Anti-Cancer Agents in Medicinal Chemistry (v.15, #9)

Meet Our Editorial: by Joaquin Maria Campos Rosa (1079-1079).

Recent Advances in Phenanthroindolizidine and Phenanthroquinolizidine Derivatives with Anticancer Activities by Maria de Fatima Pereira, Christophe Rochais, Patrick Dallemagne (1080-1091).
Phenanthroindolizidine and phenanthroquinolizidine derivatives constitute a series of compounds that are being intensively studied as potential anticancer agents. Related natural products such as antofine and tylophorine alkaloids are well known for their high cytotoxic activity; however, their clinical application has been limited because of their side effects. In this review we report, in detail, on the main structural modifications applied to the phenanthroindolizidine and phenanthroquinolizidine skeletons, and we also describe their associated anticancer activities. New derivatives with promising antitumoral activities have emerged. Simplified analogues were prepared using rapid synthetic routes, and a certain number of these analogues displayed increased anticancer activity and selectivity towards tumor cell lines. It is hoped that a better understanding of the mechanisms of action associated with structure-activity relationships (SAR) will enable us to rationalize the development of new anticancer drugs.

Cancer is known to be the second most common disease-related cause of death among humans. In drug discovery programs anti-cancer chemotherapy remains quite challenging due to issues related to resistance. Plants used in traditional medicine are known to contribute significantly within a large proportion of the African population. A survey of the literature has led to the identification of ~400 compounds from African medicinal plants, which have shown anti-cancer, anti-proliferation, anti-tumor and/or cytotoxic activities, tested by in vitro and in vivo assays (from mildly active to very active), mainly alkaloids, terpenoids, flavonoids, coumarins, phenolics, polyacetylates, xanthones, quinones, steroids and lignans. The first part of this review series focuses on xanthones, quinones, steroids, coumarins, phenolics and other compound classes, while part II is focused on alkaloids, terpenoids, flavonoids.

Chemomodulating Effects of Flavonoids in Human Leukemia Cells by Katrin Sak, Hele Everaus (1112-1126).
Flavonoids, a diverse class of polyphenolic compounds, are well known for their anticancer properties. Moreover, it is generally accepted that these plant secondary metabolites can also sensitize malignant cells to conventional chemotherapeutic drugs and could thus be considered as potential adjunctive agents in cancer treatment. In this review article we show that besides potentiating the anticancer activity of standard chemotherapeutics by modifying the molecular events that are involved in cell growth, differentiation and apoptosis, flavonoids might also act as inhibitory modulators in human leukemia cells. The specific behavior of a certain flavonoid in such combination treatments is multifactorial being dependent on various aspects, including cellular context, molecular mechanisms of clinical drugs, temporal regimen of administration, as well as doses of agents. Based on the highly complex nature of leukemogenesis it is feasible that a multifaceted therapeutic approach is also required to cure this disease and therefore, combined chemotherapeutic schemes incorporating natural plant metabolites as chemosensitizing agents can represent a new attractive strategy for more successful treatment of leukemia patients in the future. However, as highlighted in this review, caution should be taken when affecting malignant cells concurrently with chemotherapeutic drugs and flavonoids as unwisely chosen combinations can lead to inadvisable results and sometimes even deteriorate the clinical outcomes.

Protein neddylation, a newly characterized posttranslational modification that adds the ubiquitin-like molecule NEDD8 to substrates, modulates important biological processes, whereas dysfunction of neddylation may cause several serious diseases, such as cancer. Inhibition of neddylation pathway has emerged as a promising anticancer strategy, as evidenced by development of the NEDD8-activating enzyme (NAE) inhibitor MLN4924. Due to its potent anti-cancer efficacy and well-tolerated toxicity, MLN4924 has been evaluated in multiple Phase I clinical trials for solid tumors and hematologic malignancies. Recently, accumulating evidences indicate that neddylation pathway also plays a pivotal role in the regulation of multiple processes of tumor microenvironment (TME), such as tumor angiogenesis and the function of immune cells. In this review, we briefly summarize the latest progresses in this field and highlight neddylation pathway as an attractive therapeutic target against human cancer.

Immunotherapeutic Impact of Toll-like Receptor Agonists in Breast Cancer by Christine Zhang, Atheena Ben, Jade Reville, Victoria Calabrese, Nina Nicole Villa, Mausumi Bandyopadhyay, Subhajit Dasgupta (1134-1140).
Onset of tumors in breast cancer is a multi-factorial event at different ages and ethnic populations. The conventional treatment strategy suggests use of anti-estrogen drugs and selective estrogen receptor modulators (SERMs). Although, this strategy has achieved significant success to prevent tumor growth and metastasis and is still developing under an active field of research, the emergence of immunotherapy is a potential modern approach for breast cancer. In addition to SERMs, the screening of selective agonists for toll-like receptor (TLR) signals confers a new area of breast cancer therapy. Recent investigations also indicate significance of TLR signals in the regulation of tumor suppressor p53 gene expression. The TLR agonists have an ability to facilitate activation of natural killer cells, CD8 T cells, B cells, and alpha and beta interferons and induce cellular cytotoxicity. The ongoing developments in cancer research also suggested an approach for intra-tumoral generation of cellular cytotoxicity to induce apoptosis. Both of these events promote destruction of tumor cells in a localized manner and thus, having impact on immunotherapy. Keeping a cautious eye on the context, we propose the prospect of TLR signals in the development of therapy for breast cancer.

Effects of CAP-regimen Chemotherapy on Blood Redox Status in Patients with Ovarian Cancer by Inna I. Antoneeva, Dinara R. Dolgova, Tatyana P. Gening, Tatyana V. Abakumova, Snezhanna O. Gening, Sabina S. Pirmamedova, Anastasia V. Fomina, Alla A. Mikheenko (1141-1147).
Background: Ovarian cancer (OC) is the most lethal of gynecologic tumors because women generally present with advanced stage disease. Platinum-based chemotherapy play a pivotal role in OC treatment. The aim of the study was to assess the effects of CAP-regimen chemotherapy on blood redox status in patients with ovarian cancer.
Materials and Methods: Patients were 132 women with primary OC with FIGO stage III-IV. Patients were examined before treatment, 3 and 14 days after the first and 3 and 14 days after the second course of CAP-regimen chemotherapy. The activity of antioxidant enzymes, the intensity of lipid peroxidation, the level of oxidative modification of proteins (OMP) were evaluated.
Results: We have found elevated levels of OMP products in plasma and erythrocytes of patients with ovarian cancer in comparison with donors. Our results suggest activation of lipid peroxidation in plasma and erythrocytes of ovarian cancer patients in comparison with healthy women. Sensitive and specific indicators of oxidative stress are levels of glutathione-S-transferase (sensitivity 80%, specificity 89%), diene conjugates (sensitivity 85,71%, specificity 72,73%) and OMP 430 nm (sensitivity 80%, specificity 90%) in blood plasma and the activity of catalase in erythrocytes (sensitivity 100%, specificity 89%).
Conclusion: CAP chemotherapy in patients with ovarian cancer with FIGO stage III-IV induces radical formation and changes the homeostasis of the patient. The lipid peroxidation and antioxidant system in plasma move to a higher level of functioning, and the erythrocytes develop oxidative stress.

21 new structures of isoxazole-moiety-containing thieno[2,3-d]pyrimidine derivatives(3a~3u) were synthesized for the first time and characterized using IR, 1H NMR, 13C NMR, ESI-MS and elemental analysis techniques. And then their in vitro anticancer activity against lung cancer A549, colorectal HCT116 and breast cancer MCF-7 cell lines was preliminarily evaluated using the MTT method. Among them, most compounds exhibited good to excellent anticancer activity. In particular, 3g, 3j and 3n exhibited a broad spectrum and more potent anticancer activity against A549, HCT116 and MCF-7 cell lines, which can be regarded as the promising anticancer drug-candidates.

Generation of Redox Imbalance Mediates the Cytotoxic Effect of Malabaricone-A in a Multidrug Resistant Cell Line by Alak Manna, Ajay K Bauri, Subrata Chattopadhyay, Mitali Chatterjee (1156-1163).
Multidrug resistance (MDR) refers to cross-resistance to a range of structurally and functionally unrelated compounds, and is accompanied by an elevated expression of ATP driven cell-membrane transporters. The cytotoxicity of Malabaricone-A (MAL-A), a diarylnonanoid derived from Myristica malabarica was demonstrated in leukemic cell lines, but its effectiveness in drug-resistant cancer cell lines has not been evaluated. Accordingly, this study tested its cytotoxic potential in a T-lymphoblastic leukemic cell line, CCRF CEM and its MDR counterpart, CEM/ADR5000. The effectiveness of MAL-A was 1.8 fold higher in CEM/ADR5000 than CCRF CEM cell line, the IC50 being value 5.40 ± 1.41 vs. 9.72 ± 1.08 µg/ml, respectively, suggesting that MAL-A demonstrated 'collateral sensitivity'. This cytotoxicity of MAL-A was attributed to an enhanced generation of oxidative stress, as the IC50 value increased following the addition of an anti-oxidant, N-acetyl cysteine (NAC). Furthermore, MAL-A depleted glutathione and inhibited glutathione peroxidase activity, which too contributed towards generation of a redox imbalance. This culminated in an apoptosis mediated cell death as evident by mitochondrial membrane depolarization, enhanced caspase-3 activity, increased externalization of phosphatidylserine and an increase in the sub G0/G1 population. Collectively, compounds with pro-oxidant activity have promising therapeutic potential in drug resistant phenotypes, worthy of future pharmacological consideration.

Intracellular ROS Generation Mediates Maleimide-induced Cytotoxicity in Leukemia Cells by Daiane Rosolen, Vania F. Noldin, Evelyn Winter, Fabiola B. Filippin-Monteiro, Fatima Campos-Buzzi, Valdir Cechinel-Filho, Tania B. Creczynski-Pasa (1164-1173).
Maleimides consist of an important class of compounds easily synthesized with multiple functional group modification that provides expressive pharmacological properties including, antitumoral activity, mediated mainly by oxidative stress. For this reason, the present study was designed to evaluate the cytotoxicity and the role of reactive oxygen species (ROS) in maleimide-induced cell death. Cell viability assays were performed to determine the cell death type in leukemia cell line induced by the compounds. The oxidative stress in maleimidetreated cells was characterized by antioxidant enzymes activities, intracellular ROS generation, and lipid peroxidation. In addition, we evaluated mitochondrial membrane potential and ATP level. Maleimide derivatives exhibited cytotoxic effects in leukemia cells with significantly increased ROS generation. However, cell viability was partly restored by catalase-treated cells. Caspases activities and caspase-independent key genes related to apoptosis were not altered by maleimides, suggesting necrosis as the main cell death process. Maleimide-induced necrosis was associated with oxidative stress, as an imbalance between ROS levels and glutathione reductase (GR) activity. This damage was also demonstrated by loss of mitochondrial membrane potential (MMP) and ATP depletion in cells treated with maleimide derivatives. These findings strongly confirmed that maleimide derivatives promoted cell death in leukemia cells triggered by oxidative stress, indicating that these compounds might be promising antitumor agents or lead molecules.

Benzimidazole ring is a versatile structure which has been extensively utilized in medicinal chemistry. Since we are working on 1,2-disubstutited benzimidazoles, we have reported new antitumor active derivatives. As a continuation to our previous work, we have synthesized a new series of 1-(2-aryl-2-oxoethyl)-2-[(N,Ndimethylamino/ pyrrolidinyl/piperidinyl)thiocarbamoyl] benzimidazole derivatives. Anticancer activity of the compounds was evaluated using MTT assay, BrdU assay and flow cytometric analysis on A549 human lung carcinoma and C6 rat glioma cell lines. Compounds bearing dimethylamino moiety exhibited higher antitumor activity.

Quercetin Increase the Chemosensitivity of Breast Cancer Cells to Doxorubicin Via PTEN/Akt Pathway by Shi-zheng Li, Shi-feng Qiao, Jun-hua Zhang, Kun Li (1185-1189).
Our previous study indicated that nontoxic doses of quercetin (Que) could increase the chemosensitivity of breast cancer cells to doxorubicin (Dox) although the mechanism still remains elusive. Therefore, in this study, we aimed to investigate the underlying mechanisms. MCF-7 cells and MCF-7/dox cells were exposed to PTEN inhibitor bpV (HOpic), Dox, or combination of Dox and Que with or without bpV (HOpic) intervention for 24 hours. Cell proliferation, cell apoptosis, cell invasion and expression of PTEN and phospho-Akt (p-Akt) were then assessed. bpV (HOpic) had little effect on cell proliferation at concentrations less than 1 ?M. Compared to treatment with Dox alone, combined treatment with Dox and Que significantly inhibited cell proliferation and invasion, increased cell apoptosis, up-regulated the expression of PTEN and down-regulated the expression of p-Akt. However, co-treatment with PTEN inhibitor bpV (HOpic) could revert the effects of Que on Dox. These data indicate that Que can increase the sensitivity of breast cancer cells to Dox through down regulation of p-Akt expression arising from increased expression of PTEN.

Ozone Dosage Effect on C6 Cell Growth: in Vitro and in Vivo Tests by Arizbeth Pérez, Clara L. Santos Cuevas, Isaac Chairez, Tatyana Poznyak, David Ordaz-Rosado, Rocío García-Becerra, Mario E. Romero Piña (1190-1196).
C6 rat glioma cells are one of the most aggressive carcinogenic tumors, due to its high mortality rate in human beings and animals. The current treatment for this illness includes surgery, radio and chemotherapy, showing relapse in patients treated with those therapies. Since the ozone was found to be an effective bioreactive to inhibit growth of several carcinoma cells in vitro and in vivo. In this research, therapeutic peritoneum insufflation of ozone/oxygen dissolved in the physiological solution of NaCl 0.9% was dosed for fifteen days on different female mice groups in an advanced stage of C6 tumor (n=6). The first of them was the control group which had no treatment, the second group was dosage with oxygen every second day, the third group was dosed with ozone every second day, and finally the fourth group was dosed with ozone dissolved every fifth day. The size of the tumor was higher in both groups dosage by ozone, nevertheless tumor activity measured by microPET was 98% less in the fourth group compared with the control group. That result proves that ozone provokes an increase in the tumor volume even though the decrease of the cell activity. Those results were confirmed by the quantification of hydroperoxides, total cholesterol and total triglycerides

Design, Synthesis, and Evaluation of Genistein Analogues as Anti-Cancer Agents by Pahoua Xiong, Rubing Wang, Xiaojie Zhang, Eduardo DeLa Torre, Francisco Leon, Qiang Zhang, Shilong Zheng, Guangdi Wang, Qiao-Hong Chen (1197-1203).
Genistein is a bioactive isoflavone derived from soybeans. The tie-in between the intake of genistein and the decreased incidence of some solid tumors (including prostate cancer) has been demonstrated by epidemiological studies. The potential of genistein in treating prostate cancer has also been displayed by in vitro cell-based and in vivo animal experiments. Genistein has entered clinical trials for both chemoprevention and potential treatment of prostate cancer. Even though the low oral bioavailability has presented the major challenges to genistein's further clinical development, chemical modulation of genistein holds the promise to generate potential anti-prostate cancer agents with enhanced potency and/or better pharmacokinetic profiles than genistein. As part of our ongoing project to develop natural products-based anti-prostate cancer agents, the current study was undertaken to synthesize eight genistein analogues for cytotoxic evaluation in three prostate cancer cell lines (PC-3, DU-145, LNCaP; both androgen-sensitive and androgen-refractory cell lines), as well as one aggressive cervical cancer cell line (HeLa). Eight genistein analogues have been successfully synthesized with Suzuki-Miyaura coupling reaction as a key step. Their in vitro anti-cancer potential was evaluated by trypan blue exclusion assay and WST-1 cell proliferation assay against a panel of four human cancer cell lines. The acquired data suggest i) that the C-5 and C-7 hydroxyl groups in genistein are very important for the cytotoxicity and anti-proliferative activity; and ii) that 1-alkyl-1H-pyrazol-4-yl and pyridine-3-yl might act as good bioisosteres for the 4'-hydroxyphenyl moiety in genistein.

Synthesis and characterization of a new retinoic acid ECPIRM as potential chemotherapeutic agent for human cutaneous squamous carcinoma by Mengli Zhang, Yue Tao, Pengcheng Ma, Dechuan Wang, Chundi He, Yuping Cao, Jun Wei, Lingjun Li, Lei Tao (1204-1212).
Cutaneous squamous cell carcinoma (CSCC) is one of the most common cancers worldwide, requiring effective therapeutic interventions. Retinoids are important chemopreventive and therapeutic agents for a variety of human cancers including CSCC. In this study we synthesized a novel retinoic derivative N-(4-ethoxycarbonylphenyl) isoretinamide (ECPIRM) and evaluated its biological activities and possible mechanisms in human cutaneous squamous cell lines. ECPIRM had better inhibitory effect on the proliferation of squamous carcinoma cells SCL-1 and colo-16, compared with All-trans retinoic acid and 13-cis retinoic acid. ECPIRM had less toxicity to normal keratinocyte cell line HaCaT. Mechanistically, ECPIRM induced G1 cell cycle arrest in SCL-1 cells, via the downregulation of CDK2, CDK4, cycling D1 and cyclin E expression and upregulation of p21. In addition, these effects were at least partially due to the inhibition of JNK/ ERK-AP-1 signaling pathway by ECPIRM. Importantly, these effects of ECPIRM are independent of the classical retinoid receptor pathway, suggesting that the novel compound will have less side-effects in chemotherapy. These findings demonstrate that ECPIRM is a potential inhibitor of MPAK-AP-1 pathway, and is a potential therapeutic agent against CSCC.