Elbert L. Myles

In vitro anticancer screening of 24 locally used Nigerian medicinal plants

BackgroundPlants that are used as traditional medicine represent a relevant pool for selecting plant candidates that may have anticancer properties. In this study, the ethnomedicinal approach was used to select several medicinal plants native to Nigeria, on the basis of their local or traditional uses. The collected plants were then evaluated for cytoxicity.MethodsThe antitumor activity of methanolic extracts obtained from 24 of the selected plants, were evaluated in vitro on five human cancer cell lines.ResultsResults obtained from the plants screened indicate that 18 plant extracts of folk medicine exhibited promising cytotoxic activity against human carcinoma cell lines. Erythrophleum suaveolens (Guill. & Perr.) Brenan was found to demonstrate potent anti-cancer activity in this study exhibiting IC50 = 0.2-1.3 μg/ml.ConclusionsBased on the significantly potent activity of some plants extracts reported here, further studies aimed at mechanism elucidation and bio-guided isolation of active anticancer compounds is currently underway.

Synergistic effect of pro-inflammatory TNFα and IL-17 in periostin mediated collagen deposition: Potential role in liver fibrosis

BACKGROUND The pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-17, have been implicated in the pathogenesis of liver fibrosis. In this study, we investigated the role of TNFα and IL-17 toward induction of profibrotic factor, periostin. METHODS HepG2 cells were cultured and treated with inflammatory cytokines, TNFα and IL-17. Computational promoter sequence analysis of the periostin promoter was performed to define the putative binding sites for transcription factors. Transcription factors were analyzed by Western blot and Chromatin Immunoprecipitation. Periostin and transcription factor expression analysis was performed by RT-PCR, Western blot, and fluorescence microscopy. Type I collagen expression from fibroblast cultures was analyzed by Western blot and Sircol soluble collagen assay. RESULTS Activation of HepG2 Cells with TNFα and IL-17 enhanced the expression of periostin (3.5 and 4.4 fold, respectively p<0.05) compared to untreated cells. However, combined treatment with both TNFα and IL-17 at similar concentration demonstrated a 13.3 fold increase in periostin (p<0.01), thus suggesting a synergistic role of these cytokines. Periostin promoter analysis and specific siRNA knock-down revealed that TNFα induces periostin through cJun, while IL-17 induced periostin via STAT-3 signaling mechanisms. Treatment of the supernatant from the cytokine activated HepG2 cells on fibroblast cultures induced enhanced expression of type I collagen (>9.1 fold, p<0.01), indicative of a direct fibrogenic effect of TNFα and IL-17. CONCLUSION TNFα and IL-17 induced fibrogenesis through cJun and STAT-3 mediated expression of profibrotic biomarker, periostin. Therefore, periostin might serve as a novel biomarker in early diagnosis of liver fibrosis.

Sodium channel γENaC mediates IL-17 synergized high salt induced inflammatory stress in breast cancer cells.

Chronic inflammation is known to play a critical role in the development of cancer. Recent evidence suggests that high salt in the tissue microenvironment induces chronic inflammatory milieu. In this report, using three breast cancer-related cell lines, we determined the molecular basis of the potential synergistic inflammatory effect of sodium chloride (NaCl) with interleukin-17 (IL-17). Combined treatment of high NaCl (0.15M) with sub-effective IL-17 (0.1 nM) induced enhanced growth in breast cancer cells along with activation of reactive nitrogen and oxygen (RNS/ROS) species known to promote cancer. Similar effect was not observed with equi-molar mannitol. This enhanced of ROS/RNS activity correlates with upregulation of γENaC an inflammatory sodium channel. The similar culture conditions have also induced expression of pro-inflammatory cytokines such as IL-6, TNFα etc. Taken together, these data suggest that high NaCl in the cellular microenvironment induces a γENaC mediated chronic inflammatory response with a potential pro-carcinogenic effect.

Critical role of SIK3 in mediating high salt and IL-17 synergy leading to breast cancer cell proliferation

Chronic inflammation is a well-known precursor for cancer development and proliferation. We have recently demonstrated that high salt (NaCl) synergizes with sub-effective interleukin (IL)-17 to induce breast cancer cell proliferation. However, the exact molecular mechanisms mediating this effect are unclear. In our current study, we adopted a phosphoproteomic-based approach to identify salt modulated kinase-proteome specific molecular targets. The phosphoprotemics based binary comparison between heavy labelled MCF-7 cells treated with high salt (Δ0.05 M NaCl) and light labelled MCF-7 cells cultured under basal conditions demonstrated an enhanced phosphorylation of Serine-493 of SIK3 protein. The mRNA transcript and protein expression analysis of SIK3 in MCF-7 cells demonstrated a synergistic enhancement following co-treatment with high salt and sub-effective IL-17 (0.1 ng/mL), as compared to either treatments alone. A similar increase in SIK3 expression was observed in other breast cancer cell lines, MDA-MB-231, BT20, and AU565, while non-malignant breast epithelial cell line, MCF10A, did not induce SIK3 expression under similar conditions. Biochemical studies revealed mTORC2 acted as upstream mediator of SIK3 phosphorylation. Importantly, cell cycle analysis by flow cytometry demonstrated SIK3 induced G0/G1-phase release mediated cell proliferation, while SIK3 silencing abolished this effect. Also, SIK3 induced pro-inflammatory arginine metabolism, as evidenced by upregulation of the enzymes iNOS and ASS-1, along with downregulation of anti-inflammatory enzymes, arginase-1 and ornithine decarboxylase. Furthermore, gelatin zymography analysis has demonstrated that SIK3 induced expression of tumor metastatic CXCR4 through MMP-9 activation. Taken together, our data suggests a critical role of SIK3 in mediating three important hallmarks of cancer namely, cell proliferation, inflammation and metastasis. These studies provide a mechanistic basis for the future utilization of SIK3 as a key drug discovery target to improve breast cancer therapy.

Violacein induces p44/42 mitogen-activated protein kinase-mediated solid tumor cell death and inhibits tumor cell migration.

Microbial secondary metabolites have emerged as alternative novel drugs for the treatment of human cancers. Violacein, a purple pigment produced by Chromobacterium violaceum, was investigated in the present study for its anti-tumor properties in tumor cell lines. Clinically applicable concentrations of violacein were demonstrated to inhibit the proliferative capacity of tumor cell lines according to a crystal violet proliferation assay. The underlying mechanism was the promotion of apoptotic cell death, as indicated by poly(ADP ribose) polymerase cleavage and p44/42 mitogen-activated protein kinase signaling determined by western blot analysis. Collectively, this provided mechanistic evidence that violacein elicits extracellular-signal regulated kinase-induced apoptosis via the intrinsic pathway. The anti-malignant properties of violacein in the present study were further demonstrated by its inhibitory effects on brain tumor cell migration, specifically glioblastomas, one of the most invasive and therapeutically resistant neoplasms in the clinic. Additionally, solid tumors examined in the present study displayed differential cellular responses and sensitivities to violacein as observed by morphologically induced cellular changes that contributed to its anti-migratory properties. In conclusion, violacein is a novel natural product with the potential to kill several types of human tumor cell lines, as well as prevent disease recurrence by antagonizing cellular processes that contribute to metastatic invasion.

Abstract 614: Cytotoxic activity of enantia chlorantha, nauclea latifolia, and citrus medica extracts on carcinoma cells

Over 562,340 Americans are expected to die of cancer, more than 1500 people a day. Cancer is the second most common cause of death in the US, exceeded only by heart disease. In the US, cancer accounts for nearly 1 of every 4 deaths. Our study focuses primarily on three plants never before investigated for antitumor activity. They were chosen based upon native ethno medicinal usages. Indigenous primarily to the southwestern region of Nigeria; Enantia chlorantha, Nauclea latifolia, and Citrus medica have all been traditionally used and studies have proven their noteworthy antibacterial, antimicrobial, and anti parasitical activities. These important characteristics provide the rationale behind studying these plants further for potential antitumor agents. Experimental: Methanolic leaf and bark extracts in a series of concentrations were taken from the previously stated plants and exposed to two breast and two colorectal cancer cells for 24 hours. Growth analysis is determined using a cell viability indicator alamar blue and a florescent plate reader. Results: Enantia chlorantha and Citrus medica demonstrated the most potential for containing novel antitumor compounds. However, E. chlorantha proved to be exceedingly toxic to the cellular proliferation of all four tumors cell lines at all concentrations. In addition to this, Nauclea latifolia extracts illustrated the least potential for antitumor activity. In most cases this extract showed little or no effect in reducing cellular proliferation. Conclusion: We conclude that leaf extracts from E. chlorantha and C. medica should be studied further to characterize their antitumor potential, investigate their main active compounds, and to better understand their mechanisms of action. Citation Format: Chenel M. Alford, Alexandra Onyejiaka, Elbert L. Myles. Cytotoxic activity of enantia chlorantha, nauclea latifolia, and citrus medica extracts on carcinoma cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 614.

Abstract 5558: Growth inhibitory effect of perganum, sage, and olive leaves plant extracts on breast and lung cancer cell lines

There are many different types of cancer, and generally each is defined by the type of cell that is affected. Cancer occurs in cells by which mutant genes are responsible for cell growth. This may result in metastasis which may affect one or more parts of the body. The current student attempts to address cancer treatment from Natural product sources. Sage leaves (Salvia officanlis), Perganum leaves (harmala), and Olive leaves (Olea europaea) were used in this study to determine their effects on two cancer cell lines, A549 and MCF-7. Our findings revealed that Salvia officanlis, Perganum harmala, and Olea europaea have significant effect on both cell lines (MCF-7 Brest cancer cell line and A549 lung cancer cell line). Salvia officanlis leaf extracts had a greater effect on MCF-7 and A549 than Perganum harmala and Olea europaea. Salvia Officanlis demonstrated a significantly decreased the growth rate and cell survival of both cancer cell lines at all concentrations. In future studies, Salvia officanlis, Perganum harmala, and Olea europaea act with MCF-7 Brest cancer cell line and A549 lung cancer cell line to inhibit their growth Citation Format: Carla Gibbs, Ola Almusallam, Trent E. Malone, Elbert L. Myles. Growth inhibitory effect of perganum, sage, and olive leaves plant extracts on breast and lung cancer cell lines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5558. doi:10.1158/1538-7445.AM2015-5558

Abstract 5117: Cytotoxic effects of hypericum extracts on breast and colorectal tumors

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA The risk of acquiring certain types of cancers has many causes which include age, environment and genetics. There have been advances in the primary treatment options available, which include surgery, radiation therapy, and chemotherapy. However, the survival prognosis for many cancer patients remains low. Cancer treatments may involve chemotherapy, which often cause harsh side effects. The Plant kingdom may provide alternative therapy that may have less side effects and possibly more effective. Hypericum perforatum possesses hypericin, which has been been shown to have antitumor effects with invitro studies on specific cell lines. In other Hypericum species, hypericin makes up a smaller percentage of the extract. However, these species contain other phytochemical compounds that may also exert an antitumor effect. The objective of the present study was to assess the cytotoxic potential of H. perforatum cv. topas, H. olympicum, and H. calycinum on breast and colorectal adenocarcinoma cell lines. MCF7, SW480, and SW620 cells were treated with varying concentrations dosages of methanolic crude extracts from the plant species. Cytotoxicity was determine by measuring the reduction of Alamar Blue after a 24 hour exposure period of 10,000 cells in 96 well fluorescent plates. The reduction was determine using the Molecular Devices fluorescent spectrophotometer. At the lowest comparable concentrations, H. perforatum cv. topas had a greater reduction in tumor growth than MCF7 and SW40 cells lines. Whereas, H. olympicum demonstrated a greater decrease in SW620 cell growth at the lowest comparable concentration. These results suggest a difference in the phytochemical composition of these plants, which should be evaluated in order to determine what metabolite(s) are having the antitumor effect and their target. Citation Format: Carla Gibbs, Johnette S. Duggans, Erin Malone, Elbert L. Myles. Cytotoxic effects of hypericum extracts on breast and colorectal tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5117. doi:10.1158/1538-7445.AM2014-5117