The Xpc gene markedly affects cell survival in mouse bone marrow

The XPC protein (encoded by the xeroderma pigmentosum Xpc gene) is a key DNA damage recognition factor that is required for global genomic nucleotide excision repair (G-NER). In contrast to transcription-coupled nucleotide excision repair (TC-NER), XPC and G-NER have been reported to contribute only modestly to cell survival after DNA damage. Previous studies were conducted using fibroblasts of human or mouse origin. Since the advent of Xpc−/− mice, no study has focused on the bone marrow of these mice. We used carboplatin to induce DNA damage in Xpc−/− and strain-matched wild-type mice. Using several independent methods, Xpc−/− bone marrow was ∼10-fold more sensitive to carboplatin than the wild type. Importantly, 12/20 Xpc−/− mice died while 0/20 wild-type mice died. We conclude that G-NER, and XPC specifically, can contribute substantially to cell survival. The data are important in the context of cancer chemotherapy, where Xpc gene status and G-NER may be determinants of response to DNA-damaging agents including carboplatin. Additionally, altered cell cycles and altered DNA damage signalling may contribute to the cell survival end point

Hipervitaminose D em animais

Por meio de revisão da literatura, são apresentados dados referentes ao metabolismo da vitamina D, bem como aos principais aspectos toxicológicos, clínicos, bioquímicos, macroscópicos, microscópicos, ultraestruturais, imuno-histoquímicos e radiográficos de animais intoxicados natural e experimentalmente por essa vitamina, em diferentes espécies. Este estudo objetiva demonstrar a existência de muitas lacunas no conhecimento sobre mineralização fisiológica e patológica, em especial na mediação hormonal do fenômeno, bem como alertar para os riscos de ocorrência dessa intoxicação

A combination of p53-activating APR-246 and phosphatidylserine-targeting antibody potently inhibits tumor development in hormone-dependent mutant p53-expressing breast cancer xenografts

Yayun Liang,1 Benford Mafuvadze,1 Cynthia Besch-Williford,2 Salman M Hyder1 1Deparment of Biomedical Sciences and Dalton Cardiovascular Research Center, Columbia, MO, USA; 2IDEXX BioResearch, Columbia, MO, USA Background: Between 30 and 40% of human breast cancers express a defective tumor suppressor p53 gene. Wild-type p53 tumor suppressor protein promotes cell-cycle arrest and apoptosis and inhibits vascular endothelial growth factor–dependent angiogenesis, whereas mutant p53 protein (mtp53) lacks these functions, resulting in tumor cell survival and metastasis. Restoration of p53 function is therefore a promising drug-targeted strategy for combating mtp53-expressing breast cancer. Methods: In this study, we sought to determine whether administration of APR-246, a small-molecule drug that restores p53 function, in combination with 2aG4, an antibody that targets phosphatidylserine residues on tumor blood vessels and disrupts tumor vasculature, effectively inhibits advanced hormone-dependent breast cancer tumor growth. Results: APR-246 reduced cell viability in mtp53-expressing BT-474 and T47-D human breast cancer cells in vitro, and significantly induced apoptosis in a dose-dependent manner. However, APR-246 did not reduce cell viability in MCF-7 breast cancer cells, which express wild-type p53. We next examined APR-246’s anti-tumor effects in vivo using BT-474 and T47-D tumor xenografts established in female nude mice. Tumor-bearing mice were treated with APR-246 and/or 2aG4 and tumor volume followed over time. Tumor growth was more effectively suppressed by combination treatment than by either agent alone, and combination therapy completely eradicated some tumors. Immunohistochemistry analysis of tumor tissue sections demonstrated that combination therapy more effectively induced apoptosis and reduced cell proliferation in tumor xenografts than either agent alone. Importantly, combination therapy dramatically reduced the density of blood vessels, which serve as the major route for tumor metastasis, in tumor xenografts compared with either agent alone. Conclusion: Based on our findings, we contend that breast tumor growth might effectively be controlled by simultaneous targeting of mtp53 protein and tumor blood vessels in mtp53-expressing cancers. Keywords: breast cancer, blood vessel targeting agent, p53, APR-246, apoptosis, angiogenesi

Luteolin inhibits lung metastasis, cell migration, and viability of triple-negative breast cancer cells

Matthew T Cook,1,2 Yayun Liang,1,2 Cynthia Besch-Williford,3 Salman M Hyder1,2 1Department of Biomedical Sciences, 2Dalton Cardiovascular Research Center, University of Missouri, 3IDEXX BioResearch, Columbia, MO, USA Abstract: Most breast cancer-related deaths from triple-negative breast cancer (TNBC) occur following metastasis of cancer cells and development of tumors at secondary sites. Because TNBCs lack the three receptors targeted by current chemotherapeutic regimens, they are typically treated with extremely aggressive and highly toxic non-targeted treatment strategies. Women with TNBC frequently develop metastatic lesions originating from drug-resistant residual cells and have poor prognosis. For this reason, novel therapeutic strategies that are safer and more effective are sought. Luteolin (LU) is a naturally occurring, non-toxic plant compound that has proven effective against several types of cancer. With this in mind, we conducted in vivo and in vitro studies to determine whether LU might suppress metastasis of TNBC. In an in vivo mouse metastasis model, LU suppressed metastasis of human MDA-MB-435 and MDA-MB-231 (4175) LM2 TNBC cells to the lungs. In in vitro assays, LU inhibited cell migration and viability of MDA-MB-435 and MDA-MB-231 (4175) LM2 cells. Further, LU induced apoptosis in MDA-MB-231 (4175) LM2 cells. Relatively low levels (10 µM) of LU significantly inhibited vascular endothelial growth factor (VEGF) secretion in MDA-MB-231 (4175) LM2 cells, suggesting that it has the ability to suppress a potent angiogenic and cell survival factor. In addition, migration of MDA-MB-231 (4175) LM2 cells was inhibited upon exposure to an antibody against the VEGF receptor, KDR, but not by exposure to a VEGF165 antibody. Collectively, these data suggest that the anti-metastatic properties of LU may, in part, be due to its ability to block VEGF production and KDR-mediated activity, thereby inhibiting tumor cell migration. These studies suggest that LU deserves further investigation as a potential treatment option for women with TNBC. Keywords: luteolin, triple-negative breast cancer, metastasis, cell migration, apoptosis, VEG

Protein and antigenic heterogeneity among isolates of Bacillus piliformis

Protein and antigenic heterogeneity among isolates of Bacillus piliformis, the etiologic agent of Tyzzer's disease, were investigated. The seven isolates utilized in this study were originally isolated from naturally infected animals of different animal species and diverse geographical locations. Isolates were propagated in mammalian cell lines, and bacterial extracts were prepared. Protein and antigenic profiles were compared among isolates, using Coomassie blue-stained polyacrylamide gels and Western blot (immunoblot) analyses, respectively. Results showed differences in protein and antigen banding patterns, indicating diversity among isolates. Western blots probed with serum preabsorbed with a heterologous bacterial extract revealed that numerous antigens have different electrophoretic mobilities among isolates but apparently share common epitopes. Immunodominant cross-reactive antigens may be candidate proteins useful for development of improved serologic diagnostic tests, allowing identification of animals infected with a wide range of B. piliformis isolates.</jats:p

Abstract P1-16-06: Luteolin inhibits progestin-dependent VEGF induction, stem-cell like characteristics, and tumor progression of human breast cancer cells

Abstract Clinical trials and epidemiological evidence show that combined estrogen (E) and progestin (P) hormone replacement therapy (HRT) increases the risk of breast cancer in postmenopausal women, whereas HRT containing E alone does not. Tumor progression is dependent on angiogenesis, which provides nutrients vital to the developing cancer. We previously showed, both in vitro and in vivo, that natural and synthetic P (including the widely used progestin Medroxyprogesterone acetate, MPA), increase production of vascular endothelial growth factor (VEGF), a potent angiogenic factor, in human breast cancer cells (Cancer Res., 1998, 58:392). This effect is blocked by the anti-progestin RU-486, suggesting involvement of progesterone receptors in the process (Int J Cancer, 2001, 92:469). Evidence from our laboratory using in vivo breast cancer models suggests that P accelerates the development of tumors from latent tumorigenic cells. This leads to the formation of palpable tumors and tumor metastasis, processes that may be attributed to increased production of VEGF (Cancer Res., 2007, 67:9929; Menopause, 2010, 17:1040). RU-486 blocks P-dependent VEGF production and thereby reduces tumor growth; however, the anti-progestin has severe side-effects averting its long-term use. Recently, we have studied less toxic naturally-occurring compounds for their ability to antagonize P-dependent VEGF induction and block tumor progression. In this study, we tested the effects of luteolin, a flavonoid commonly found in fruits and vegetables, on proliferation of BT-474 and T47-D breast cancer cells and their P-dependent production of VEGF. Luteolin treatment (25-100 μM) for 24-48 h reduced in vitro tumor cell viability and induced apoptosis. Interestingly, treatment with a lower concentration of luteolin (10 μM) blocked the production of P-dependent VEGF, indicating that VEGF suppression precedes luteolin-mediated loss of cell viability. Furthermore, luteolin (20 mg/kg, i.p.) suppressed the growth of MPA-dependent T47-D human xenograft tumors in nude mice. Immunohistochemical analysis showed that luteolin reduced P-induced VEGF in tumor sections (p&amp;lt;0.05). These findings strongly suggest that the flavonoid disrupts tumor progression by blocking P-dependent angiogenesis and preventing tumor cell proliferation. Furthermore, luteolin blocked the MPA-induced acquisition of stem cell like properties by breast cancer cells; CD44 expression, ALDH activity and mammosphere formation were all reduced by the flavonoid. We contend therefore that luteolin is a compound with valuable therapeutic properties. Its ability to reduce levels of VEGF, coupled with its capacity to interfere with the acquisition of stem-cell like properties by breast cancer cells, make luteolin a compound with significant clinical potential in the battle against P-dependent human breast cancer. Supported by a COR award from the College of Veterinary Medicine and in part by funds from generous donors to the Ellis Fischel Cancer Center, University of Missouri. Citation Format: Hyder SM, Cook MT, Besch-Williford C, Liang Y. Luteolin inhibits progestin-dependent VEGF induction, stem-cell like characteristics, and tumor progression of human breast cancer cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-16-06.</jats:p