Safe and targeted anticancer efficacy of a novel class of antioxidant-conjugated difluorodiarylidenyl piperidones: differential cytotoxicity in healthy and cancer cells

NL13, a novel curcumin analogue and polo like kinase 4 inhibitor, induces cell cycle arrest and apoptosis in prostate cancer models

BACKGROUND AND PURPOSE

Prostate cancer remains a major public health burden worldwide. Polo like kinase 4 (PLK4) has emerged as a promising therapeutic target in prostate cancer due to its key roles in cell cycle regulation and tumour progression. This study aims to develop and characterize the novel curcumin analogue NL13 as a potential therapeutic agent and PLK4 inhibitor against prostate cancer.

EXPERIMENTAL APPROACH

NL13 was synthesized and its effects were evaluated in prostate cancer cells and mouse xenograft models. Kinome screening and molecular modelling identified PLK4 as the primary target. Antiproliferative and proapoptotic mechanisms were explored via cell cycle, apoptosis, gene and protein analyses.

KEY RESULTS

Compared with curcumin, NL13 exhibited much greater potency in inhibiting PC3 (IC50, 3.51 μM vs. 35.45 μM) and DU145 (IC50, 2.53 μM vs. 29.35 μM) prostate cancer cells viability and PLK4 kinase activity (2.32 μM vs. 246.88 μM). NL13 induced G2/M cell cycle arrest through CCNB1/CDK1 down-regulation and triggered apoptosis via caspase-9/caspase-3 cleavage. These effects were mediated by PLK4 inhibition, which led to the inactivation of the AKT signalling pathway. In mice, NL13 significantly inhibited tumour growth and modulated molecular markers consistent with in vitro findings, including decreased p-AKT and increased cleaved caspase-9/3.

CONCLUSION AND IMPLICATIONS

NL13, a novel PLK4-targeted curcumin analogue, exerts promising anticancer properties against prostate cancer by disrupting the PLK4-AKT-CCNB1/CDK1 and apoptosis pathways. NL13 represents a promising new agent for prostate cancer therapy.

Mechanism insights of curcumin and its analogues in cancer: An update

Cancer is the world's second leading cause of mortality and one of the major public health problems. Cancer incidence and mortality rates remain high despite the great advancements in existing therapeutic, diagnostic, and preventive approaches. Therefore, a quest for less toxic and more efficient anti-cancer strategies is still at the forefront of the current research. Traditionally important, curcumin commonly known as a wonder molecule has received considerable attention as an anti-cancer, anti-inflammatory, and antioxidant candidate. However, limited water solubility and low bioavailability restrict its extensive utility in different pathological states. The investigators are making consistent efforts to develop newer strategies to overcome its limitations by designing different analogues with better pharmacokinetic and pharmacodynamic properties. The present review highlights the recent updates on curcumin and its analogues with special emphasis on various mechanistic pathways involved in anti-cancer activity. In addition, the structure-activity relationship of curcumin analogues has also been precisely discussed. This article will also provide key information for the design and development of newer curcumin analogues with desired pharmacokinetic and pharmacodynamic profiles and will provide in depth understanding of molecular pathways involved in the anti-cancer activities.

Discovery of two biotin-PEG4‑diarylidenyl piperidone prodrugs as potent antitumor agents with good efficacy, limited toxicity, and low resistance

Two biotin-polyethylene glycol (PEG)4‑diarylidenyl piperidone (DAP) prodrugs, compounds 3a and 3b, were designed as antineoplastic agents and synthesized by coupling biotin to bifluoro- and binitro-substituted DAP derivatives (DAP-F and DAP-NO₂) through a PEG4 linker, respectively. The results of the MTT (3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di- phenytetrazoliumromide) assay and a SW480 xenograft model identified compounds 3a and 3b as candidate antitumor agents with good efficacy, limited toxicity, and low resistance, as compared to the original drugs (DAP-F and DAP-NO₂), cisplatin, and doxorubicin (dox). The results of a preliminary pharmacokinetic study showed that compounds 3a and 3b slowly released their original drug DAP-F and DAP-NO₂ within 12 h after intraperitoneal injection, respectively. Western blot analysis and computer docking simulations indicated that DAP-F, DAP-NO₂, and compounds 3a and 3b were indeed inhibitors of signal transducer and activator of transcription 3 (STAT3) and the antitumor effects of compounds 3a and 3b were exerted by sequentially interacting with the SH2-binding domain followed by the DNA-binding domain after releasing the original drugs DAP-F and DAP-NO₂, respectively. These results suggest that the targeted prodrug model led to good antitumor efficacy with reduced toxicity, while a dual STAT3-binding model may promote antitumor efficacy and resistance.

HO-3867 Induces Apoptosis via the JNK Signaling Pathway in Human Osteosarcoma Cells

Metastatic osteosarcoma often results in poor prognosis despite the application of surgical en bloc excision along with chemotherapy. HO-3867 is a curcumin analog that induces cell apoptosis in several cancers, but the apoptotic effect and its mechanisms on osteosarcoma cells are still unknown. After observing the decrease in cellular viability of three human osteosarcoma U2OS, HOS, and MG-63 cell lines, and the induction of cellular apoptosis and arrest in sub-G1 phase in U2OS and HOS cells by HO-3867, the human apoptosis array showed that heme oxygenase (HO)-1 and cleaved caspase-3 expressions had significant increases after HO-3867 treatment in U2OS cells and vice versa for cellular inhibitors of apoptosis (cIAP)1 and X-chromosome-linked IAP (XIAP). Western blot analysis verified the results and showed that HO-3867 activated the initiators of both extrinsic caspase 8 and intrinsic caspase 9, and significantly increased cleaved PARP expression in U2OS and HOS cells. Moreover, with the addition of HO-3867, ERK1/2, and JNK1/2 phosphorylation were increased in U2OS and HOS cells. Using the inhibitor of JNK (JNK in 8), HO-3867’s increases in cleaved caspases 3, 8, and 9 could be expectedly suppressed, indicating that JNK signaling is responsible for both apoptotic pathways, including extrinsic and intrinsic, in U2OS and HOS cells caused by HO-3867. Through JNK signaling, HO-3867 has proven to be effective in causing both extrinsic and intrinsic apoptotic pathways of human osteosarcoma cells.

Molecular Targets of Curcumin and Its Therapeutic Potential for Ovarian Cancer

Ovarian cancer is the fifth most common gynecological cancer in women globally. Conventional chemotherapy is the first therapeutic approach in the treatment of ovarian cancer, but its success is limited by severe side effects, transient response, and the high prevalence of relapse. Curcumin is a natural product found in the rhizome extract of Curcuma longa and has been extensively used over the last decades for its unique biological and medicinal properties, which include: having antioxidant, analgesic, anti-inflammation, and anti-tumor activities. Curcumin exerts its anticancer properties against ovarian cancer via multiple mechanisms: interfering with cellular interactions necessary for metastasis and recurrence of OC cells, increasing pro-apoptotic proteins as well as inducing or suppressing generation of different molecules such as cytokines, transcription factors, enzymes, protein kinases, and growth factors. Moreover, curcumin down-regulates various signaling pathways such as PI3K/Akt, Wnt/β-catenin, JAK/STAT3, and MEK/ERK1/2 axes, which at least in part have a role in inhibiting further tumor proliferation, growth, and angiogenesis. In this review, we overview the potential of incorporating curcumin into the treatment of ovarian cancer. In particular, we summarize the preclinical evidence supporting its use in combination with current chemotherapeutic regimens as well as new analogues and formulations under investigation.

HO-3867 Induces ROS-Dependent Stress Response and Apoptotic Cell Death in Leishmania donovani

Lack of vaccine and increasing chemotherapeutic toxicities currently necessitate the development of effective and safe drugs against various forms of leishmaniases. We characterized the cellular stress induced by a novel curcumin analogue, HO-3867, encapsulated within the phosphatidylcholine-stearylamine (PC-SA) liposome for the first time against Leishmania. The liposomal formulation of HO-3867 (i.e., PC-SA/HO-3867) initiated oxidative stress-induced apoptosis in L. donovani, revealed by altered cell morphology, phosphatidylserine externalization, mitochondrial depolarization, intracellular lipid accumulation, and cell cycle arrest in promastigotes. Liposomal HO-3867 was observed to be a strong apoptosis inducer in L. donovani and L. major in a dose-dependent manner, yet completely safe for normal murine macrophages. Moreover, PC-SA/HO-3867 treatment induced L. donovani metacaspase and PARP1 activation along with downregulation of the Sir2 gene. PC-SA/HO-3867 arrested intracellular L. donovani amastigote burden in vitro, with reactive oxygen species (ROS) and nitric oxide (NO)-mediated parasite killing. These data suggest that liposomal HO-3867 represents a highly promising and non-toxic nanoparticle-based therapeutic platform against leishmaniasis inspiring further preclinical developments.

Redox Sensitive Cysteine Residues as Crucial Regulators of Wild-Type and Mutant p53 Isoforms

The wild-type protein p53 plays a key role in preventing the formation of neoplasms by controlling cell growth. However, in more than a half of all cancers, the TP53 gene has missense mutations that appear during tumorigenesis. In most cases, the mutated gene encodes a full-length protein with the substitution of a single amino acid, resulting in structural and functional changes and acquiring an oncogenic role. This dual role of the wild-type protein and the mutated isoforms is also evident in the regulation of the redox state of the cell, with antioxidant and prooxidant functions, respectively. In this review, we introduce a new concept of the p53 protein by discussing its sensitivity to the cellular redox state. In particular, we focus on the discussion of structural and functional changes following post-translational modifications of redox-sensitive cysteine residues, which are also responsible for interacting with zinc ions for proper structural folding. We will also discuss therapeutic opportunities using small molecules targeting cysteines capable of modifying the structure and function of the p53 mutant isoforms in view of possible anticancer therapies for patients possessing the mutation in the TP53 gene.

Curcumin and its derivatives in cancer therapy: Potentiating antitumor activity of cisplatin and reducing side effects

Curcumin is a phytochemical isolated from Curcuma longa with potent tumor-suppressor activity, which has shown significant efficacy in pre-clinical and clinical studies. Curcumin stimulates cell death, triggers cycle arrest, and suppresses oncogenic pathways, thereby suppressing cancer progression. Cisplatin (CP) stimulates DNA damage and apoptosis in cancer chemotherapy. However, CP has adverse effects on several organs of the body, and drug resistance is frequently observed. The purpose of the present review is to show the function of curcumin in decreasing CP's adverse impacts and improving its antitumor activity. Curcumin administration reduces ROS levels to prevent apoptosis in normal cells. Furthermore, curcumin can inhibit inflammation via down-regulation of NF-κB to maintain the normal function of organs. Curcumin and its nanoformulations can reduce the hepatoxicity, neurotoxicity, renal toxicity, ototoxicity, and cardiotoxicity caused by CP. Notably, curcumin potentiates CP cytotoxicity via mediating cell death and cycle arrest. Besides, curcumin suppresses the STAT3 and NF-ĸB as tumor-promoting pathways, to enhance CP sensitivity and prevent drug resistance. The targeted delivery of curcumin and CP to tumor cells can be mediated nanostructures. In addition, curcumin derivatives are also able to reduce CP-mediated side effects, and increase CP cytotoxicity against various cancer types.

PTEN as a Therapeutic Target in Pulmonary Hypertension Secondary to Left-heart Failure: Effect of HO-3867 and Supplemental Oxygenation

Pulmonary hypertension (PH) is a condition when the pressure in the lung blood vessels is elevated. This leads to increase in thickness of the blood vessels and increases the workload of the heart and lungs. The incidence and prevalence of PH has been on the increase in the last decade. It is estimated that PH affects about 1% of the global population and about 10% of individuals >65 years of age. Of the various types, Group 2 PH is the most common type seen in the elderly population. Fixed PH or PH refractive to therapies is considered a contraindication for heart transplantation; the 30-day mortality in heart transplant recipients is significantly increased in the subset of this population. In general, the pathobiology of PH involves multiple factors including hypoxia, oxidative stress, growth factor receptors, vascular stress, etc. Hence, it is challenging and important to identify specific mechanisms, diagnosis and develop effective therapeutic strategies. The focus of this manuscript is to review some of the important pathobiological processes and mechanisms in the development of PH. Results from our previously reported studies, including targeted treatments along with some new data on PH secondary to left-heart failure, are presented.

Drugging the 'undruggable'. Therapeutic targeting of protein-DNA interactions with the use of computer-aided drug discovery methods

Transcription factors (TFs) act as major oncodrivers in many cancers and are frequently regarded as high-value therapeutic targets. The functionality of TFs relies on direct protein-DNA interactions, which are notoriously difficult to target with small molecules. However, this prior view of the 'undruggability' of protein-DNA interfaces has shifted substantially in recent years, in part because of significant advances in computer-aided drug discovery (CADD). In this review, we highlight recent examples of successful CADD campaigns resulting in drug candidates that directly interfere with protein-DNA interactions of several key cancer TFs, including androgen receptor (AR), ETS-related gene (ERG), MYC, thymocyte selection-associated high mobility group box protein (TOX), topoisomerase II (TOP2), and signal transducer and activator of transcription 3 (STAT3). Importantly, these findings open novel and compelling avenues for therapeutic targeting of over 1600 human TFs implicated in many conditions including and beyond cancer.

Diarylpentanoid (1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one) (MS13) Exhibits Anti-proliferative, Apoptosis Induction and Anti-migration Properties on Androgen-independent Human Prostate Cancer by Targeting Cell Cycle-Apoptosis and PI3K Signalling Pathways

Diarylpentanoids exhibit a high degree of anti-cancer activity and stability in vitro over curcumin in prostate cancer cells. Hence, this study aims to investigate the effects of a diarylpentanoid, 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one (MS13) on cytotoxicity, anti-proliferative, apoptosis-inducing, anti-migration properties, and the underlying molecular mechanisms on treated androgen-independent prostate cancer cells, DU 145 and PC-3. A cell viability assay has shown greater cytotoxicity effects of MS13-treated DU 145 cells (EC₅₀ 7.57 ± 0.2 µM) and PC-3 cells (EC₅₀ 7.80 ± 0.7 µM) compared to curcumin (EC₅₀: DU 145; 34.25 ± 2.7 µM and PC-3; 27.77 ± 6.4 µM). In addition, MS13 exhibited significant anti-proliferative activity against AIPC cells compared to curcumin in a dose- and time-dependent manner. Morphological observation, increased caspase-3 activity, and reduced Bcl-2 protein levels in these cells indicated that MS13 induces apoptosis in a time- and dose-dependent. Moreover, MS13 effectively inhibited the migration of DU 145 and PC-3 cells. Our results suggest that cell cycle-apoptosis and PI3K pathways were the topmost significant pathways impacted by MS13 activity. Our findings suggest that MS13 may demonstrate the anti-cancer activity by modulating DEGs associated with the cell cycle-apoptosis and PI3K pathways, thus inhibiting cell proliferation and cell migration as well as inducing apoptosis in AIPC cells.

Molecular Mechanisms of Antiproliferative and Apoptosis Activity by 1,5-Bis(4-Hydroxy-3-Methoxyphenyl)1,4-Pentadiene-3-one (MS13) on Human Non-Small Cell Lung Cancer Cells

Diarylpentanoid (DAP), an analog that was structurally modified from a naturally occurring curcumin, has shown to enhance anticancer efficacy compared to its parent compound in various cancers. This study aims to determine the cytotoxicity, antiproliferative, and apoptotic activity of diarylpentanoid MS13 on two subtypes of non-small cell lung cancer (NSCLC) cells: squamous cell carcinoma (NCI-H520) and adenocarcinoma (NCI-H23). Gene expression analysis was performed using Nanostring PanCancer Pathways Panel to determine significant signaling pathways and targeted genes in these treated cells. Cytotoxicity screening revealed that MS13 exhibited greater inhibitory effect in NCI-H520 and NCI-H23 cells compared to curcumin. MS13 induced anti-proliferative activity in both cells in a dose- and time-dependent manner. Morphological analysis revealed that a significant number of MS13-treated cells exhibited apoptosis. A significant increase in caspase-3 activity and decrease in Bcl-2 protein concentration was noted in both MS13-treated cells in a time- and dose-dependent manner. A total of 77 and 47 differential expressed genes (DEGs) were regulated in MS13 treated-NCI-H520 and NCI-H23 cells, respectively. Among the DEGs, 22 were mutually expressed in both NCI-H520 and NCI-H23 cells in response to MS13 treatment. The top DEGs modulated by MS13 in NCI-H520—DUSP4, CDKN1A, GADD45G, NGFR, and EPHA2—and NCI-H23 cells—HGF, MET, COL5A2, MCM7, and GNG4—were highly associated with PI3K, cell cycle-apoptosis, and MAPK signaling pathways. In conclusion, MS13 may induce antiproliferation and apoptosis activity in squamous cell carcinoma and adenocarcinoma of NSCLC cells by modulating DEGs associated with PI3K-AKT, cell cycle-apoptosis, and MAPK pathways. Therefore, our present findings could provide an insight into the anticancer activity of MS13 and merits further investigation as a potential anticancer agent for NSCLC cancer therapy.

Structural and Drug Targeting Insights on Mutant p53

p53 is a transcription factor with a pivotal role in cell homeostasis and fate. Its impairment is a major event in tumor onset and development. In fact, about half of human cancers bear TP53 mutations that not only halt the normal function of p53, but also may acquire oncogenic gain of functions that favor tumorigenesis. Although considered undruggable for a long time, evidence has proven the capability of many compounds to restore a wild-type (wt)-like function to mutant p53 (mutp53). However, they have not reached the clinic to date. Structural studies have strongly contributed to the knowledge about p53 structure, stability, dynamics, function, and regulation. Importantly, they have afforded relevant insights into wt and mutp53 pharmacology at molecular levels, fostering the design and development of p53-targeted anticancer therapies. Herein, we provide an integrated view of mutp53 regulation, particularly focusing on mutp53 structural traits and on targeting agents capable of its reactivation, including their biological, biochemical and biophysical features. With this, we expect to pave the way for the development of improved small molecules that may advance precision cancer therapy by targeting p53.

Perspectives for synthetic curcumins in chemoprevention and treatment of cancer: An update with promising analogues

Curcumin, a pure compound extracted from the flowering plant, turmeric (Curcuma longa. Zingiberaceae), is a common dietary ingredient found in curry powder. It has been studied extensively for its anti-inflammatory, antioxidant, antimicrobial and anti-tumour activities. Evidence is accumulating demonstrating its potential in chemoprevention and as an anti-tumour agent for the treatment of cancer. Despite demonstrated safety and tolerability, the clinical application of curcumin is frustrated by its poor solubility, metabolic instability and low oral bioavailability. Consequently researchers have tried novel techniques of formulation and delivery as well as synthesis of analogues with enhanced properties to overcome these barriers. This review presents the synthetic analogues of curcumin that have proven their anticancer potential from different studies. It also highlights studies that combined these analogues with approved chemotherapies and delivered them via novel techniques. Currently, there are no reports of clinical studies on any of the synthetic congeners of curcumin and this presents an opportunity for future research. This review presents the synthetic analogues of curcumin and makes a compelling argument for their potential application in the management of cancerous disease.

Dienone Compounds: Targets and Pharmacological Responses

The biological responses to dienone compounds with a 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore have been studied extensively. Despite their expected general thiol reactivity, these compounds display considerable degrees of tumor cell selectivity. Here we review in vitro and preclinical studies of dienone compounds including b-AP15, VLX1570, RA-9, RA-190, EF24, HO-3867, and MCB-613. A common property of these compounds is their targeting of the ubiquitin–proteasome system (UPS), known to be essential for the viability of tumor cells. Gene expression profiling experiments have shown induction of responses characteristic of UPS inhibition, and experiments using cellular reporter proteins have shown that proteasome inhibition is associated with cell death. Other mechanisms of action such as reactivation of mutant p53, stimulation of steroid receptor coactivators, and induction of protein cross-linking have also been described. Although unsuitable as biological probes due to widespread reactivity, dienone compounds are cytotoxic to apoptosis-resistant tumor cells and show activity in animal tumor models.

The Curcumin Analogue, MS13 (1,5-Bis(4-hydroxy-3- methoxyphenyl)-1,4-pentadiene-3-one), Inhibits Cell Proliferation and Induces Apoptosis in Primary and Metastatic Human Colon Cancer Cells

The cytotoxic and apoptotic effects of turmeric (Curcuma longa) on colon cancer have been well documented but specific structural modifications of curcumin have been shown to possess greater growth-suppressive potential on colon cancer than curcumin. Therefore, the aim of this study is to identify the anti-cancer properties of curcumin analogue-MS13, a diarylpentanoid on the cytotoxicity, anti-proliferative and apoptotic activity of primary (SW480) and metastatic (SW620) human colon cancer cells. A cell viability assay showed that MS13 has greater cytotoxicity effect on SW480 (EC₅₀: 7.5 ± 2.8 µM) and SW620 (EC₅₀: 5.7 ± 2.4 µM) compared to curcumin (SW480, EC₅₀: 30.6 ± 1.4 µM) and SW620, EC₅₀: 26.8 ± 2.1 µM). Treatment with MS13 at two different doses 1X EC₅₀ and 2X EC₅₀ suppressed the colon cancer cells growth with lower cytotoxicity against normal cells. A greater anti-proliferative effect was also observed in MS13 treated colon cancer cells compared to curcumin at 48 and 72 h. Subsequent analysis on the induction of apoptosis showed that MS13 treated cells exhibited morphological features associated with apoptosis. The findings are also consistent with cellular apoptotic activities shown by increased caspase-3 activity and decreased Bcl-2 protein level in both colon cancer cell lines. In conclusion, MS13 able to suppress colon cancer cell growth by inhibiting cell proliferation and induce apoptosis in primary and metastatic human colon cancer cells.

Selective Induction of Cellular Toxicity and Anti-tumor Efficacy by N-Methylpiperazinyl Diarylidenylpiperidone and its Pro-nitroxide Conjugate through ROS-mediated Mitochondrial Dysfunction and G2/M Cell-cycle Arrest in Human Pancreatic Cancer

Pancreatic adenocarcinoma is an aggressive cancer with poor clinical prognosis and limited therapeutic options. There is a significant lack of effective, safe, and targeted therapies for successful treatment of pancreatic cancer. In this report, we describe the anticancer efficacy of two novel compounds, N-methylpiperazinyl diarylidenylpiperidone (L-2663) and its pro-nitroxide conjugate (HO-4589) evaluated on human pancreatic adenocarcinoma (AsPC-1) cell line and xenograft tumor in mice. Using flow cytometry, we determined the effect of the L-2663 and HO-4589 drugs in inducing mitochondrial toxicity, triggering cell-cycle arrest, and apoptosis. EPR spectroscopy was used to quantify cellular uptake, metabolic conversion and stability of HO-4589 in cells and in vivo monitoring of tumor oxygenation as a function of growth. The results established different antiproliferative efficacy of the L-2663 and HO-4589 compounds, with a targeted action on cancer cells while being less toxic to noncancerous cells. The study may have important implications in the future designs of safe and effective chemotherapeutic agents for the treatment of pancreatic cancer.

Coffea arabica Bean Extracts and Vitamin C: A Novel Combination Unleashes MCF-7 Cell Death

BACKGROUND

Vitamin C (VC) is believed to enhance immunity and is regularly integrated as a supplementary agent during several treatments.

OBJECTIVE

The green (GC) and roasted (RC) coffee (Coffea arabica) aqueous extracts (0, 125, 250 and 500 μg/ml) combined with VC (50 μg/ml) were examined on the cancerous MCF-7 cell line and normal human lymphocytes.

METHODS

Neutral red uptake assay, comet assay, immunocytochemical reactivity for protein expression and mRNA expression of apoptosis-related genes were performed.

RESULTS

A significant (P< 0.05) concentration-dependent increase of apoptotic features, such as morphological changes, and abundant nuclear condensation, altered the expression of p53 and caspase-3 mRNA, down-regulation of Bcl-2 protein as well as the acidic autophagosomal vacuolization in treated cells. The oxidative stress and DNA single-strand breaks were noticed too.

CONCLUSION

These results suggest that coffee in combination with VC undergoes apoptotic anticancer pathway. This supports the integration of coffee and VC as a valuable candidate for anticancer research and treatments.

Therapeutic Inducers of Apoptosis in Ovarian Cancer

Ovarian cancers remain one of the most common causes of gynecologic cancer-related death in women worldwide. The standard treatment comprises platinum-based chemotherapy, and most tumors develop resistance to therapeutic drugs. One mechanism of developing drug resistance is alterations of molecules involved in apoptosis, ultimately assisting in the cells' capability to evade death. Thus, there is a need to focus on identifying potential drugs that restore apoptosis in cancer cells. Here, we discuss the major inducers of apoptosis mediated through various mechanisms and their usefulness as potential future treatment options for ovarian cancer. Broadly, they can target the apoptotic pathways directly or affect apoptosis indirectly through major cancer-pathways in cells. The direct apoptotic targets include the Bcl-2 family of proteins and the inhibitor of apoptotic proteins (IAPs). However, indirect targets include processes related to homologous recombination DNA repair, micro-RNA, and p53 mutation. Besides, apoptosis inducers may also disturb major pathways converging into apoptotic signals including janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3), wingless-related integration site (Wnt)/β-Catenin, mesenchymal-epithelial transition factor (MET)/hepatocyte growth factor (HGF), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), and phosphatidylinositol 3-kinase (PI3K)/v-AKT murine thymoma viral oncogene homologue (AKT)/mammalian target of rapamycin (mTOR) pathways. Several drugs in our review are undergoing clinical trials, for example, birinapant, DEBIO-1143, Alisertib, and other small molecules are in preclinical investigations showing promising results in combination with chemotherapy. Molecules that exhibit better efficacy in the treatment of chemo-resistant cancer cells are of interest but require more extensive preclinical and clinical evaluation.

Investigation of anti-cancer and migrastatic properties of novel curcumin derivatives on breast and ovarian cancer cell lines

Background

Curcumin is known for its multitude of medicinal properties, including anti-cancer and migrastatic activity. Efforts to overcome poor bioavailability, stability, and side effects associated with the higher dose of curcumin has led to the development of newer derivatives of curcumin. Thus, the focus of this study is to screen novel curcumin derivatives, namely ST03 and ST08, which have not been reported before, for their cytotoxicity and migrastatic property on cancer cells.

Methods

Anti-cancer activity of ST03 and ST08 was carried out using standard cytotoxicity assays viz., LDH, MTT, and Trypan blue on both solid and liquid cancer types. Flow cytometric assays and western blotting was used to investigate the cell death mechanisms. Transwell migration assay was carried out to check for migrastatic properties of the compounds.

Results

Both the compounds, ST03 and ST08, showed ~ 100 fold higher potency on liquid and solid tumour cell lines compared to its parent compound curcumin. They induced cytotoxicity by activating the intrinsic pathway of apoptosis in the breast (MDA-MB-231) and ovarian cancer cell lines (PA-1) bearing metastatic and stem cell properties, respectively. Moreover, ST08 also showed inhibition on breast cancer cell migration by inhibiting MMP1 (matrix metalloproteinase 1).

Conclusion

Both ST03 and ST08 exhibit anti-cancer activity at nanomolar concentration. They induce cell death by activating the intrinsic pathway of apoptosis. Also, they inhibit migration of the cancer cells by inhibiting MMP1 in breast cancer cells.

Molecular Pathways Modulated by Curcumin Analogue, Diarylpentanoids in Cancer

While curcumin has a range of therapeutic benefits, its potent anticancer activity remains an attractive avenue for anticancer research owing to the multifactorial nature of cancer itself. The structure of curcumin has thus been used as a lead to design more potent analogues, and diarylpentanoids in particular have shown improved cytotoxicity over curcumin. Investigations of diarylpentanoids have demonstrated that these compounds exert anti-cancer effects through several signalling pathways that are associated with cancer. This review focuses on selected diarylpentanoids and highlights molecular targets that modulate key pathways involved in cancer such as NF-κB, MAPK/ERK, and STAT signalling. Future research will need to focus on drug interactions to explore potential synergistic actions of diarylpentanoids and further establish the use of diverse animal models.

Diarylidenylpiperidones, H-4073 and HO-3867, Induce G2/M Cell-Cycle Arrest, Apoptosis and Inhibit STAT3 Phosphorylation in Human Pancreatic Cancer Cells

Pancreatic cancer has a 5-year survival rate below 10% and the treatment options are limited. Signal transducer and activator of transcription (STAT3) is a constitutively expressed protein in human pancreatic cancers and is associated with their poor prognosis. Targeting of STAT3 signaling using novel therapeutic agents is a potential strategy for pancreatic cancer treatment. Diarylidenylpiperidone (DAP) compounds, such as H-4073 and HO-3867, have been shown to be STAT3 inhibitors in several human ovarian cancers. Particularly, HO-3867 is an N-hydroxypyrroline derivative of DAP that has targeted cytotoxicity toward cancer cells without affecting healthy cells. In the present study, we evaluated the anticancer efficacy of H-4073 and HO-3867 in a human pancreatic cell line (AsPC-1). We found that both the compounds exhibited potential cytotoxicity to AsPC-1 cells by inducing G2/M cell-cycle arrest, apoptosis, and cell death, by mitochondrial damage and inhibition of STAT3 phosphorylation. In summary, H-4073 and HO-3867 are cytotoxic to AsPC-1 cells and seem to act through similar mechanisms, including STAT3 inhibition, cell-cycle arrest, and apoptosis.

Nitroxides as Antioxidants and Anticancer Drugs

Nitroxides are stable free radicals that contain a nitroxyl group with an unpaired electron. In this paper, we present the properties and application of nitroxides as antioxidants and anticancer drugs. The mostly used nitroxides in biology and medicine are a group of heterocyclic nitroxide derivatives of piperidine, pyrroline and pyrrolidine. The antioxidant action of nitroxides is associated with their redox cycle. Nitroxides, unlike other antioxidants, are characterized by a catalytic mechanism of action associated with a single electron oxidation and reduction reaction. In biological conditions, they mimic superoxide dismutase (SOD), modulate hemoprotein’s catalase-like activity, scavenge reactive free radicals, inhibit the Fenton and Haber-Weiss reactions and suppress the oxidation of biological materials (peptides, proteins, lipids, etc.). The use of nitroxides as antioxidants against oxidative stress induced by anticancer drugs has also been investigated. The application of nitroxides and their derivatives as anticancer drugs is discussed in the contexts of breast, hepatic, lung, ovarian, lymphatic and thyroid cancers under in vivo and in vitro experiments. In this article, we focus on new natural spin-labelled derivatives such as camptothecin, rotenone, combretastatin, podophyllotoxin and others. The applications of nitroxides in the aging process, cardiovascular disease and pathological conditions were also discussed.

Targeting STAT3 by HO3867 induces apoptosis in ovarian clear cell carcinoma

Advanced ovarian clear cell carcinoma (OCCC) carries a very poor prognosis in large part secondary to the extremely high rate of resistance to standard platinum and taxane chemotherapy. Signal transducer and activator of transcription 3(STAT3) expression and activation has been shown to regulate tumor progression in various human cancers, though has not been well studied in OCCC. Preliminary work in our lab has demonstrated constitutive activation of STAT3 (pSTAT3Tyr705 or pSTAT3727) in OCCC cell lines as well as human OCCC tumor tissue samples. Significantly, pSTAT3 is expressed in the absence of other forms of activated STAT (pSTAT1, 2, 6). Therefore, this work was planned to investigate the role of STAT3 and examine the efficacy of a novel anti-cancer compound -HO-3867, which is an inhibitor of STAT3, using known OCCC cell lines. Results demonstrate that treatment with HO-3867 decreased expression of pSTAT3 Tyr705 as well pSTAT3 Ser727, while total STAT3 remained constant. STAT3 overexpression increased the migration capability in OVTOKO cells in vitro and led to an increased tumor size when injected in vivo. The inhibitory effect of HO-3867 on cell proliferation and cell survival was accompanied by increased apoptosis, within 24 h post treatment. Treatment with HO-3867 resulted in a decrease in Bcl-2 and increase of cleavage of caspase 3, caspase 7, and PARP, confirming induction of apoptosis after treatment with HO-3867. In addition, HO-3867 significantly inhibited formation of human umbilical vein endothelial cells capillary-like structures and invasion at both 5 and 10 µM concentrations. STAT3 expression plays an important role in the spread of OCCC in vitro as well as in vivo. Thus, we can exploit the STAT3 pathway for targeted drug therapy. Inhibition of pSTAT3 using HO-3867in OCCC cell lines appears to be a promising therapy. This is of utmost importance given the poor response of OCCC to standard chemotherapy regimens.

Anticancer potential of diarylidenyl piperidone derivatives, HO-4200 and H-4318, in cisplatin resistant primary ovarian cancer

We have previously developed a novel class of bi-functional compounds based on a diarylidenyl-piperidone (DAP) backbone conjugated to an N-hydroxypyrroline (-NOH; a nitroxide precursor) group capable of selectively inhibiting STAT3 activation, translocation, and DNA binding activity. HO-4200 and H-4318 are 2 such derivatives capable of inducing apoptosis in ovarian cancer cells through this mechanism and demonstrated efficacy in platinum resistant primary ovarian cancer cell populations and tumor tissues. The improved absorption and cellular uptake of HO-4200 by cancer cells was determined using optical and electron paramagnetic resonance spectrometry. Treatment of ovarian cancer cells with HO-4200 and H-4318 resulted in cleavage of caspase proteins 3, 7, and 9, as well as PARP and inhibition of the pro-survival protein, Bcl-xL, resulting in significantly decreased cell survival and increased apoptosis. HO-4200 and H-4318 significantly inhibit fatty acid synthase (FAS) and pSTAT3 and decreased the expression of STAT3 target proteins: Survivin, c-myc, Bcl-xl, Bcl-2, cyclin D1/D2, and VEGF were suppressed as analyzed using quantitative real time PCR. In addition, HO-4200 and H-4318 significantly inhibited migration/invasion, in primary ovarian cancer cell populations isolated from primary and recurrent ovarian cancer patients. Treatment of freshly collected human ovarian tumor sections with HO-4200 demonstrated significant suppression of pSTAT3 Tyr 705, angiogenesis (VEFG), and markers of proliferation (Ki-67) in ex vivo models. We have shown, for the first time, that the DAP compounds, HO-4200 and H-4318, inhibit cell migration/invasion and induce apoptosis by targeting FAS/STAT3 in human ovarian cancer cells, including primary ovarian cancer cell populations and tumor tissues. Therefore, our results highlight the clinical anti-cancer potential of HO-4200 and H-4318.

Anti-apoptotic effect of interleukin-22 on fibroblast-like synoviocytes in patients with rheumatoid arthritis is mediated via the signal transducer and activator of transcription 3 signaling pathway

AIM

Inadequate apoptosis of fibroblast-like synoviocytes (FLS) plays a crucial role in the immunopathogenesis of rheumatoid arthritis (RA). Interleukin-22 (IL-22) is a novel member of the cytokine network that has been found to be involved in the immunological process underlying RA. In this study, we investigated the effect of IL-22 on the survival of RA-FLS from RA patients and examined the possible mechanism to determine new therapeutic strategies for RA.

METHODS

FLS obtained from patients with RA were cultured in vitro and treated with sodium nitroprussiate (SNP) to induce apoptosis in the presence or absence of IL-22. RA-FLS viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RA-FLS apoptosis was analyzed by annexin V/propidium iodide staining (AV/PI). The levels of IL-22R1, pSTAT3-Y705, pSTAT3-S727, total STAT3, Bcl-xL and Bcl-2 were detected by Western blot analysis.

RESULTS

IL-22R1 was expressed on RA-FLS. IL-22 pretreatment at concentrations ranging from 10 to 100 ng/mL increased RA-FLS viability and prevented SNP-induced apoptosis. Treatment with the STAT3 inhibitors, HO3867 or STA21, reversed the protective effect of IL-22 on SNP-induced apoptosis of RA-FLS. IL-22-induced phosphorylation of STAT3 (pSTAT3-Y705 and pSTAT3-S727) was increased in RA-FLS. Also IL-22 increased Bcl-2 expression in SNP-treated RA-FLS, and the effect was reversed by treatment with HO3867 or STA21.

CONCLUSION

IL-22 protects against SNP-induced apoptosis in RA-FLS by activating the STAT3 pathway and the downstream target gene, Bcl-2. Therefore, therapeutic strategies that target the IL-22/STAT3 pathway are implicated as candidates for RA treatment.

The Curcumin Analogue 1,5-Bis(2-hydroxyphenyl)-1,4-pentadiene-3-one Induces Apoptosis and Downregulates E6 and E7 Oncogene Expression in HPV16 and HPV18-Infected Cervical Cancer Cells

In an effort to study curcumin analogues as an alternative to improve the therapeutic efficacy of curcumin, we screened the cytotoxic potential of four diarylpentanoids using the HeLa and CaSki cervical cancer cell lines. Determination of their EC₅₀ values indicated relatively higher potency of 1,5-bis(2-hydroxyphenyl)-1,4-pentadiene-3-one (MS17, 1.03 ± 0.5 μM; 2.6 ± 0.9 μM) and 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one (MS13, 2.8 ± 0.4; 6.7 ± 2.4 μM) in CaSki and HeLa, respectively, with significantly greater growth inhibition at 48 and 72 h of treatment compared to the other analogues or curcumin. Based on cytotoxic and anti-proliferative activity, MS17 was selected for comprehensive apoptotic studies. At 24 h of treatment, fluorescence microscopy detected that MS17-exposed cells exhibited significant morphological changes consistent with apoptosis, corroborated by an increase in nucleosomal enrichment due to DNA fragmentation in HeLa and CaSki cells and activation of caspase-3 activity in CaSki cells. Quantitative real-time PCR also detected significant down-regulation of HPV18- and HPV16-associated E6 and E7 oncogene expression following treatment. The overall data suggests that MS17 treatment has cytotoxic, anti-proliferative and apoptosis-inducing potential in HPV-positive cervical cancer cells. Furthermore, its role in down-regulation of HPV-associated oncogenes responsible for cancer progression merits further investigation into its chemotherapeutic role for cervical cancer.

Deoxidation rates play a critical role in DNA damage mediated by important synthetic drugs, quinoxaline 1,4-dioxides

Quinoxaline 1,4-dioxides (QdNOs) are synthetic agents with a wide range of biological activities. However, the mechanism of DNA damage mediated by QdNOs is far from clear. Five classical QdNOs, quinocetone (QCT), mequindox (MEQ), carbadox (CBX), olaquindox (OLA), and cyadox (CYA), were used to investigate the genotoxicity of QdNOs. The deoxidation rate of QdNOs was presumed to play a role in their genotoxicity. Deoxidation rates of QdNOs in both rat and pig liver microsomes were investigated using LC/MS-IT/TOF, and their relative quantification was achieved with HPLC. To reveal the relationships between the deoxidation rate and genotoxicity, cell damage, oxidative stress, and DNA damage were detected. Under low oxygen conditions, the rank order of the desoxy and bidesoxy rates in rat and pig liver microsomes was QCT < CBX < MEQ < OLA < CYA and QCT < MEQ < CBX < OLA < CYA, respectively. Only desoxy-quinoxalines were detected under aerobic conditions. The concentrations of deoxidized metabolites under low oxygen conditions were at least 6 times higher than those under aerobic conditions. In rats, porcine primary hepatocytes, and HepG2 cells, oxidative stress indices and DNA damage showed inverse relationships with the deoxidation rate, indicating that the deoxidation rate of QdNOs, especially bidesoxy rates, might play a critical role in mediating their ability to promote DNA damage. These results indicated that faster deoxidation of QdNOs results in lower DNA-damage-induced toxicity. Our results shed new light on the prevention of DNA damage mediated by QdNOs and help to understand the relationships among the chemical structures, metabolism, and DNA damage of QdNOs.

Cytotoxic and Antioxidant Activity of a Set of Hetero Bicylic Methylthiadiazole Hydrazones: A Structure-Activity Study

The current study highlights the in vitro antioxidant and antitumor activity of the previously-synthesized hydrazone derivatives against various free radicals and human cancer cell lines, respectively. The anticancer efficacies of the compound were tested by measuring cytotoxicity in cancer cell lines HeLa, A549, and non-cancerous NL20 cells. Compounds possessing electron-donor methoxy and methyl substitutions at the para position of the phenyl ring moiety showed a concentration dependent free radical scavenging effects. The free radical-scavenging potential of synthetic compounds 11 and 14 may have significant impact on the prevention of free radical-induced oxidative stress and carcinogenesis. The results from cytotoxicity and cell migration assay showed that the substitution of electron-withdrawing fluoro, chloro and bromo functional groups induced a significant (P< 0.001) loss of cell viability and inhibited the invasive potential of the human cancer cells. Additionally, these compounds showed significantly (P< 0.05) a less toxicity toward non-cancerous NL20 cells. Docking studies revealed interactions of compound 10 with p38α MAP kinase, which may be responsible of its anti-invasive and anti-proliferative effects.

Potential application of curcumin and its analogues in the treatment strategy of patients with primary epithelial ovarian cancer

Recent findings on the molecular basis of ovarian cancer development and progression create new opportunities to develop anticancer medications that would affect specific metabolic pathways and decrease side systemic toxicity of conventional treatment. Among new possibilities for cancer chemoprevention, much attention is paid to curcumin—A broad-spectrum anticancer polyphenolic derivative extracted from the rhizome of Curcuma longa L. According to ClinicalTrials.gov at present there are no running pilot studies, which could assess possible therapeutic benefits from curcumin supplementation to patients with primary epithelial ovarian cancer. Therefore, the goal of this review was to evaluate potential preclinical properties of curcumin and its new analogues on the basis of in vivo and in vitro ovarian cancer studies. Curcumin and its different formulations have been shown to display multifunctional mechanisms of anticancer activity, not only in platinum-resistant primary epithelial ovarian cancer, but also in multidrug resistant cancer cells/xenografts models. Curcumin administered together with platinum-taxane chemotherapeutics have been reported to demonstrate synergistic effects, sensitize resistant cells to drugs, and decrease their biologically effective doses. An accumulating body of evidence suggests that curcumin, due to its long-term safety and an excellent profile of side effects should be considered as a beneficial support in ovarian cancer treatment strategies, especially in patients with platinum-resistant primary epithelial recurrent ovarian cancer or multidrug resistant disease. Although the prospect of curcumin and its formulations as anticancer agents in ovarian cancer treatment strategy appears to be challenging, and at the same time promising, there is a further need to evaluate its effectiveness in clinical studies.

Aberrantly activated pSTAT3-Ser727 in human endometrial cancer is suppressed by HO-3867, a novel STAT3 inhibitor

OBJECTIVE

Constitutive activation of STAT3 is a hallmark of various human cancers, however an increased pSTAT3 expression in high grade human endometrial cancer has not been reported. In the present study, we examine the expression of STAT family of proteins in endometrial cancer cell lines and the efficacy of HO-3867, a novel STAT3 inhibitor designed in our lab.

METHODS

Expression of STAT family proteins was evaluated via Western blot. The cell viability, post-treatment with HO-3867, was assessed using MTT, cell-cycle profile and Annexin assay. In vivo efficacy of HO-3867 was evaluated using xenograft mice.

RESULTS

Expression of activated STATs was inconsistent among the cell lines and 18 human endometrial cancer specimens tested. While pSTAT3 Tyr705 was not expressed in any of the cell lines, pSTAT3 Ser727 was highly expressed in endometrial cancer cell lines and tumor specimens. HO-3867 decreased the expression of pSTAT3 Ser727 while total STAT3 remained constant; cell viability decreased by 50-80% and induced G2/M arrest in 55% of Ishikawa cells at the G2/M cell cycle checkpoint. There was an increase in p53, a decrease in Bcl2 and Bcl-xL, and cleavage of caspase-3, caspase-7 and PARP. HO-3867 mediated a dosage-dependent inhibition of the growth of xenografted endometrial tumors.

CONCLUSIONS

HO-3867 treatment decreases the high levels of pSTAT3 Ser727 in endometrial cancer cells by inducing cell cycle arrest and apoptosis. This suggests a specific role of serine-phosphorylated STAT3, independent of tyrosine phosphorylation in the oncogenesis of endometrial cancer. HO-3867 could potentially serve as an adjunctive targeted therapy.

A novel curcumin analog (H-4073) enhances the therapeutic efficacy of cisplatin treatment in head and neck cancer

Chemotherapy constitutes the standard modality of treatment for localized head and neck squamous cell carcinomas (HNSCC). However, many patients fail to respond and relapse after this treatments due to the acquisition of chemo-resistance. Therefore, there is an urgent need to develop novel drugs that could reverse the resistant phenotype. Curcumin, the constituent of the spice turmeric has been shown to have anti-inflammatory, anti-oxidant and anti-proliferative properties in several tumor types. However, use of curcumin has been limited due to its poor bio-absorption. Recently, a novel class of curcumin analogs, based on diarylidenylpiperidones (DAP), has been developed by incorporating a piperidone link to the beta-diketone structure and fluoro substitutions on the phenyl groups. In this study, we evaluated the effectiveness of H-4073, a parafluorinated variant of DAP, using both in vitro and in vivo head and neck cancer models. Our results demonstrate that H-4073 is a potent anti-tumor agent and it significantly inhibited cell proliferation in all the HNSCC cell lines tested in a dose-dependent manner. In addition, pretreatment of cisplatin-resistant HNSCC cell lines with H-4073 significantly reversed the chemo-resistance as observed by cell viability assay (MTT), apoptosis assay (Annexin V binding) and cleaved caspase-3 (Western blot). H-4073 mediated its anti-tumor effects by inhibiting JAK/STAT3, FAK, Akt and VEGF signaling pathways that play important roles in cell proliferation, migration, survival and angiogenesis. In the SCID mouse xenograft model, H-4073 significantly enhanced the anti-tumor and anti-angiogenesis effects of cisplatin, with no added systemic toxicity. Interestingly, H-4073 inhibited tumor angiogenesis by blocking VEGF production by tumor cells as well as directly inhibiting endothelial cell function. Taken together, our results suggest that H-4073 is a potent anti-tumor agent and it can be used to overcome chemotherapy resistance in HNSCC.

HO-3867, a safe STAT3 inhibitor, is selectively cytotoxic to ovarian cancer

STAT3 is well corroborated preclinically as a cancer therapeutic target, but tractable translational strategies for its blockade by small molecule inhibitors have remained elusive. In this study, we report the development of a novel class of bifunctional STAT3 inhibitors, based on conjugation of a diarylidenyl-piperidone (DAP) backbone to an N-hydroxypyrroline (-NOH) group, which exhibits minimal toxicity against normal cells and good oral bioavailability. Molecular modeling studies of this class suggested direct interaction with the STAT3 DNA binding domain. In particular, the DAP compound HO-3867 selectively inhibited STAT3 phosphorylation, transcription, and DNA binding without affecting the expression of other active STATs. HO-3867 exhibited minimal toxicity toward noncancerous cells and tissues but induced apoptosis in ovarian cancer cells. Pharmacologic analysis revealed greater bioabsorption and bioavailability of the active (cytotoxic) metabolites in cancer cells compared with normal cells. The selective cytotoxicity of HO-3867 seemed to be multifaceted, eliciting differential activation of the Akt pathway in normal versus cancer cells. RNAi attenuation experiments confirmed the requirement of STAT3 for HO-3867-mediated apoptosis in ovarian cancer cells. In vivo testing showed that HO-3867 could block xenograft tumor growth without toxic side effects. Furthermore, in primary human ovarian cancer cells isolated from patient ascites, HO-3867 inhibited cell migration/invasion and survival. Our results offer preclinical proof-of-concept for HO-3867 as a selective STAT3 inhibitor to treat ovarian cancer and other solid tumors where STAT3 is widely upregulated.

Novel 3,5-bis(arylidiene)-4-piperidone based monocarbonyl analogs of curcumin: anticancer activity evaluation and mode of action study

Piperidone-sulphonamide and curcumin based molecular hybrids were synthesised, which showed anti-cancer activity on 60 human tumor cell line panels and their inhibitory effect due to apoptosis.

Synthesis of 4-methyl-N′-(3-alkyl-2r,6c-diarylpiperidin-4-ylidene)-1,2,3-thiadiazole-5-carbohydrazides with antioxidant, antitumor and antimicrobial activities

The structures of the newly synthesized 4-methyl-N′-(3-alkyl-2r,6c-diarylpiperidin-4-ylidene)-1,2,3-thiadiazole-5-carbohydrazide (5a–5l) were confirmed by spectral and elemental analysis.

Safe and targeted anticancer therapy for ovarian cancer using a novel class of curcumin analogs

A diagnosis of advanced ovarian cancer is the beginning of a long and arduous journey for a patient. Worldwide, approximately half of the individuals undergoing therapy for advanced cancer will succumb to the disease, or consequences of treatment. Well-known and widely-used chemotherapeutic agents such as cisplatin, paclitaxel, 5-fluorouracil, and doxorubicin are toxic to both cancer and non-cancerous cells, and have debilitating side effects Therefore, development of new targeted anticancer therapies that can selectively kill cancer cells while sparing the surrounding healthy tissues is essential to develop more effective therapies. We have developed a new class of synthetic curcumin analogs, diarylidenyl-piperidones (DAPs), which have higher anticancer activity and enhanced bio-absorption than curcumin. The DAP backbone structure exhibits cytotoxic (anticancer) activity, whereas the N-hydroxypyrroline (-NOH) moiety found on some variants functions as a cellular- or tissue-specific modulator (antioxidant) of cytotoxicity. The anticancer activity of the DAPs has been evaluated using a number of ovarian cancer cell lines, and the safety has been evaluated in a number of non-cancerous cell lines. Both variations of the DAP compounds showed similar levels of cell death in ovarian cancer cells, however the compounds with the -NOH modification were less toxic to non-cancerous cells. The selective cytotoxicity of the DAP-NOH compounds suggests that they will be useful as safe and effective anticancer agents. This article reviews some of the key findings of our work with the DAP compounds, and compares this to some of the targeted therapies currently used in ovarian cancer therapy.

Effects of simvastatin and rosuvastatin on RAS protein, matrix metalloproteinases and NF-κB in lung cancer and in normal pulmonary tissues

OBJECTIVES

In this study, we have evaluated effects of 24-hour treatments with simvastatin or rosuvastatin on RAS protein, NF-κB and MMP expression in LC tissues obtained from 12 patients undergoing thoracic surgery.

MATERIALS AND METHODS

Normal and lung tumour tissues obtained from each sample were exposed to simvastatin (2.5-30 μm) or rosuvastatin (1.25-30 μm) and western blot analysis was then performed.

RESULTS

We documented increased expression of proteins, MMP-2, MMP-9 and NF-κB-p65 in LC tissues, with respect to normal tissues (P < 0.01). In the malignant tissues, simvastatin and rosuvastatin significantly (P < 0.01) and dose-dependently reduced RAS protein, MMP-2/9 and NF-κB-p65 expression.

CONCLUSIONS

In conclusion, our results suggest that simvastatin and rosuvastatin could play a role in LC treatment by modulation of RAS protein, MMP-2/9 and NF-κB-p65.

Pulmonary hypertension secondary to left-heart failure involves peroxynitrite-induced downregulation of PTEN in the lung

Pulmonary hypertension (PH) that occurs after left-heart failure (LHF), classified as Group 2 PH, involves progressive pulmonary vascular remodeling induced by smooth muscle cell (SMC) proliferation. However, mechanisms involved in the activation of SMCs remain unknown. The objective of this study was to determine the involvement of peroxynitrite and phosphatase-and-tensin homolog on chromosome 10 (PTEN) in vascular SMC proliferation and remodeling in the LHF-induced PH (LHF-PH). LHF was induced by permanent ligation of left anterior descending coronary artery in rats for 4 weeks. MRI, ultrasound, and hemodynamic measurements were performed to confirm LHF and PH. Histopathology, Western blot, and real-time polymerase chain reaction analyses were used to identify key molecular signatures. Therapeutic intervention was demonstrated using an antiproliferative compound, HO-3867. LHF-PH was confirmed by significant elevation of pulmonary artery pressure (mean pulmonary artery pressure/mm Hg: 35.9±1.8 versus 14.8±2.0, control; P<0.001) and vascular remodeling. HO-3867 treatment decreased mean pulmonary artery pressure to 22.6±0.8 mm Hg (P<0.001). Substantially higher levels of peroxynitrite and significant loss of PTEN expression were observed in the lungs of LHF rats when compared with control. In vitro studies using human pulmonary artery SMCs implicated peroxynitrite-mediated downregulation of PTEN expression as a key mechanism of SMC proliferation. The results further established that HO-3867 attenuated LHF-PH by decreasing oxidative stress and increasing PTEN expression in the lung. In conclusion, peroxynitrite and peroxynitrite-mediated PTEN inactivation seem to be key mediators of lung microvascular remodeling associated with PH secondary to LHF.

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.