Guidance on the management of adverse reactions induced by poly(ADP-ribose) polymerase inhibitors / 浙江大学学报·医学版

The common adverse reactions caused by poly (ADP-ribose) polymerase (PARP) inhibitors include hematological toxicity, gastrointestinal toxicity and fatigue. The main prevention and treatment of hematological toxicity include: regular blood tests, referral to hematology department when routine treatment is ineffective, and being alert of myelodysplastic syndrome/acute myeloid leukemia. The key points to deal with gastrointestinal toxicity include: taking medicine at the right time, light diet, appropriate amount of drinking water, timely symptomatic treatment, prevention of expected nausea and vomiting, and so on. For fatigue, full assessment should be completed before treatment because the causes of fatigue are various; the management includes massage therapy, psychosocial interventions and drugs such as methylphenidate and Panax quinquefolius according to the severity. In addition, niraparib and fluzoparib can cause hypertension, hypertensive crisis and palpitation. Blood pressure and heart rate monitoring, timely symptomatic treatment, and multidisciplinary consultation should be taken if necessary. When cough and dyspnea occur, high resolution CT and bronchoscopy should be performed to exclude pneumonia. If necessary, PARP inhibitors should be stopped, and glucocorticoid and antimicrobial therapy should be given. Finally, more attention should be paid to drug interaction management, patient self-management and regular monitoring to minimize the risk and harm of adverse reactions of PARP inhibitors.

Protective effect of borneol on the cutaneous toxicity of gilteritinib / 浙江大学学报·医学版

OBJECTIVES@#To investigate the effect of borneol on cutaneous toxicity of gilteritinib and to explore possible compounds that can intervene with the cutaneous toxicity.@*METHODS@#C57BL/6J male mice were given gilteritinib by continuous gavage for 28 d and the damage to keratinocytes in the skin tissues was observed with hematoxylin and eosin (HE) staining, TUNEL assay and immunohistochemistry. Human keratinocytes HaCaT were treated with gilteritinib, and cell death and morphological changes were examined by SRB staining and microscopy; apoptosis of HaCaT cells was examined by Western blotting, flow cytometry with propidium iodide/AnnexinⅤ double staining and immunofluorescence; the accumulation of cellular reactive oxygen species (ROS) was examined by flow cytometry with DCFH-DA. Compounds that can effectively intervene the cutaneous toxicity of gilteritinib were screened from a natural compound library using SRB method, and the intervention effect of borneol on gilteritinib cutaneous toxicity was further investigated in HaCaT cells and C57BL/6J male mice.@*RESULTS@#In vivo studies showed pathological changes in the skin with apoptosis of keratinocytes in the stratum spinosum and stratum granulosum in the modeling group. Invitro studies showed apoptosis of HaCaT cells, significant up-regulation of cleaved poly (ADP-ribose) polymerase (c-PARP) and gamma-H2A histone family member X (γ-H2AX) levels, and increased accumulation of ROS in gilteritinib-modeled skin keratinocytes compared with controls. Screening of the natural compound library revealed that borneol showed excellent intervention effects on the death of HaCaT cells. In vitro, cell apoptosis was significantly reduced in the borneol+gilteritinib group compared to the gilteritinib control group. The levels of c-PARP, γ-H2AX and ROS in cells were significantly decreased. In vivo, borneol alleviated gilteritinib-induced skin pathological changes and skin cell apoptosis in mice.@*CONCLUSIONS@#Gilteritinib induces keratinocytes apoptosis by causing intracellular ROS accumulation, resulting in cutaneous toxicity. Borneol can ameliorate the cutaneous toxicity of gilteritinib by reducing the accumulation of ROS and apoptosis of keratinocytes in the skin tissue.

ADP-ribosylhydrolases: from DNA damage repair to COVID-19 / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Adenosine diphosphate (ADP)-ribosylation is a unique post-translational modification that regulates many biological processes, such as DNA damage repair. During DNA repair, ADP-ribosylation needs to be reversed by ADP-ribosylhydrolases. A group of ADP-ribosylhydrolases have a catalytic domain, namely the macrodomain, which is conserved in evolution from prokaryotes to humans. Not all macrodomains remove ADP-ribosylation. One set of macrodomains loses enzymatic activity and only binds to ADP-ribose (ADPR). Here, we summarize the biological functions of these macrodomains in DNA damage repair and compare the structure of enzymatically active and inactive macrodomains. Moreover, small molecular inhibitors have been developed that target macrodomains to suppress DNA damage repair and tumor growth. Macrodomain proteins are also expressed in pathogens, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, these domains may not be directly involved in DNA damage repair in the hosts or pathogens. Instead, they play key roles in pathogen replication. Thus, by targeting macrodomains it may be possible to treat pathogen-induced diseases, such as coronavirus disease 2019 (COVID-19).

Poly adenosine diphosphate-ribosylation and neurodegenerative diseases / 浙江大学学报·医学版

The morbidity of neurodegenerative diseases are increased in recent years, however, the treatment is limited. Poly ADP-ribosylation (PARylation) is a post-translational modification of protein that catalyzed by poly(ADP-ribose) polymerase (PARP). Studies have shown that PARylation is involved in many neurodegenerative diseases such as stroke, Parkinson's diseases, Alzheimer's disease, amyotrophic lateral sclerosis and so on, by affecting intracellular translocation of protein molecules, protein aggregation, protein activity, and cell death. PARP inhibitors have showed neuroprotective efficacy for neurodegenerative diseases in pre-clinical studies and phase Ⅰ clinical trials. To find new PARP inhibitors with more specific effects and specific pharmacokinetic characteristics will be the new direction for the treatment of neurodegenerative diseases. This paper reviews the recent progress on PARylation in neurodegenerative diseases.

Role of Trypanosoma cruzi nucleoside diphosphate kinase 1 in DNA damage responses

BACKGROUND NME23/NDPKs are well conserved proteins found in all living organisms. In addition to being nucleoside diphosphate kinases (NDPK), they are multifunctional enzymes involved in different processes such as DNA stability, gene regulation and DNA repair among others. TcNDPK1 is the canonical NDPK isoform present in Trypanosoma cruzi, which has nuclease activity and DNA-binding properties in vitro. OBJECTIVES In the present study we explored the role of TcNDPK1 in DNA damage responses. METHODS TcNDPK1 was expressed in mutant bacteria and yeasts and over-expressed in epimastigotes. Mutation frequencies, tolerance to genotoxic agents and activity of DNA repair enzymes were evaluated. FINDINGS Bacteria decreased about 15-folds the spontaneous mutation rate and yeasts were more resistant to hydrogen peroxide and to UV radiation than controls. Parasites overexpressing TcNDPK1 were able to withstand genotoxic stresses caused by hydrogen peroxide, phleomycin and hidroxyurea. They also presented less genomic damage and augmented levels of poly(ADP)ribose and poly(ADP)ribose polymerase, an enzyme involved in DNA repair. MAIN CONCLUSION These results strongly suggest a novel function for TcNDPK1; its involvement in the maintenance of parasite's genome integrity.

Integrating a Next Generation Sequencing Panel into Clinical Practice in Ovarian Cancer

PURPOSE: Few efforts have been made to integrate a next generation sequencing (NGS) panel into standard clinical treatment of ovarian cancer. The aim of this study was to investigate the clinical utility of NGS and to identify clinically impactful information beyond targetable alterations. MATERIALS AND METHODS: We conducted a retrospective review of 84 patients with ovarian cancer who underwent NGS between March 1, 2017, and July 31, 2018, at the Yonsei Cancer Hospital. We extracted DNA from formalin-fixed, paraffin-embedded tissue samples of ovarian cancer. The TruSight Tumor 170 gene panel was used to prepare libraries, and the MiSeq instrument was used for NGS. RESULTS: Of the 84 patients, 55 (65.1%) had high-grade serous carcinomas. Seventy-three (86.7%) patients underwent NGS at the time of diagnosis, and 11 (13.3%) underwent NGS upon relapse. The most common genetic alterations were in TP53 (64%), PIK3CA (15%), and BRCA1/2 (13%), arising as single nucleotide variants and indels. MYC amplification (27%) was the most common copy number variation and fusion. Fifty-seven (67.9%) patients had more than one actionable alteration other than TP53. Seven (8.3%) cases received matched-target therapy based on the following sequencing results: BRCA1 or 2 mutation, poly ADP ribose polymerase inhibitor (n=5); PIK3CA mutation, AKT inhibitor (n=1); and MLH1 mutation, PD-1 inhibitor (n=1). Fifty-three (63.0%) patients had a possibility of treatment change, and 8 (9.5%) patients received genetic counseling. CONCLUSION: Implementation of NGS may help in identifying patients who might benefit from targeted treatment therapies and genetic counseling.

Homologous recombination deficiency in ovarian cancer: a review of its epidemiology and management

Ovarian cancer patients with homologous recombination deficiencies exhibit specific clinical behaviors, and improved responses to treatments, such as platinum-based chemotherapy and poly (ADP-ribose) polymerase (PARP) inhibitors, have been observed. Germline mutations in the BRCA 1/2 genes are the most well-known mechanisms of homologous recombination deficiency. However, other mechanisms, such as germline and somatic mutations in other homologous recombination genes and epigenetic modifications, have also been implicated in homologous recombination deficiency. The epidemiology and implications of these other mechanisms need to be better understood to improve the treatment strategies for these patients. Furthermore, an evaluation of various diagnostic tests to investigate homologous recombination deficiency is essential. Comprehension of the role of homologous recombination deficiency in ovarian cancer also allows the development of therapeutic combinations that can improve the efficacy of treatment. In this review, we discuss the epidemiology and management of homologous recombination deficiency in ovarian cancer patients.

Exogenous spermidine ameliorates tubular necrosis during cisplatin nephrotoxicity / 대한해부학회지

The hallmark of cisplatin-induced acute kidney injury is the necrotic cell death in the kidney proximal tubules. However, an effective approach to limit cisplatin nephrotoxicity remains unknown. Spermidine is a polyamine that protects against oxidative stress and necrosis in aged yeasts, and the present study found that exogenous spermidine markedly attenuated tubular necrosis and kidney dysfunction, but not apoptosis, during cisplatin nephrotoxicity. In addition, exogenous spermidine potently inhibited oxidative/nitrative DNA damage, poly(ADP-ribose) polymerase 1 (PARP1) activation and ATP depletion after cisplatin injection. Conversely, inhibition of ornithine decarboxylase (ODC) via siRNA transfection in vivo significantly increased DNA damage, PARP1 activation and ATP depletion, resulting in acceleration of tubular necrosis and kidney dysfunction. Finally, exogenous spermidine removed severe cisplatin injury induced by ODC inhibition. In conclusion, these data suggest that spermidine protects kidneys against cisplatin injury through DNA damage and tubular necrosis, and this finding provides a novel target to prevent acute kidney injury including nephrotoxicity.

Acer okamotoanum Inhibit the Hydrogen Peroxide-Induced Oxidative Stress in C6 Glial Cells

Chronic oxidative stress due to the accumulation of reactive oxygen species (ROS) in neuronal cells ultimately leads to neurodegenerative diseases. The use of natural therapies for the prevention of ROS-induced cell damage and for the treatment of neurodegenerative disorders has shown promising results. In this study, we evaluated the neuroprotective effects of the ethyl acetate (EtOAc) fraction of A. Okamotoanum against the hydrogen peroxide (H₂O₂)-induced oxidative stress in C6 glial cells. Results show that cell viability was decreased in cells incubated with H₂O₂, whereas the addition of EtOAc fraction treatments in such cells significantly increased viability. The EtOAc fraction showed the highest inhibitory activity against ROS production and it also decreased the expressions of inflammatory proteins including cyclooxygenase-2, inducible nitric oxide synthase and interleukin-1β. Furthermore, the EtOAc fraction inhibited apoptosis by regulating the protein expressions cleaved caspase

Major clinical research advances in gynecologic cancer in 2017 / 부인종양

In 2017, 10 topics were selected as major clinical research advances in gynecologic oncology. For cervical cancer, efficacy and safety analysis results of a 9-valent human papillomavirus (HPV) vaccine and long-term impact of reduced dose of quadrivalent vaccine were updated. Brief introduction of KEYNOTE trials of pembrolizumab, a monoclonal antibody that blocks the interaction between programmed death (PD)-1 and its ligands, PD-L1 and PD-L2, followed. Tailored surveillance programs for gynecologic cancer related with Lynch syndrome and update on sentinel lymph node mapping were reviewed for uterine corpus cancer. For ovarian cancer, 5 topics were selected including poly(ADP-ribose) polymerases inhibitors and immunotherapy. The other potential practice changers covered in this review were lymphadenectomy in advanced disease, secondary cytoreductive surgery in recurrent disease, weekly dose-dense regimen for first-line chemotherapy, incorporation of bevacizumab maintenance in platinum-sensitive recurrent disease, and effect of platinum-free interval prolongation. Conflicting opinions of academic societies on periodic pelvic examination were introduced in conjunction with relevant literature review. For the field of radiation oncology, results of 2 big trials, The Postoperative Radiation Therapy in Endometrial Carcinoma-3 and Gynecologic Oncology Group-258, for endometrial cancer and recent advance in high-dose-rate brachytherapy for cervical cancer were reported. Topics for breast cancer covered adjuvant capecitabine after preoperative chemotherapy, adjuvant pertuzumab and trastuzumab in early human epidermal growth factor receptor 2-positive disease, olaparib for metastatic cancer in patients with a germline BRCA mutation, 20-year risks of recurrence after stopping endocrine therapy at 5 years, and contemporary hormonal contraception and the risk of breast cancer.

Reactive oxygen species-dependent apoptosis induction by water extract of Citrus unshiu peel in MDA-MB-231 human breast carcinoma cells

BACKGROUND/OBJECTIVES: Although several recent studies have reported the anti-cancer effects of extracts or components of Citrus unshiu peel, which has been used for various purposes in traditional medicine, the molecular mechanisms for their effects remain unclear. In the present study, the anti-cancer activity of a water-soluble extract of C. unshiu peel (WECU) in MDA-MB-231 human breast carcinoma cells at the level of apoptosis induction was investigated. MATERIALS/METHODS: Cytotoxicity was evaluated using the MTT assay. Apoptosis was detected using DAPI staining and flow cytometry analyses. Mitochondrial membrane potential, reactive oxygen species (ROS) assay, caspase activity and Western blotting were used to confirm the basis of apoptosis. RESULTS: The results indicated that WECU-induced apoptosis was related to the activation of caspase-8, and -9, representative initiator caspases of extrinsic and intrinsic apoptosis pathways, respectively, and caspase-3 accompanied by proteolytic degradation of poly(ADP-ribose) polymerase and down-regulation of the inhibitors of apoptosis protein family members. WECU also increased the pro-apoptotic BAX to anti-apoptotic BCL-2 ratio, loss of mitochondrial membrane potential and cytochrome c release from mitochondria to cytoplasm. Furthermore, WECU provoked the generation of ROS, but the reduction of cell viability and induction of apoptosis by WECU were prevented when ROS production was blocked by antioxidant N-acetyl cysteine. CONCLUSIONS: These results suggest that WECU suppressed proliferation of MDA-MB-231 cells by activating extrinsic and intrinsic apoptosis pathways in a ROS-dependent manner.

A New Neolignan Derivative, Balanophonin Isolated from Firmiana simplex Delays the Progress of Neuronal Cell Death by Inhibiting Microglial Activation

Excessive activation of microglia causes the continuous production of neurotoxic mediators, which further causes neuron degeneration. Therefore, inhibition of microglial activation is a possible target for the treatment of neurodegenerative disorders. Balanophonin, a natural neolignoid from Firmiana simplex, has been reported to have anti-inflammatory and anti-cancer effects. In this study, we aimed to evaluate the anti-neuroinflammatory effects and mechanism of balanophonin in lipopolysaccharide (LPS)-stimulated BV2 microglia cells. BV2 microglia cells were stimulated with LPS in the presence or absence of balanophonin. The results indicated that balanophonin reduced not only the LPS-mediated TLR4 activation but also the production of inflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), Interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α), in BV2 cells. Balanophonin also inhibited LPS-induced inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX2) protein expression and mitogen activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 MAPK. Interestingly, it also inhibited neuronal cell death resulting from LPS-activated microglia by regulating cleaved caspase-3 and poly ADP ribose polymerase (PARP) cleavage in N2a cells. In conclusion, our data indicated that balanophonin may delay the progression of neuronal cell death by inhibiting microglial activation.

Targeted therapy of ovarian cancer including immune check point inhibitor

Epithelial ovarian cancer is the eighth most common cause of cancer-related deaths in women because most patients present with advanced stage disease at the time of diagnosis. Although cytoreductive surgery and platinum-based chemotherapy remain the gold standards of treatment, the recurrence rate of ovarian cancer remains high. Attempts to improve this standard two-drug chemotherapy by adding a third cytotoxic drug have failed to affect either progression-free survival or overall survival and have resulted in an increase in toxic side effects. Some anti-angiogenic agents, poly(ADP-ribose) polymerase, and immune checkpoint inhibitors have shown efficacy in early stages of development for the treatment of epithelial ovarian cancer. As demonstrated in recent clinical trials, the use of bevacizumab, cediranib, pazopanib, olaparib, and rucaparib, either alone or in combination with conventional cytotoxic agents, improves progression-free survival. Trials on immune checkpoint inhibitors such as nivolumab have revealed prolonged responses in a small set of ovarian cancer cases but require further exploration. In this review, we discuss the role of targeted therapies against ovarian cancer, including the use of immune checkpoint inhibitors.

Spermidine is protective against kidney ischemia and reperfusion injury through inhibiting DNA nitration and PARP1 activation / 대한해부학회지

Kidney ischemia and reperfusion injury (IRI) is associated with a high mortality rate, which is attributed to tubular oxidative and nitrative stresses; however, an effective approach to limit IRI remains elusive. Spermidine, a naturally occurring polyamine, protects yeast cells against aging through the inhibition of oxidative stress and necrosis. In the present study, spermidine supplementation markedly attenuated histological damage and kidney dysfunction during IRI. In addition, exogenous spermidine potently inhibited poly(ADP-ribose) polymerase 1 (PARP1) activation and DNA nitrative/oxidative stress following IRI. Conversely, inhibition of ornithine decarboxylase (ODC) via siRNA transfection in vivo significantly enhanced DNA nitration, PARP1 activation, and functional damage during IRI. Finally, in ODC knockdown kidneys, PARP1 inhibition attenuated histological and functional damage induced by IRI, but not DNA nitrative stress. In conclusion, these data suggest that spermidine protects kidneys against IRI through blocking DNA nitration and PARP1 activation and this finding provides a novel target for prevention of acute kidney injury including IRI.

Poly(ADP-ribose) polymerase regulates glycolytic activity in kidney proximal tubule epithelial cells / 대한해부학회지

After renal injury, selective damage occurs in the proximal tubules as a result of inhibition of glycolysis. The molecular mechanism of damage is not known. Poly(ADP-ribose) polymerase (PARP) activation plays a critical role of proximal tubular cell death in several renal disorders. Here, we studied the role of PARP on glycolytic flux in pig kidney proximal tubule epithelial LLC-PK1 cells using XFp extracellular flux analysis. Poly(ADP-ribosyl)ation by PARP activation was increased approximately 2-fold by incubation of the cells in 10 mM glucose for 30 minutes, but treatment with the PARP inhibitor 3-aminobenzamide (3-AB) does-dependently prevented the glucose-induced PARP activation (approximately 14.4% decrease in 0.1 mM 3-AB-treated group and 36.7% decrease in 1 mM 3-AB-treated group). Treatment with 1 mM 3-AB significantly enhanced the glucose-mediated increase in the extracellular acidification rate (61.1±4.3 mpH/min vs. 126.8±6.2 mpH/min or approximately 2-fold) compared with treatment with vehicle, indicating that PARP inhibition increases only glycolytic activity during glycolytic flux including basal glycolysis, glycolytic activity, and glycolytic capacity in kidney proximal tubule epithelial cells. Glucose increased the activities of glycolytic enzymes including hexokinase, phosphoglucose isomerase, phosphofructokinase-1, glyceraldehyde-3-phosphate dehydrogenase, enolase, and pyruvate kinase in LLC-PK1 cells. Furthermore, PARP inhibition selectively augmented the activities of hexokinase (approximately 1.4-fold over vehicle group), phosphofructokinase-1 (approximately 1.6-fold over vehicle group), and glyceraldehyde-3-phosphate dehydrogenase (approximately 2.2-fold over vehicle group). In conclusion, these data suggest that PARP activation may regulate glycolytic activity via poly(ADP-ribosyl)ation of hexokinase, phosphofructokinase-1, and glyceraldehyde-3-phosphate dehydrogenase in kidney proximal tubule epithelial cells.

Gene Expression Profile of Apoptosis in Leukemia Cells Induced by Hsp90 Selective inhibitor 17-AAG / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the apoptotic effects of Hsp90 selective inhibitor 17-AAG on human leukemia HL-60 and NB4 cells and analyse its possible mechanism.</p><p><b>METHODS</b>CCK-8 assay was used to quantify the growth inhibition of cells after exposure to 17-AAG for 24 hours. Flow cytometrve with annexin V/propidium iodide staining was used to detect apoptosis of leukemia cells. Then Western blot was used to detect the activation of apoptosis related protein caspase-3 and PARP level. Gene expression profile of NB4 cells treated with 17-AAG was analyzed with real-time PCR arrays.</p><p><b>RESULTS</b>The inhibition of leukemia cell proliferation displayed a dose-dependent manner. Annexin V assay, cell cycle analysis and activation of PARP demonstrate that 17-AAG induced apoptosis leukemia cells. Real-time PCR array analysis showed that expression of 56 genes significantly up-regulated and expression of 23 genes were significantly down-regulated after 17-AAG treatment.</p><p><b>CONCLUSION</b>The 17-AAG can inhibit the proliferation and induce the apoptosis of leukemia cells. After leukemia cells are treated with 17-AAG, the significant changes of apoptosis-related genes occured, and the cell apoptosis occurs via activating apoptosis related signaling pathway.</p>

Poly(ADP-ribose) polymerase 1 contributes to oxidative stress through downregulation of sirtuin 3 during cisplatin nephrotoxicity / 대한해부학회지

Enhanced oxidative stress is a hallmark of cisplatin nephrotoxicity, and inhibition of poly(ADP-ribose) polymerase 1 (PARP1) attenuates oxidative stress during cisplatin nephrotoxicity; however, the precise mechanisms behind its action remain elusive. Here, using an in vitro model of cisplatin-induced injury to human kidney proximal tubular cells, we demonstrated that the protective effect of PARP1 inhibition on oxidative stress is associated with sirtuin 3 (SIRT3) activation. Exposure to 400 µM cisplatin for 8 hours in cells decreased activity and expression of manganese superoxide dismutase (MnSOD), catalase, glutathione peroxidase (GPX), and SIRT3, while it increased their lysine acetylation. However, treatment with 1 µM PJ34 hydrochloride, a potent PARP1 inhibitor, restored activity and/or expression in those antioxidant enzymes, decreased lysine acetylation of those enzymes, and improved SIRT3 expression and activity in the cisplatin-injured cells. Using transfection with SIRT3 double nickase plasmids, SIRT3-deficient cells given cisplatin did not show the ameliorable effect of PARP1 inhibition on lysine acetylation and activity of antioxidant enzymes, including MnSOD, catalase and GPX. Furthermore, SIRT3 deficiency in cisplatin-injured cells prevented PARP1 inhibition-induced increase in forkhead box O3a transcriptional activity, and upregulation of MnSOD and catalase. Finally, loss of SIRT3 in cisplatin-exposed cells removed the protective effect of PARP1 inhibition against oxidative stress, represented by the concentration of lipid hydroperoxide and 8-hydroxy-2'-deoxyguanosine; and necrotic cell death represented by a percentage of propidium iodide–positively stained cells. Taken together, these results indicate that PARP1 inhibition protects kidney proximal tubular cells against oxidative stress through SIRT3 activation during cisplatin nephrotoxicity.

Effect of Emodin Derivative E11 on T Lymphocytic Leukemia Cell Line Molt-4 and Its Possible Mechanisms / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To explore the effect of a new emodin derivative E11 on proliferation and apoptosis of T lymphocytic leukemia cell line Molt-4 and its possible mechanisms.</p><p><b>METHODS</b>MTT method was used to plot cell growth curve. Colony culture assay was performed for studying the effect of emodin derivative E11 on colony-formation of Molt-4. The fluorescent microscopy with DAPI staining was used to examine the cell morphological changes after E11 treatment. DNA fragmentation method was used to detect the inducing effect of emodin derivative E11 on cell apoptosis. Western blot was used to determine the expressions of apoptosis-related proteins including procaspase-9, procaspase-3, PARP and PI3K/AKT, MAPK signalling pathway.</p><p><b>RESULTS</b>Emodin derivative E11 could strongly inhibit the growth of Molt-4 with the IC50 in 48 h at 1.381 ± 0.1552 µmol/L in dose-dependent manner. 0.1 µmol/L of E11 could inhibit cell colony formation. The typrical apopototic morphologic changes of Molt cells treated with E11 could be observed under fluorescence microscope with DAPI staining. DNA apoptotic ladder could be observed by DNA fragmentation.The expressions of procaspase -9, procaspase-3, PARP, p-MAPK, p-AKT, mTOR, p-mTOR, p-P70 and p-4BEP1 were down-regulated, while expressions of MAPK, AKT, 4EBP1 and P70 were not changed remarkably after Molt-4 were treated with E11 for 48 h.</p><p><b>CONCLUSION</b>E11 can remarkably inhibit the proliferation and induce the apoptosis of Molt-4 cells. The mechanism of apoptosis of Molt-4 cells may be related with the suppression of PI3K/AKT and MAPK signalling pathways.</p>

Synergistic anti-tumor effect of obatoclax and MG-132 in esophageal cancer cell line CaES-17 / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore whether MG-132 could enhance the anti-tumor activity of obatoclax against esophageal cancer cell line CaES-17.</p><p><b>METHODS</b>MTT assay was used to determine the cytotoxicity of obatoclax and MG-132 in CaES-17 cells. The IC(50) of obatoclax and MG-132 were used to determine the molar ratio (1:2.4) of the two drugs for combined treatment of the cells. The concentrations of obatoclax and MG-132 ranged from 1/8 IC(50) to 4 IC(50) after serial dilution, and their combination index (CI) was calculated using CompuSyn software. The expression of ubiquitin and the cleavage of PARP, caspase-9, phospho-histone H3 and phospho-aurora A/B/C in the exposed cells were examined with Western blotting; the cell apoptosis was measured by flow cytometry with Annexin V staining, and the percentage of cells in each cell cycle phase was also determined by flow cytometry.</p><p><b>RESULTS</b>The CI of obatoclax and MG-132 was 0.296 for a 50% inhibition of Caes-17 cells and was 0.104 for a 95% inhibition. The cells treated with obatoclax or MG-132 alone showed increased expression of ubiquitin and cleavage of PARP and caspase-9. Compared with the cells treated with obatoclax or MG-132 alone, the cells with a combined treatment exhibited significantly increased expression of ubiquitin, cleavage of PARP and caspase-9, and expression of phospho-Histone H3 (P<0.05). The combined treatment of the cells also resulted in significantly increased expression of phospho-Aurora A/B/C compared with obatoclax treatment alone. The cells with the combined treatment showed significantly higher percentages of apoptotic cells and cells in sub-G(1) and G(2)/M phases compared with the cells treated with either of the drugs (P<0.05).</p><p><b>CONCLUSION</b>Obatoclax combined with MG-132 shows a significant synergistic anti-tumor effect against esophageal cancer CaES-17 cells by inducing apoptosis and cell cycle arrest.</p>

Poly(ADP-ribosyl)ation of Apoptosis Antagonizing Transcription Factor Involved in Hydroquinone-Induced DNA Damage Response / 生物医学与环境科学（英文）

The molecular mechanism of DNA damage induced by hydroquinone (HQ) remains unclear. Poly(ADP-ribose) polymerase-1 (PARP-1) usually works as a DNA damage sensor, and hence, it is possible that PARP-1 is involved in the DNA damage response induced by HQ. In TK6 cells treated with HQ, PARP activity as well as the expression of apoptosis antagonizing transcription factor (AATF), PARP-1, and phosphorylated H2AX (γ-H2AX) were maximum at 0.5 h, 6 h, 3 h, and 3 h, respectively. To explore the detailed mechanisms underlying the prompt DNA repair reaction, the above indicators were investigated in PARP-1-silenced cells. PARP activity and expression of AATF and PARP-1 decreased to 36%, 32%, and 33%, respectively, in the cells; however, γ-H2AX expression increased to 265%. Co-immunoprecipitation (co-IP) assays were employed to determine whether PARP-1 and AATF formed protein complexes. The interaction between these proteins together with the results from IP assays and confocal microscopy indicated that poly(ADP-ribosyl)ation (PARylation) regulated AATF expression. In conclusion, PARP-1 was involved in the DNA damage repair induced by HQ via increasing the accumulation of AATF through PARylation.