Anti-Cancer Agents in Medicinal Chemistry (v.15, #2)

Curcumin-Based Anti-Prostate Cancer Agents by Qiao-Hong Chen (138-156).
Prostate cancer possesses the highest occurrence rate and is the second-paramount disease that causes canceraffiliated death among men in the United States. Approximately 30,000 men die each year of castration-resistant prostate cancer due to the inevitable progression of resistance to first-line treatment with docetaxel. The safety profile of dietary curcumin in humans has been well-documented, and its therapeutic prospect in treating prostate cancer, especially for castration-resistant prostate cancer, has been evidenced in several cell culture systems and human xenograft mouse models. The critical disadvantage of curcumin as a drug candidate is its low bioavailability caused by poor water solubility and rapid in vivo metabolism. Curcumin is characteristic of regulating multiple targets, representing a good example for the philosophy to search for multitargeted drugs in the realm of drug design and drug development. This feature, together with its potential in treating castration-resistant prostate cancer and its safety profile, enables curcumin to serve as an ideal lead compound for the design and syntheses of curcuminbased agents with improved potential for the clinical therapies of prostate cancer. Several researches aiming to improve its bioavailability and potency resulted in the discovery and development of a wealth of curcumin-based compounds with an enhanced anticancer potential and/or an improved pharmacokinetic profile. This review starts with a brief summarization of the prospect of curcumin in treating prostate cancer and its mechanisms of action, then provides an in-depth overview of current development of curcumin-based anti-prostate cancer agents and their structure-activity relationships, and ends with the syntheses and pharmacokinetic studies of curcumin.

p42.3: An Abductor of Cell Cycle by Wen-Jia Cao, Lin-Lin Mao, Jun-Nian Zheng, Dong-Sheng Pei (157-162).
As a newly discovered tumor-associated gene, p42.3 was originally ascertained in gastric cancer cell line BGC823 and has been confirmed as a cell cycle-dependent gene that is overexpressed in many human tumor cell lines and embryonic tissues. p42.3 can regulate the level of relevant cycle-dependent proteins and promote malignant transformation of cells. A variety of cellular functions, including cell proliferation, cell invasion and cell migration, are under control of p42.3. Our review, namely the introduction of the structure of p42.3, underlying activity regulation mechanisms of p42.3 as well as the role p42.3 plays in malignant cellular transformation process, are accompanied by the presentation of potential directions of further researches of cancer prevention and therapy in which p42.3 is inevitable.

Recent Developments on Thiourea Based Anticancer Chemotherapeutics by Vikas Kumar, Swapandeep Singh Chimni (163-175).
The recent emergence of anticancer activity of thiourea derivatives have inspired the medicinal chemist to design and synthesize new thiourea derivatives. These thiourea based anticancer chemotherapeutics inhibit cancer propagation by acting as inhibitors of topoisomerase, protein tyrosine kinase, somatostatin agonists, sirtuins, and carbonic anhydrase (CA). This review summarizes the recent developments on the thiourea based anticancer chemotherapeutics.

Poly(Ethylene Glycol) Amphiphilic Copolymer for Anticancer Drugs Delivery by Runliang Feng, Wenxia Zhu, Fangfang Teng, Na Liu, Fengying Yang, Ning Meng, Zhimei Song (176-188).
Poly(ethylene glycol) is a water-soluble polymer. Due to its high safety and biocompatibility, it has been widely used to prepare amphiphilic copolymers for drug delivery. These copolymers can enhance water-solubility of hydrophobic drugs, improve their pharmacokinetic parameters and control their release from corresponding nanocarriers formed by its self-assembly. Anticancer drugs have some shortcomings such as lower water-solubility, bad targeting and some serious side-effects, which limit their applications and are dangerous to patients. So encapsulation of anticancer drugs into nanocarriers originated from its copolymeric derivates can improve their absorption, distribution, metabolism and excretion with better release properties and activities against cancer cells, increase their therapeutic effects, and realize their passive or active target delivery through structure modification. Recent research development of its drug delivery systems for anticancer drugs will be discussed.

Chrysin Induces Apoptosis in Peripheral Blood Lymphocytes Isolated from Human Chronic Lymphocytic Leukemia by Milan Zaric, Marina Mitrovic, Ivana Nikolic, Dejan Baskic, Suzana Popovic, Predrag Djurdjevic, Zoran Milosavljevic, Ivanka Zelen (189-195).
Chronic lymphocytic leukemia (CLL) develops due to an imbalance between apoptosis and proliferation of B lymphocytes. Chrysin induced apoptosis in leukemia cell lines such as U937, MO7e, THP-1 and HL-60, but there has not yet been data demonstrating the apoptotic effect of chrysin on CLL cells. Therefore, in our investigation we examined the cytotoxicity of chrysin against two leukemia cell lines, MOLT-4 and JVM-13, peripheral blood lymphocytes isolated from B-CLL patients and peripheral blood mononuclear cells (PBMC) from healthy individuals in vitro. ; The effect of chrysin on viability of MOLT-4 and JVM-13 cell lines, B-CLL cells derived from 28 patients and PBMC from 16 healthy subjects was determined by MTT assay. The type of cell death induced by chrysin was verified by Annexin V/7AAD assay and acridine orange and ethidium bromide (AO/EB) staining assay. Intracellular localisation and endogenic expression of apoptotic proteins including Bax, Bcl-2, cytochrome c and caspase-3 were determined by flow cytometry and fluorescent microscopy. ; Our results demonstrated that exposure of MOLT-4, JVM-13 cell lines and B-CLL cells to the concentration of chrysin of 10?M and higher selectively decreased viability of cells in this cell population, but not in the PBMC derived from healthy subjects; LC50 values of chrysin for B-CLL cells were 51μM for 24 hours and 32μM for 48 hours of incubation, respectively. Our findings demonstrated that chrysin induces the activation of proapoptotic Bax and decreases the expression of antiapoptotic Bcl-2 protein, releases cytochrome c from mitochondria into cytosol and cleavages/activates caspase-3, subsequently leading to the activation of apoptosis of B-CLL cells. ; Together, these findings suggest that chrysin selectively induces apoptosis of peripheral blood lymphocytes isolated from human chronic lymphocytic leukemia patients via mitochondrial pathway in vitro and that it might have a promising role as a potential future antileukemic remedy.

The all trans retinoic acid (ATRA) is found to have a promising regulatory effect on immune system and inflammatory responses in experimental research. The purpose of this study was to investigate whether this therapeutic efficiency of ATRA could be enhanced by encapsulating into a liposome formulation composed of Distearoyl-Lphosphatidylcholine (DSPC) and cholesterol utilizing a well-established mice model. The humoral antibody titer (HA), delayed-type hypersensitivity (DTH), bone marrow cellularity, hematology, and levels of ?- esterase-positive cells, were taken as parameters to assess the level of immunomodulation in the sheep red blood cells (SRBC) immunized and challenged BALB/c mice. The anti-inflammatory effect of encapsulated ATRA was evaluated by the size changes in the induced inflammation edema in the mice paw as well as its histopathology. The results showed a significant immunostimulatory effect for both the free and encapsulated ATRA as indicated by the increase in the levels of total leukocyte, bone marrow and ?-esterase positive cells and decreased Hb level respectively. We have also observed an enhanced specific antibody hemagglutinin titre value and the DTH response developed in response to SRBC challenge in these treatments. Both the immunostimulatory as well as inflammation reducing property were significantly higher in encapsulated ATRA treated group of mice over that of in free ATRA treated group of mice. Based on these results, we conclude that the encapsulated ATRA has a higher potency over free ATRA in its immunomodulatory activity and also has a significant impact on reducing inflammation in BALB/c mice model.

Synthesis of Nitroaromatic Compounds as Potential Anticancer Agents by Marcela Silva Lopes, Camila Filizzola de Andrade Sena, Bruno Leonardo Silva, Cristina Maria de Souza, Jonas Pereira Ramos, Geovanni Dantas Cassali, Elaine Maria de Souza-Fagundes, Ricardo Jose Alves, Mônica Cristina de Oliveira, Renata Barbosa de Oliveira (206-216).
Twenty-seven nitrated and non-nitrated compounds have been synthesized and tested for their growth inhibitory activity on three human cancer cells lines. Fourteen compounds were able to inhibit more than 50% of the growth of at least one of the cancer cell lines and five compounds exhibited high antiproliferative activity on human cancer cell lines (IC50 < 8.5 μM). The cytotoxicity of the compounds on Vero cell line was established in vitro to evaluate the selectivity. All active compounds have a good leaving group (bromide or chloride) at the benzylic position, indicating that the mechanism of action of these compounds is related to their alkylating properties. Two compounds (3 and 24) were selected for further studies in mice with Ehrlich solid tumors and display significant antitumor effects in vivo.

Cystine Dimethyl Ester Induces Apoptosis Through Regulation of PKC-δ and PKC-ε in Prostate Cancer Cells by Nilgun Gurbuz, Margaret A. Park, Paul Dent, Asim B. Abdel Mageed, Suresh C. Sikka, Asli Baykal (217-227).
Protein kinase C-δ (PKC-δ) and PKC-ε are reported to be effective in cancer prevention via S-thiolationmediated mechanisms. This may be through stimulation of the pro-apoptotic, tumor-suppressive isozyme PKC-δ and/or inactivation of the growth stimulatory, oncogenic isozyme PKC-ε. We investigated oxidative regulatory responses of PKC-δ and PKC-ε to cystine dimethyl ester (CDME), a metabolic precursor of cystine, which, by inducing release of cellular cystine stimulates apoptosis in different prostate cancer cells, PC3 and LNCaP, compared to normal RWPE1 cells. Treatment of CDME in doses of 0.5mM and 5mM significantly induces apoptosis due to regulation of concentration-dependent PKC-δ stimulation and PKC-ε reduction in these prostate cancer cells. This apoptotic regulation was confirmed by immunoblot analyses and specific PKC enzyme assays in immunoprecipitated samples. Additionally, inhibition of PKC-δ by small interfering RNA (siRNA) proved that CDMEinduced cell death was dependent on PKC-δ activity in prostate cancer cells. These data demonstrated that CDME induces apoptosis by cysteinylation of both PKC-δ and PKC-ε in tumorigenic prostate epithelial cells compared to control nontumorigenic cells. Cellular cystine may play a critical role in treatment and/or prevention of prostate cancer by regulating PKC activity.

Anti-Proliferative Activities of Terpenoids Isolated from Alisma orientalis and their Structure-Activity Relationships by Wen Xu, Ting Li, Jian-Fang Qiu, Shui-Sheng Wu, Ming-Qing Huang, Li-Gen Lin, Qing-Wen Zhang, Xiu-Ping Chen, Jin-Jian Lu (228-235).
This study aimed to isolate terpenoids from Alisma orientalis (Sam.) Juzep. and elucidate their antiproliferative activities, as well as structure-activity relationships. Fourteen protostane-type triterpenoids were isolated from the rhizome of A. orientalis. Among these triterpenoids, alisol A (1), alisol A 24-acetate (2), alisol B (3), alisol B 23-acetate (4), and alisol G (8) presented inhibitory effects on cancer cell lines tested. Compounds 3 and 4 showed the highest potential; IC50 values for HepG2, MDA-MB-231, and MCF-7 cells were 16.28, 14.47, and 6.66 μM for 3 and 18.01, 15.97, and 13.56 μM for 4, respectively. Based on these results, we concluded that the degree of C-16 oxidation and the double bond between C-13 and C-17 may be significant in anti-proliferative activities. Further study showed that 3 and 4 effectively induced apoptosis, as confirmed by flow cytometry. Increased intracellular calcium concentration and endoplasmic reticulum stress were detected after treatment with 4 in HepG2 cells. Although compounds 1 and 2 induced minimal apoptosis, they evidently delayed the G2/M phase in HepG2 cells. Further study showed that 1-4 also enhanced LC3II expression, indicating autophagy is occured.

Growth Inhibition of Various Human Cancer Cell Lines by Imperatorin and Limonin from Poncirus Trifoliata Rafin. Seeds by Atiqur Rahman, Shah Alam Siddiqui, Rekha Jakhar, Sun Chul Kang (236-241).
We examined the anticancer effects of limonin and imperatorin on various human cancer cells by MTT assay, and the results showed that imperatorin inhibited the cell growth of SNU 449 (liver cancer) and HCT-15 (colon cancer) cells in a dose-dependent manner, while limonin had less effect. Exposure of different concentrations of limonin and imperatorin caused morphological changes in cancer cells, but not in normal dermal fibroblast cells. Limonin and imperatorin induced apoptotic cell death concurrent to cell cycle arrest in SNU 449 and HCT-15 cells. Limonin and imperatorin up regulated proapoptotic protein Bax expression and down regulated anti-apoptotic protein Bcl-2 expression in a dose-dependent manner in HCT-15 and SNU 449 cells. In conclusion, our data demonstrate that limonin and imperatorin have anticancer potential which is associated with promoting cell apoptosis through expression of apoptosis-related proteins.

The newly synthesized naftopidil analogue HUHS1015 reduced viability of MKN28 and MKN45 human gastric cancer cells in a concentration (0.3-100 ?M)-dependent manner, with the potential greater than that for naftopidil. In the cell cycle analysis, HUHS1015 significantly increased the proportion at the subG1 phase of cell cycling in MKN28 cells. In the flow cytometry using propidium iodide (PI) and annexin V, HUHS1015 significantly increased the populations of PI-positive/annexin V-negative and PI-positive/annexin V-positive MKN28 cells, corresponding to primary necrosis and late apoptosis/secondary necrosis, respectively. HUHS1015-induced MKN28 cell death was attenuated by the necroptosis inhibitor Nec-1. In the enzymatic caspase assay, caspase-3, -4, -8, and -9 were not sufficiently activated by HUHS1015. HUHS1015 increased nuclear localization of apoptosis-inducing factor-homologous mitochondrion-associated inducer of death (AMID), without affecting expression of the AMID mRNA and protein in MKN28 cells. HUHS1015 caused nuclear fragmentation and condensation in MKN28 cells treated with HUHS1015. Taken together, these results of the present study indicate that HUHS1015 induces both necroptosis and caspase-independent apoptosis of MKN28 cells, possibly the latter effect being due to AMID accumulation in the nucleus.

The aim was to analyse the efficacy of piceatannol (PIC) loaded chitosan (CS)/poly(lactic acid)(PLA) nanoparticles (CS/PLA-PIC NPs) in zebra fish embryos exposed to aflatoxin B1 (AFB1). FTIR confirmed the chemical interaction between the polymers and drug. SEM showed the size of CS/PLA-PIC NPs approximately 87 to 200nm, compared to CS-PLA NPs of 150nm size. The size was further affirmed as 127nm (CS-PLA NPs) and 147nm (CS/PLA-PIC NPs) by zetasizer depiction. CS/PLA-PIC NPs have not illustrated toxicity at high concentrations when tested in zebrafish embryos. AFB1 wielded their toxic effects on the survival, spontaneous movement, hatching and heart rate and development of embryos were observed in both time and dose-dependent manner at 4μM. Our results suggested that the addition of CS/PLA-PIC NPs increases the survival, heart rate and hatching in time dependent manner at the dosage of 20μg/ml. These hopeful results may prompt the advancement of drug encapsulated polymeric nanoparticles which may have the potential role in improving the AFB1 induced toxicity in humans as well.

Anticancer Activity and Mechanism Investigation of Beauvericin Isolated from Secondary Metabolites of the Mangrove Endophytic Fungi by Yi-wen Tao, Yong-cheng Lin, Zhi-gang She, Min-ting Lin, Pin-xian Chen, Jian-ye Zhang (258-266).
One known cyclic peptide, beauvericin, was isolated from the secondary metabolites of mangrove endophytic fungi Fusarium sp. (No. DZ27) in South China Sea. Its structure was determined by spectral analyses and comparisons with reference data from literatures. Beauvericin inhibited growth of KB and KBv200 cells potently with IC50 values of 5.76 ± 0.55 and 5.34 ± 0.09 μM, respectively. Furthermore, beauvericin induced apoptosis through mitochondrial pathway, including decrease of relative oxygen species generation, loss of mitochondrial membrane potential, release of cytochrome c, activation of Caspase-9 and -3, and cleavage of PARP. Additionally, regulation of Bcl-2 or Bax was not involved in the apoptosis induced by beauvericin in KB and KBv200 cells.

Design, Synthesis and Biological Evaluation of Quinoxalin-2(1H)-one Derivatives as EGFR Tyrosine Kinase Inhibitors by Xuemei Qin, Xiao Han, Liming Hu, Zhipeng Li, Zhufeng Geng, Zhanyang Wang, Chengchu Zeng, Xiangqian Xiao (267-273).
With the successful use of gefitinib and erlotinib in clinic, some potent EGFR tyrosine kinase receptor inhibitors have gained widespread concern in the treatment of ovarian or non-small-cell lung cancer. However, the emergence of EGFR-activating mutations resist to the drugs, there is an impending need to design new inhibitor targeted EGFR. Furthermore, the understanding of mutual effect between EGFR and drug has been available, it has become a hot spot for the research of anticancer drugs. We have designed and synthesized a series of 6-methoxy-7-(3-morpholinopropoxy)-1-(2- phenoxyethyl)-quinoxalin-2(1H)-one derivatives as novel EGFR inhibitors. Most of the compounds have showed inhibitory activity toward EGFR kinase. This work has demonstrated it is possible to construct a new type of EGFR protein kinase inhibitor using a designin strategy.