subhas s karki
@klepharmblr.org
Professor and Head, Pharmaceutical Chemistry
KLE College of Pharmacy-Bengaluru
RESEARCH INTERESTS
Synthesis of small molecules as anticancer agents
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Snehal Nirgude, Shahana M. V., Febina Ravindran, Sujeet Kumar, Shivangi Sharma, Raghunandan Mahadeva, Anisha Mhatre, Subhas S. Karki, and Bibha Choudhary
MDPI AG
Despite several treatment options for blood cancer, mortality remains high due to relapse and the disease’s aggressive nature. Elevated levels of HSP90, a molecular chaperone essential for protein folding, are associated with poor prognosis in leukemia and lymphoma. HSP90 as a target for chemotherapy has been met with limited success due to toxicity and induction of heat shock. This study tested the activity of an HSP90 inhibitor, SP11, against leukemic cells, mouse lymphoma allograft, and xenograft models. SP11 induced cytotoxicity in vitro in leukemic cell lines and induced cell death via apoptosis, with minimal effect on normal cells. SP11 induced cell death by altering the status of HSP90 client proteins both in vitro and in vivo. SP11 reduced the tumor burden in allograft and xenograft mouse models without apparent toxicity. The half-life of SP11 in the plasma was approximately 2 h. SP11 binding was observed at both the N-terminal and C-terminal domains of HSP90. C-terminal binding was more potent than N-terminal binding of HSP90 in silico and in vitro using isothermal calorimetry. SP11 bioavailability and minimal toxicity in vivo make it a potential candidate to be developed as a novel anticancer agent.
Pravesh M. Jain, Denisse A. Gutierrez, Sujeet Kumar, Renato J. Aguilera, and Subhas S. Karki
Wiley
AbstractA novel series of pyrazole‐oxindole conjugates were prepared and characterized as potential cytotoxic agents by FT‐IR, NMR and HR‐MS. The cytotoxic activity of these compounds was tested in the Jurkat acute T cell leukemia, CEM acute lymphoblastic leukemia, MCF10 A mammary epithelial and MDA‐MB 231 triple negative breast cancer cell lines. Among the tested conjugates, 5‐methyl‐3‐((3‐(1‐phenyl)‐3‐(p‐tolyl)‐1H‐pyrazol‐4‐yl)methylene)indolin‐2‐one 6h emerged as the most cytotoxic with a CC50 of 4.36+/−0.2 μM against Jurkat cells. The mechanism of cell death induced by 6h was investigated through the Annexin V‐FITC assay via flow cytometry. Reactive oxygen species (ROS) accumulation, mitochondrial health and the cell cycle progression were also evaluated in cells exposed to 6h. Results demonstrated that 6h induces apoptosis in a dose‐response manner, without generating ROS and/or altering mitochondrial health. In addition, 6h disrupted the cell cycle distribution causing an increase in DNA fragmentation (Sub G0‐G1), and an arrest in the G0‐G1 phase. Taken together, the 6h compound revealed a strong potential as an antineoplastic agent evidenced by its cytotoxicity in leukemia cells, the activation of apoptosis and restriction of the cell cycle progression.
Nishith Teraiya, Subhas S. Karki, and Ashlesha Chauhan
Bentham Science Publishers Ltd.
Background: Hexahydroquinoline as a small molecule was reported for good cytotoxicity and affinity towards Mcl-1. Hence, new compounds were explored as Mcl-1 inhibitors to be potent anticancer agents. Objective: Compounds were synthesized and screened for cytotoxicity. The active compound was evaluated for cell cycle analysis, Mcl-1 inhibition, caspase-3, and caspase-9 activation. Further compounds were docked with Mcl-1 to confirm the mechanism of cytotoxicity. Methods: Compounds were confirmed by spectral techniques and screened for cytotoxicity at National Cancer Institute (USA). The active derivatives were screened by SRB and MTT. In addition, the potent compound was studied for apoptosis and cell cycle analysis by PI staining, Mcl-1 inhibition by TR-FRET assay, and activation assay of caspase-3 and caspase-9 with the Elisa technique. Results: Compounds 6a and 6b exhibited the highest growth inhibition of 86.28% and 93.20% against SR and HOP- 62, respectively. Compound 6a showed higher cytotoxicity (IC50 = 0.4 μM) against THP-1 and HL-60. It showed 15- fold higher apoptosis compared to control by arresting cells at the Sub-G1 in the cell cycle. It also showed a potent inhibition with IC50 of 1.5 μM against the anti-apoptotic protein Mcl-1, which may induce apoptosis. Furthermore, apoptosis was evidenced by an increase in cleaved caspase-3 and caspase-9 to 4.20 and 3 folds, respectively higher than control. The docking score of compound 6a was in good agreement with the Mcl-1 inhibition assay. Conclusion: Compound 6a inhibited anti-apoptotic protein Mcl-1 and induced activation of pro-apoptotic proteins caspase-3 and caspase-9. These dual results suggested the mechanism of apoptosis and cytotoxicity.
Arnika Das, Giulia Greco, Sujeet Kumar, Elena Catanzaro, R. Morigi, A. Locatelli, D. Schols, Hakan Alici, Hakan Tahtaci, Febina Ravindran,et al.
Lisett Contreras, Stephanie Medina, Austre Y. Schiaffino Bustamante, Edgar A. Borrego, Carlos A. Valenzuela, Umashankar Das, Subhas S. Karki, Jonathan R. Dimmock, and Renato J. Aguilera
Springer Science and Business Media LLC
Abstract Background Cancer is an ongoing worldwide health problem. Although chemotherapy remains the mainstay therapy for cancer, it is not always effective and has detrimental side effects. Here, we present piperidone compounds P3, P4, and P5 that selectively target cancer cells via protein- and stress-mediated mechanisms. Methods We assessed typical apoptotic markers including phosphatidylserine externalization, caspase-3 activation, and DNA fragmentation through flow cytometry. Then, specific markers of the intrinsic pathway of apoptosis including the depolarization of the mitochondria and the generation of reactive oxygen species (ROS) were investigated. Finally, we utilized western blot techniques, RT-qPCR, and observed the cell cycle profile after compound treatment to evaluate the possible behavior of these compounds as proteasome inhibitors. For statistical analyses, we employed the one-way ANOVA followed by Bonferroni post hoc test. Results P3, P4, and P5 induce cytotoxic effects towards tumorigenic cells, as opposed to non-cancerous cells, at the low micromolar range. Compound treatment leads to the activation of the intrinsic pathway of apoptosis. The accumulation of poly-ubiquitinated proteins and the pro-apoptotic protein Noxa, both typically observed after proteasome inhibition, occurs after P3, P4, and P5 treatment. The stress-related genes PMAIP1, ATF3, CHAC1, MYC, and HMOX-1 were differentially regulated to contribute to the cytotoxic activity of P3–P5. Finally, compound P5 causes cell cycle arrest at the G2/M phase. Conclusion Taken together, compounds P3, P4, and P5 exhibit strong potential as anticancer drug candidates as shown by strong cytotoxic potential, activation of the intrinsic pathway of apoptosis, and show typical proteasome inhibitor characteristics.
Nishith Teraiya, Subhas S. Karki, and Ashlesha Chauhan
Bentham Science Publishers Ltd.
Background: Fluorine containing Hexahydroquinoline-3-carbonitrile derivatives were found to have potent cytotoxicity. Further, Fluorine can modulate pharmacokinetic and pharmacodynamic profile of drugs. Hence, new derivatives containing fluorine were explored as potential cytotoxic agents. Objective: Difluoro substituted compounds containing aromatic/heteroaromatic rings were designed, synthesized and screened for in vitro cytotoxicity on cancer cell lines. The active compounds were subjected to docking on Mcl-1 and ADME/T prediction. Methods: The synthesized compounds were characterized using various spectral techniques like FT-IR, 1 H NMR, 13C NMR and Mass spectra. Compounds were screened for cytotoxicity on NCI-60 cell lines at National Cancer Institute. The active compounds were evaluated additionally by MTT and SRB assay. Results: Compounds (6l and 6o) showed maximum cytotoxicity with (% GI) of 69 and 63.7 at 10 µM drug concentration respectively. Compound 6i showed potent cytotoxicity with GI50 of 7.2 µM against Ishikawa cell line. Compound 6o was nearly as active as reference with IC50 of 9.39 µM and 13.54 µM against HT-29 and HCT-116 respectively and compound 6l also showed equal potency to that of reference with IC50 of 9.66 µM against Caco-2. Compounds 6i, 6o and 6l showed high docking score suggesting their cytotoxicity. Further, ADME/T prediction revealed that all the compounds have drug likeness properties. Conclusion: Enhanced lipophilic interaction of compounds due to presence of fluorine in compounds 6i and 6l was revealed during docking study. Compound 6i can be explored as a lead molecule against other endometrial cancer in futuristic drug development.
Jinsha Koroth, Raghunandan Mahadeva, Febina Ravindran, Tanvi R Parashar, Vinay Teja, Subhas S Karki, and Bibha Choudhary
Elsevier BV
E. Vijaya Sekhar, Subhas S. Karki, Javarappa Rangaswamy, Mahesh Bhat, and Sujeet Kumar
Springer Science and Business Media LLC
Abstract Background Sulfonamides (sulfa drugs) and the metals like mercury, copper, and silver bear antimicrobial properties. The discovery of broad-spectrum antibiotics such as penicillins, cephalosporins, and fluoroquinolones has reduced their use. However, in some instances these drugs are the first-line treatment. The metal-based sulfonamide (e.g., silver sulfadiazine) is considered as first choice treatment in post-burn therapy while the use of silver nanoparticle-cephalexin conjugate to cure Escherichia coli infection explains the synergistic effect of sulfa drugs and their metal conjugates. With growing interest in metal-based sulfonamides and the Schiff base chemistry, it was decided to synthesize sulfonamide Schiff base metal complexes as antioxidant and antimicrobial agent. Results The Fe (III), Ru (III), Co (II), Ni (II), Cu (II), Pd (II), Zn (II), Cd (II), and Hg (II) metal complexes of 4-((thiophen-2-ylmethylene)-amino)-benzenesulfonamide (TMABS) were prepared and studied for thermal stability, geometry, and other electronic properties. The ligand TMABS (Schiff base) and its metal complexes were screened in-vitro for 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and antimicrobial properties against Gram-positive (+ve) Bacillus subtilis (MTCC-441), Staphylococcus aureus (MTCC 7443), Gram-negative (-ve) Escherichia coli (MTCC 40), Salmonella typhi (MTCC 3231), and fungal strains Aspergillus niger (MTCC-1344) and Penicillium rubrum by agar well diffusion method. Results summarized in Tables 3, 4, and 5 represent the inhibitory concentration (IC50) in micromole (μM). The zone of inhibition (ZI) in millimeter (mm) represents antimicrobial properties of TMABS and its metal complexes. Conclusions The synthesized sulfanilamide Schiff base (TMABS) behaved as a neutral and bidentate ligand coordinating with metal ions through its azomethine nitrogen and thiophene sulfur to give complexes with coordination number of 4 and 6 (Fig. 3). The nucleophilic addition of sulfanilamide amino group (–NH2) group to carbonyl carbon (>C=O) of benzaldehyde gave sulfanilamide Schiff base (imine) (Fig. 2). All the metal complexes were colored and stable at room temperature. With IC50 of 9.5 ± 0.1 and 10.0 ± 0.7 μM, the Co, Cu, and Pd complexes appeared better antioxidant than the ligand TMABS (155.3±0.1 μM). The zone of inhibition (ZI) of Hg (28 mm) and Ru complexes (20 mm) were similar to the ligand TMABS (20 mm) against Aspergillus niger (MTCC-1344) as in Figs. 4, 5, and 6. None of the synthesized derivatives had shown better antimicrobial properties than the standard streptomycin sulfate and fluconazole.
Choodamani B, Sujeet Kumar, Alok Kumar Gupta, Dominique Schols, Hakan Tahtaci, Tuncay Karakurt, Satvik Kotha, Swapna B, Ramachandra Setty, and Subhas S. Karki
Elsevier BV
Ammankallu Sowmya, Gudibande N. A. Kumar, Sujeet Kumar and S. Karki
B. Choodamani, Karla G. Cano Hernandez, Sujeet Kumar, Ann Maria Tony, Austre Y. Schiaffino Bustamante, Renato J. Aguilera, Dominique Schols, C. Gopi Mohan, and Subhas S. Karki
Wiley
In this study, we synthesized 22 compounds in a series with various substitution on imidazo[2,1‐b][1,3,4]thiadiazole. The potential cytotoxic activity of these compounds investigated in leukemia cell lines by Differential Nuclear Staining (DNS). Our results identified two compounds, 2‐(4‐methoxybenzyl)‐6‐(2‐oxo‐2H‐chromen‐3‐yl)imidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl thiocyanate and 6‐(4‐chlorophenyl)‐2‐(4‐methoxybenzyl)imidazo[2,1‐b][1,3,4]thiadiazole‐5‐carbaldehyde, exhibited the most cytotoxic effect against murine leukemia cells (L1210), human T‐lymphocyte cells (CEM) and human cervix carcinoma cells (HeLa) with IC50 values ranging between 0.79 and 1.6 μM. The results indicate that 2‐(4‐methoxybenzyl)‐6‐(2‐oxo‐2H‐chromen‐3‐yl)imidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl thiocyanate is inducing phosphatidylserine externalization and caspase‐3 activation which are both a hallmark of apoptosis. Docking studies showed that 2‐(4‐methoxybenzyl)‐6‐(2‐oxo‐2H‐chromen‐3‐yl)imidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl thiocyanate binds within the active sites of transforming growth factor beta (TGF‐β) type I receptor kinase domain by strong hydrogen binding and hydrophobic interactions.
Arnika Das, Sujeet Kumar, Leentje Persoons, Dirk Daelemans, Dominique Schols, Hakan Alici, Hakan Tahtaci, and Subhas S. Karki
Elsevier BV
Snehal Nirgude, Raghunandan Mahadeva, Jinsha Koroth, Sujeet Kumar, Kothanahally S. Sharath Kumar, Vidya Gopalakrishnan, Subhas S Karki, and Bibha Choudhary
MDPI AG
Purpose: Curcumin is known for its anticancer and migrastatic activity in various cancers, including breast cancer. Newer curcumin derivatives are being explored to overcome limitations of curcumin like low bioavailability, stability, and side effects due to its higher dose. In this study, the synthesis of ST09, a novel curcumin derivative, and its antiproliferative, cytotoxic, and migrastatic properties have been explored both in vitro and in vivo. Methods: After ST09 synthesis, anticancer activity was studied by performing standard cytotoxicity assays namely, lactate dehydrogenase (LDH) release assay, 3-(4, 5-dimethylthiazol-2-yl)-2–5-diphenyletrazolium bromide (MTT), and trypan blue exclusion assay. Annexin-FITC, cell cycle analysis using flow cytometry, and Western blotting were performed to elucidate cell death mechanisms. The effect on the inhibition of cell migration was studied by transwell migration assay. An EAC (Ehrlich Ascites carcinoma) induced mouse tumor model was used to study the effect of ST09 on tumor regression. Drug toxicity was measured using aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and flow-cytometry based lymphocyte count. Histological analysis was performed for assessment of any tissue injury post ST09 treatment. Results: ST09 shows an approximate 100-fold higher potency than curcumin, its parent compound, on breast tumor cell lines MCF-7 and MDA-MB231. ST09 arrests the cell cycle in a cell type-specific manner and induces an intrinsic apoptotic pathway both in vitro and in vivo. ST09 inhibits migration by downregulating matrix metalloprotease 1,2 (MMP1,2) and Vimentin. In vivo, ST09 administration led to decreased tumor volume in a mouse allograft model by boosting immunity with no significant drug toxicity. Conclusion: ST09 exhibits antiproliferative and cytotoxic activity at nanomolar concentrations. It induces cell death by activation of the intrinsic pathway of apoptosis both in vitro and in vivo. It also inhibits migration and invasion. This study provides evidence that ST09 can potentially be developed as a novel antitumor drug candidate for highly metastatic and aggressive breast cancer.
A. Sowmya, G.N. Anil Kumar, Sujeet Kumar, and Subhas S. Karki
Elsevier BV
Jinsha Koroth, Snehal Nirgude, Shweta Tiwari, Vidya Gopalakrishnan, Raghunandan Mahadeva, Sujeet Kumar, Subhas S. Karki, and Bibha Choudhary
Springer Science and Business Media LLC
Abstract Background Curcumin is known for its multitude of medicinal properties, including anti-cancer and migrastatic activity. Efforts to overcome poor bioavailability, stability, and side effects associated with the higher dose of curcumin has led to the development of newer derivatives of curcumin. Thus, the focus of this study is to screen novel curcumin derivatives, namely ST03 and ST08, which have not been reported before, for their cytotoxicity and migrastatic property on cancer cells. Methods Anti-cancer activity of ST03 and ST08 was carried out using standard cytotoxicity assays viz., LDH, MTT, and Trypan blue on both solid and liquid cancer types. Flow cytometric assays and western blotting was used to investigate the cell death mechanisms. Transwell migration assay was carried out to check for migrastatic properties of the compounds. Results Both the compounds, ST03 and ST08, showed ~ 100 fold higher potency on liquid and solid tumour cell lines compared to its parent compound curcumin. They induced cytotoxicity by activating the intrinsic pathway of apoptosis in the breast (MDA-MB-231) and ovarian cancer cell lines (PA-1) bearing metastatic and stem cell properties, respectively. Moreover, ST08 also showed inhibition on breast cancer cell migration by inhibiting MMP1 (matrix metalloproteinase 1). Conclusion Both ST03 and ST08 exhibit anti-cancer activity at nanomolar concentration. They induce cell death by activating the intrinsic pathway of apoptosis. Also, they inhibit migration of the cancer cells by inhibiting MMP1 in breast cancer cells.
Kalaimathi Murugesan, Jinsha Koroth, Padma Priya Srinivasan, Amrita Singh, Sanjana Mukundan, Subhas S Karki, Bibha Choudhary, and Chhitar M Gupta
Informa UK Limited
Background In recent years, green synthesized silver nanoparticles have been increasingly investigated for their anti-cancer potential. In the present study, we aimed at the biosynthesis of silver nanoparticles (AgNPs) using a curcumin derivative, ST06. Although, the individual efficacies of silver nanoparticles or curcumin derivatives have been studied previously, the synergistic cytotoxic effects of curcumin derivative and silver nanoparticles in a single nanoparticulate formulation have not been studied earlier specifically on animal models. This makes this study novel compared to the earlier synthesized curcumin derivative or silver nanoparticles studies. The aim of the study was to synthesize ST06 coated silver nanoparticles (ST06-AgNPs) using ST06 as both reducing and coating agent. Methods The synthesized nanoparticles AgNPs and ST06-AgNPs were characterised for the particle size distribution, morphology, optical properties and surface charge by using UV-visible spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Elemental composition and structural properties were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). The presence of ST06 as capping agent was demonstrated by Fourier transform infrared spectroscopy (FTIR). Results The synthesized nanoparticles (ST06-AgNPs) were spherical and had a size distribution in the range of 50–100 nm. UV-Vis spectroscopy displayed a specific silver plasmon peak at 410 nm. The in vitro cytotoxicity effects of ST06 and ST06-AgNPs, as assessed by MTT assay, showed significant growth inhibition of human cervical cancer cell line (HeLa). In addition, studies carried out in EAC tumor-induced mouse model (Ehrlich Ascites carcinoma) using ST06-AgNPs, revealed that treatment of the animals with these nanoparticles resulted in a significant reduction in the tumor growth, compared to the control group animals. Conclusion In conclusion, green synthesized ST06-AgNPs exhibited superior anti-tumor efficacy than the free ST06 or AgNPs with no acute toxicity under both in vitro and in vivo conditions. The tumor suppression is associated with the intrinsic apoptotic pathway. Together, the results of this study suggest that ST06-AgNPs could be considered as a potential option for the treatment of solid tumors.
A. Sowmya, G.N. Anil Kumar, Sujeet Kumar, and Subhas S. Karki
Elsevier BV
Supriya V. Vartak, Hassan A. Swarup, Vidya Gopalakrishnan, Vindya K. Gopinatha, Virginie Ropars, Mridula Nambiar, Franklin John, Sharath Kumar S. Kothanahally, Rupa Kumari, Nitu Kumari,et al.
Wiley
Nonhomologous DNA end joining (NHEJ) is the major DNA double‐strand break (DSB) repair pathway in mammals. Previously, we have described a small molecule inhibitor, SCR7, which can inhibit NHEJ in a Ligase IV‐dependent manner. Administration of SCR7 within the cells resulted in the accumulation of DNA breaks, cell death, and inhibition of tumor growth in mice. In the present study, we report that parental SCR7, which is unstable, can be autocyclized into a stable form. Both parental SCR7 and cyclized SCR7 possess the same molecular weight (334.09) and molecular formula (C18H14N4OS), whereas its oxidized form, SCR7‐pyrazine, possesses a different molecular formula (C18H12N4OS), molecular weight (332.07), and structure. While cyclized form of SCR7 showed robust inhibition of NHEJ in vitro, both forms exhibited efficient cytotoxicity. Cyclized and oxidized forms of SCR7 inhibited DNA end joining catalyzed by Ligase IV, whereas their impact was minimal on Ligase III, Ligase I, and T4 DNA Ligase‐mediated joining. Importantly, both forms inhibited V(D)J recombination, although the effect was more pronounced for SCR7‐cyclized. Both forms blocked NHEJ in a Ligase IV‐dependent manner leading to the accumulation of DSBs within the cells. Although cytotoxicity due to SCR7‐cyclized was Ligase IV specific, the pyrazine form exhibited nonspecific cytotoxicity at higher concentrations in Ligase IV‐null cells. Finally, we demonstrate that both forms can potentiate the effect of radiation. Thus, we report that cyclized and oxidized forms of SCR7 can inhibit NHEJ in a Ligase IV‐dependent manner, although SCR7‐pyrazine is less specific to Ligase IV inside the cell.
Supriya V. Vartak, Divyaanka Iyer, T.R. Santhoshkumar, Sheetal Sharma, Archita Mishra, Gunaseelan Goldsmith, Mrinal Srivastava, Shikha Srivastava, Subhas S. Karki, Avadhesha Surolia,et al.
Elsevier BV
Monica Pandey, Sujeet Kumar, Gunaseelan Goldsmith, Mrinal Srivastava, Santhini Elango, Mohammad Shameem, Dibyendu Bannerjee, Bibha Choudhary, Subhas S. Karki, and Sathees C. Raghavan
Wiley
The terminal step of ligation of single and/or double‐strand breaks during physiological processes such as DNA replication, repair and recombination requires participation of DNA ligases in all mammals. DNA Ligase I has been well characterised to play vital roles during these processes. Considering the indispensable role of DNA Ligase I, a therapeutic strategy to impede proliferation of cancer cells is by using specific small molecule inhibitors against it. In the present study, we have designed and chemically synthesised putative DNA Ligase I inhibitors. Based on various biochemical and biophysical screening approaches, we identify two prospective DNA Ligase I inhibitors, SCR17 and SCR21. Both the inhibitors blocked ligation of nicks on DNA in a concentration‐dependent manner, when catalysed by cell‐free extracts or purified Ligase I. Docking studies in conjunction with biolayer interferometry and gel shift assays revealed that both SCR17 and SCR21 can bind to Ligase I, particularly to the DNA Binding Domain of Ligase I with KD values in nanomolar range. The inhibitors did not show significant affinity towards DNA Ligase III and DNA Ligase IV. Further, addition of Ligase I could restore the joining, when the inhibitors were treated with testicular cell‐free extracts. Ex vivo studies using multiple assays showed that even though cell death was limited in the presence of inhibitors in cancer cells, their proliferation was compromised. Hence, we identify two promising DNA Ligase I inhibitors, which can be used in biochemical and cellular assays, and could be further modified and optimised to target cancer cells. © 2016 Wiley Periodicals, Inc.
Eshwari Addala, Hossein Rafiei, Swagatika Das, Brian Bandy, Umashankar Das, Subhas S. Karki, and Jonathan R. Dimmock
Elsevier BV
Supriya V. Vartak, Mahesh Hegde, Divyaanka Iyer, Snehal Gaikwad, Vidya Gopalakrishnan, Mrinal Srivastava, Subhas S. Karki, Bibha Choudhary, Pritha Ray, T.R. Santhoshkumar,et al.
Elsevier BV
Elizabeth Thomas, Vidya Gopalakrishnan, Mahesh Hegde, Sujeet Kumar, Subhas S. Karki, Sathees C. Raghavan, and Bibha Choudhary
Springer Science and Business Media LLC
Resveratrol is one of the most widely studied bioactive plant polyphenols which possesses anticancer properties. Previously we have reported synthesis, characterization and identification of a novel resveratrol analog, SS28. In the present study, we show that SS28 induced cytotoxicity in several cancer cell lines ex vivo with an IC50 value of 3–5 μM. Mechanistic evaluation of effect of SS28 in non-small cell lung cancer cell line (A549) and T-cell leukemic cell line (CEM) showed that it inhibited Tubulin polymerization during cell division to cause cell cycle arrest at G2/M phase of the cell cycle at 12–18 h time period. Immunofluorescence studies confirmed the mitotic arrest upon treatment with SS28. Besides, we show that SS28 binds to Tubulin with a dissociation constant of 0.414 ± 0.11 μM. Further, SS28 treatment resulted in loss of mitochondrial membrane potential, activation of Caspase 9 and Caspase 3, leading to PARP-1 cleavage and finally cell death via intrinsic pathway of apoptosis. Importantly, treatment with SS28 resulted in regression of tumor in mice. Hence, our study reveals the antiproliferative activity of SS28 by disrupting microtubule dynamics by binding to its cellular target Tubulin and its potential to be developed as an anticancer molecule.
Divyaanka Iyer, Supriya V. Vartak, Archita Mishra, Gunaseelan Goldsmith, Sujeet Kumar, Mrinal Srivastava, Mahesh Hegde, Vidya Gopalakrishnan, Mark Glenn, Mahesh Velusamy,et al.
Wiley
The antiapoptotic protein BCL2 is overexpressed in several cancers and contributes to prolonged cell survival and chemoresistance, lending itself as an excellent target for cancer therapy. Here, we report the design, synthesis, and characterization of Disarib, a novel BCL2 inhibitor. Disarib showed selective cytotoxicity in BCL2 high cancer cell lines, and CLL patient primary cells, as compared to BCL2 low cell lines. BCL2 knockdown in cells rendered remarkable resistance to Disarib, while sensitivity was regained upon its ectopic expression, establishing target specificity. In silico, biochemical and biophysical studies demonstrated strong affinity of Disarib to BCL2, but not to other antiapoptotic BCL2 family members viz., BCL‐xL, BCL2A1 etc. Interestingly, biophysical studies showed that BH1 domain deletion mutant demonstrated ~ 67‐fold reduction in BCL2‐Disarib interaction, while it was only ~ 20‐fold in the case of BH3 deletion mutant, suggesting predominant involvement of the BH1 domain for Disarib binding. Thus, we report identification of a novel BCL2 inhibitor with a unique mechanism of BCL2 inhibition, as opposed to the well‐studied BH3 domain targeting.