Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 18, Issue 12, 2018

Background: Amygdalin is a cyanogenic glycoside which is described as a naturally occurring anticancer agent. Current review highlights apoptosis-inducing attributes of amygdalin towards different cancers and its potential application as an anti-cancer agent in cancer therapy. Method: Data about amygdalin was retrieved from all major scientific databases i.e., PubMed, ScienceDirect, Google Scholar, Scopus and Medline by using combination of keywords like amygdalin, apoptosis, laetrile, vitamin B- 17, pro-apoptotic proteins, anti-apoptotic proteins, hydrogen cyanide, mechanism of action of amygdalin and amygdalin therapy on humans. However, no specific time frame was followed for collection of data. Results: Data collected from already published articles revealed that apoptosis is a central process activated by amygdalin in cancer cells. It is suggested to stimulate apoptotic process by upregulating expression of Bax (proapoptotic protein) and caspase-3 and downregulating expression of Bcl-2 (anti-apoptotic protein). It also promotes arrest of cell cycle in G0/G1 phase and decrease number of cells entering S and G2/M phases. Thus, it is proposed to enhance deceleration of cell cycle by blocking cell proliferation and growth. Conclusion: The current review epitomizes published information and provides complete interpretations about all known anti-cancer mechanisms of amygdalin, possible role of naturally occurring amygdalin in fight against cancer and mistaken belief about cyanide toxicity causing potential of amygdalin. However, well-planned clinical trials are still needed to be conducted to prove effectiveness of this substance in vivo and to get approval for human use.

Background: The 26S proteasome is a proteolytic complex of multimeric protease, which operates at the executive end of the Ubiquitin-Proteasome System (UPS) and degrades the polyubiquitylated proteins. Methods: After a brief introduction of 26S proteasome and Ubiquitin-Proteasome System (UPS), this review focuses on the structure and function of the 26S proteasome in intracellular protein level regulation. Then, physiological regulation mechanisms and processes are elaborated. In addition, the advantages and defects of approved 26S proteasome inhibitors were discussed. Finally, we summarized the novel peptide 26S proteasome inhibitors according to their structural classifications, highlighting their design strategies, inhibitory activity and Structure-Activity Relationships (SARs). Results: Cellular function maintenance relies on the proteasome metabolizing intracellular proteins to control intracellular protein levels, which is especially important for cancer cells to survive and proliferate. In primary tumors, proteasomes had a higher level and more potent activity. Currently, the approved small peptide inhibitors have proved their specific 26S proteasome inhibitory effects and considerable antitumor activities, but with obvious defects. Increasingly, novel peptide inhibitors are emerging and possess promising values in cancer therapy. Conclusion: Overall, the 26S proteasome is an efficient therapeutic target and novel 26S proteasome inhibitors hold potency for cancer therapy.

Background: Six-Transmembrane epithelial antigen of the prostate-1 (STEAP-1) is present at the intercellular junctions of the secretory epithelium of prostate and is overexpressed in all steps of prostate cancer. STEAP-1 acts as a transporter protein or a putative channel between cancer cells while it has limited expression in normal human tissues. This protein has been suggested as an attractive target for prostate cancer immunotherapy. Objective: This study aimed at the development of a specific single chain fragment variable (scFv) antibody against STEAP-1 epitope and testing the inhibitory effect of the selected scFv antibody in blocking gap junctions between tumor cells. Method: In the current study, a phage library was used and a specific scFv antibody was isolated against STEAP-1 epitope using panning process. Results: PCR and DNA fingerprinting of the obtained clones demonstrated a dominant pattern of a specific clone. Binding of the selected scFv to the corresponding target on PC3 and LNCaP cell lines was tested using ELISA and flow cytometry techniques. The inhibitory effect of the selected scFv antibody in blocking gap junctions between the cells was tested using intercellular communication assay. The selected antibody reacted with the corresponding epitope in ELISA and bound to prostate cancer cells with an intensity of 44.6% (PC3 cells) and 73.4% (LNCap cells) as shown by FACS analysis. Intercellular communication assay indicated that dye transfer between the cells in PC3 and LNCaP cell lines treated with 1000 scFv/cell was significantly inhibited (80-90%). Conclusion: Our results suggested that the selected specific anti-STEAP1 scFv highly inhibited intercellular communication between prostate cancer cells and has the potential to be used as a new effective agent in prostate cancer immunotherapy.

Background: Nrf2 pathway and autophagy are abnormally activated in response to cellular stress in various types of human cancers. In this study, we selected Beclin1 as an enter point to discuss the relationship between Nrf2 pathway and autophagy, and defined their associations with clinic pathological features and survival of the patients. Method: NSCLC specimens were processed for immunohistochemical and qRT-PCR to analyses the expression of Beclin1 and Nrf2. Kaplan-Meier method and log-rank test were used in the survival data. Results: Beclin1 protein level was found to be significantly associated with more advanced TNM stage (P = 0.035), lymph node metastasis (P = 0.017) and distant metastasis (P = 0.005). The expression of Nrf2 protein was associated with larger tumor size (P = 0.032), more advanced TNM stage (P = 0.011), lymph node metastasis (P = 0.045) and distant metastasis (P = 0.013). Beside there was a strong inverse relationship between Beclin1 and Nrf2 expression in the NSCLC tissues. Distant metastasis, Beclin1, Nrf2, and Beclin1-/Nrf2+ expression was conformed to be independent prognostic factors of patients. Conclusion: Both Nrf2 overexpression and Beclin1 lower-expression are independent indicators of a poor prognosis in NSCLC patients.

Background: NF-kB (nuclear factor kappa B) is a transcription factor composed of two subunits, p50 and p65, which plays a key role in the inflammatory process. Melatonin has oncostatic, antiangiogenic and antimetastatic properties, and some recent studies have indicated an inhibitory effect of melatonin on NF-kB in some types of cancer. This work aims to investigate the effects of melatonin treatment on the expression of NFkB in breast and liver cancer models. Method: The breast cancer xenographic model was performed using female Balb/c nude athymic mice injected with MDA-MB-231 cells. The animals were treated with 40 mg/Kg of melatonin for 21 days. Volume of the tumors was measured with a digital caliper. Hepatocarcinoma model was developed by using the HepG2 cells in vitro, treated with 1 mM melatonin for 24 h. The expression of NF-kB protein was verified by immunohistochemistry and immunocytochemistry and quantified by optical densitometry, in vivo study and in vitro study, respectively. NF-kB gene expression was performed by quantitative RT-PCR. Results: The breast cancer xenografts nude mice treated with melatonin showed reduced tumor size (P=0.0022). There was a decrease in NF-kB protein staining (P=0.0027) and gene expression (P=0.0185) in mice treated with melatonin. The opposite results were observed for the hepatocarcinoma model. HepG2 cells treated with melatonin showed an increase in the NF-kB immunostaining when compared to control cells (P=0.0042). Conclusion: Our results indicated that the treatment with melatonin was able to decrease both gene and protein expressions of NF-kB in breast cancer cells and, conversely, increase the transcription factor protein expression in hepatocarcinoma cells. These data highlighted a double role in the expression of NF-kB, depending on the cell type. Further studies are needed to better elucidate the action of melatonin in NF-kB, since this transcription factor acts on different signaling pathways that are fundamental for carcinogenesis.

Background: In recent years, targeted cancer treatment methods at various molecular levels have been developed for Non-Small Cell Lung Cancer (NSCLC), one of two major subtypes of lung cancer. miRNAbased clinical trials are currently the preferred targeted therapeutic strategy. Also, ceRNAs (competing endogenous RNA) would be the newest and the most effective approach to uncover novel interactions between mRNAs and miRNAs in NSCLC carcinogenesis. There are many factors influencing the efficiency of a miRNA to suppress or silence translation of the target mRNA. The most effective event is the presence of other RNAs showing ceRNA activity. These RNAs contain binding sites for specific miRNAs and enable miRNAs to bind these pseudo targets, instead of the original binding sites on the target mRNA. Therefore, the mRNA of the target gene is less affected by this miRNA, while the amount of miRNA remains the same in the media. Method: For this project, we determined that five clinically important different oncogenes (PDL1, FGFR1, DDX3X, SLC1A5, FXR1 ) are involved in the pathogenesis of NSCLC. For this purpose, we transfected model NSCLC cell line, A549, with miRNAs (miR-150-5p, miR-15a-5p, miR-503-5p) targeting these oncogenes to investigate whether these oncogenes will be suppressed at the mRNA level and also how the suppression efficiency of these miRNA on the oncogenes will be affected by possible ceRNA (CNKSR3, POU2F1, HIPK2) activities. Results: miR-15a-5p was determined to have the most suppressive effect on the five genes and three potential ceRNAs (p<0.05). Furthermore, CNKSR3 was the ceRNA most affected by all three miRNAs (p<0.05). Conclusion: CNKSR3 was affected more than the oncogenes known to act on NSCLC and this might make it a stronger and novel marker for use in possible treatment regimens designed using miR-15a-5p silencing effect on oncogenes in NSCLC pathogenesis. According to the literature, this is the first study associating NSCLC with miR-15a-5p and CNKSR3.

Background: The anti-mitotic activity of podophyllotoxin derivative targeting tubulin enzyme proved them as strong polymerization inhibitors. The introduction of heteroatom along with different heteroaryl systems in naturally obtained lignans created a latitude for design of bioactive components. A novel one-pot sequential propargylation/cycloaddition reaction strategy has been followed to synthesize triazolo-heterolignans. Objective: To screen anti-proliferative activity of novel heterolignans and to determine their mode of action. Method: SRB assay, Cytotoxicity evaluation, PI uptake for analysis of cell cycle, caspase-3 activity, Western blot analysis and Immunofluorescence and molecular docking studies. Results: SRB assay of synthesised compounds were provided compound 3a and 5f to be highly active among the synthesized compounds. The Compound 3a showed cell cycle arrest at G2/M phase and 5f arrest the cells at G1 phase. Compound 5f displayed caspase 3 mediated apoptotic effect at lower levels. Compound 3a and 5f displayed microtubule disassembly inhibition same as paclitaxel and found to be occupying colchicine binding site of tubulin, both ligands were depicted π-cation interaction with Lys352 residue and triazole ring accommodated at the lactone binding site. Conclusion: A novel one-pot sequential propargylation/cycloaddition reaction has been developed for the synthesis of triazolo-heterolignans. Compound 3a and 5f were displayed good cytotoxic activities and found to inhibit microtubule disassembly. The importance of triazole ring of heterolignans has been studied by molecular docking experiments and results were compared.

Background: A wide range of heterocyclic steroidal derivatives gained a special attention due to their wide range of pharmacological activities especially the therapeutic activities. Many pharmacological drugs containing the steroid nucleus are known in the market. Objective: Our main aim of this work was to synthesise a series of heterocyclic compounds especially thiophene and thienopyridine derivatives containing the estrone nucleus. The synthesized compounds posses antitumor and kinases inhibitions. Method: Thiophene derivatives of estrone were synthesized and used for further heterocyclization reactions through the reaction with the different reagent. Results: Antiproliferative evaluations and c-Met kinase, Pim-1 kinase inhibitions were performed where some compounds revealed high activities. Conclusion: Compounds that showed high antiproliferative activity and c-Met- kinase inhibitions were tested for all compounds. The most promising compounds 3b, 5c, 6c, 8d, 8f, 13e, 13f, 18b and 20d were further investigated against tyrosine kinase (c-Kit, Flt-3, VEGFR-2, EGFR, and PDGFR). Compounds 6b, 13b, 16b and 16c were selected to examine their Pim-1 kinase inhibition activity where compounds 11c, 18b and 20f showed high activities. Structure-Activity Relationship (SAR) was rationalized by looking at the varying structural features of the molecules.

Background: Caffeic acid phenethyl ester and Dasatinib in combination, when used incongruous proportions and durations, present an antitumor potential for glioma in vitro, suggesting a high therapeutic potential for glioma treatment. Objective: In the present study, we addressed the question whether CAPE and Dasatinib target multiple pathways involved in tumor growth, proliferation and development on an in vivo rat model of glioma. Method: Expression analysis of proteins thought to be mediating proliferation, cell motility, angiogenesis, and invasion was carried out to delineate the antineoplastic action of CAPE and Dasatinib. Results: CAPE and Dasatinib modulate the expression of proteins having potential interactive crosstalk with major oncogenic pathways involved in glioma progression. Our results showed that combination treatment modulates the expression of p53 in group co-administered with CAPE and Dasatinib after glioma induction in comparison to the group induced with glioma only. EGFR and PCNA expression were significantly altered in the co-treated group in comparison with the glioma-induced group. The effects of CAPE and Dasatinib treatment were further evaluated on the AKT pathway by Western blot analysis. The co-treated group showed a significant reduction in the expression of AKT. The histopathological analysis further backed the antiproliferative and anti invasive effects of CAPE and Dasatinib. Conclusion: This study in totality suggests that the combinational therapy remarkably reduces the proliferation of glioma cells in vivo, suggesting that CAPE and Dasatinib therapy could be exploited for the management of gliomas without showing drug-related resistances and side effects, suggesting a high therapeutic potential of the therapy in glioma.

Background: Among the wide range of heterocycles, tetrahydrobenzothienopyridine derivatives acquired a special attention due to their wide range of pharmacological activities especially the therapeutic activities. Many pharmacological drugs containing the thiophene nucleus were known in the market. Method: A series of tetrahydrobenzothienopyridine derivatives were synthesized from the reaction of 2-amino- 3-benzoyl-4,5-dihydrobenzo[b]thiophen-6(7H)-one, synthesized and used for further heterocyclization reactions through reaction with different reagents. Results: Antiproliferative evaluations and c-Met kinase, Pim-1 kinase inhibitions were performed where some compounds revealed high activities. Conclusion: The inhibition of the newly synthesized compounds towards c-Met kinase, the five c-Metdependent cancer cell lines (A549, HT-29, MKN-45, U87MG, and SMMC-7721) and one c-Met-independent cancer cell line (H460) were investigated using foretinib as a standard drug. The results showed that compounds 6b, 7e, 9b, 9e, 16c and 20d were more active than foretinib. Furthermore, compounds 6b, 13b, 16b and 16c were selected to examine their Pim-1 kinase inhibition activity, where compounds 16b and 16c were of high potencies with IC50 values of 0.28 and 0.32 μM, while compounds 6b and 13b were less effective (IC50 > 10 μM).

Background: Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) is the main bioactive component of Brazilian green propolis, and possesses, among other things, anticancer properties. However, to the best of our knowledge, there are no studies of artepillin C in cervical cancer. Method: To explore a new therapeutic candidate for cervical cancer, we have evaluated the effects of artepillin C on cellular viability in a comprehensive panel of human cervical cancer-derived cell lines including HeLa (human papillomavirus/HPV 18-positive), SiHa (HPV 16-positive), CaSki (HPV 16- and 18-positive) and C33A (HPV-negative) cells compared to a spontaneously immortalized human epithelial cell line (HaCaT). Results: Our results demonstrated that artepillin C had a selective effect on cellular viability and could induce apoptosis possibly by intrinsic pathway, likely a result of oxidative stress, in all cancer-derived cell lines but not in HaCaT. Additionally, artepillin C was able to inhibit the migration and invasion of cancer cells. Conclusion: Thus, artepillin C appears to be a promising new candidate as an anticancer drug for cervical cancer induced by different HPV types.

Background: Developing new chemotherapeutic agents with molecular targets, larger margin of safety against normal cells and low cost is the target many scientists try to achieve. Objective: The present study was undertaken to investigate the anticancer activity of a novel series of thiophene compounds and the molecular mechanisms associated. Method: A series of novel heterocyclic compounds including pyrimidine derivatives (2, 3, 4, 5 8, 11, 12, 13, 14, and 15), thiophene derivatives (6, 7, and 10) and oxoisothiazolidine derivative (9) was synthesized from 4,5,6,7- tetrahydrobenzo[b] thiophene (1). The newly synthesized derivatives along with the parent compound were evaluated for their anticancer activity against human HepG2, MCF7 and HCT116 cell lines and compared to doxorubicin as a reference drug. Results: Compound 7 was very selective in targeting only the colon cells. Compounds 1, 5, and 12 showed strong cytotoxic activities against the 3 cell lines at 6-16 μM without any apparent toxicity to the normal fibroblasts WI-38. They had DNA affinity at 29-36 μM. The three compounds enhanced apoptosis to varying degrees elevating the expression of Bax, caspase 9 and caspase 3 in HepG2. Compound 5 was the most potent analogue and was superior to the standard drug used in upregulating the apoptotic genes and inhibiting tyrosine kinase at 1 μM. The IC50 value for compound 5 against TK was 296 nM. Conclusion: Taken together, this study presents some thiophene scaffolds as auspicious hits for further optimization as specific antiproliferative agents against cancer cells and promising tyrosine kinase inhibitors at nanomolar concentrations.

Background: In this study, new azafluorenones, 4-(4-fluorophenyl)-2-(4-substitutedphenyl)-5Hindeno[ 1,2-b] pyridin-5-one, I1-I8 were synthesized and chemical structures were elucidated by spectral analysis. All compounds were reported for the first time here. Method: Compounds were tested in terms of cytotoxicity. They were found as cytotoxins/anticancer compounds. Results: It was found that the lead compounds of the series were I5 and I8 according to SI, TS, PSE calculations. When PSE values were considered, compound I5 having chlorine had the highest PSE value of 126.4. Second highest PSE value of 50.5 belonged to I8, which had thiophene ring in its chemical structure. I8 as a representative compound of the series was forwarded to cell cycle analysis. I8 arrested S phase of the cell cycle and lead to apoptosis by inducing PARP cleavage suggesting that at least one of the mechanisms of cytotoxic action of the series was apoptosis. Conclusion: It was clearly demonstrated that compound I8 can induce early apoptosis at a concentration of 5 μM. The compounds I5 and I8 can be considered as lead compounds of the series with the highest SI, TS, PSE values for further studies.

Background: Warburg effect is characterized by the upregulation of HIF-1 and c-Myc regulated LDH-A, even aerobically owing to hypoxic environment and alterations in oncogenes or tumor suppressor genes in cancer. Reduced antioxidant defence system in transformed cells favors higher ROS production, which plays a significant role in carcinogenesis and acts as an important regulator of NF-ΚB. In addition, various proinflammatory cytokines play active roles in maintenance and progression of cancer. Objective: In continuation with our previous studies illustrating the long-term effect of curcumin using a liver tissue, present study was aimed to elucidate the anti-cancer effect of curcumin due to its long-term effect in the regulation of glycolytic metabolism, NF-ΚB activation, expression of proinflammatory cytokines in Dalton’s lymphoma ascites cells in vivo. Method: Spectrophotometric assays, RT-PCR and EMSA were performed to address the problems. Results: Results revealed that curcumin-induced activation of antioxidant enzymes, Nrf2 and downstream signaling gene NQO1. Reduction of oxidative stress, down-regulation of NADPH: Oxidase, decline in ROS and H2O2 levels were also observed. Activation of NF-ΚB, expression of COX2, HIF-1α and cMyc, as well as expression and activity of LDH-A were significantly reduced by curcumin. Besides, expression of proinflammatory cytokines was significantly down-regulated via reducing binding of nuclear protein with AP-1, NF-IL6, ETS and NF-ΚB binding elements of IL-1α, IL-1β, TNF-α and IL-6 promoters, respectively. Conclusion: Curcumin downregulates glycolytic metabolism via modulation of stress-activated genes and reduces oxidative stress by enhancing antioxidant defence system, which inhibits activation of NF-ΚB signaling and expression of proinflammatory cytokines in Dalton’s lymphoma ascites cells in vivo.