Synthesis of N-substituted 3,5-bis(arylidene)-4-piperidones with high antitumor and antioxidant activity

A series of 3,5-bis(arylidene)-4-piperidones (DAP compounds) are considered as synthetic analogs of curcumin for anticancer and anti-inflammatory properties. We performed structureactivity relationship studies by synthesizing a number of 3,5-bis(arylidene)-4-piperidones Nalkylated or acylated with nitroxides or their amine precursors as potent antioxidant moieties. Both subtituents on arylidene rings and on piperidone nitrogen (five- or six-membered, 2- or 3- or 3,4-disubstituted, isoindoline nitroxides) were varied. The anticancer efficacy of the new DAP compounds was tested by measuring their cytotoxicity to cancer cell lines A2780 (human epithelial ovarian cancer cell line) and MCF-7 (human breast cancer cell line) and to H9c2, a noncancerous (healthy) cardiac cell line. The results showed that all DAP compounds induced a significant loss of cell viability in both the human cancer cell lines tested, however only pyrroline appended nitroxides (5c,1 5e, 7, 9) showed limited toxicity toward noncancerous cell lines. Computer docking simulations support the biological activity tested. These results suggest that antioxidant-conjugated DAPs will be useful as a safe and effective anticancer agent for cancer therapy

HO-3867, a STAT3 inhibitor induces apoptosis by inactivation of STAT3 activity in BRCA1-mutated ovarian cancer cells

BRCA1 plays an important role in DNA damage and repair, homologous recombination, cell-cycle regulation and apoptosis. BRCA-mutated ovarian cancer often presents at an advanced stage, however, tend to have better response to platinum-based chemotherapy as compared with sporadic cases of epithelial ovarian cancer (EOC). In spite of this, most patients will develop a recurrence and eventually succumb to the disease. Preclinical studies are currently investigating natural compounds and their analogs for tumor-directed targets in ovarian cancer. The aim of this study is to investigate whether the STAT3 inhibitor HO-3867, a novel curcumin analog, has a therapeutic effect on BRCA1-mutated ovarian cancer. Our novel agent, HO-3867 and a commercial STAT3 inhibitor, STATTIC, significantly inhibited BRCA-mutated ovarian cancer cells in vitro in a dose- and time-dependent manner. BRCA-mutated ovarian cancer cells treated with HO-3867 exhibited a significant degree of apoptosis with elevated levels of cleaved caspase-3, caspase-7 and PARP. HO-3867 treatment induced more reactive oxygen species (ROS) in BRCA-mutated cells compared with wild-type cells, however, there was no increased ROS when benign ovarian surface epithelial cells were treated with HO-3867. BRCA1-mutated cancer cells had higher expression of Tyrosine-phosphorylated STAT3 (pTyr705) as compared with other STAT proteins. Furthermore, treatment of these cells with HO-3867 resulted in decreased expression of pTyr705 and its downstream targets cyclin D1, Bcl-2 and survivin. In addition, overexpression of STAT3 cDNA provided resistance to HO-3867-induced apoptosis. Our results show that HO-3867, a potent STAT3 inhibitor, may have a role as a biologically targeted agent for BRCA1-mutated cancers either as an adjunct to cytotoxic chemotherapy or as a single agent

Anticancer Efficacy of a Difluorodiarylidenyl Piperidone (HO-3867) in Human Ovarian Cancer Cells and Tumor Xenografts

The purpose of this study was to evaluate the anticancer potency and mechanism of a novel difluorodiarylidenyl piperidone (H-4073) and its N-hydroxypyrroline modification (HO-3867) in human ovarian cancer. Studies were done using established human ovarian cancer cell lines (A2870, A2780cDDP, OV-4, SKOV3, PA-1, and OVCAR3) as well as in a murine xenograft tumor (A2780) model. Both compounds were comparably and significantly cytotoxic to A2780 cells. However, HO-3867 showed a preferential toxicity toward ovarian cancer cells while sparing healthy cells. HO-3867 induced G2-M cell cycle arrest in A2780 cells by modulating cell cycle regulatory molecules p53, p21, p27, cyclin-dependent kinase 2, and cyclin, and promoted apoptosis by caspase-8 and caspase-3 activation. It also caused an increase in the expression of functional Fas/CD95 and decreases in signal transducers and activators of transcription 3 (STAT3; Tyr705) and JAK1 phosphorylation. There was a significant reduction in STAT3 downstream target protein levels including Bcl-xL, Bcl-2, survivin, and vascular endothelial growth factor, suggesting that HO-3867 exposure disrupted the JAK/STAT3 signaling pathway. In addition, HO-3867 significantly inhibited the growth of the ovarian xenografted tumors in a dosage-dependent manner without any apparent toxicity. Western blot analysis of the xenograft tumor tissues showed that HO-3867 inhibited pSTAT3 (Tyr705 and Ser727) and JAK1 and increased apoptotic markers cleaved caspase-3 and poly ADP ribose polymerase. HO-3867 exhibited significant cytotoxicity toward ovarian cancer cells by inhibition of the JAK/STAT3 signaling pathway. The study suggested that HO-3867 may be useful as a safe and effective anticancer agent for ovarian cancer therapy

HO-3867, a curcumin analog, sensitizes cisplatin-resistant ovarian carcinoma, leading to therapeutic synergy through STAT3 inhibition

Cisplatin resistance is a major obstacle in the treatment of ovarian cancer. Drug combinations with synergistic or complementary functions are a promising strategy to overcome this issue. We studied the anticancer efficacy of a novel compound, HO-3867, used in combination with cisplatin against chemotherapy-resistant ovarian cancer. A2780R cells, a cisplatin-resistant human ovarian cancer cell line, were exposed to 1, 5 or 10 μM of HO-3867 alone or in combination with cisplatin (10 μg/ml) for 24 h. Cell viability (MTT), proliferation (BrdU), cell cycle analysis (FACS), and protein expression (protein gel blot) were used for in vitro studies. STAT3 overexpression was performed using transfected STAT3 cDNA. In vivo studies used cisplatin-resistant xenograft tumors grown in nude mice and treated with 100-ppm HO-3867 and weekly injections of 4-mg/kg cisplatin. HO-3867/cisplatin combination treatment significantly inhibited cisplatin-resistant cell proliferation in a concentration-dependent manner. The inhibition was associated with increased expression of p53 and p21, and decreased expression of cdk5 and cyclin D1. Apoptosis was induced by activation of Bax, cytochrome c release, and stimulated cleavage of caspase-9, caspase-3 and PA RP. Overexpression of STAT3 decreased the HO-3867-induced apoptosis. The combination treatment significantly inhibited the growth of cisplatin-resistant xenograft tumors with significant downregulation of pSTAT3, and without apparent toxicity to healthy tissues. The combination treatment exhibited synergistic anticancer efficacy, which appears largely due to HO-3867-induced downregulation of pSTAT3. The results, combined with the previously-reported safety features of HO-3867, suggest the potential use of this compound as a safe and effective adjuvant for the treatment of ovarian cancer

HO-3867, a Synthetic Compound, Inhibits the Migration and Invasion of Ovarian Carcinoma Cells through Downregulation of Fatty Acid Synthase and Focal Adhesion Kinase

Fatty acid synthase (FAS) and focal adhesion kinase (FAK), which are overexpressed in a variety of human epithelial tumors, play a key role in the migration and invasion of cancer cells. Hence, strategies targeted at inhibiting the FAS/FAK proteins may have therapeutic potential for cancer treatment. The goal of the present study was to determine the effect of HO-3867, a synthetic compound, on the migratory ability of ovarian cancer cells and to understand the mechanistic pathways including the involvement of FAS, FAK, and associated signaling proteins. The study was done using two established human ovarian cancer cell lines, A2780 and SKOV3. Incubation with 10 μmol/L HO-3867 for 24 hours significantly inhibited the native as well as the vascular endothelial growth factor (VEGF)–mediated migration and invasion of the cells. HO-3867 significantly attenuated FAS and FAK protein levels apparently through accelerated ubiquitin-dependent degradation, as shown by a clear downregulation of isopeptidase USP2a. Exposure of cells to HO-3867 also significantly inhibited FAS activity and mRNA levels and a number of downstream proteins, including phospho-extracellular signal–regulated kinase 1/2, phospho-human epidermal growth factor receptor 1, sterol regulatory element binding protein 1, VEGF, and matrix metalloproteinase 2. Western blot and immunohistochemical analyses of A2780 xenograft tumors in mice treated with HO-3867 showed significant reduction in FAS, FAK, VEGF, and downstream protein levels when compared with the untreated control. Collectively, the results showed that HO-3867 suppressed the migration and invasion of ovarian cancer cells by inhibiting the expression or activity of FAS and FAK proteins. The study suggests that molecular targeting of FAS and FAK by HO-3867 may be a potential strategy for ovarian cancer therapy

Amelioration of doxorubicin-induced cardiotoxicity by an anticancer-antioxidant dual-function compound, HO-3867

Doxorubicin (DOX) is a commonly-used drug for the treatment of cancer. The development of resistance to DOX is common, and high cumulative doses cause potentially lethal cardiac sideeffects. HO-3867, a synthetic curcumin analog, has been shown to exhibit both anticancer and cardioprotective effects. However, its cardioprotection in the setting of a conventional cancer therapy has not been established. This work investigated the use of HO-3867 and DOX to achieve a complementary outcome, i.e. increased toxicity towards cancer cells, and reduced cardiac toxicity. Combination treatment was investigated using DOX-resistant MCF-7 breast cancer cells (MCF-7 MDR) and Balb/c mice. Lower doses of HO-3867 and DOX (5 and 2.5 μM, respectively), reduce viability of MCF-7 MDR cells to an extent significantly greater than that when either drug was used alone, an effect equivalent to that induced by exposure to 50 μM DOX. In normal cardiac cells, the loss of viability from combination treatment was significantly lower than that induced by 50 μM of DOX. Increases in apoptotic markers, e.g. cleaved-caspase-3, and decreases in FAS and pAkt expressions were observed by western blotting. Mice treated with both HO-3867 and DOX showed significant improvement in cardiac functional parameters when compared to mice treated with DOX alone. Reduced expression of Bcl-2 and pAkt was observed in mice treated with DOX alone, while mice given combination treatment showed levels similar to control. The study indicates that combination treatment of HO-3867 and DOX is a viable option for treatment of cancer with reduced cardiotoxic side effects