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In this study, a series of shikonin derivatives combined with benzoylacrylic had been designed and synthesized, which showed an inhibitory effect on both tubulin and the epidermal growth factor receptor (EGFR). In vitro EGFR and cell growth inhibition assay demonstrated that compound PMMB-317 exhibited the most potent anti-EGFR (IC 50  = 22.7 nM) and anti-proliferation activity (IC 50  = 4.37 μM) against A549 cell line, which was comparable to that of Afatinib (EGFR, IC 50  = 15.4 nM; A549, IC 50  = 6.32 μM). Our results on mechanism research suggested that, PMMB-317 could induce the apoptosis of A549 cells in a dose- and time-dependent manner, along with decrease in mitochondrial membrane potential (MMP), production of ROS and alterations in apoptosis-related protein levels. Also, PMMB-317 could arrest cell cycle at G2/M phase to induce cell apoptosis, and inhibit the EGFR activity through blocking the signal transduction downstream of the mitogen-activated protein MAPK pathway and the anti-apoptotic kinase AKT pathway; typically, such results were comparable to those of afatinib. In addition, PMMB-317 could suppress A549 cell migration through the Wnt/β-catenin signaling pathway in a dose-dependent manner. Additionally, molecular docking simulation revealed that, PMMB-317 could simultaneously combine with EGFR protein (5HG8) and tubulin (1SA0) through various forces. Moreover, 3D-QSAR study was also carried out, which could optimize our compound through the structure-activity relationship analysis. Furthermore, the in vitro and in vivo results had collectively confirmed that PMMB-317 might serve as a promising lead compound to further develop the potential therapeutic anticancer agents., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Naturally occurring naphthoquinones, usually in forms of botanical extracts, have been implicated with human life since ancient time, far earlier than their isolation and identification in modern era. The long use history of naphthoquinones has witnessed their functional shift from the original purposes as dyes and ornaments toward medicinal benefits. Hitherto, numerous studies have been carried out to elucidate the pharmacological profile of both natural and artificial naphthoquinones. A number of entities have been identified with promising therapeutic potential. Apart from the traditional effects of wound healing, anti-inflammatory, hemostatic, antifertility, insecticidal and antimicrobial, etc., the anticancer potential of naphthoquinones either in combination with other treatment approaches or on their own is being more and more realized. The molecular mechanisms of naphthoquinones in cells mainly fall into two categories as inducing oxidant stress by ROS (reactive oxygen species) generation and directly interacting with traditional therapeutic targets in a non-oxidant mechanism. Based on this knowledge, optimized agents with naphthoquinones scaffold have been acquired and further tested. Hereby, we summarize the explored biological mechanisms of naphthoquinones in cells and review the application perspective of promising naphthoquinones in cancer therapies., (© 2017 John Wiley & Sons A/S.)

Shikonin exhibits powerful anticancer activities for various cancer cells, but its poor solubility and strong toxicity hinder its development as clinical anticancer agent. We previously confirmed that shikonin and its derivatives can disturb mitosis through targeting tubulin. In this study, α-lipoic acid, the naturally-occurring co-factor of pyruvate dehydrogenase (PDH), was introduced into shikonin to design the twin drugs against both mitosis (tubulin) and glycolysis (PDK). 18 kinds of α-lipoic acid shikonin ester derivatives were achieved through three rounds of screening process performed by computer assistant drug design method, being designated as the outstanding compounds. Among them, 1c displayed the most potent cytotoxicity towards cervical cancer cells (HeLa) with an IC 50 value of 3.14 ± 0.58 μM and inhibited xenotransplanted tumor growth in a dose-dependent manner. Further pharmacologic study demonstrated that 1c can cause cell cycle arrest in G2/M phase as tubulin polymerization inhibitor. Moreover, it also showed good PDK1 inhibitory activity, promoting PDH activity and forced HeLa cells to process more aerobic metabolism to undergo cell apoptosis. We reported here the first dual inhibitors of tubulin and PDK1 based on shikonin. It may form a basis for shikonin optimization through twin drug design framework for the discovery of new and potent shikonin derivatives in the study of targeted cancer therapy., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

In current study, a series of shikonin derivatives were synthesized and its anticancer activity was evaluated. As a result, PMMB232 showed the best antiproliferation activity with an IC 50 value of 3.25±0.35μM. Further, treatment of HeLa cells with a variety of concentrations of target drug resulted in dose-dependent event marked by apoptosis. What's more, the mitochondrial potential (Δym) analysis was consistent with the apoptosis result. In addition, PARP was involved in the progress of apoptosis revealed by western blotting. To identify the detailed role and mechanism of PMMB232 in the progression of human cervical cancer, we detected the expression of HIF-1α and E-cadherin in HeLa cells. Results showed that expression of HIF-1α was downregulated, while E-cadherin protein was upregulated. Meanwhile, glycolysis related protein PDK1 was decreased in HeLa cells. Conversely, the expression of PDH-E1α was upregulated. Docking simulation results further indicate that PMMB232 could be well bound to HIF-1α. Taken together, our data indicate that compound PMMB232 could be developed as a potential anticancer agent., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

The signal transducer and activator of transcription 3 is a constitutively activated oncogenic protein in various human tumors and represents a valid target for anticancer drug design. In this study, we have achieved a new type of STAT3 inhibitors based on structural modifications on shikonin scaffold, guided by computational modelling. By tests, PMMB-187 exhibited a more outstanding profile than shikonin on a small panel of human breast cancer cells, especially for the MDA-MB-231 cells. For the cellular mechanisms research, PMMB-187 was found to induce cell apoptosis in MDA-MB-231 cells, associated with the reduction of mitochondrial membrane potential, production of ROS and alteration of the levels of apoptosis-related proteins. Furthermore, PMMB-187 inhibited constitutive/inducible STAT3 activation, transcriptional activity, nuclear translocation and downstream target genes expression in STAT3-dependent breast cancer cells MDA-MB-231. Besides, no obvious inhibitory effect on activation of STAT1 and STAT5 was observed with PMMB-187 treatment. Most notably, the in vivo studies further revealed that PMMB-187 could dramatically suppress the MDA-MB-231 cells xenografted tumor growth. The in vitro and in vivo results collectively suggest that PMMB-187 may serve as a promising lead compound for the further development of potential therapeutic anti-neoplastic agents., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The flavonoid quercetin exhibits significant anticancer activities with few side effects. In the current study, we characterized TL-2-8, a quercetin derivative, as a novel anticancer agent in vitro and in vivo. Cell proliferation and viability were assessed using Cell Counting Kit-8 and CellTiter-Blue assay, respectively. Cell death was examined using PI staining or a TUNEL assay. Mitophagy was determined by measuring autophagic flux and by confocal imaging. Protein expression was examined by Western blotting. We found that TL-2-8 selectively inhibited the proliferation and decreased the viability of various cancer cells (the anti-proliferation IC50 values in MDA-MB-231, MDA-MB-468 and MCF-7 breast cancer cells at 72 h were 8.28, 8.56, and 9.58 μmol/L, respectively), and it displayed only slight cytotoxicity against normal MCF-10A and HEK-293 cells. In MDA-MB-231 and MDA-MB-468 breast cancer cells, TL-2-8 treatment induced the degradation of multiple Hsp90 client proteins without inducing Hsp70. TL-2-8 (3, 6, 12 μmol/L) dose-dependently inhibited the expression of AHA1, an activator of Hsp90 ATPase, and decreased Hsp90-AHA1 complex formation, leading to decreased Hsp90 chaperone function and reduced polo-like kinase 1 (PLK1) signaling. Consequently, impaired mitophagy was induced via the downregulation of lysosomal-associated membrane protein 2 (LAMP2). The in vivo anticancer effects of TL-2-8 were evaluated in an MDA-MB-231 breast cancer xenograft model, which was treated with TL-2-8 (25, 50, 100 mg·kg -1 ·d -1 , po). Administration of TL-2-8 resulted in tumor growth inhibition rates of 37.9%, 58.9% and 70.9%, respectively, whereas quercetin treatment (100 mg·kg -1 ·d -1 , po) produced only a lower tumor growth inhibition rate (49.5%). Furthermore, TL-2-8 treatment significantly extended the lifespan of mice bearing MDA-MB-231 breast cancer cell xenografts. Our results demonstrate that TL-2-8 induces significant cell death and immature mitophagy in breast cancer cells in vitro and in vivo via AHA1 abrogation.

In this paper, a series of podophyllotoxin piperazine acetate ester derivatives were synthesized and investigated due to their antiproliferation activity on different human cancer cell lines. Among the congeners, C5 manifested prominent cytotoxicity towards the cancer cells, without causing damage on the non-cancer cells through inhibiting tubulin assembly and having high selectively causing damage on the human breast (MCF-7) cell line (IC 50 =2.78±0.15μM). Treatments of MCF-7 cells with C5 resulted in cell cycle arrest in G2/M phase and microtubule network disruption. Moreover, regarding the expression of cell cycle relative proteins CDK1, a protein required for mitotic initiation was up-regulated. Besides, Cyclin A, Cyclin B1 and Cyclin D1 proteins were down-regulated. Meanwhile, it seems that the effect of C5 on MCF-7 cells apoptosis inducing was observed to be not obvious enough. In addition, docking analysis demonstrated that the congeners occupy the colchicine binding pocket of tubulin., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The advancement of cancer-fighting drugs has never been a simple linear process. Those drug design professionals begin to find inspiration from the nature after failing to find the ideal products by creative drug design and high-throughput screening. To obtain new molecules for inhibiting tubulin, podophyllotoxin was adopted as the leading compound and 1,3,4-oxadiazole was brought in to the C-4 site of podophyllotoxin in this research. A series of seventeen podophyllotoxin-derived esters have been achieved and then evaluated their antitumor activities against four different cancer cell lines: A549, MCF-7, HepG2, and HeLa. Among all the compounds, compound 7c showed the best antiproliferating properties with IC 50  = 2.54 ± 0.82 μm against MCF-7 cancer cell line. It was obvious that the content of ROS grew significantly in MCF-7 in a way depending on the dosage. The time- and dose-dependent cell cycle assays revealed that compound 7c could apparently block cell cycle in the phase of G2/M along with the upregulation of cyclin A2 and CDK2 protein. According to further studies, confocal microscopy experiment has certified that compound 7c could restrain cancer from growing by blocking the polymerization of microtubule. Meanwhile, compound 7c could be ideally integrated with the colchicine site of tubulin. In future, it would be feasible to selectively design tubulin inhibitors with the help of 3D-QSAR. This means that it is hopeful to develop compound 7c as a potential agent against cancer due to its biological characteristics., (© 2017 John Wiley & Sons A/S.)

Signal transducer and activator of transcription 3 (STAT3) is hyper-activated in diversiform human tumors and has been validated as an attractive therapeutic target. Current research showed that a natural product, shikonin, along with its synthetic analogues, is able to inhibit the activity of STAT3 potently. The potential space of shikonin in developing novel anti-cancer agents encouraged us to carry out the investigation of the probable binding mode with STAT3. From this foundation, we have designed new types of STAT3 SH2 inhibitors. Combined simulations were performed to filter for the lead compound, which was then substituted, synthesized and evaluated by a variety of bioassays. Among the entities, PMM-172 exhibited the best anti-proliferative activity against MDA-MB-231 cells with IC 50 value 1.98 ± 0.49 μM. Besides, it was identified to decrease luciferase activity, induce cell apoptosis and reduce mitochondrial transmembrane potential in MDA-MB-231 cells. Also, PMM-172 inhibited constitutive/inducible STAT3 activation without affecting STAT1 and STAT5 in MDA-MB-231 cells, and had no effect in non-tumorigenic MCF-10A cells. Moreover, PMM-172 suppressed STAT3 nuclear localization and STAT3 downstream target genes expression. Overall, these results indicate that the antitumor activity of PMM-172 is at least partially due to inhibition of STAT3 in breast cancer cells.

The biological importance of microtubules in mitosis makes them an interesting target for the development of anticancer agents. In this study, a series of novel chalcone-containing shikonin derivatives was designed, synthesized, and evaluated for biological activities. Among them, derivative PMMB-259 [(R)-1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-en-1-yl (E)-2-(4-(3-oxo-3-(3-(trifluoromethoxy)phenyl)prop-1-en-1-yl)phenoxy)acetate] was identified as a potent inhibitor of tubulin polymerization. Further investigation confirmed that PMMB-259 can induce MCF-7 cell apoptosis, reduce the mitochondrial transmembrane potential, and arrest the cell cycle at the G 2 /M phase. Moreover, the morphological variation of treated cells was visualized by confocal microscopy. The results, along with docking simulations, further indicated that PMMB-259 can bind well to tubulin at the colchicine site. Overall, these studies may provide a new molecular scaffold for the further development of antitumor agents that target tubulin., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this study, we designed and synthesized eighteen podophyllotoxin-norcantharidin hybrid drugs which could exhibit more potent anti-cancer activity than the parent drugs. Through the anti-proliferation assay, the most potent anti-cancer agent was screened out, namely Q9 (IC50=0.88±0.18μM against MCF-7 cell line), and it showed lower cytotoxicity against non-cancer cells, human embryonic kidney cells (293T) (IC50=54.38±3.78μM). Additionally, based on the flow cytometry analysis result, it can cause a remarkable cell cycle arrest at G2/M phase and induce apoptosis in MCF-7 cells more significantly than podophyllotoxin or norcantharidin per se. Moreover, the expression of cell cycle relative protein CDK1 was up regulated while a protein required for mitotic initiation, Cyclin B1 was down regulated. Furthermore, according to the confocal microscopy observation results, it was shown that Q9 was a potent tubulin polymerization inhibitor and the effect is comparable to that of colchicine. For further investigation on the aforementioned mechanisms, we performed western blot experiments, thus finding the increase of the cleavage of PARP. Consistent with these new findings, molecular docking observations suggested that compound Q9 could be developed as a potential anticancer agent., (Copyright © 2016. Published by Elsevier Ltd.)

COX-2 has long been exploited in the treatment of inflammation and relief of pain; however, research increasingly suggests COX-2 inhibitors might possess potential benefits to thwart tumour processes. In the present study, we designed a series of novel COX-2 inhibitors based on analysis of known inhibitors combined with an in silico scaffold modification strategy. A docking simulation combined with a primary screen in vitro were performed to filter for the lead compound, which was then substituted, synthesized and evaluated by a variety of bioassays. Derivative 4d was identified as a potent COX-2 enzyme inhibitor and exerted an anticancer effect through COX-2 inhibition. Further investigation confirmed that 4d could induce A549 cell apoptosis and arrest the cell cycle at the G2/M phase. Moreover, treatment with 4d reduced A549 cell adhesive ability and COX-2 expression. The morphological variation of treated cells was also visualized by confocal microscopy. Overall, the biological profile of 4d suggests that this compound may be developed as a potential anticancer agent., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The high incidence of cancer and the side effects of traditional anticancer drugs motivate the search for new and more effective anticancer drugs. In this study, we synthesized 17 kinds of aryl dihydrothiazol acyl shikonin ester derivatives and evaluated their anticancer activity through MTT assay. Among them, C13 showed better antiproliferation activity with IC50=3.14 ± 0.21 μM against HeLa cells than shikonin (IC50=5.75 ± 0.47 μM). We then performed PI staining assay, cell cycle distribution, and cell apoptosis analysis for C13 and found that it can cause cell arrest in G2/M phase, which leads to cell apoptosis. This derivative can also reduce the adhesive ability of HeLa cells. Docking simulation and confocal microscopy assay results further indicated that C13 could bind well to the tubulin at paclitaxel binding site, leading to tubulin polymerization and mitotic disruption., (Copyright © 2015 Elsevier Inc. All rights reserved.)

In this study, a shikonin ester derivative, compound , was selected to evaluate its anticancer activities and we found that compound exhibited better antitubulin activities against the human HepG2 cell line with an IC50 value of 1.097 μM. Furthermore, the inhibition of tubulin polymerization results indicated that compound demonstrated the most potent antitubulin activity (IC50  = 13.88), which was compared with shikonin and colchicine as positive controls (IC50  = 25.28 μM and 22.56 μM), respectively. Compound was simulated to have good binding site with tubulin and arrested the cell cycle at G2/M phase, which also induces apoptosis in HepG2 cells, in which P53 and members of Bcl-2 protein family were both involved in the progress of apoptosis revealed by western blot. Confocal microscopy observations revealed compound targeted tubulin and altered its polymerization by interfering with microtubule organization. Based on these results, compound functions as a potent anticancer agent targeting tubulin., (© 2015 Wiley Periodicals, Inc.)

In this study, we report the identification of a new shikonin-phenoxyacetic acid derivative, as an inhibitor of tubulin. A series of compounds were prepared; among them, compound 16 [(R)-1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-enyl 2-(4- phenoxyphenyl) acetate] potently inhibited the function of microtubules, inducing cell growth inhibition, apoptosis of cancer cell lines in a concentration and time-dependent manner. Molecular docking involving 16 at the vinblastine binding site of tubulin indicated that a phenoxy moiety interacted with tubulin via hydrogen bonding with asparaginate (Asn) and tyrosine (Tyr). Analysis of microtubules with confocal microscopy demonstrated that 16 altered the microtubule architecture and exhibited a significant reduction in microtubule density. Cell cycle assay further proved that HepG2 cells were blocked in G2/M phase. Our study provides a new, promising compound for the development of tubulin inhibitors by proposing a new target for the anticancer activity of shikonin., (© 2014 John Wiley & Sons A/S.)

A series of novel 2-(1,3-diaryl- 4,5-dihydro-1H-pyrazol-5-yl)phenol derivatives (C1-C24) have been synthesized. The B-Raf inhibitory activity and anti-proliferation activity of these compounds have been tested. Compound C6 displayed the most potent biological activity against B-RafV600E (IC50 = 0.15 µM) and WM266.4 human melanoma cell line (GI50 = 1.75 µM), being comparable with the positive control (Vemurafenib and Erlotinib) and more potent than our previous best compounds. The docking simulation was performed to analyze the probable binding models and poses while the QSAR model was built to check the previous work as well as to introduce new directions. This work aimed at seeking more potent inhibitors as well as discussing some previous findings. As a result, the introduction of ortho-hydroxyl group on 4,5-dihydro-1H-pyrazole skeleton did reinforce the anti-tumor activity while enlarging the group on N-1 of pyrazoline was also helpful.

A series of shikonin derivatives, selectively acylated by various fluorinated carboxylic acids at the side chain of shikonin, were synthesized and their anticancer activity evaluated, in which eight compounds are reported for the first time. Among all the compounds tested, compound showed the most potent anticancer activity against B16-F10 (malignant melanoma cells), MG63 (human osteosarcoma cells), and A549 (lung cancer cells) with IC50 0.39 ± 0.01, 0.72 ± 0.04 and 0.58 ± 0.02 µmol/L. Docking simulation of compound was carried out to position into a tubulin active site to determine the probable binding conformation. All the results suggested that compound may be a potential anticancer agent., (Copyright © 2013 Wiley Periodicals, Inc.)

It was discovered that a number of cyclin dependent kinase inhibitors containing the pyrazole core structure exhibited high inhibitory potency against broad-range CDKs and corresponding anti-proliferative activities. This information guided us to design and synthesize a series of 1,3-diphenyl-N-(phenylcarbamothioyl)-1H-pyrazole-4-carboxamide derivatives (5a-10d), and evaluate their biological activities as CDKs inhibitors. Among all the synthesized compounds, compound 10b inhibited CDK2 with an IC50 value of 25 nM, counteracting tumor cell proliferation of three cancer cell lines (H460, MCF-7, A549) in the micromolar range (from 0.75 μM to 4.21 μM), In addition, flow cytometry indicated that compound 10b could induce cycle G0/G1 phase arrest in A549 cells with a dose dependent. Taken together, compound 10b could be selected for further preclinical evaluation., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

1,3,4-Oxadiazole derivatives have drawn continuing interest over the years because of their varied biological activities. In order to search for novel anticancer agents, we designed and synthesized a series of new 1,3,4-oxadiazole derivatives containing benzotriazole moiety as potential focal adhesion kinase (FAK) inhibitors. All the synthesized compounds were firstly reported. Among the compounds, compound 4 shows the most potent inhibitory activity against MCF-7 and HT29 cell lines with IC50 values of 5.68 μg/ml and 10.21 μg/ml, respectively. Besides, all the compounds were assayed for FAK inhibitory activity using the TRAP-PCR-ELISA assay. The results showed compound 4 exhibited the most potent FAK inhibitory activity with IC50 values of 1.2±0.3 μM. Docking simulation by positioning compound 4 into the FAK structure active site was performed to explore the possible binding mode. Apoptosis which was analyzed by flow cytometry, demonstrated that compound 4 induced apoptosis against MCF-7 cells. Therefore, compound 4 may be a potential anticancer agent against MCF-7 cancer cell., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Inducing apoptosis is an important and promising therapeutic approach to overcome cancer. Here, we described a series of novel synthesized compounds, cinnamic acyl shikonin derivatives (1b-19b), which were synthesized starting from shikonin and cinnamic acids, which exhibit anticancer activity via inducing apoptosis in vitro. Our flow cytometry results showed that compound 8b((E)-1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent -3-enyl-3-(3-(trifluoromethyl) phenyl)acrylate) (IC(50) = 0.69, 0.65, 1.62 μM for human SW872-s, A875 and A549 cell lines, respectively) exhibited conspicuous anticancer activities and has low cell toxicity in vitro. Therefore, we considered that compound 8b is potentially to be a candidate of anticancer agent. The proliferation inhibitory effect of compound 8b was associated with its apoptosis-inducing effect by activating caspase-3, caspase-7, caspase-9, and PARP. When the level of cleaved caspase-3, cleaved caspase-7, cleaved caspase-9, and cleaved PARP are rise, apoptosis of cancer cells will be induced., (© 2012 John Wiley & Sons A/S.)

The kinesin spindle protein (KSP) is involved in the formation of bipolar mitotic spindle during cell division and it becomes a new target to overcome the neurotoxicity of MTs inhibitors. A series of flavone and isoflavone derivatives (1a-7c) have been designed, synthesized and evaluated as potential KSP inhibitors. Among them, 2c displayed the most potent inhibitory activity in vitro, which inhibited the growth of MCF-7 and Hela cell lines with IC50 values of 4.8 and 4.3 μM, respectively, and also exhibited significant KSP inhibitory activity (IC₅₀ = 0.023 μM). The new compounds can induce irregular monoastral spindles, the characteristic phenotype for KSP inhibiting agents. Docking simulation was further performed to determine the probable binding model., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Background: Tamoxifen (TAM) is a cell type-specific anti-estrogen and is applied to improve the survival of patients with estrogen receptor positive (ER +) breast cancer. However, long-term TAM use can induce serious drug resistance, leading to breast cancer recurrence and death in patients. Further, it is almost useless among patients with estrogen receptor negative (ER −) breast cancer. Shikonin (SK) is a natural product broadly explored in cancer therapy. Some studies have demonstrated the combined treatment of SK and clinical anticancer drugs including TAM on various tumors. However, the combined effect of SK and 4-hydroxytamoxifen (4-OHT) on ER- breast cancer is not known. The current study aimed to assess the combination effects of SK and 4-OHT on human breast cancer cells, MCF-7 (ER +) and MDA-MB-435S (ER −), in vitro and in vivo and to investigate the underlying mechanisms. Methods: CCK-8 assays and flow cytometry were conducted to determine the cell viability and apoptotic profiles of human breast cancer cell lines (MCF-7 and MDA-MB-435S) treated with SK, 4-OHT, and the combination. ROS and JC-1 assays were used to determine ROS level and mitochondrial membrane potential. Western blot analysis was performed to investigate proteins that are associated with apoptosis. Haematoxylin & Eosin (HE) staining was used to detect the tumor and kidney morphology of mice. TUNEL and immunohistochemical staining were performed to detect Ki67 expression level and cell apoptotic profile in tumor tissues. Results: SK and 4-OHT synergistically inhibited MCF-7 and MDA-MB-435S cell proliferation and promoted apoptosis by reducing mitochondrial membrane potential and increasing the intracellular ROS level. The combination of SK and 4-OHT activated the mitochondrial-dependent apoptosis and the death receptor pathways, significantly regulating the PI3K/AKT/Caspase 9 signaling pathway. Compared with SK and 4-OHT alone, the combination of SK and 4-OHT could better inhibit tumor growth in mice. Conclusion: The combination of SK and 4-OHT shows highly efficient anticancer effects on breast cancer therapy. SK may be a promising candidate as an adjuvant to 4-OHT for breast cancer treatments, especially for ER- breast cancer. [ABSTRACT FROM AUTHOR]

In this study, a shikonin ester derivative, compound 3g, was selected to evaluate its anticancer activities and we found that compound 3g exhibited better antitubulin activities against the human HepG2 cell line with an IC50 value of 1.097 μM. Furthermore, the inhibition of tubulin results indicated that compound 3g demonstrated the most potent antitubulin activity (IC50 = 13.88), which was compared with shikonin and colchicine as positive controls (IC50 = 25.28 μM and 22.56 μM), respectively. Compound 3g was simulated to have good binding site with tubulin and arrested the cell cycle at G2/M phase, which also induces apoptosis in HepG2 cells, in which P53 and members of Bcl-2 protein family were both involved in the progress of apoptosis revealed by western blot. Confocal microscopy observations revealed compound 3g targeted tubulin and altered its by interfering with microtubule organization. Based on these results, compound 3g functions as a potent anticancer agent targeting tubulin. Chirality 27:274-280, 2015.. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]