Anti-Cancer Agents in Medicinal Chemistry - Volume 17, Issue 13, 2017

Lung cancer is a major human malignancy. Nowadays, the lack of specific diagnostic markers of lung cancer restricts the early diagnosis and therapy of patients. Exosomes, as spherical 30-100 nm microvesicles, are released by normal and cancer cells in both physiological and pathological circumstances. Exosomes carry various molecular cargos such as miRNA, proteins, mRNA, DNA and lipids. Therefore, analysis of the molecular profiles of exosomes may provide beneficial biomarkers for disease diagnosis. Exosomes can be transported by body fluids. The molecules (miRNAs and proteins) detected in body fluid exosomes may contribute to lung cancer diagnosis. In this review, we summarize typical molecules (miRNAs and proteins) in body fluids-derived exosomes to reveal the potential biomarkers in lung cancer. Besides, the role and the application of exosomes in chemotherapy and radiotherapy of lung cancer patients have also been discussed in this review.

Background: Bendamustine, an N-mustard-benzoimidazole hybrid conjugate, was recently approved for the treatment of chronic lymphocytic leukemia. However, the short half-life of bendamustine may limit its clinical applications. Objective: The purpose of this study is to design and synthesize compounds with a more favorable pharmacokinetic profile. Methods: We synthesized a series of hybrid molecules comprising a phenyl N-mustard moiety and benzothiazole or benzimidazole scaffold linked via a urea linker and evaluated their antitumor activity and plasma stability. Results: We revealed that these agents exhibited significant cytotoxicity against a panel of human lymphoblastic leukemia and human solid tumor cells in culture. Human lymphoblastic leukemia CCRM-CEM cells were the most sensitive to the tested compounds. In general, the new hybrids were as potent as cisplatin, but significantly more cytotoxic than bendamustine. Phenyl N-mustard-benzothiazole compound 27d and phenyl N-mustardbenzimidaloe compound 32b possessed significant cytotoxicity and led to apoptotic death in the treated tumor cells. These two agents were able to induce DNA interstrand cross-linking and arrested cell cycle progression at the G2/M phase. Furthermore, we showed that these new hybrids were more chemically stable than bendamustine in rat plasma. Conclusion: Our results suggest that conjugation of phenyl N-mustard pharmacophore at C6 of benzimidazole or at C8 of the benzothiazole ring via a urea linker is likely an approach to increase the chemical stability and bioavailability. Highlights ⇒ Series of benzimidazoles and benzothiazoles linked to N-mustard were synthesized. ⇒ The newly synthesized derivatives induced DNA interstrand cross-links. ⇒ These derivatives induced cell cycle arrest in the G2/M phase and triggered apoptosis in H460 cells. ⇒ The new compounds are more cytotoxic than bendamustine. ⇒ The new compounds were chemically more stable than bendamustine in rat plasma.

Background: Androgen receptor is an attractive target for the treatment of prostate cancer. The 1,3- thiazolidine-2,4-diones possess a wide diversity of important biochemical effects and interesting pharmacological properties. Objective: The aim of the study is to find the experimental and computational methods to investigate the interference of 1,3-thiazolidine-2,4-diones with androgen receptor against prostate cancer. Method: Structural modification and molecular docking-based virtual screening approaches were imposed to identify the novel 1,3-thiazolidine-2,4-diones by using Schrödinger (Maestro 9.5). The best fit molecules (3-12 & 23-31) were synthesized and characterized using spectroscopic techniques, then in vitro antioxidant and antiprostate cancer activities were evaluated. Further, the structure of the intermediate (18) was confirmed by single crystal XRD analysis. The mechanism studies were performed through the gene expression for the compounds, 29, 30, and 31, the standards, dihydrotestosterone and R-bicalutamide. Results: The compounds, 29, 30 and 31 showed comparatively significant antioxidant activity and better antiproliferative activity against PC-3 and LNCaP cell lines. Also, very low cytotoxicity was observed in the noncancerous cell (3T3). The compounds, 29, 30 and 31 significantly decreased the mRNA expression of ARstimulated genes, PSA and TMPRSS2, which demonstrated their anti-prostate cancer activities. ADME/T properties prediction of the compounds (3-12 and23-31) showed the promising drug-likeness and pharmacokinetic parameters without toxicity. Moreover, DFT calculations apparently confirmed the stable conformer of the compound, 31. Conclusion: These findings may provide the essential information for the development of anti-prostate cancer agents.

Background: The formation of the complex interleukin-11(IL-11) and IL-11 receptor (IL-11R) is closely related with tumor progression. Binding of IL-11 to the IL-11 receptor α-chain (IL-11Rα) has been suggested as a target for human cancer. The cyclic peptide c(CGRRAGGSC) is a mimic of IL-11. Objective: To explore 131I-Y-c(CGRRAGGSC) synthesis and radiosynthesis, and metabolism in SKOV3 tumorbearing mice. Method: In this study, 131I labeled c(CGRRAGGSC) was designed and characterized. For radiolabeling, tyrosine was used as a linker to connect c(CGRRAGGSC) and 131I. Balb/c nude mice bearing SKOV3 human ovarian carcinoma were used for in vivo studies. Uptake of 131I-cyclic nonapeptide by the tumor was visualized by single photon emission computerized tomography (SPECT). Results: The entire labeling process, which took 15 min by chloramine-T method, resulted in a high labeling yield (93.03±6.78%), and high radiochemical purity (RCP) (>95%). SPECT imaging showed that accumulation of the probe in the tumor was close to background levels. In addition, biodistribution studies showed that the accumulation of 131I-Y-c(CGRRAGGSC) in normal mice was similar to that of Na131I. Conclusion: Tyrosine is a suitable chelating agent for the use of radioiodine labeling, however the bioactivity of the conjugate needs further investigation.

Background: Chronic myeloid leukemia (CML) is currently treated with imatinib, a Bcr-Abl inhibitor. However, resistance to this drug usually develops over time. Triptolide, a diterpenoid triepoxide, has been shown active against CML cells resistant to imatinib, acting mainly on the level of Bcr-Abl transcription inhibition. Objective: Here, we used the triterpene betulinic acid, a known proteasome inhibitor with potential antileukemic activity, as a scaffold for the generation of analogues with predicted triptolide biological activity. Method: Betulinic acid derivatives were designed based on the structure-activity relationship of triptolide and evaluated for their cytotoxic effects in CML cells, lymphocytes and human keratinocytes (HaCaT), as well as against the proteasome complex. The main modification performed on betulinic acid was fluorination at C-28 and epoxidation, both of which are responsible for enhancing activity of triptolide. A total of 10 compounds were obtained: 6 previously described and 4 novel compounds. The cytotoxic activity over a CML cell line (K562) was assessed using flow cytometry and compared to lymphocytes and HaCaT. Result: The results show that betulinic acid was the most cytotoxic compound against CML cells, showing a good selectivity index for cancer over normal cells. The most important trend for the activity in betulinic acid derivatives is the presence of a free hydroxyl group at C-3 and a carboxyl group at C-28. Results also indicated that the epoxide is important for enhancing the activity, while modification at C-28 worsens the activity. Conclusion: Proteasome inhibition assays suggest that proteasome is the main target for betulinic acid and its derivatives.

Background: Myc (c-Myc) alone activates the embryonic stem cell-like transcriptional module in both normal and transformed cells. Its dysregulation might lead to increased cancer stem cells (CSCs) population in some tumor cells. Objective: In order to investigate the potential of Myc decoy oligodeoxynucleotides for differentiation therapy, mouse embryonic stem cells (mESCs) were used in this study as a model of CSCs. To our best of knowledge this is the first report outlining the application of Myc decoy in transcription factor decoy “TFD” strategy for inducing differentiation in mESCs. Methods: A 20-mer double-stranded Myc transcription factor decoy and scrambled oligodeoxynucleotides (ODNs) were designed, analyzed by electrophoretic mobility shift (EMSA) assay and transfected into the mESCs under 2 inhibitors (2i) condition. Further investigations were carried out using fluorescence and confocal microscopy, cell proliferation and apoptosis analysis, alkaline phosphatase and embryoid body formation assay, real-time PCR and western blotting. Results: EMSA data showed that Myc decoy ODNs bound specifically to c-Myc protein. They were found to be localized in both cytoplasm and nucleus of mESCs. Our results revealed the potential capability of Myc decoy ODNs to decrease cell viability by (16.1±2%), to increase the number of cells arrested in G0/G1 phases and apoptosis by (14.2±3.1%) and (12.1±3.2%), respectively regarding the controls. Myc decoy could also modulate differentiation in mESCs despite the presence of 2i/LIF in our medium the presence of 2i/LIF in our medium. Conclusion: The optimized Myc decoy ODNs approach might be considered as a promising alternative strategy for differentiation therapy investigations.

Aims/Objective: Phosphonium salts are compounds whose structural characteristics enable them to cross the plasma and mitochondrial membrane with ease. Cancer cells have higher plasma membrane potentials than normal cells; phosphonium salts selectively accumulate in the mitochondria of neoplastic cells and inhibit mitochondrial function. Method: In the present work, we investigated the cytotoxic activity of lipophilic phosphonium salt (11- methoxy11-oxo-undecyl) triphenylphosphonium bromide (MUTP) as well as of the two new phosphine oxide salts, 3,3'-(methylphosphoryl) dibenzenaminium chloride (SBAMPO) and 3,3' (phenylphosphoryl) dibenzenaminium chloride (SBAPPO) on the proliferation of breast cancer cell line (MCF-7) and human uterin cervix adenocarcinoma cells (HeLa). Result: We showed that only MUTP exhibits antiproliferative effects on both cell lines, without affecting the normal breast epithelial cell proliferation. More specifically, we demonstrated that MUTP treatment of breast cancer cells is associated with impaired cell-cycle progression and metabolically induces mitochondrial damage and triggers apoptotic cell death in MCF-7 and HeLa cells. Taken together, these findings suggest that MUTP may be capable of selectively targeting neoplastic cell growth and therefore has potential applications as anticancer agent.

Background: Genetics play a significant role in drug metabolism of endocrine therapy of breast cancer. These aspects have been studied extensively in patients on tamoxifen, but the pharmacogenetics of aromatase inhibitors are less established. In contrast to the protective effect of tamoxifen, aromatase inhibitors are linked with an increased risk for bone loss and fractures. Objective: This review outlines key issues in the implementation of pharmacogenetics of cytochrome P450 and tamoxifen as a model for optimal use of aromatase inhibitors in postmenopausal women with estrogen receptor positive breast cancer. Methods: Lessons learnt from the association between tamoxifen and CYP2D6 genotyping were applied to identify polymorphisms with the potential to change clinical decision-making in patients on aromatase inhibitors. The ability of next generation sequencing to supersede single-gene analysis was furthermore evaluated in a subset of breast cancer patients on aromatase inhibitors selected from a central genomics database. Results: Methodological flaws in major randomised controlled trials and continued referral to incorrect results in expert consensus statements are important factors delaying the implementation of CYP2D6 pharmacogenetics in tamoxifen treatment. This highlighted the importance of a clinical pipeline including comprehensive genotyping, to define the target population most likely to benefit from aromatase inhibitor pharmacogenetics. Conclusion: The clinical utility of CYP2D6 genotyping is well-established in patients at increased risk of tamoxifen resistance due to cumulative risk. The pharmacogenetics of CYP19A1 requires further clarification in terms of bone risk assessment for appropriate use in the treatment algorithm of high-risk patients at the onset of aromatase inhibitors.

Objective: To synthesize a novel chemotype based on the naphthoquinone scaffold with retained cytotoxicity and provisionally low intracellular oxidation potential. Background: Derivatives of naphthoquinone, although potent anticancer agents, can exert heart toxicity due to generation of free oxygen species. Methods: In this study, we modified the scaffold by replacing one carbonyl group with the oxime moiety. Interestingly, only one carbonyl group in 1-R-1H-naphtho[2,3-d][1,2,3]triazole-4,9-dione 2-oxides reacted with hydroxylamine. The spatial structure was determined by X-ray analysis. New compounds were tested for the ability to form stable complexes with double stranded DNA by spectroscopy and molecular docking and to induce death of tumor cell lines and non-malignant counterparts. Results: The resulting 1-R-1H-naphtho[2,3-d][1,2,3]triazole-4,9-dione 4-oxime 2-oxides were further acylated to produce a series of 1-R-1H-naphtho[2,3-d][1,2,3]triazole-4,9-dione 4-(O-acyloxime) 2-oxides. Newly synthesized compounds demonstrated a higher (in submicromolar or low micromolar range) cytotoxic potency against human colon and breast adenocarcinoma cell lines than to non-malignant skin fibroblasts. Spectroscopic measurements revealed that, unlike other classes of quinone derivatives, new naphthotriazoledione oxides did not form stable complexes with double stranded DNA regardless of their fitting to the DNA minor groove (as determined by molecular modeling). Conclusion: Thus, our chemical modifications yielded a new chemotype with good cytotoxic properties and yet-to-be-identified intracellular target(s).

Background: Emerging evidence indicates that the transcription factor nuclear factor-E2-related factor 2 (Nrf2) plays an essential role in cellular defense against oxidative stress; its activation has been related to cytoprotection. Objective: Here, we investigated the role of Nrf2 in improving the efficacy of methyl pyropheophorbide-amediated photodynamic therapy (Mppa-PDT) via the downregulation of Nrf2. Method: Human ovarian cancer A2780 cells and SKOV3 cells were treated with Mppa-PDT and siRNA transfection was performed to inhibit Nrf2. After treated with siRNA and Mppa-PDT, the cell viability was examined with CCK-8 assay; cell apoptosis was detected tested by flow cytometry with Annexin V-FITC/PI; the celluar reactive oxygen species (ROS) and mitochondrial membrane potential were measured with DCFHDA and JC-1 staining; expression of protein was assessed by western blot analysis. Results: We found that Nrf2 translocated from the cytoplasm to the nucleus in vitro and in vivo, and the expression of Nrf2 and P-Nrf2 increased through a possible mechanism regulated by mitogen-activated protein kinase (MAPK) after Mppa-PDT treatment. Furthermore, cytotoxicity and apoptosis induced by Mppa-PDT increased after Nrf2down-regulation. Nrf2 down -regulation increased reactive oxygen species (ROS) levels by attenuating antioxidants or pumping Mppa out of cells,which resulted from the inhibition of Nrf2-HO-1 or Nrf2- ABCG2 signaling. In addition, SKOV3 cells exhibited increased resistance to Mppa-PDT, and the expression levels of P-Nrf2 and ABCG2 were higher in SKOV3 cells than in A2780 cells, suggesting that Nrf2-ABCG2 signaling might be involved in the intrinsic resistanceto Mppa-PDT. Conclusion: These results provided evidence that Nrf2 down-regulation can enhance the effect of Mppa-PDT.

Objective and Method: A new series of benzothiazole-piperazine derivatives was synthesized and a complete chemical characterization of the novel compounds was provided. In vitro cytotoxic activities were screened against colorectal (HCT-116), breast (MCF-7) and hepatocellular (Huh7) cancer cell lines by Sulforhodamine B assay. Result and Discussion: All compounds showed cytotoxic activity against hepatocellular (Huh7) and breast (MCF-7) cancer cell lines. Dihalo substituted benzylpiperazine derivatives (2a, 2e) had the highest cytotoxic activities in all the tested cell lines. In addition, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities of synthesized compounds were investigated by in vitro Ellman's method. Compound 2j led to moderate and selective inhibition against AChE. Docking study was utilized to understand the binding mode of compound 2j in comparision with donepezil on AChE. The other tested compounds showed weak or no inhibition against AChE as promising anticancer agents.

Background: Triazine ring is a prominent structural motif found in some azanucleosides whose efficiency improved many times in the research area of antitumor agents. Objective: In this study, we have designed and synthesized novel 2-[(5,6-diphenyl-1,2,4-triazin-3-yl)thio]-N-(6- substituted benzo/(thiazol)-2-yl)acetamide (2a-d, 3a-f) derivatives using 1,2,4-triazine core along with two important heterocyles, thiazole and benzothiazole rings. Method: The acquired ten final compounds were screened to investigate their antitumor activity against lung adenocarcinoma cell line, A549 and mouse fibroblast cell line, NIH/3T3. Five compounds with higher antiproliferative activity have been further studied to evaluate whether the cell death due to necrosis or apoptosis using flow cytometry. Results and Conclusion: Compound 3b bearing 6-methylbenzothiazole moiety has been established as the most active antitumor compound with a selective profile and higher apoptotic cell level. All final componds were also screened against acetylcholine/butyrylcholinesterase enzymes to state their anticholinesterase activity.