A novel mechanism of dasatinib-induced apoptosis in chronic myeloid leukemia; Ceramide synthase and ceramide clearance genes

Sphingolipids are bioeffector molecules that control various aspects of cell growth, proliferation, apoptosis, and drug resistance. Ceramides, the central molecule of sphingolipid metabolism, are inducer of apoptosis and inhibitors of proliferation. Sphingosine-1- phosphate (S1P) and glucosyleceramide, converted from ceramides by sphingosine kinase-1 (SK-1) and glucosyleceramide synthase (GCS) enzymes, respectively, inhibit apoptosis and develop resistance to chemotherapeutic drugs. In this study, we examined the therapeutic potentials of bioactive sphingolipids in chronic myeloid leukemia (CML) alone and in combination with dasatinib in addition to investigate the roles of ceramide-metabolizing genes in dasatinib-induced apoptosis. Cytotoxic effects of dasatinib, C8:ceramide, PDMP, and SK-1 inhibitor were determined by XTT cell proliferation assay. Changes in caspase-3 enzyme activity and mitochondrial membrane potential (MMP) were measured using caspase-3 colorimetric assay and JC-1 MMP detection kit. Expression levels of ceramide-metabolizing genes were examined by qRT-PCR. Application of ceramide analogs and inhibitors of ceramide clearance genes decreased cell proliferation and induced apoptosis. Targeting bioactive sphingolipids towards generation/accumulation of ceramides increased apoptotic effects of dasatinib, synergistically. It was shown for the first time that dasatinib induces apoptosis through downregulating expression levels of antiapoptotic SK-1 but not GCS, and upregulating expression levels of ceramide synthase (CerS) genes, especially CerS1, in K562 cells. On the other hand, dasatinib downregulates expression levels of both GCS and SK-1 and upregulate apoptotic CerS2, -5 and -6 genes in Meg-01 cells. Increasing endogenous ceramide levels and decreasing prosurvival lipids, S1P, and GC, can open the way of more effective treatment of CML.TÜBİTAK grant number 107S317; Turkish Academy of Science

Effects of triethylene glycol dimethacrylate (TEGDMA) on the odontoclastic differentiation ability of human dental pulp cells

Objectives: The primary purpose of this study was to examine the effects of triethylene glycol dimethacrylate (TEGDMA) on odontoclastic differentiation in the dental pulp tissue. Material and Methods: The effects of different TEGDMA dosages on the odontoclastic differentiation capability of dental pulp cells were analyzed in vitro using the following methodologies: i) flow cytometry and tartrate-resistant acid phosphatase (TRAP) staining; ii) apoptotic effects using Annexin V staining; iii) mRNA expression of osteoprotegerin (OPG) and receptor activator of nuclear factor (NF)-kB ligand (RANKL) genes by quantitative Real-time PCR (qRT-PCR); and iv) OPG and RANKL protein expression by enzyme-linked immunosorbent assay (ELISA). Results: TEGDMA caused relatively less odontoclastic differentiation in comparison with the control group; however, odontoclastic differentiation augmented with increasing doses of TEGDMA (

The Efficacy of Mesenchymal Stem Cell Transplantation in Caustic Esophagus Injury: An Experimental Study

Introduction. Ingestion of corrosive substances may lead to stricture formation in esophagus as a late complication. Full thickness injury seems to exterminate tissue stem cells of esophagus. Mesenchymal stem cells (MSCs) can differentiate into specific cell lineages and have the capacity of homing in sites of injury. Aim and Methods. We aimed to investigate the efficacy of MSC transplantation, on prevention of esophageal damage and stricture formation after caustic esophagus injury in rats. 54 rats were allocated into four groups; 4 rats were sacrificed for MSC production. Group 1, untreated controls (n: 10). Group 2, membrane labeled MSCs-treated rats (n: 20). Group 3, biodistribution of fluorodeoxyglucose labeled MSCs via positron emission tomography (PET) imaging (n: 10). Group 4, sham operated (n: 10). Standard caustic esophageal burns were created and MSCs were transplanted 24 hours after. All rats were sacrificed at the 21st days. Results. PET scan images revealed the homing behavior of MSCs to the injury site. The histopathology damage score was not significantly different from controls. However, we demonstrated Dil labeled epithelial and muscle cells which were originating from transplanted MSCs. Conclusion. MSC transplantation after caustic esophageal injury may be a helpful treatment modality; however, probably repeated infusions are needed

In vitro synergistic cytoreductive effects of zoledronic acid and radiation on breast cancer cells

INTRODUCTION: Bisphosphonates are mostly used in the treatment of bone metastases. They have been shown to act synergistically with other chemotherapeutic agents. It is not known, however, whether similar synergistic effects exist with radiation on breast cancer cells. METHODS: Human MCF-7 breast cancer cells were treated with up to 100 μM zoledronic acid, were irradiated with up to 800 cGy or were exposed to combinations of both treatments to determine the antiproliferative effects of zoledronic acid and radiation. RESULTS: Zoledronic acid and radiation caused a dose-dependent and time-dependent decrease in cell viability (approximate 50% growth inhibition values were 48 μM and 20 μM for 24 hours and 72 hours, respectively, for zoledronic acid and 500 cGy for radiation). A synergistic cytotoxic effect of the combination of zoledronic acid and radiation was confirmed by isobologram analysis. CONCLUSION: These data constitute the first in vitro evidence for synergistic effects between zoledronic acid and radiation. This combination therapy might thus be expected to be more effective than either treatment alone in patients with metastatic breast carcinoma

Bisphosphonates may retrieve endothelial function in vascular diseases similar to statins' effects

WOS: 000256853500012PubMed: 1833159

Bisphosphonate treatment and radiotherapy in metastatic breast cancer

Patients with advanced breast cancer frequently develop metastasis to bone. Bone metastasis results in intractable pain and high risk of pathologic fractures due to osteolysis. The treatment of breast cancer patients with bone metastases requires a multidisciplinary approach. Radiotherapy is an established treatment for metastatic bone pain. It may be delivered either as a localized low dose treatment for localized bone pain or systemically for more widespread symptoms. Bisphosphonates have been shown to reduce morbidity and bone pain from bone metastases when given to patients with metastatic bone disease. In vivo studies indicate that early bisphosphonates administration in combination with radiotherapy improves remineralization and restabilization of osteolytic bone metastases in animal tumor models. This review focused on a brief discussion about biology of bone metastases, the effects of radiotherapy and bisphosphonate therapy, and possible mechanisms of combination therapy in metastatic breast cancer patients

Aberrant expressions of leptin and adiponectin receptor isoforms in chronic myeloid leukemia patients

WOS: 000299580800011PubMed: 22082804Background: Leptin and adiponectin receptors mediate the role of leptin in stimulating the growth of leukemic cells and the protective function of adiponectin undertaken in several malignancies such as leukemia. In this study, we investigated the involvement of the expression of leptin and adiponectin receptors in chronic myeloid leukemia (CML) pathogenesis. Methods: The expression of leptin receptor isoforms, OB-Rt, OB-Ra, and OB-Rb, and the expression of adiponectin receptors, AdipoR1 and AdipoR2, were measured as mRNA levels in two CML cell lines (K562 and Meg-01) and 20 CML patients and 24 healthy controls by using RT-PCR. Results: OB-Rt and OB-Ra isoforms expression of the leptin receptors were found to be significantly lower in Meg-01 cell lines than K562 cells. All leptin receptors were downregulated in CML patients and more particularly OB-Rb level was found to be undetectably low in normal PBMC as well as in CML patients. AdipoR1 expression level was higher in Meg-01 than in K562, whereas AdipoR2 level was found to be unchanged in both cell lines. Interestingly, while AdipoR1 expression increased in CML patients, AdipoR2 decreased. Moreover, imatinib therapy did not affect both leptin and adiponectin isoform expressions. Conclusion: While the decrease in leptin receptor levels in CML patients was confirmed, the increase in AdipoR1 levels and relevant decrease in AdipoR2 levels depicted their possible involvement in CML pathogenesis. This suggests different functions of adiponectin receptors in CML development. (C) 2011 Elsevier Ltd. All rights reserved.Gulhane Military Medical AcademyThis work was supported by Gulhane Military Medical Academy Research Fund

Cytotoxic effects of four different endodontic materials in human periodontal ligament fibroblasts

The purpose of this study was to compare the cytotoxicity, induced apoptosis and/or necrosis, and apoptotic mechanisms in human periodontal ligament (PDL) fibroblasts treated with four different endodontic materials: White ProRoot mineral trioxide aggregate (MTA) (MTA/Dentsply; Tulsa Dental, Memphis, TN), Diaket (ESPE, Seefeld, Germany), Endion (VOCO, Cuxhaven, Germany), and CYMED 8410 (NANO, Kaohsiung, Taiwan). The effects of these four materials on the viability of PDL fibroblasts were determined by MTT (3-(4,5-dimethyl-thiazoyl)-2,5-diphenyl-SH-tetrazolium bromide) assay. Apoptotic pathways were evaluated via several mechanisms. Exposure to MTA for 24, 48, and 72 hours resulted in no significant differences in MTT reduction and viable cell number compared with controls. However, treatment of PDL fibroblasts with Diaket Endion, and CYMED 8410 for 24, 48, and 72 hours resulted in cytotoxicity with MTT and a reduction of viable cell number with trypan blue dye exclusion test compared with controls (from p < 0.05 to p < 0.001). Annexin V-FITC/PI staining showed that Diaket, Endion, and CYMED 8410 induced higher percentages of apoptosis and/or necrosis than in controls (45.6%, 25.5%, and 6.3%, respectively). Results of cell-cycle analyses were concordant with annexin V-FITC/PI staining findings. These results suggest that MTA is a very biocompatible filling material. However, Diaket, Endion, and CYMED 8410 are toxic to PDL fibroblasts in vitro. The main form of cell death induced by these filling materials was determined to be apoptosis and/or necrosis