Anti-Cancer Agents in Medicinal Chemistry (v.13, #5)

The Use of Lentinan for Treating Gastric Cancer by Kenji Ina, Takae Kataoka, Takafumi Ando (681-688).
Natural compounds containing fungal β-glucans have been used to improve general health for thousands of years in China andJapan. Lentinan, the backbone of β-(1, 3)-glucan with β-(1, 6) branches, is one of the active ingredients purified from Shiitakemushrooms and has been approved as a biological response modifier for the treatment of gastric cancer in Japan. Despite recent advancesin chemotherapeutic agents, unresectable or recurrent gastric cancer remains an incurable disease, with survival rates being far fromsatisfactory. Recent clinical studies have shown that chemo-immunotherapy using lentinan prolongs the survival of patients withadvanced gastric cancer, as compared to chemotherapy alone. In addition, trastuzumab, an antibody against HER2/neu growth factorreceptor, has been used for the treatment of gastric cancer in combination with cytotoxic chemotherapeutic agents. Lentinan may exert asynergistic action with anti-cancer monoclonal antibodies to activate complement systems through the mechanism of antibody-dependentcellular cytotoxicity and complement dependent cytotoxicity. Because a better understanding of its biological activities should enable usto use lentinan more efficiently in the treatment of gastric cancer, immunological effects provided by β-glucans, a possible mode ofaction of lentinan, and its clinical application including future potential uses are discussed in the present review.

β-Glucans are polysaccharides of β-D-glucose extracted from the cell walls of different species of mushrooms, yeast, oat,barley, seaweeds, algae and bacteria. Modern biomedical research has identified β-glucans as biological response modifiers (BRM) withanti-tumor properties that elicit potent immune responses through their recognition by a variety of pattern recognition receptors (PRRs)on dendritic cells (DCs), macrophages and neutrophils. Complement receptor-3 (CR3), lactosylceramides, scavenger receptors anddectin-1 are involved in β-glucan recognition, triggering a series of signaling events that modulate innate and subsequently adaptiveimmune responses. β-Glucan binding to specific receptors in DCs and macrophages triggers their activation and maturation, increasestheir antigen-presentation ability and enhances the production of proinflammatory cytokines that stimulate the polarization of TH1 orTH17 responses, and induces the activation of antigen-specific CD8+ cytotoxic T lymphocytes (CTL). Moreover, large β-glucans can bedegraded by macrophages into smaller moieties, when released, prime CR3 receptor on neutrophils and natural killer (NK) cellsmediating CR3-dependent cellular cytotoxicity (CR3-DCC) of iC3b opsonized tumor cells. Elucidating the molecular mechanisms of β-glucan-induced signaling in immune cells is essential for the design of new therapeutic strategies against cancer. Future studies should bedone to translate β-glucan research to the clinic.

The Effects of β-glucans on Cancer Metastasis by Taek Joon Yoon, Sushruta Koppula, Kwang Ho Lee (699-708).
Beta-glucans (β-glucans), naturally occurring polysaccharides, are present as constituents of the cell wall of cereal grains,mushrooms, algae, or microbes including bacteria, fungi, and yeast. Since Pillemer et al. first prepared and investigated zymosan in the1940s and others followed with the investigation of β-glucans in the 1960s and 1970s, researchers have well established the significantrole of β-glucans on the immune system relative to cancer treatment, infection immunity, and restoration of damaged bone marrow.However, information on their biological role in anti-metastatic activity remains limited. As an immunomodulating agent, β-glucan actsthrough the activation of innate immune cells such as macrophages, dendritic cells, granulocytes, and natural killer cells. This activationtriggers the responses of adaptive immune cells such as CD4+ or CD8+ T cells and B cells, resulting in the inhibition of tumor growth andmetastasis. Reports have shown that β-glucans exert multiple effects on cancer cells and cancer prevention. However the mechanisms oftheir actions appear complex due to differences in source, chemical structure, insufficiently defined preparation, and molecular weight,hence the inconsistent and often contradictory results obtained. This review is focused on the potential of β-glucans as anti-metastaticagents and the known mechanisms underlying their biological effects.

β-glucans belong to a group of polysaccharides located in the cell wall of bacteria, fungi including mushrooms, as well ascereals such as barley and oats. All β-glucans are glucose polymers linked together by a (β 1-3) linear β-glycosidic chain core and theydiffer by their length and branching structures. They are considered biological response modifiers with immunomodulatory and healthbeneficial effects including anticancer properties. Few studies using purified β- glucans were performed, but their anticancer potentialwas demonstrated mainly through studies using extracts from mushrooms, yeast or other sources which contain β-glucan as a keycomponent. Their anticancer effects were demonstrated mainly in in vitro and in vivo experimental systems but fewer studies from humanpopulations are available. β-glucans have been used as adjuvant therapy in clinical trials, mainly in the Far East, with a positive effect onpatients'survival and quality of life. The mechanism of action is suggested to be through its stimulation of the immune system. Thisreview focuses on human studies; clinical trials and epidemiological data assessing the efficacy and safety of mushroom-derived β-glucans in cancer treatment and prevention. The potential direct effects of β-glucans on cancer cells are also described.

It is well established that glucans enhance the efficacy of anti-cancer and anti-infection immunotheraphy, both in clinical andexperimental conditions. However, the considerable variations among batches of natural glucan in molecular weight, branchingfrequency, as well as linkage to chitins and mannoproteins, make the clinical applications of natural glucan questionable. The futuremight be in the use of small synthetic oligosaccharides prepared on the basis of natural glucans. Some of these non naturaloligosaccharides showed biological activities such as stimulation of phagocytosis, modulation of gene expression and anti-canceractivity, which were superior to natural glucans. The recent studies strongly suggest the possibility of small chemical changes in thestructure of these oligoglucans oriented towards their improved biological activities. This review highlights recent achievements in theimmunological effects of synthetic, glucan-based oligosaccharides.

The Application of Fungal Beta-glucans for the Treatment of Colon Cancer by Jiezhong Chen, Xu Dong Zhang, Zhengyi Jiang (725-730).
Mushrooms have been consumed for their health benefits for thousands of years in China, and the main active component wasrecently identified as beta-glucan. The immune-stimulating effect of beta-glucans has been well studied, and several beta-glucanreceptors have been identified on the surface of immune cells. In addition, mushroom extracts with high levels of beta-glucans have alsobeen shown to have direct cytotoxic effects on cancer cells, and beta-glucans are used for the treatment of cancer. This reviewsummarizes the use of beta-glucans in colon cancer. Evidence has supported the idea that beta-glucans can decrease the size ofxenografted colon cancer tumors via the stimulation of the immune system and direct cytotoxicity. Beta-glucans can also have synergisticeffects with chemotherapeutic agents and other immune stimulators, and an innovative strategy is to use beta-glucans to delivernanoparticles containing chemotherapeutic agents to the site of the colon cancer and, thus, improve the therapeutic efficacy.

Type II Kinase Inhibitors: An Opportunity in Cancer for Rational Design by Javier Blanc, Raphael Geney, Christel Menet (731-747).
With the advent of the Type II kinase inhibitor imatinib (Gleevec) for treatment against cancer, rational design of tailoredmolecules has brought a revolution in medicinal chemistry for treating tumours caused by kinase malfunctioning. Among different typesof kinase inhibitors, the design of Type II inhibitors has been rationalized for maximizing the benefits and reducing drawbacks. Here wehighlight the development made in Type II inhibitors, discussing the advantages and disadvantages of these types of molecules.Furthermore, we present the strategies for designing druggable molecules that either selectively inhibit target kinases or overcome drugresistance.

Receptor tyrosine kinases (RTKs) are transmembrane proteins that play a critical role in stimulating signal transductioncascades to influence cell proliferation, growth, and differentiation and they have also been shown to promote angiogenesis when theyare up-regulated or mutated. For this reason, their dysfunction has been implicated in the development of human cancer. Over the pastdecade, much attention has been devoted to developing inhibitors and antibodies against several classes of RTKs, including vascularendothelial growth factor receptors (VEGFRs), epidermal growth factor receptors (EGFRs), and platelet-derived growth factor receptors(PDGFRs). More recently, interest in the fibroblast growth factor receptor (FGFR) class of RTKs as a drug target for the treatment ofcancer has emerged. Signaling through FGFRs is critical for normal cellular function and their dysregulation has been linked to variousmalignancies such as breast and prostate cancer. This review will focus on the current state of both small molecules and antibodies asFGFR inhibitors to provide insight into their development and future potential as anti-cancer agents.

Inhibition of PCAF by Anacardic Acid Derivative Leads to Apoptosis and Breaks Resistance to DNA Damage in BCR-ABL-expressing Cells by Monika Kusio- Kobialka, Wioleta Dudka- Ruszkowska, Massimo Ghizzoni, Frank J. Dekker, Katarzyna Piwocka (762-767).
Acetylation of histones and nonhistone proteins is a posttranslational modification which plays a major role in the regulationof intracellular processes involved in tumorigenesis. It was shown that different acetylation of proteins correlates with development ofleukemia. It is proposed that histone acetyltransferases (HATs) are important novel drug targets for leukemia treatment, however data arestill not consistent. Our previous data showed that a derivative of anacardic acid - small molecule MG153, which has been designed andsynthesized to optimize the HAT inhibitory potency of anacardic acid, is a potent inhibitor of p300/CBP associated factor (PCAF)acetyltransferase. Here we ask whether inhibition of PCAF acetyltransferase with MG153 will show proapoptotic effects in cellsexpressing BCR-ABL, which show increased PCAF expression and are resistant to apoptosis. We found that inhibition of PCAFdecreases proliferation and induces apoptosis, which correlates with loss of the mitochondrial membrane potential and DNAfragmentation. Importantly, cells expressing BCR-ABL are more sensitive to PCAF inhibition compared to parental cells without BCRABL.Moreover, inhibition of PCAF in BCR-ABL-expressing cells breaks their resistance to DNA damage-induced cell death. Thesefindings provide direct evidence that targeting the PCAF alone or in combination with DNA-damaging drugs shows cytotoxic effects andshould be considered as a prospective therapeutic strategy in chronic myeloid leukemia cells. Moreover, we propose that anacardic acidderivative MG153 is a valuable agent and further studies validating its therapeutic relevance should be performed.

Antiproliferative Activities on Renal, Prostate and Melanoma Cancer Cell Lines of Sarcopoterium spinosum Aerial Parts and its Major Constituent Tormentic Acid by Monica R. Loizzo, Marco Bonesi, Nicodemo G. Passalacqua, Antoine Saab, Francesco Menichini, Rosa Tundis (768-776).
The search for improved cytotoxic agents continues to be an important line in the discovery of modern anticancer drugs.Sarcopoterium spinosum (L.) Spach is mentioned in ethnobotanical surveys as a medicinal plant used for the treatment of cancer. Theaim of this study is to investigate and to compare the aerial parts of S. spinosum collected in Italy and Lebanon for their chemicalcomposition and their antiproliferative activity against ACHN, C32, A375, MCF-7, LNCaP and HeLa human cancer cell lines using SRBassay. The main constituent tormentic acid was isolated by MPLC and characterized by spectroscopic techniques (NMR, MS). Non polarcompounds were analyzed by GC and GC-MS. S. spinosum showed an interesting antiproliferative activity against ACHN and C32 celllines with IC50 values of 2.4 and 2.7 μg/ml for S. spinosum from Italy and Lebanon, respectively. Remarkable results were obtained alsoagainst A375 and LNCaP cell lines. The cytotoxicity against ACHN cell line could be partially attributed to tormentic acid thatdemonstrated a higher cytotoxicity than the positive control vinblastine. Close association between the radical scavenging activity(evaluated by DPPH and ABTS assay) and cytotoxicity was also demonstrated. This investigation demonstrated the potential cytotoxicactivity of S. spinosum taking into account also that none of the tested extracts, fractions and isolated compound affected the proliferationof normal cell line 142BR. Tormentic acid, the major constituent isolated from S. spinosum, play an important role in the cytotoxicityexhibited by the extract.

NF-κB Down-regulation and PARP Cleavage by novel 3-α-butyryloxy-β-boswellic Acid Results in Cancer Cell Specific Apoptosis and in vivo Tumor Regression by Yasrib Qurishi, Abid Hamid, Parduman R. Sharma, Zahoor A. Wani, Dilip M. Mondhe, Shashank K. Singh, Mohmmad A. Zargar, Samar S. Andotra, Bhahwal A. Shah, Subhash C. Taneja, Ajit K. Saxena (777-790).
The present study relates to the induction of apoptosis thereof cytotoxicity and anti-cancer activity displayed by semi-syntheticanalog of Boswellic acid i.e. 3-α-Butyryloxy-β-boswellic acid (BOBA). The cytotoxicity data revealed the differential sensitivity ofcancer cell lines towards BOBA which may display its impact against different types of cancers. Considering the inhibitory potential ofBOBA, we further sought to understand the target for BOBA deciphering the mechanism of action leading to apoptotic cell death and itwas for the first time reported about the triterpenoid ring especially the β-boswellic acid derivative is targeting PI3K pathway. Our datarevealed that BOBA treatment provides evidence about the apoptotic nature showing the potential of targeting mitochondria dependentpathways during apoptosis in HL-60 cells. BOBA induced hypo-diploid sub-G1 DNA population in HL-60 cells as was also evident fromthe pattern of DNA fragmentation and mitochondrial membrane potential (ΛΨm) loss. Morphological analysis under fluorescent andscanning electron microscopy displayed typical features such as cell shrinkage, membrane blebbing, chromatin condensation and nuclearfragmentation. These events paralleled with the down-regulation of NF-κB and induced PARP cleavage. Furthermore, it is noteworthythat BOBA also depicted significant growth inhibition in Ehrlich Ascitic Tumour (EAT), Ehrlich Ascitic Carcinoma (EAC) and Sarcoma-180 tumour models. Taken together, BOBA treatment may represent as potential agent to the currently available anticancer agents in bothprophylactic and/or therapeutic applications. Also, our findings may open up a new perspective in the construction of novel anticanceragents based on boswellic acids that will facilitate the development of these agents for anticancer therapeutics.

Unified Multi-target Approach for the Rational in silico Design of Anti-bladder Cancer Agents by Alejandro Speck- Planche, Valeria V. Kleandrova, Feng Luan, M. N. D. S. Cordeiro (791-800).
Bladder cancer (BLC) is a very dangerous and common disease which is characterized by an uncontrolled growth ofthe urinary bladder cells. In the field of chemotherapy, many compounds have been synthesized and evaluated as anti-BLC agents.The future design of more potent anti-BLC drugs depends on a rigorous and rational discovery, where the computer-aided design(CADD) methodologies should play a very important role. However, until now, there is no CADD methodology able to predict anti-BLCactivity of compounds versus different BLC cell lines. We report in this work the first unified approach by exploring Quantitative-Structure Activity Relationship (QSAR) studies using a large and heterogeneous database of compounds. Here, we constructedtwo multi-target (mt) QSAR models for the classification of compounds as anti-BLC agents against four BLC cell lines. The firstmodel was based on linear discriminant analysis (mt-QSAR-LDA) employing fragment-based descriptors while the second modelwas obtained using artificial neural networks (mt-QSAR-ANN) with global 2D descriptors. Both models correctly classified more than90% of active and inactive compounds in training and prediction sets. We also extracted different substructural patterns which could beresponsible for the activity/inactivity of molecules against BLC and we suggested new molecular entities as possible potent and versatileanti-BLC agents.

Computational and Functional Analysis of the Androgen Receptor Antagonist Atraric Acid and Its Derivatives by Maria Papaioannou, Annu A. Soderholm, Wei Hong, Yifan Dai, Julia Roediger, Daniela Roell, Marie Thiele, Tommi H. Nyronen, Aria Baniahmad (801-810).
Androgen receptor (AR) antagonists are important compounds for the treatment of prostate cancer (PCa). The atraric acid(AA), a natural compound, binds to the AR and acts as a specific AR antagonist. Interestingly, AA represents a novel chemical platformthat could serve as a potential basis for new AR antagonists. Therefore, one objective of this study was to analyze the chemical/structuralrequirements for AR antagonism and to obtain predictions of where and how AA binds to the AR. Further, this study describes thechemical synthesis of 12 AA derivatives and their analysis using a combination of computational and functional assays. Functionalanalysis of AA derivatives indicated that none activated the AR. Both the para-hydroxyl group and the benzene ortho- and the metamethylgroups of AA appeared to be essential to antagonize androgen-activated AR activity. Furthermore, extension of the hydrophobicside chain of AA led to slightly stronger AR antagonism. In silico data suggest that modifications to the basic AA structure change thehydrogen-bonding network with the AR ligand binding domain (LBD), so that the para-hydroxyl group of AA forms a hydrogen bondwith the LBD, confirming the functional importance of this group for AR antagonism. Moreover, in silico modeling also suggested thatthe ortho- and meta- methyl groups of AA interact with hydrophobic residues of the ligand pocket of AR, which might explain theirfunctional importance for antagonism. Thus, these studies identify the chemical groups of AA that play key roles in allowing the AAbasedchemical platform to act as an AR antagonist.

The Role of Autophagic Cell Death and Apoptosis in Irinotecan-treated p53 Null Colon Cancer Cells by Stanislav John, Jan Mls, Miroslav Cervinka, Emil Rudolf (811-820).
The roles of autophagic cell death and apoptosis induced by topoisomerase inhibitor irinotecan in colon cancer cells withdeleted p53 were investigated during 48 h. We report that irinotecan-dependent cytotoxicity and proapoptotic activity were reduced in thepresent model while autophagy levels significantly increased. Upon p53 transfection, cell demise rates increased, with cells bearing thefeatures of apoptosis and autophagic cell death. The subsequent studies into mechanisms of cell death process revealed the important roleof Bax in mediating mitochondrial and lysosomal leakage which might serve as leading signals for both apoptosis and autophagic celldeath. These results suggest that different modes of cell death in p53 null colon cancer cells treated with cytostatics (irinotecan) may beactivated simultaneously. Moreover, their interactions possibly occur at several stages and aren't mutually exclusive. This might thus leadto a potential synergism with interesting therapeutic ramifications.

Background: Cancer is a potentially fatal diagnosis, but due to modern medicine there is a potential cure in many of thesecases. The rate of treatment success depends on early disease detection and timely, effective delivery of tumour specific treatment. Thereare many ongoing researches aimed to improve diagnostics or treatment, but the option to use both modalities concomitantly is deficient.In this project we are using the advances in nanotechnology to develop new theranostic tool using single walled carbon nanotubes(SWCNT) and Quantum dots (QDs) for early cancer cell detection, and option to deliver targeted treatment.</p><p>Method: SWCNTs were refluxed in HNO3/H2SO4 (1:3) at 120ºC for 120 minutes. Functionalised SWCNT was then covalently attachedto octa-ammonium polyhedral oligomeric silsesquioxane (POSS), QDs and conjugated with antibodies for targeted cell detection. Fouriertransforms infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), UV/NIR analysis, Raman and UV-VIS spectroscopywere used in order to prove the successful conjugation. Toxicology study using alamar blue analysis and DNA assay was conducted inorder to choose the best concentration of SWCNT, octa-ammonium-POSS and QDs before commencing the conjugation process. Humancolorectal cancer cell line HT29, pancreas cancer cell line PANC-1 and mouse fibroblasts 3T3 were then treated with or without antibodyconjugated SWCNT-POSS-QDs (CPQ) compound solution. The cell response was observed under the microscope after 24, 48 and 72 hours.</p><p>Results: FTIR and Raman spectroscopies confirmed covalent binding of the SWCNTs to Octa-Ammonium-POSS. This was supported byTEM images and photos obtained, which showed well dispersed SWCNTs following its treatment with Octa-Ammonium-POSScompared to pristine SWCNT samples. UV-VIS graphs determined the presence of antibody within the compound. UV/NIRdemonstrated QD fluorescence even after attachment of SWCNT-POSS. The cellular behaviour revealed high CPQ-antibody complexaffinity towards cancer cells when compared to healthy cell line which internalised the complex only on day three. The pancreas cancercell line had appearance of lysed pulp after 72 hours of incubation. Colonic cancer cells seemed to regain ability to populate from daythree signifying that higher treatment payload is necessary.</p><p>Conclusion: We have successfully manufactured novel compound consisting of Octa-Ammonium-POSS linked SWCNTs, QDs, andtumour specific antibodies. The complex has proven its potential as cell probing tool, and the attachment of antibodies has shown highaffinity to cancer cells rendering this an attractive model for further theranostic developments.