AEE788 potentiates celecoxib-induced growth inhibition and apoptosis in human colon cancer cells

Hypothesis-generating proteome perturbation to identify NEU-4438 and acoziborole modes of action in the African Trypanosome

NEU-4438 is a lead for the development of drugs against Trypanosoma brucei, which causes human African trypanosomiasis. Optimized with phenotypic screening, targets of NEU-4438 are unknown. Herein, we present a cell perturbome workflow that compares NEU-4438's molecular modes of action to those of SCYX-7158 (acoziborole). Following a 6 h perturbation of trypanosomes, NEU-4438 and acoziborole reduced steady-state amounts of 68 and 92 unique proteins, respectively. After analysis of proteomes, hypotheses formulated for modes of action were tested: Acoziborole and NEU-4438 have different modes of action. Whereas NEU-4438 prevented DNA biosynthesis and basal body maturation, acoziborole destabilized CPSF3 and other proteins, inhibited polypeptide translation, and reduced endocytosis of haptoglobin-hemoglobin. These data point to CPSF3-independent modes of action for acoziborole. In case of polypharmacology, the cell-perturbome workflow elucidates modes of action because it is target-agnostic. Finally, the workflow can be used in any cell that is amenable to proteomic and molecular biology experiments.

A new bio-active asymmetric-Schiff base: synthesis and evaluation of calf thymus DNA interaction, topoisomerase IIα inhibition, in vitro antiproliferative activity, SEM analysis and molecular docking studies

In this paper, the asymmetric-Schiff base 2-(4-(2-hydroxybenzylideneamino)benzylideneamino)benzoic acid (SB-2) was newly synthesized and characterized by various spectroscopic methods. The interaction of SB-2 with calf thymus DNA was investigated by UV-vis, fluorescence spectroscopy and molecular docking methods. It was determined that SB-2 effectively binds to DNA via the intercalation mode. DNA electrophoretic mobility experiments displayed that topoisomerase IIα could not cleave pBR322 plasmid DNA in the presence of SB-2, confirming that the Schiff base acts as a topo II suppressor. In the molecular docking studies, SB-2 was found to show an affinity for both the DNA-topoisomerase IIα complex and the DNA. In vitro antiproliferative activity of SB-2 was screened against HT-29 (colorectal) and HeLa (cervical) human tumor cell lines by MTT assay. SB-2 diminished the cell viability in a concentration- and incubation time-dependent manner. The ability of SB-2 to measure DNA damage in tumor cells was evaluated with cytokinesis-block micronucleus assay after incubation 24 h and 48 h. Light and scanning electron microscopy experiments of tumor cells demonstrated an incubation time-dependent increase in the proportion of apoptotic cells (nuclear condensation and apoptotic bodies) suggesting that autophagy and apoptosis play a role in the death of cells. Based on the obtained results, it may be considered that SB-2 is a candidate for DNA-targeting antitumor drug.Communicated by Ramaswamy H. Sarma.

Molecular Mechanisms of Colon Cancer Progression and Metastasis: Recent Insights and Advancements

Colorectal cancer (CRC), the third most common type of cancer, is the second leading cause of cancer-related mortality rates worldwide. Although modern research was able to shed light on the pathogenesis of CRC and provide enhanced screening strategies, the prevalence of CRC is still on the rise. Studies showed several cellular signaling pathways dysregulated in CRC, leading to the onset of malignant phenotypes. Therefore, analyzing signaling pathways involved in CRC metastasis is necessary to elucidate the underlying mechanism of CRC progression and pharmacotherapy. This review focused on target genes as well as various cellular signaling pathways including Wnt/β-catenin, p53, TGF-β/SMAD, NF-κB, Notch, VEGF, and JAKs/STAT3, which are associated with CRC progression and metastasis. Additionally, alternations in methylation patterns in relation with signaling pathways involved in regulating various cellular mechanisms such as cell cycle, transcription, apoptosis, and angiogenesis as well as invasion and metastasis were also reviewed. To date, understanding the genomic and epigenomic instability has identified candidate biomarkers that are validated for routine clinical use in CRC management. Nevertheless, better understanding of the onset and progression of CRC can aid in the development of early detection molecular markers and risk stratification methods to improve the clinical care of CRC patients.

Near infra-red polymeric nanoparticle based optical imaging in Cancer diagnosis

Cancer disease is a foremost health concern and top basis of death in comparison with many diseases including cardiovascular disorders. During initial diagnosis (usually late diagnosis), a majority of cancer patients suffer from metastatic and advanced cancer stages which resulted in limited therapeutic modalities based interventions and effectiveness. Though considerable advancement has been made in combating the disease, continuous and intense efforts are ongoing for early diagnosis and development of therapies. Generally applied treatment options for cancer are surgery, chemotherapy and radiotherapy, which are restricted by failure to early diagnose, insufficient on-targeted drug delivery, systemic toxicity, and lack of real-time monitoring of therapeutic responses in cancer. Noninvasive imaging or minimally invasive imaging methodology is valuable in clinical diagnostic settings. Specifically, noninvasive optical imaging integrated with polymeric nanomaterial have been extensively investigated in the field of cancer diagnostics and therapy. Currently, optical imaging methods go together with polymer-based fluorescent nanoparticles in accomplishing the molecular level detection of tumor boundaries. NIR probe tagged polymeric nanoparticles have potential to provide an advantage in the early cancer detection, therapeutic monitoring and image guided surgery procedures. This article review the recent progress in state-of-the-art NIRF polymeric nanoparticles used for optical imaging particularly on cancer diagnosis.

Targeting of EGFR, VEGFR2, and Akt by Engineered Dual Drug Encapsulated Mesoporous Silica-Gold Nanoclusters Sensitizes Tamoxifen-Resistant Breast Cancer

Tamoxifen administration enhanced overall disease-free survival and diminished mortality rates in cancer patients. However, patients with breast cancer often fail to respond for tamoxifen therapy due to the development of a drug-resistant phenotype. Functional analysis and molecular studies suggest that protein mutation and dysregulation of survival signaling molecules such as epidermal growth factor receptor, vascular endothelial growth factor receptor 2, and Akt contribute to tamoxifen resistance. Various strategies, including combinatorial therapies, show chemosensitize tamoxifen-resistant cancers. Based on chemotoxicity issues, researchers are actively investigating alternative therapeutic strategies. In the current study, we fabricate a mesoporous silica gold cluster nanodrug delivery system that displays exceptional tumor-targeting capability, thus promoting accretion of drug indices at the tumor site. We employ dual drugs, ZD6474, and epigallocatechin gallate (EGCG) that inhibit EGFR2, VEGFR2, and Akt signaling pathways since changes in these signaling pathways confer tamoxifen resistance in MCF 7 and T-47D cells. Mesoporous silica gold cluster nanodrug delivery of ZD6474 and EGCG sensitize tamoxifen-resistant cells to apoptosis. Western and immune-histochemical analyses confirmed the apoptotic inducing properties of the nanoformulation. Overall, results with these silica gold nanoclusters suggest that they may be a potent nanoformulation against chemoresistant cancers.

Treatment mechanism of matrine in combination with irinotecan for colon cancer

The inhibitory effect of matrine (MA) was studied in combination with irinotecan (CPT-11) on proliferation of human colon carcinoma cell line HT29. We also explored the mechanism of cell apoptosis induction in HT29. HT29 cells were treated with different concentrations of MA and CPT-11 alone and in combination. The growth inhibition in HT29 cells was evaluated using MTT assay. Apoptosis was detected using AV-PI double staining flow cytometry. Transmission electron microscopy was used to detect structural changes in cells. Topoisomerase (TOPO) I, Bax and Caspase-3 expression levels were evaluated using western blot analysis. MA and CPT-11 alone and in combination, inhibited the proliferation of HT29 cells, whereas the combination treatment exhibited higher inhibitory effect (P<0.01). This suggests the existence of synergistic cytotoxicity. Compared with each treatment alone, the combination treatment caused more significant damage to cell structure, and caused a significantly higher apoptosis rate (P<0.01). Additionally, the combination treatment increased TOPO I, Bax and Caspase-3 expression levels (P<0.01). In conclusion, MA in combination with CPT-11 synergistically inhibited HT29 cell proliferation and induced apoptosis in these cells. The mechanism may be related to upregulation of the TOPO I, Bax and Caspase-3 protein expression.

Therapeutic implication of 'Iturin A' for targeting MD-2/TLR4 complex to overcome angiogenesis and invasion

Tumor angiogenesis and invasion are deregulated biological processes that drive multistage transformation of tumors from a benign to a life-threatening malignant state activating multiple signaling pathways including MD-2/TLR4/NF-κB. Development of potential inhibitors of this signaling is emerging area for discovery of novel cancer therapeutics. In the current investigation, we identified Iturin A (A lipopeptide molecule from Bacillus megaterium) as a potent inhibitor of angiogenesis and cancer invasion by various in vitro and in vivo methods. Iturin A was found to suppress VEGF, a powerful inducer of angiogenesis and key player in tumor invasion, as confirmed by ELISA, western blot and real time PCR. Iturin A inhibited endothelial tube arrangement, blood capillary formation, endothelial sprouting and vascular growth inside the matrigel. In addition, Iturin A inhibited MMP-2/9 expression in MDA-MB-231 and HUVEC cells. Cancer invasion, migration and colony forming ability were significantly hampered by Iturin A. Expressions of MD-2/TLR4 and its downstream MyD88, IKK-α and NF-κB were also reduced in treated MDA-MB-231 and HUVEC cells. Western blot and immunofluorescence study showed that nuclear accumulation of NF-κB was hampered by Iturin A. MD-2 siRNA or plasmid further confirmed the efficacy of Iturin A by suppressing MD-2/TLR4 signaling pathway. The in silico docking study showed that the Iturin A interacted well with the MD-2 in MD-2/TLR4 receptor complex. Conclusively, inhibition of MD-2/TLR4 complex with Iturin A offered strategic advancement in cancer therapy.

Simultaneous inhibition of EGFR/VEGFR and cyclooxygenase-2 targets stemness-related pathways in colorectal cancer cells

Despite the demonstrated benefits of anti-EGFR/VEGF targeted therapies in metastatic colorectal cancer (mCRC), many patients initially respond, but then show evidence of disease progression. New therapeutic strategies are needed to make the action of available drugs more efficient. Our study aimed to explore whether simultaneous targeting of EGFR/VEGF and cyclooxygenase-2 (COX-2) may aid the treatment and management of mCRC patients. The dual tyrosine kinase inhibitor AEE788 and celecoxib were used to inhibit EGFR/VEGFR and COX-2, respectively, in colorectal cancer cells. COX-2 inhibition with celecoxib augmented the antitumoral and antiangiogenic efficacy of AEE788, as indicated by the inhibition of cell proliferation, induction of apoptosis and G1 cell cycle arrest, down-regulation of VEGF production by cancer cells and reduction of cell migration. These effects were related with a blockade in the EGFR/VEGFR signaling axis. Notably, the combined AEE788/celecoxib treatment prevented β-catenin nuclear accumulation in tumor cells. This effect was associated with a significant downregulation of FOXM1 protein levels and an impairment in the interaction of this transcription factor with β-catenin, which is required for its nuclear localization. Furthermore, the combined treatment also reduced the expression of the stem cell markers Oct 3/4, Nanog, Sox-2 and Snail in cancer cells, and contributed to the diminution of the CSC subpopulation, as indicated by colonosphere formation assays. In conclusion, the combined treatment of AEE788 and celecoxib not only demonstrated enhanced anti-tumoral efficacy in colorectal cancer cells, but also reduced colon CSCs subpopulation by targeting stemness-related pathways. Therefore, the simultaneous targeting of EGFR/VEGF and COX-2 may aid in blocking mCRC progression and improve the efficacy of existing therapies in colorectal cancer.

Thymoquinone restores radiation-induced TGF-β expression and abrogates EMT in chemoradiotherapy of breast cancer cells

Radiotherapy remains a prime approach to adjuvant therapies in patients with early and advanced breast cancer. In spite of therapeutic success, metastatic progression in patients undergoing therapy, limits its application. However, effective therapeutic strategies to understand the cellular and molecular machinery in inhibiting radiation-induced metastatic progression, which is poorly understood so far, need to be strengthened. Ionizing radiation was known to prompt cancer cell's metastatic ability by eliciting Transforming Growth Factor-beta (TGF-β), a key regulator in epithelial-mesenchymal transdifferentiation and radio-resistance. In this viewpoint, we employed thymoquinone as a radiosensitizer to investigate its migration and invasion reversal abilities in irradiated breast cancer cell lines by assessing their respective attributes. The role of metastasis regulatory molecules like TGF-β, E-cadherin, and integrin αV and its downstream molecules were determined using RT-PCR, western blotting, immunofluorescence, and extracellular TGF-β levels affirmed through ELISA assays. These studies affirmed the TGF-β restoring ability of thymoquinone in radiation-driven migration and invasion. Also, results demonstrated that the epithelial markers E-cadherin and cytokeratin 19 were downregulated whereas mesenchymal markers like integrin αV, MMP9, and MMP2 were upregulated by irradiation treatment; however thymoquinone pre-sensitization has reverted the expression of these proteins back to control proteins expression. Here, paclitaxel was chosen as an apoptosis inducer in TGF-β restored cells and confirmed its cytotoxic effects in radiation alone and thymoquinone sensitized irradiated cells. We conclude that this therapeutic modality is effective in preventing radiation-induced epithelial-mesenchymal transdifferentiation and concomitant induction of apoptosis in breast cancer.

Combined therapy with COX-2 inhibitor and 20-HETE inhibitor reduces colon tumor growth and the adverse effects of ischemic stroke associated with COX-2 inhibition

20-Hydroxyeicosatetraenoic acid (20-HETE), Cyp4a-derived eicosanoid, is a lipid mediator that promotes tumor growth, as well as causing detrimental effects in cerebral circulation. We determined whether concurrent inhibition of cyclooxygenase-2 (COX-2) and 20-HETE affects colon tumor growth and ischemic stroke outcomes. The expression of Cyp4a and COXs and production of 20-HETE and PGE2 were determined in murine colon carcinoma (MC38) cells. We then examined the effects of combined treatment with rofecoxib, a potent COX-2 inhibitor, and HET0016, a potent Cyp4a inhibitor, on the growth and proliferation of MC38 cells. Subsequently, we tested the effects of HET0016 plus rofecoxib in MC38 tumor and ischemic stroke models. Cyp4a and COXs are highly expressed in MC38 cells. Respectively, HET0016 and rofecoxib inhibited 20-HETE and PGE2 formation in MC38 cells. Moreover, rofecoxib combined with HET0016 had greater inhibitory effects on the growth and proliferation of MC38 cells than did rofecoxib alone. Importantly, rofecoxib combined with HET0016 provided greater inhibition on tumor growth than did rofecoxib alone in MC38 tumor-bearing mice. Prolonged treatment with rofecoxib selectively induced circulating 20-HETE levels and caused cerebrovascular damage after ischemic stroke, whereas therapy with rofecoxib and HET0016 attenuated 20-HETE levels and reduced rofecoxib-induced cerebrovascular damage and stroke outcomes during anti-tumor therapy. Thus these results demonstrate that combination therapy with rofecoxib and HET0016 provides a new treatment of colon tumor, which can not only enhance the anti-tumor efficacy of rofecoxib, but also reduce rofecoxib-induced cerebrovascular damage and stroke outcomes.

Molecular targeting of Akt by thymoquinone promotes G(1) arrest through translation inhibition of cyclin D1 and induces apoptosis in breast cancer cells

AIM

Thymoquinone (TQ), the predominant bioactive constituent of black seed oil (Nigella Sativa), has been shown to possess antineoplastic activity against multifarious tumors. However, the meticulous mechanism of TQ on Akt mediated survival pathway is still unrevealed in breast cancer. Here, we investigated TQ's mechanism of action against PI3K/Akt signaling and its downstream targets by modulating proteins translational machinery, leading to apoptosis in cancer cells.

MAIN METHODS

MDA-MB-468 and T-47D cells were treated with TQ and evaluated for its anticancer activity through phase distribution and western blot. Modulatory effects of TQ on Akt were affirmed through kinase and drug potential studies.

KEY FINDINGS

Studies revealed G1 phase arrest till 24h incubation with TQ while extended exposure showed phase shift to subG1 indicating apoptosis, supported by suppression of cyclin D1, cyclin E and cyclin dependent kinase inhibitor p27 expression. Immunoblot and membrane potential studies revealed mitochondrial impairment behind apoptotic process with upregulation of Bax, cytoplasmic cytochrome c and procaspase-3, PARP cleavage along with Bcl-2, Bcl-xL and survivin downregulation. Moreover, we construed the rationale behind mitochondrial dysfunction by examining the phosphorylation status of PDK1, PTEN, Akt, c-raf, GSK-3β and Bad in TQ treated cells, thus ratifying the involvement of Akt in apoptosis. Further, the consequential effect of Akt inhibition by TQ is proven by translational repression through deregulated phosphorylation of 4E-BP1, eIF4E, S6R and p70S6K.

SIGNIFICANCE

Our observations for the first time may provide a new insight for the development of novel therapies for Akt overexpressed breast cancer by TQ.

Celecoxib alleviates tamoxifen-instigated angiogenic effects by ROS-dependent VEGF/VEGFR2 autocrine signaling

BACKGROUND

Tamoxifen (TAM) is widely used in the chemotherapy of breast cancer and as a preventive agent against recurrence after surgery. However, extended TAM administration for breast cancer induces increased VEGF levels in patients, promoting new blood vessel formation and thereby limiting its efficacy. Celecoxib (CXB), a selective COX-2 inhibitor, suppresses VEGF gene expression by targeting the VEGF promoter responsible for its inhibitory effect. For this study, we had selected CXB as non-steroidal anti-inflammatory drug in combination with TAM for suppressing VEGF expression and simultaneously reducing doses of both the drugs.

METHODS

The effects of CXB combined with TAM were examined in two human breast cancer cell lines in culture, MCF7 and MDA-MB-231. Assays of proliferation, apoptosis, angiogenesis, metastasis, cell cycle distribution, and receptor signaling were performed.

RESULTS

Here, we elucidated how the combination of TAM and CXB at nontoxic doses exerts anti-angiogenic effects by specifically targeting VEGF/VEGFR2 autocrine signaling through ROS generation. At the molecular level, TAM-CXB suppresses VHL-mediated HIF-1α activation, responsible for expression of COX-2, MMP-2 and VEGF. Besides low VEGF levels, TAM-CXB also suppresses VEGFR2 expression, confirmed through quantifying secreted VEGF levels, luciferase and RT-PCR studies. Interestingly, we observed that TAM-CXB was effective in blocking VEGFR2 promoter induced expression and further 2 fold decrease in VEGF levels was observed in combination than TAM alone in both cell lines. Secondly, TAM-CXB regulated VEGFR2 inhibits Src expression, responsible for tumor progression and metastasis. FACS and in vivo enzymatic studies showed significant increase in the reactive oxygen species upon TAM-CXB treatment.

CONCLUSIONS

Taken together, our experimental results indicate that this additive combination shows promising outcome in anti-metastatic and apoptotic studies. In a line, our preclinical studies evidenced that this additive combination of TAM and CXB is a potential drug candidate for treatment of breast tumors expressing high levels of VEGF and VEGFR2. This ingenious combination might be a better tailored clinical regimen than TAM alone for breast cancer treatment.