Willie Davis

Strategies to Extend Thrombolytic Time Window for Ischemic Stroke Treatment: An Unmet Clinical Need

To date, reperfusion with tissue plasminogen activator (tPA) remains the gold standard treatment for ischemic stroke. However, when tPA is given beyond 4.5 hours of stroke onset, deleterious effects of the drug ensue, especially, hemorrhagic transformation (HT), which causes the most significant morbidity and mortality in stroke patients. An important clinical problem at hand is to develop strategies that will enhance the therapeutic time window for tPA therapy and reduce the adverse effects (especially HT) of delayed tPA treatment. We reviewed the pharmacological agents which reduced the risk of HT associated with delayed (beyond 4.5 hours post-stroke) tPA treatment in preclinical studies, which we classified into those that putatively preserve the blood-brain barrier (e.g., minocycline, cilostazol, fasudil, candesartan, and bryostatin) and/or enhance vascularization and protect the cerebrovasculature (e.g., coumarin derivate IMM-H004 and granulocyte colony-stimulating factor). Recently, other new therapeutic modalities (e.g., oxygen transporters) have been reported which improved delayed tPA-associated outcomes by acting through other mechanisms. While the above-mentioned interventions unequivocally reduced delayed tPA-induced HT in stroke models, the long-term efficacy of these drugs are not yet established. Further optimization is required to expedite their future clinical application. The findings from this review indicate the need to explore the most ideal adjunctive interventions that will not only reduce delayed tPA–induced HT, but also preserve neurovascular functions. While waiting for the next breakthrough drug in acute stroke treatment, it is equally important to allocate considerable effort to find approaches to address the limitations of the only FDA-approved stroke therapy.

Aryl Hydrocarbon Receptor Ligand 5F 203 Induces Oxidative Stress That Triggers DNA Damage in Human Breast Cancer Cells.

Breast tumors often show profound sensitivity to exogenous oxidative stress. Investigational agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) induces aryl hydrocarbon receptor (AhR)-mediated DNA damage in certain breast cancer cells. Since AhR agonists often elevate intracellular oxidative stress, we hypothesize that 5F 203 increases reactive oxygen species (ROS) to induce DNA damage, which thwarts breast cancer cell growth. We found that 5F 203 induced single-strand break formation. 5F 203 enhanced oxidative DNA damage that was specific to breast cancer cells sensitive to its cytotoxic actions, as it did not increase oxidative DNA damage or ROS formation in nontumorigenic MCF-10A breast epithelial cells. In contrast, AhR agonist and procarcinogen benzo[a]pyrene and its metabolite, 1,6-benzo[a]pyrene quinone, induced oxidative DNA damage and ROS formation, respectively, in MCF-10A cells. In sensitive breast cancer cells, 5F 203 activated ROS-responsive kinases: c-Jun-N-terminal kinase (JNK) and p38 mitogen activated protein kinase (p38). AhR antagonists (alpha-naphthoflavone, CH223191) or antioxidants (N-acetyl-l-cysteine, EUK-134) attenuated 5F 203-mediated JNK and p38 activation, depending on the cell type. Pharmacological inhibition of AhR, JNK, or p38 attenuated 5F 203-mediated increases in intracellular ROS, apoptosis, and single-strand break formation. 5F 203 induced the expression of cytoglobin, an oxidative stress-responsive gene and a putative tumor suppressor, which was diminished with AhR, JNK, or p38 inhibition. Additionally, 5F 203-mediated increases in ROS production and cytoglobin were suppressed in AHR100 cells (AhR ligand-unresponsive MCF-7 breast cancer cells). Our data demonstrate 5F 203 induces ROS-mediated DNA damage at least in part via AhR, JNK, or p38 activation and modulates the expression of oxidative stress-responsive genes such as cytoglobin to confer its anticancer action.

Effects of a meal replacement system alone or in combination with phentermine on weight loss and food cravings.

To examine the effects of phentermine combined with a meal replacement program on weight loss and food cravings and to investigate the relationship between food cravings and weight loss.

One-pot synthesis of cinnamylideneacetophenones and their in vitro cytotoxicity in breast cancer cells

A series of cinnamylideneacetophenones were synthesized via a modified Claisen-Schmidt condensation reaction and evaluated for cytotoxicity against breast cancer cells using the Alamar Blue™ assay. Derivatives 17 and 18 bearing a 2-nitro group on the B ring, exhibited sub-micromolar cytotoxicity in MCF-7 cells (IC50=71 and 1.9 nM), respectively. Derivative 17 also displayed sub-micromolar (IC50=780 nM) cytotoxicity in MDA-MB-468 cells. Additionally, 17 and 18 displayed significantly less cytotoxicity than the chemotherapeutic doxorubicin in non-tumorigenic MCF-10A cells. This study provides evidence supporting the continued development of nitro-substituted cinnamylideneacetophenones as small molecules to treat breast cancer.

Adjunctive Therapy Approaches for Ischemic Stroke: Innovations to Expand Time Window of Treatment

Tissue plasminogen activator (tPA) thrombolysis remains the gold standard treatment for ischemic stroke. A time-constrained therapeutic window, with the drug to be given within 4.5 h after stroke onset, and lethal side effects associated with delayed treatment, most notably hemorrhagic transformation (HT), limit the clinical use of tPA. Co-administering tPA with other agents, including drug or non-drug interventions, has been proposed as a practical strategy to address the limitations of tPA. Here, we discuss the pharmacological and non-drug approaches that were examined to mitigate the complications—especially HT—associated with delayed tPA treatment. The pharmacological treatments include those that preserve the blood-brain barrier (e.g., atovarstatin, batimastat, candesartan, cilostazol, fasudil, minocycline, etc.), enhance vascularization and protect the cerebrovasculature (e.g., coumarin derivate IMM-H004 and granulocyte-colony stimulating factor (G-CSF)), and exert their effects through other modes of action (e.g., oxygen transporters, ascorbic acid, etc.). The non-drug approaches include stem cell treatments and gas therapy with multi-pronged biological effects. Co-administering tPA with the abovementioned therapies showed promise in attenuating delayed tPA-induced side effects and stroke-induced neurological and behavioral deficits. Thus, adjunctive treatment approach is an innovative therapeutic modality that can address the limitations of tPA treatment and potentially expand the time window for ischemic stroke therapy.

Glaucarubulone glucoside from Castela macrophylla suppresses MCF-7 breast cancer cell growth and attenuates benzo[a]pyrene-mediated CYP1A gene induction.

Quassinoids often exhibit antioxidant and antiproliferative activity. Emerging evidence suggests that these natural metabolites also display chemopreventive actions. In this study, we investigated the potential for the quassinoid glaucarubulone glucoside (Gg), isolated from the endemic Jamaican plant Castela macrophylla (Simaroubaceae), to display potent cytotoxicity and inhibit human cytochrome P450s (CYPs), particularly CYP1A enzymes, known to convert polyaromatic hydrocarbons into carcinogenic metabolites. Gg reduced the viability of MCF‐7 breast adenocarcinoma cells (IC50 = 121 nm) to a greater extent than standard of care anticancer agents 5‐fluorouracil, tamoxifen (IC50 >10 μm) and the tamoxifen metabolite 4‐hydroxytamoxifen (IC50 = 2.6 μm), yet was not cytotoxic to non‐tumorigenic MCF‐10A breast epithelial cells. Additionally, Gg induced MCF‐7 breast cancer cell death. Gg blocked increases in reactive oxygen species in MCF‐10A cells mediated by the polyaromatic hydrocarbon benzo[a]pyrene (B[a]P) metabolite B[a]P 1,6‐quinone, yet downregulated the expression of genes that promote antioxidant activity in MCF‐7 cells. This implies that Gg exhibits antioxidant and cytoprotective actions in non‐tumorigenic breast epithelial cells and pro‐oxidant, cytotoxic actions in breast cancer cells. Furthermore, Gg inhibited the activities of human CYP1A according to non‐competitive kinetics and attenuated the ability of B[a]P to induce CYP1A gene expression in MCF‐7 cells. These data indicate that Gg selectively suppresses MCF‐7 breast cancer cell growth without impacting non‐tumorigenic breast epithelial cells and blocks B[a]P‐mediated CYP1A induction. Taken together, our data provide a rationale for further investigations of Gg and similar plant isolates as potential agents to treat and prevent breast cancer. Copyright

Abstract 3936: Identification and validation of the potential biomarker insulin-like growth factor binding protein acid-labile subunit for breast cancer in African American women

Breast cancer is the most frequently diagnosed cancer in women, with an estimated 40, 730 breast cancer deaths in the US in 2015. African American (AA) women have a lower breast cancer incidence rate, but a higher breast cancer death rate, than non-Hispanic White women. Research indicates that breast tumor biology in AA women is different from that in Caucasian women. AA women are more likely to be diagnosed with breast cancer at an earlier age and with more aggressive form of the disease, characterized by higher grade and negative estrogen and progesterone receptor status. Because of the aggressive nature of these tumors and current lack of targeted therapies, identification of novel relevant protein markers is of great importance. The purpose of this study was to validate serum proteins that were previously identified by serum proteomic profiling in 22 serum samples by 2D-DIGE/MS analysis and a subset of samples by shotgun LC/MS technology. Methods and new data: The current study included serum samples from 15 African American breast cancer patients and 12 healthy controls. Patients were grouped into triple negative (TN), HER2 and Luminal A and B subtypes. Proteins of biological significance were validated using western blot analysis. For ceruloplasmin, and insulin-like growth factor binding protein acid-labile subunit (IGFBP-ALS), one-way ANOVA was used to compare mean density among the three groups. For Vitamin D Binding protein (VDB), a two-sample t-test was used to compare the density between the groups. Due to the small sample size, we have also conducted nonparametric tests. IGFBP-ALS was significantly lower in triple negative breast cancer patients (p = 0.016) and in HER2 (p = 0.025) subtypes. There was no significant difference in VDB protein in the luminal A and B subtypes (p = 0.98). Future efforts will focus on validating the identified panel of biomarkers to gain insight into their role(s) in the etiology of aggressive breast tumors. Funded by Susan G Komen for the Cure and SEED grant SPH. Citation Format: Padma P. Tadi Uppala, Carlos Garberoglio, Sharon Lum, Willie Davis, Hon-Chiu Eastwood Leung, Michael Liebman, Keiji Oda, Utkarsh P. Patel. Identification and validation of the potential biomarker insulin-like growth factor binding protein acid-labile subunit for breast cancer in African American women. [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 3936.

Abstract 5163: Differential effects of IGF-2 on epithelial mesenchymal transition (EMT) in African- American and Caucasian breast cancer cell lines

Breast cancer is a multifactorial disease that disproportionately affects women. Breast cancer patients with the worst prognosis tend to be premenopausal, African-American (AA) and present with aggressive, estrogen-independent tumors unresponsive to standard endocrine therapy. Because of these factors, it is important to discover unique biomarkers for screening and treatment of breast cancer. One potential candidate is the insulin-like growth factor-II (IGF-2). Studies indicate that tumors that express high levels of IGF-2 are more aggressive, exhibit a basal-like phenotype and tend to metastasize. Suggesting that enhanced or altered IGF-2-mediated cell signaling pathways may be involved in the pathogenesis and disease progression of metastatic, ER-null breast cancer. We hypothesize that this may be due to the ability of IGF-2 to affect the mesenchymal epithelial transition (EMT) of these cells. To assess the potential effect(s) of proIGF-2 on EMT, we have over-expressed pro- and mature- forms of IGF-2 in human breast cancer cell lines: MCF-7, T47D, Hs578T, CRL-2329, CRL-2335 and Z75D-30. There are phenotypic changes that are characteristic of EMT, cellular morphology was evaluated by phase-contrast and confocal microscopy on days 5, 15, 20, and 30 post-transfection. In cells overexpressing proIGF-2 and mIGF-2, qRT-PCR and Western immunoblot analysis were used to assess expression and activation of E-cadherin, PI3K/AKT, SNAI1/2, RelB, Bcl-2, ERα and ERβ. This project will evaluate proIGF-2 as an initator of EMT and cancer metastisis. [Research support from the Robert Wood Johnson Foundation and Loma Linda University School of Pharmacy] Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5163. doi:1538-7445.AM2012-5163

Abstract 3658: 5F 203 modulates oxidative stress, induces single-strand break formation and promotes mitochondrial membrane potential loss in sensitive breast cancer cells

Targeted pharmacotherapeutic agents have been successful in treating women with breast cancer that either over-expresses human epidermal growth factor receptor 2 (Her2/neu) or is dependent upon estrogen receptor signaling. However, patients with Her2/neu-negative or hormone-independent breast cancer do not benefit from these targeted agents. A candidate anticancer agent 2-(4-amino-3-methylphenyl)-5-benzothiazole (5F 203) targets the aryl hydrocarbon receptor signaling pathway and potently inhibits the growth of breast cancer cells irrespective of either estrogen receptor or Her2/neu status. 5F 203 may represent a promising agent for women who lack targeted therapeutic options. We have previously assessed the role reactive oxygen species (ROS) play in mediating the anticancer activity of 5F 203. In our current studies, we pretreated 5F 203-sensitive breast cancer cells with rotenone prior to treatment with 5F 203. This pretreatment diminished 5F 203-mediated ROS formation as measured by DCF-DA staining followed by flow cytometry. This suggests 5F 203-induced ROS production is partially derived from the mitochondria. Using the comet assay and a JC1 dye-based fluorometry assay respectively, we found 5F 203 induced single-strand break formation and mitochondrial membrane potential loss in sensitive breast cancer cells. Pretreatment with the antioxidant N-acetyl-L-cysteine partially diminished apoptosis as assessed by relief contrast microscopy and the Annexin V/PI assay. This implies that 5F 203-induced apoptosis depends at least in part on ROS derived from mitochondria. We also analyzed 84 oxidative stress-responsive genes using PCR-array and determined that 5F 203 significantly increased the expression of cytoglobin, a novel tumor suppressor, in sensitive breast cancer cells. These data imply ROS and cytoglobin contribute to the anticancer activity of 5F 203. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3658.