p53 modulates the effect of ribosomal protein S6 kinase1 (S6K1) on cisplatin toxicity in chronic myeloid leukemia cells.

Chronic myeloid leukemia (CML) is characterized by the expression of the oncoprotein, BCR-ABL. BCR-ABL inhibitors revolutionized CML chemotherapy while blast crisis (BC) CML patients are less responsive. Since suppression of ribosomal protein S6 kinase1 (S6K1) phosphorylation reverses the resistance to BCR-ABL inhibitor in CML cells and S6K1 inhibitors augment cisplatin toxicity in lung cancer cells, we speculated that combination of S6K1 inhibitor and cisplatin may be beneficial for eliminating BC CML cells. To our surprise, S6K1 inhibition decreased cisplatin-induced DNA damage and cell death only in p53-/- BC CML cells but not in p53+/+ BC CML cells. During the progression of CML, p53 expression either decreases or mutates. Moreover, the expression of p53 affects drug response of CML cells. Our results confirmed that S6K1 inhibition reversed cisplatin toxicity is dependent on p53 expression in CML cells. Moreover, p53 attenuated the phosphorylation and localization of S6K1 via attenuating 3-phosphoinositide dependent protein kinase-1 (PDK1) phosphorylation. Furthermore, S6K1 acts via DNA-PKcs to regulate H2AX phosphorylation and PARP cleavage, respectively. Taken together, our results suggest that p53/PDK1/S6K1 is a novel pathway regulating cisplatin toxicity in BC CML cells.

Poly ADP-ribose polymerase inhibition suppresses cisplatin toxicity in chronic myeloid leukemia cells.

Cancer cells may acquire drug resistance by activating DNA repair signaling. Poly ADP-ribose polymerase (PARP) plays an important role in DNA repair and it is overexpressed in many cancers including chronic myeloid leukemia (CML). PARP inhibitors have been used either alone or with other drugs to augment cancer cell death. However, whether PARP inhibitors may also augment cell death induced by chemotherapeutic agents in CML cells has not been studied. K562 cells with or without PARP-1 knockdown were treated with cisplatin alone or together with olaparib. The cell death was investigated by propidium iodide staining and apoptosis-related proteins were detected by western blotting. Olaparib suppressed cisplatin-induced cell death in K562 and MEG01 cells. Moreover, PARP-1 knockdown also attenuated cisplatin toxicity in CML cells. Inhibition of PARP decreased cisplatin toxicity by attenuating caspase-3 and caspase-9 activity. These results indicated that the toxicity of cisplatin in CML cells requires PARP activity. Therefore, PARP inhibitors may not be useful with DNA-damaging agents such as cisplatin in CML treatment.

Cyclic AMP (cAMP) confers drug resistance against DNA damaging agents via PKAIA in CML cells.

Cyclic adenosine monophosphate (cAMP) regulates many vital functions such as metabolism, proliferation, differentiation and death. Depending on cell types and stimulators, cAMP could either promote or attenuate cell death. cAMP signal can be transduced by protein kinase A (PKA) and/or exchange protein directly activated by cAMP (EPAC). In CML cells, cAMP may suppress their proliferation and enhance their differentiation. However, the role of cAMP on DNA damaging agent toxicity and the mechanism involved has not been studied. In this study, we studied the effect of cAMP on the sensitivity of CML cells to DNA damaging agents. We observed that forskolin (FSK) and dibutyryl-cAMP (DBcAMP) decreased cisplatin and etoposide-induced cell death in K562 cells. Moreover, PKA activator prevented K562 cells from DNA damaging agent-induced cell death while EPAC activator had no effect. Furthermore, we found that the PKA subtype, PKAIA, was involved in cAMP-attenuated resistance in K562 cells. Taken together, our results suggest that increased cAMP level confers CML cells to acquire a novel mechanism against DNA damaging agent toxicity via PKAIA. Thus, PKAIA inhibitor may be helpful in overcoming the resistance to DNA damaging agents in CML cells.

Astrocytic CCAAT/Enhancer-Binding Protein Delta Contributes to Glial Scar Formation and Impairs Functional Recovery After Spinal Cord Injury.

After spinal cord injury, inflammatory reaction induces the aggregation of astrocytes to form a glial scar that eventually blocks axonal regeneration. Transcription factor CCAAT/enhancer-binding protein delta (C/EBPδ) is a regulatory protein of genes responsive to inflammatory factors, but its role in glial scar formation after spinal cord injury remains unknown. By using a model of moderate spinal cord contusion injury at the mid-thoracic level, we found that C/EBPδ was expressed mostly in the reactive astrocytes bordering the lesion in wild-type mice from 7 days after the injury. C/EBPδ-deficient mice showed reduced glial scar formation, more residual white matter, and better motor function recovery compared with wild-type mice 28 days after the injury. Upon interleukin (IL)-1ß stimulation in vitro, the increased expression of C/EBPδ in reactive astrocytes inhibited RhoA expression and, subsequently, the ability of astrocyte migration. However, these reactive astrocytes also produced an increased amount of matrix metalloproteinase-3, which promoted the migration of non-IL-1ß-treated, inactive astrocytes. Although the involvement of other non-astroglial C/EBPδ cannot be entirely excluded, our studies suggest that astrocytic C/EBPδ is integral to the inflammatory cascades leading to glial scar formation after spinal cord injury.

Down-regulation of superoxide dismutase 1 by PMA is involved in cell fate determination and mediated via protein kinase D2 in myeloid leukemia cells.

Myeloid leukemia cells maintain a high intracellular ROS level and use redox signals for survival. The metabolism of ROS also affects cell fate, including cell death and differentiation. Superoxide dismutases (SODs) are major antioxidant enzymes that have high levels of expression in myeloid leukemia cells. However, the role of SODs in the regulation of myeloid leukemia cells' biological function is still unclear. To investigate the function of SODs in myeloid leukemia cell death and differentiation, we used myeloid leukemia cell lines K562, MEG-01, TF-1, and HEL cells for this study. We found that PMA-induced megakaryocytic differentiation in myeloid leukemia cells is accompanied by cell death and SOD1 down-regulation, while SOD2 expression is not affected. The role of SOD1 is verified when ATN-224, a SOD1 specific inhibitor, inhibits cell proliferation and promotes cell death in myeloid leukemia cells without PMA treatment. Moreover, inhibition or silencing of SODs further increases cell death and decreases polyploidization induced by PMA while they were partially reversed by SOD1 overexpression. Thus, SOD1 expression is required for myeloid leukemia cell fate determination. In addition, the knockdown of PKD2 reduces cell death and promotes polyploidization induced by PMA. PMA/PKD2-mediated necrosis via PARP cleavage involves both SOD1-dependent and -independent pathways. Finally, ATN-224 enhanced the inhibition of cell proliferation by Ara-C. Taken together, the results demonstrate that SOD1 regulates cell death and differentiation in myeloid leukemia cells. ATN-224 may be beneficial for myeloid leukemia therapy.

Effects of a workplace multiple cardiovascular disease risks reduction program.

PURPOSE: Interventions targeting multiple risk behaviors have the potential to offer greater health benefits on public health. The purpose of this study was to evaluate the effects of a Workplace Multiple Cardiovascular Disease Risks Reduction Program (WMCVDRRP) on male participants at high risk for cardiovascular disease. METHODS: One group pretest-posttest design was applied in this study. No control group was assigned as this study was the first one in Taiwan conducted to promote participants' health using WMCVDRRP and thus with the nature of a pilot study. The program design was based on the collaboration between the health clinic at the corporation and a nursing school targeting six health behaviors. Of the 465 individuals who participated, data from 283 participants were included in the analysis. The change in any of six health behaviors and eight physical indicators were tested as the effect of the WMCVDRRP. RESULTS: Nearly 40% of the participants improved their regular exercise, diet control, stress management, and medication adherence. Although the improvement in drinking behaviors did not show statistical significance, 21% of the participants changed in alcohol consumption and 21% quit smoking. Eight physical indicators including systolic and diastolic blood pressure, total cholesterol, triglyceride, body mass index, waist-hip ratio, body fat, and muscle weight improved significantly. CONCLUSION: Dual collaboration between the industry and nursing schools could establish a cost-effective program to improve health behaviors and health status of participants.

Patients' perceptions and expectations of family participation in the informed consent process of elective surgery in taiwan.

PURPOSE: This study investigated patients' perceptions and expectations of their families' participation in the informed consent process of elective surgery. METHODS: This is a survey study. Anonymous questionnaires that were mailed to potential participants included a demographic data sheet and a scale, measuring patients' perceptions of themselves and their families' participation level in the informed consent process. A convenience sample of patients who had undergone surgery and had been discharged within 4 months from a medical center in southern Taiwan (n = 1,737) were recruited. RESULTS: One hundred and forty-five recipients replied, gaining a response rate of 10.0%, and 120 provided complete data. The mean age of the participants was 56.0 years (range 20-85, SD = 14.98), and more than half were female (54.2%). Twenty-one participants (17.5%) perceived having less family participation than their own participation in the surgery informed consent process, and 40% expected more family participation in the process. The mean scores of the self-rated participation level was significantly higher than that of the families (p < .001). Patients' expectations of family participation were significantly higher than their perceptions of family participation (p < .001). Eleven patients (9.2%) reported having more family participation than they expected. Participants received the most information about the disease during the informed consent process and the least information about alternatives to surgery. Age, gender, number of previous surgeries and admissions influenced the study participants' perceived level of participation in the informed consent process. CONCLUSION: This preliminary study demonstrates that patients' perceptions and expectations for family participation in the surgical informed consent process vary. Healthcare providers should be aware of patients' expectation to appropriately invite their family into the informed consent process.

The effect of prostacyclin agonists on the differentiation of phorbol ester treated human erythroleukemia cells.

Phorbol-12-myristate-13-acetate (PMA) induces megakaryocytopoeisis in human erythroleukemia (HEL) cells which is characterized by the increase in cell size, increase in nuclear polyploidization and expression of megakaryocyte marker, CD41. However, upon treatment with 100 nM of selective prostacyclin (IP) agonist beraprost inhibits the induced differentiation. Moreover, selective non-prostanoid IP agonist, BMY 45778 prevents PMA induced megakaryocytopoeisis in HEL cells similarly, while prostaglandin E(2) and specific EP(3) agonist sulprostone have no effect. Thus, IP receptor is involved. Furthermore, adenylate cyclase activator forskolin and cAMP analog dibutyryl-cAMP also prevented PMA induced megakaryocytopoeisis in HEL cells. Thus, IP agonists inhibition of PMA induced megakaryocytopoeisis in HEL cells may involve a cAMP dependent pathway.