malignant cells. UP's cytotoxic effect was due to apoptosis, as confirmed by positive TUNEL signals, annexin V-binding, caspase 9 activation and PARP cleavage. Notably, UP-induced apoptosis was blocked by the pan-caspase inhibitor z-VAD.fmk, further indicating the involvement of caspase activity. Moreover, UP caused a marked decrease of the levels of antiapoptotic BCL-X(L), Survivin and XIAP while enhancing the levels of proapoptotic BIK, BIM, MCL-1S and NOXA, consequently favoring induction of apoptosis. Additionally, we found that cells with functional p53 (MCF-7, T47D) or mutant p53 (BT-20, MDA-MB-231) were both susceptible to UP's cytotoxicity. Importantly, UP was able to induce apoptosis in MCF-7 cells with p53 knockdown by RNA interference, confirming the dispensability of p53 in UP-induced apoptosis. Overall, our results establish that UP induces p53-independent apoptosis in breast carcinoma cells with no marked toxicity to nonmalignant cells, raising the possibility of its use as a new chemotherapeutic drug for breast cancer irrespective of p53 status.     

Treatment of PTEN-Null Breast Cancer by a Synthetic Lethal Approach Involving PARP1 Gene Silencing

The loss of the phosphatase and tensin homolog (PTEN) deleted from chromosome 10 is frequently observed in a variety of human cancers and appears to be an ideal target in synthetic lethality–based treatment. In this study, the synthetic lethal interaction between PTEN loss and the gene silencing of poly [ADP-ribose] polymerase 1 (PARP1) was examined in human triple-negative breast cancer cells (PTEN-null MDA-MB-468 and PTEN-positive MDA-MB-231 cells). Polycation liposomes previously developed by us were employed to deliver the small interfering ribonucleic acid (siRNA) targeted toward PARP1 (siPARP1) into the cancer cells. The silencing of the PARP1 gene exerted a cytocidal effect on the MDA-MB-468 cells but had no effect on the MDA-MB-231 cells and the human umbilical vein endothelial cells employed as normal cells. The simultaneous knockdown of PARP1 and PTEN in the MDA-MB-231 cells resulted in the significant inhibition of cell growth. The data suggest that the effects of the PARP1 knockdown on the cells were dependent on the PTEN status. A significant increase in the DNA breaks and the extent of apoptosis, possibly due to the failure of DNA repair, was observed upon PARP1 knockdown in the MDA-MB-468 cells compared with the case in the MDA-MB-231 cells. Our findings suggest that the synthetic lethal approach via PARP1 gene silencing holds promise for the treatment of patients with PTEN-null breast cancer.     

Cyclopentenyl cytosine induces senescence in breast cancer cells through the nucleolar stress response and activation of p53

The induction of senescence has emerged as a potentially important contributor to the effects of chemotherapeutic agents against tumors. We have demonstrated that depletion of CTP induced by cyclopentenyl cytosine (CPEC; NSC 375575), a specific inhibitor of the enzyme CTP synthetase, induces irreversible growth arrest and senescence characterized by altered morphology and expression of senescence-associated β-galactosidase activity in MCF-7 breast cancer cells expressing wild-type p53. In contrast, differentiation in the absence of senescence resulted from CPEC treatment in MDA-MB-231 breast cancer cells that express a mutated p53. Both senescence of MCF-7 cells and differentiation of MDA-MB-231 cells were prevented by repletion of CTP through the cytidine salvage pathway. Senescence in MCF-7 cells was associated with a G(2)- and S-phase arrest, whereas differentiation in MDA-MB-231 cells was associated with arrest in G(1) phase at 5 days. Mechanistic studies revealed that CTP depletion induced a rapid translocation of nucleolar proteins, including nucleostemin and nucleolin into the nucleoplasm. This nucleolar stress response resulted in a sustained elevation of p53 and the p53 target genes, p21 and Mdm2, in cells with wild-type p53. Furthermore, short interfering RNA-induced knockdown of p53 in MCF-7 cells treated with CPEC prevented cellular senescence and increased apoptotic cell death. We conclude that CTP depletion and the resulting nucleolar stress response results in a senescence-like growth arrest through activation of p53, whereas cells with mutated p53 undergo differentiation or apoptotic cell death.     

Evaluation of lapatinib cytotoxicity and genotoxicity on MDA-MB-231 breast cancer cell line

Lapatinib, one of the tyrosine kinase inhibitors (TKIs), is used to reduce epidermal growth factor family proteins overexpression. This study aims to assess the cytotoxic and genotoxic effects of lapatinib on the triple negative breast cancer cell line “MDA-MB-231”. We investigated the cytotoxicity of lapatinib by MTT assay, mode of cell death using apoptosis-necrosis assay, DNA damage using micronucleus test, EGFR protein expression by immunocytochemistry, and assessed its effect on EGFR (7p11.2 locus) and TP53 (17p13 locus) genes using interphase-FISH technique. Lapatinib induced cytotoxicity on MDA-MB-231 cell line by elevating the concentration and its IC₅₀ value was 32.5 μM after 24 h. Lapatinib increased apoptotic cells and micronuclei in binucleated cells gradually by increasing the concentration for 24 h. The EGFR protein expression was reduced by double fold that expressed in non-treated cells. Lapatinib enhanced deletion of EGFR gene signals highly significantly from the lowest concentration. Alternatively, lapatinib amplified signals of TP53 gene effectively by raising the concentration. In conclusion, lapatinib induced cytotoxic and genotoxic effects on MDA-MB-231 cell line. However, laptinib reduced the EGFR protein expression and EGFR signals, it raised the apoptotic cells and TP53 gene signals, which triggered extensive DNA damage. Therefore, lapatinib is an effective TKI in triple negative breast cancer cells as elucidated by its mode of cell death.     

Riccardin D,a Macrocyclic Bisbibenzy,Inhibits Human Breast Cancer Growth through the Suppression of Telomerase Activity

Riccardin D, a liverwort‐derived naturally occurring macrocyclic bisbibenzyl, has been found to exert anticancer effects in multiple cancer cell types. In this study, we investigated the effect and mechanism of Riccardin D on human breast cancer. Experiments were performed on human breast cancer MCF‐7 and MDA‐MB‐231 cells. The antitumour effects of Riccardin D were assessed by the 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyltetrazolium bromide (MTT) assay and human breast cancer xenografts mice model. TRAPeze^® XL Telomerase Detection assay was used for the detection of telomerase activity. γ‐H₂AX foci formation was tested for the induction of DNA damage response. Cell cycle distribution was analysed by flow cytometry, and cell apoptosis was determined by annexin V‐FITC/PI staining, terminal deoxynucleotidyl transferase‐mediated dUTP nick end labelling (TUNEL) assay and Western blotting. Riccardin D effectively inhibited the growth of MCF‐7 and MDA‐MB‐231 cells in vitro. And Riccardin D also effectively delayed the growth of MCF‐7 and MDA‐MB‐231‐luc‐D3H2LN xenografts without significant loss of body‐weight. Further analysis suggested that Riccardin D's effects may arise from its suppression of telomerase activity, which led to telomere dysfunction. Telomerase inhibition and telomere dysfunction could activate the canonical ataxia telangiectasia‐mutated (ATM) kinase‐mediated DNA damage response, as shown by elevated expression of γ‐H₂AX, p‐ATM and p‐Chk2. This is finally followed by the induction of cell cycle arrest and apoptosis, as shown by the increase of TUNEL‐stained cells, caspase activation, PARP cleavage and the increase of bax/bcl‐2 ratio. Moreover, Riccardin D induced p53‐proficient MCF‐7 cells to arrest in G1 phase and p53‐deficient MDA‐MB‐231 cells to arrest in G2/M phase. Overall, these results demonstrate that Riccardin D may inhibit human breast cancer growth through suppression of telomerase activity.     

Different apoptotic effects of saxifragifolin C in human breast cancer cells

Breast cancer is currently the most common form of cancer affecting women. Recent studies have reported that triterpenoid saponins isolated from Androsace umbellata exhibit anti-proliferative effects in several types of cancer cells. However, the cytotoxic effect of saxifragifolin C (Saxi C) on breast cancer cells remains unclear. The purpose of this study is to evaluate the in vitro anti-tumor activity of Saxi C in human breast cancer cells. Our data indicated that MDA-MB-231 cells were more sensitive than MCF-7 cells to Saxi C treatment. In addition, Saxi C inhibited cell survival through the induction of reactive oxygen species and the caspase-dependent pathway in the MDA-MB-231 cells, whereas MCF-7 cells treated with Saxi C underwent the apoptotic cell death in a caspase-independent manner. Although Saxi C treatment resulted in the induction of activation of MAPKs in both types of human breast cancer cells, p38 MAPK and JNK, but not ERK1/2, appeared to be involved in Saxi C-induced apoptosis. Moreover, ERα-overexpressing MDA-MB-231 cells remained alive, whereas the survival of shERα-transfected MCF-7 cells decreased. Taken together, Saxi C induced apoptosis in MCF-7 cells and MDA-MB-231 cells via different regulatory mechanisms, and ERα status might be essential for regulating Saxi C-induced apoptosis in breast cancer cells. Thus, Saxi C is a potential chemotherapeutic agent in breast cancer.     

Germacrone inhibits the proliferation of breast cancer cell lines by inducing cell cycle arrest and promoting apoptosis

Traditional medicinal herbs are an untapped source of potential pharmaceutical compounds. This study aims to determine whether the proliferation of breast cancer cell lines could be inhibited by germacrone, a natural product isolated from Rhizoma curcuma. Germacrone treatment significantly inhibited cell proliferation, increased lactate dehydrogenase (LDH) release, and induced mitochondrial membrane potential (ΔΨm) depolarization in both MCF-7 and MDA-MB-231 cells in a dose-dependent manner. Germacrone induced MDA-MB-231 and MCF-7 cell cycle arrest at the G0/G1 and G2/M phases respectively and induced MDA-MB-231 cell apoptosis. Furthermore, germacrone treatment significantly increased Bok expression and cytochrome c release from mitochondria without affecting Bcl-2, Bcl-xL, Bax, and Bim protein expressions. In addition, germacrone treatment induced caspase-3, 7, 9, PARP cleavage. We concluded that germacrone inhibited the proliferation of breast cancer cell lines by inducing cell cycle arrest and apoptosis through mitochondria-mediated caspase pathway. These results might provide some molecular basis for the anti-tumor activity of Rhizoma curcuma.     

Amygdalin Regulates Apoptosis and Adhesion in Hs578T Triple-Negative Breast Cancer Cells

Amygdalin, D-mandelonitrile-β-D-glucoside-6-β-glucoside, belongs to aromatic cyanogenic glycoside group derived from rosaceous plant seed. Mounting evidence has supported the anti-cancer effects of amygdalin. However, whether amygdalin indeed acts as an anti-tumor agent against breast cancer cells is not clear. The present study aimed to investigate the effect of amygdalin on the proliferation of human breast cancer cells. Here, we show that amygdalin exerted cytotoxic activities on estrogen receptors (ER)-positive MCF7 cells, and MDA-MB-231 and Hs578T triple-negative breast cancer (TNBC) cells. Amygdalin induced apoptosis of Hs578T TNBC cells. Amygdalin downregulated B-cell lymphoma 2 (Bcl-2), upregulated Bcl-2-associated X protein (Bax), activated of caspase-3 and cleaved poly ADP-ribose polymerase (PARP). Amygdalin activated a pro-apoptotic signaling molecule p38 mitogen-activated protein kinases (p38 MAPK) in Hs578T cells. Treatment of amygdalin significantly inhibited the adhesion of Hs578T cells, in which integrin α5 may be involved. Taken together, this study demonstrates that amygdalin induces apoptosis and inhibits adhesion of breast cancer cells. The results suggest a potential application of amygdalin as a chemopreventive agent to prevent or alleviate progression of breast cancer, especially TNBC.     

Frondoside A inhibits human breast cancer cell survival, migration, invasion and the growth of breast tumor xenografts

Breast cancer is a major challenge for pharmacologists to develop new drugs to improve the survival of cancer patients. Frondoside A is a triterpenoid glycoside isolated from the sea cucumber, Cucumaria frondosa. It has been demonstrated that Frondoside A inhibited the growth of pancreatic cancer cells in vitro and in vivo. We investigated the impact of Frondoside A on human breast cancer cell survival, migration and invasion in vitro, and on tumor growth in nude mice, using the human estrogen receptor-negative breast cancer cell line MDA-MB-231. The non-tumorigenic MCF10-A cell line derived from normal human mammary epithelium was used as control. Frondoside A (0.01-5 μM) decreased the viability of breast cancer cells in a concentration- and time-dependent manner, with 50%-effective concentration (EC50) of 2.5 μM at 24h. MCF10-A cells were more resistant to the cytotoxic effect of Frondoside A (EC50 superior to 5 μM at 24 h). In the MDA-MB-231 cells, Frondoside A effectively increased the sub-G1 (apoptotic) cell fraction through the activation of p53, and subsequently the caspases 9 and 3/7 cell death pathways. In addition, Frondoside A induced a concentration-dependent inhibition of MDA-MB-231 cell migration and invasion. In vivo, Frondoside A (100 μg/kg/dayi.p. for 24 days) strongly decreased the growth of MDA-MB-231 tumor xenografts in athymic mice, without manifest toxic side-effects. Moreover, we found that Frondoside A could enhance the killing of breast cancer cells induced by the chemotherapeutic agent paclitaxel. These findings identify Frondoside A as a promising novel therapeutic agent for breast cancer.     

LncRNA XIST promotes chemoresistance of breast cancer cells to doxorubicin by sponging miR-200c-3p to upregulate ANLN

The resistance of breast cancer cells to drugs is a major obstacle to effective cancer chemotherapy. Here, we study the function mechanisms of long non-coding RNA XIST in chemoresistance of breast cancer to doxorubicin. We examined the 50% inhibitive concentration of doxorubicin to MDA-MB-231 and MDA-MB-231/ADM cells, showing that the doxorubicin resistance of MDA-MB-231/ADM cells was much higher than MDA-MB-231 cells. The gene or protein expression of XIST and ANLN were also higher in MDA-MB-231/ADM cells than that in MDA-MB-231 cells. Moreover, XIST overexpression promoted cell proliferation and inhibited apoptosis of doxorubicin-treated MDA-MB-231 cells by promoting ANLN expression. XIST silencing inhibited cell proliferation and promoted apoptosis of doxorubicin-treated MDA-MB-231/ADM cells by inhibiting ANLN expression. Luciferase reporter assay showed that XIST functioned as a competing endogenous RNA to repress miR-200c-3p, which controlled its downstream target ANLN. In conclusion, these data reveal that XIST promotes chemoresistance of breast cancer cells to doxorubicin by sponging miR-200c-3p to upregulate ANLN. This work explores the relationship between lncRNA XIST and doxorubicin resistance in breast cancer cells and highlights a novel therapeutic target for the treatment of breast cancer.     

Tanshinone IIA induces mitochondria dependent apoptosis in prostate cancer cells in association with an inhibition of phosphoinositide 3-kinase/AKT pathway

Tanshinone IIA (Tan IIA; 14,16-epoxy-20-nor-5(10),6,8,13,15-abietapentaene-11,12-dione), a phytochemical derived from the roots of Salvia miltiorrhiza BUNGE, has been reported to posses anti-angiogenic, anti-oxidant, anti-inflammatory and apoptotic activities. However, the cancer growth inhibitory/cytocidal effects and molecular mechanisms in prostate cancer cells have not been well studied. In the present study, we demonstrate that Tan IIA significantly decreased the viable cell number of LNCaP (phosphate and tensin homolog (PTEN) mutant, high AKT, wild type p53) prostate cancer cells more sensitively than against the PC-3 (PTEN null, high AKT, p53 null) prostate cancer cells. Tan IIA significantly increased TdT-mediated dUTP nick-end labeling (TUNEL) positive index and sub-G1 DNA contents of treated cells, consistent with apoptosis. Tan IIA treatment led to cleavage activation of pro-caspases-9 and 3, but not pro-caspase-8, and cleavage of poly (ADP ribose) polymerase (PARP), a caspase-3 substrate. Additionally, Tan IIA treatment induced cytochrome c release from the mitochondria into the cytosol and reduced mitochondrial membrane potential and suppressed the expression of mitochondria protective Bcl-2 family protein Mcl-1(L). Tan IIA reduced the expression of phosphoinositide 3-kinase (PI3K) p85 subunit, and the phosphorylation of AKT and mammalian target of rapamycin (mTOR) in a concentration-dependent manner. Moreover, the combination of Tan IIA and LY294002, a specific PI3K inhibitor, enhanced PARP cleavage of LNCaP and PC-3, but not in MDA-MB-231 breast cancer cells which do not contain detectable active AKT. The findings suggest that Tan IIA-induced apoptosis involves mitochondria intrinsic caspase activation cascade and an inhibition of the PI3K/AKT survival pathway.     

MK-4827, a PARP-1/-2 inhibitor, strongly enhances response of human lung and breast cancer xenografts to radiation

The poly-(ADP-ribose) polymerase (PARP) inhibitor, MK-4827, is a novel potent, orally bioavailable PARP-1 and PARP-2 inhibitor currently in phase I clinical trials for cancer treatment. No preclinical data currently exist on the combination of MK-4827 with radiotherapy. The current study examined combined treatment efficacy of MK-4827 and fractionated radiotherapy using a variety of human tumor xenografts of differing p53 status: Calu-6 (p53 null), A549 (p53 wild-type [wt]) and H-460 (p53 wt) lung cancers and triple negative MDA-MB-231 human breast carcinoma. To mimic clinical application of radiotherapy, fractionated radiation (2?Gy per fraction) schedules given once or twice daily for 1 to 2?weeks combined with MK-4827, 50?mg/kg once daily or 25?mg/kg twice daily, were used. MK-4827 was found to be highly and similarly effective in both radiation schedules but maximum radiation enhancement was observed when MK-4827 was given at a dose of 50?mg/kg once daily (EF?=?2.2). MK-4827 radiosensitized all four tumors studied regardless of their p53 status. MK-4827 reduced PAR levels in tumors by 1?h after administration which persisted for up to 24?h. This long period of PARP inhibition potentially adds to the flexibility of design of future clinical trials. Thus, MK-4827 shows high potential to improve the efficacy of radiotherapy.     

磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶信号通路参与核因子-κB受体活化因子配体诱导的MDA-MB-231乳腺癌细胞迁移

目的探讨磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(PI3K/Akt)信号通路在核因子-κB受体活化因子配体(RANKL)诱导的乳腺癌细胞迁移中的作用。方法 Transwell法测定RANKL刺激后MDA-MB-231细胞迁移能力的改变。蛋白印迹法检测MDA-MB-231细胞表面RANK蛋白的表达及RANKL刺激后pAkt及Akt的表达;检测数据用x珚±s表示,采用SPSS 16.0软件进行t检验。结果 MDA-MB-231细胞表达RANK蛋白,RANKL诱导MDA-MB-231细胞迁移能力增强,RANKL的圈套受体骨保护素(OPG)可阻断RANKL诱导的细胞迁移(P<0.01)。RANKL刺激后MDA-MB-231细胞p-Akt表达升高,PI3K抑制剂LY294002抑制RANKL诱导的细胞迁移(P<0.01)。结论 PI3K/Akt信号通路参与RANKL诱导的乳腺癌细胞MDA-MB-231迁移。     

Characterization of human breast cancer cell lines for the studies on p53 in chemical carcinogenesis

To know whether the molecular responses to chemical carcinogens reflect only cell line specific molecular responses, or whether they can be regarded as characteristic of breast tissue, we have characterized four human breast cancer cell lines (MDA-MB-231, MDA-MB-468, T47-D, ZR-75-1). The activation of benzo(a)pyrene (BP), a model compound of polycyclic aromatic hydrocarbons, to its genotoxic BP-diolepoxide (BPDE) and p53 response and cell viability after BP exposure, and the p53 status in these cell lines were analyzed. Both TP53 (exons 5-8) mutations and total and phospho-p53 were analyzed. Three of the four cell lines clearly activated BP to BPDE-DNA adducts (MDA-MB-468, T47-D, ZR-75-1) and three had a mutation in the TP53 gene (MDA-MB-231, MDA-MB-468, T47-D). After BP-treatment the strongest p53 protein induction and phosphorylation at serine 392 was found in ZR-75-1 cells with a wt TP53 gene. Viability decreased dramatically only in ZR-75-1 and MDA-MB-468 cells although the relative cell number was reduced in all the cell lines suggesting that BP affects cell proliferation. In conclusion, a TP53 mutation does not necessarily lead to a loss of p53 protein response. This study stresses the importance of characterization of all human cancer cell lines for the intended targets of study.     

Inhibition of cyclooxygenase-2 and induction of apoptosis in estrogen-nonresponsive breast cancer cells by Antrodia camphorata.

The objective of this study was to investigate the fermented culture broth of Antrodia camphorata (A. camphorata) to induce apoptosis and inhibit cyclooxygenase-2 (COX-2) in estrogen-nonresponsive (MDA-MB-231) human breast cancer cells. Treatment of the highly invasive MDA-MB-231 cells with A. camphorata (40-240 microg/ml) resulted in dose and time-dependent sequences of events marked by apoptosis, as evidenced by loss of cell viability, chromatin condensation, and internucleosomal DNA fragmentation. Apoptosis in the MDA-MB-231 cells was accompanied by release of cytochrome c, activation of caspase-3, -8, and -9, and specific proteolytic cleavage of poly (ADP-ribose) polymerase (PARP). Although the A. camphorata-induced apoptosis was associated with a reduction in Bcl-2 protein levels, negligible Bax increase was observed. Furthermore, A. camphorata treatment inhibited COX-2 protein expression and prostaglandin E2 (PGE2) production in MDA-MB-231 cells. Analysis of the study data suggests that A. camphorata exerts growth inhibition on (highly invasive) estrogen-nonresponsive human breast cancer cells through apoptosis induction associated with COX-2 inhibition, and that it may possess anticancer properties potentially valuable for application in drug products.