Persistent DNA damage inhibits S-phase and G2 progression, and results in apoptosis

TRIM47 silencing inhibits the malignant biological behaviors of prostate cancer cells by regulating MDM2/p53 signaling

Prostate cancer (PCa) is a prevalent male malignancy globally. Tripartite motif 47 (TRIM47) has been reported to be associated with PCa. However, how TRIM47 acts on PCa is still incompletely understood. Here, we explored the biological roles of TRIM47 in PCa cells and investigated its potential regulatory mechanism. TRIM47 expression in PCa cells was detected by qRT-PCR and western blot. After TRIM47 silencing, the viability of PCa cells was measured using CCK-8 method. Flow cytometry was employed to estimate cell cycle. Cell apoptotic level was subjected to appraisement with TUNEL assay. Additionally, wound healing- and transwell assays were adopted for evaluation of migration and invasion of PCa cells. Moreover, the Biogrid database and HDOCK SERVER predicated that TRIM47 could interact with mouse double minute 2 (MDM2), which was detected using the Co-immunoprecipitation (co-IP) assay and glutathione S-transferase (GST) pull-down assay. The expression of proteins in MDM2/p53 signaling was detected by western blot analysis. Results indicated that TRIM47 expression was highly expressed in PCa cells. TRIM47 knockdown inhibited PCa proliferation and cell cycle whereas promoted cell apoptosis. Besides, TRIM47 knockdown significantly inhibited the migration and invasion of PCa cells. In addition, TRIM47 was proved to bind to MDM2 and regulated MDM2/p53 expression. Importantly, MDM2 overexpression counteracted the impacts of TRIM47 knockdown on cell viability, cell cycle, apoptosis, migration and invasion by regulating the MDM2/p53 pathway. Collectively, our results suggested that TRIM47 silencing inhibits the malignant biological behaviors of prostate cancer cells by regulating MDM2/p53 signaling, which may provide a novel therapeutic target for PCa treatment.

AKR1C3 silencing inhibits autophagy-dependent glycolysis in thyroid cancer cells by inactivating ERK signaling

Thyroid cancer is a highly differentiated and poorly malignant tumor. Interfering with glycolysis has become an effective means of controlling cancer progression and autophagy is negatively correlated with glycolysis. Aldo-keto reductase family 1 member C3 (AKR1C3) has been demonstrated to be highly expressed in thyroid cancer tissue and the higher AKR1C3 expression predicted the worse prognosis. We aimed to explore whether AKR1C3 could affect thyroid cancer progression by regulating autophagy-dependent glycolysis. AKR1C3 expression in thyroid cancer cells was detected by western blot. Then, AKR1C3 was knocked down by transfection with short hairpin RNA specific to AKR1C3 in the absence or presence of 3-methyladenine (3-MA) or PMA treatment. Cell cycle and apoptosis was detected by flow cytometry. Immunofluorescence staining was used to analyze LC3B expression. Extracellular acidification, glucose uptake and lactic acid secretion were detected. To evaluate the tumorigenicity of AKR1C3 insufficiency on thyroid cancer in vivo, TPC-1 cells with AKR1C3 knockdown were injected subcutaneously into nude mice. Then, cyclinD1 and Ki67 expression in tumorous tissues was measured by immunohistochemical analysis. Apoptosis was assessed by terminal-deoxynucleoitidyl transferase mediated nick end labeling staining. Additionally, the expression of proteins related to cell cycle, apoptosis, glycolysis, autophagy, and extracellular signal-regulated kinase (ERK) signaling in cells and tumor tissues was assessed by western blot. Highly expressed AKR1C3 was observed in thyroid cancer cells. AKR1C3 knockdown induced cell cycle arrest and apoptosis of TPC-1 cells. Besides, autophagy was activated and glycolysis was inhibited following AKR1C3 silencing, and 3-MA treatment restored the impacts of AKR1C3 silencing on glycolysis. The further experiments revealed that AKR1C3 insufficiency inhibited ERK signaling and PMA application reversed AKR1C3 silencing-induced autophagy in TPC-1 cells. The in vivo results suggested that AKR1C3 knockdown inhibited the development of subcutaneous TPC-1 tumors in nude mice and inactivated the ERK signaling. Collectively, AKR1C3 silencing inhibited autophagy-dependent glycolysis in thyroid cancer by inactivating ERK signaling.

KLF14 activates the JNK-signaling pathway to induce S-phase arrest in cervical cancer cells

Objective

To explore the role of Krüppel-like factor 14 (KLF14) and its underlying mechanism(s) of action in cell-cycle regulation in cervical cancer.

Methods

Lentiviral infection was used to construct KLF14, KLF14 zinc-finger structural mutations, and empty vector controls in SiHa and HeLa cervical cancer cells. The effect of KLF14 on cervical cancer cell cycle was detected by flow cytometry. The effect of KLF14 on the expression of cyclin-dependent kinase 2 (CDK2), cyclin A2 (CCNA2), and MAPK signalling pathway-related molecules was detected by fluorescence quantitative RT-PCR (qRT-PCR) and western blot. Cervical cancer cells were treated with JNK-pathway inhibitors/agonists before we assessed changes in the cell cycle and the expression of the CDK2, CCNA2, and p-JNK/JNK. Subcutaneous xenograft studies to explore the effects of KLF14 on cervical cancer cell proliferation in vivo, and western blotting was implemented to measure the expression of CCNA2, CDK2, and the activation levels of the MAPK-signaling pathway proteins in tumours.

Results

The proportion of cells in the S phase was increased in the KLF14-overexpressing group compared with the control group (P<0.001); CDK2, CCNA2, and p-JNK/JNK expression levels were elevated in the KLF14-overexpressing group relative to the control group (all P<0.05). When JNK-pathway activation was inhibited/promoted, the proportion of cells in the S phase was reduced/increased (P<0.05) and CDK2 and CCNA2 expression levels were reduced/decreased, respectively (all P<0.05). Vivo experiments revealed that KLF14 inhibited cervical cancer cell proliferation (P<0.01) and that p-JNK/JNK, CDK2, and CCNA2 expression levels were augmented in tumours in the overexpression group (P<0.01).

Conclusion

KLF14 induced S-phase arrest in cervical cancer cells and inhibited the proliferation of cervical cancer cells in vivo; the induction of S-phase arrest was related to its zinc-finger structure. KLF14 also activated the JNK pathway to induce S-phase arrest and promote the expression of CDK2 and CCNA2. In summary, KLF14 activates the JNK-signaling pathway to induce S-phase arrest in cervical cancer cells.

Synthesis, docking study, and structure-activity relationship of novel niflumic acid derivatives acting as anticancer agents by inhibiting VEGFR or EGFR tyrosine kinase activities

A new series of niflumic acid (NF) derivatives were synthesized by esterification of (NF) to give ester compound 1, which was treated with hydrazine hydrate to produce (NF) hydrazide 2. Hydrazine-1-carboxamide compounds (3A–C), and hydrazine-1-carbothioamide derivatives (4A–D) were synthesized by treatment of (NF) hydrazide with phenyl isocyanate, and phenyl isothiocyanate derivatives, respectively. The cyclization of (4B–D) and (3B) was achieved using NaOH solution to produce 1,2,4-triazole derivatives (5A–C) and 6, respectively. The prepared compounds were characterized using IR, 1HNMR, 13CNMR, and MS (ESI) spectroscopy. A molecular docking study was performed to evaluate the binding affinity of the synthesized compounds against EGFR and VEGFR kinase domains which revealed that compounds 3B, and 4A had the best binding energy (-7.87, and -7.33 kcal/mol, respectively) against VEGFR, while compound 5A had the best binding energy (-7.95 kcal/mol) against EGFR. The biological investigation results indicated that all the tested compounds caused cell killing in the two cancer cell lines (Hep G2 and A549) studied, with compound 4C being the most cytotoxic, as well as being cancer selective. Additionally, compound 4C-treated Hep G2 cells were arrested at the S and G2/M cell cycle phases. Cytotoxicity of compound 4C was attributed to apoptosis as determined by flow cytometry and qRT-PCR results of the apoptosis markers p53, BAX, and caspase-3. Finally, compound 4C inhibited VEGFR kinase activity, while compound 5B inhibited EGFR kinase activity. In conclusion, the novel (NF) derivatives are potent anticancer agents, inhibiting cell proliferation by inhibiting EGFR and VEGFR tyrosine kinase enzymes.

The cyto-protective effects of LH on ovarian reserve and female fertility during exposure to gonadotoxic alkylating agents in an adult mouse model

STUDY QUESTION

Does LH protect mouse oocytes and female fertility from alkylating chemotherapy?

SUMMARY ANSWER

LH treatment before and during chemotherapy prevents detrimental effects on follicles and reproductive lifespan.

WHAT IS KNOWN ALREADY

Chemotherapies can damage the ovary, resulting in premature ovarian failure and reduced fertility in cancer survivors. LH was recently suggested to protect prepubertal mouse follicles from chemotoxic effects of cisplatin treatment.

STUDY DESIGN, SIZE, DURATION

This experimental study investigated LH effects on primordial follicles exposed to chemotherapy. Seven-week-old CD-1 female mice were randomly allocated to four experimental groups: Control (n = 13), chemotherapy (ChT, n = 15), ChT+LH-1x (n = 15), and ChT+LH-5x (n = 8). To induce primary ovarian insufficiency (POI), animals in the ChT and ChT+LH groups were intraperitoneally injected with 120 mg/kg of cyclophosphamide and 12 mg/kg of busulfan, while control mice received vehicle. For LH treatment, the ChT+LH-1x and ChT+LH-5x animals received a 1 or 5 IU LH dose, respectively, before chemotherapy, then a second LH injection administered with chemotherapy 24 h later. Then, two animals/group were euthanized at 12 and 24 h to investigate the early ovarian response to LH, while remaining mice were housed for 30 days to evaluate short- and long-term reproductive outcomes. The effects of LH and chemotherapy on growing-stage follicles were analyzed in a parallel experiment. Seven-week-old NOD-SCID female mice were allocated to control (n = 5), ChT (n = 5), and ChT+LH-1x (n = 6) groups. Animals were treated as described above, but maintained for 7 days before reproductive assessment.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the first experiment, follicular damage (phosphorylated H2AX histone (γH2AX) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay), apoptotic biomarkers (western blot), and DNA repair pathways (western blot and RT-qPCR) were assessed in ovaries collected at 12 and 24 h to determine early ovarian responses to LH. Thirty days after treatments, remaining mice were stimulated (10 IU of pregnant mare serum gonadotropin (PMSG) and 10 IU of hCG) and mated to collect ovaries, oocytes, and embryos. Histological analysis was performed on ovarian samples to investigate follicular populations and stromal status, and meiotic spindle and chromosome alignment was measured in oocytes by confocal microscopy. Long-term effects were monitored by assessing pregnancy rate and litter size during six consecutive breeding attempts. In the second experiment, mice were stimulated and mated 7 days after treatments and ovaries, oocytes, and embryos were collected. Follicular numbers, follicular protection (DNA damage and apoptosis by H2AX staining and TUNEL assay, respectively), and ovarian stroma were assessed. Oocyte quality was determined by confocal analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

LH treatment was sufficient to preserve ovarian reserve and follicular development, avoid atresia, and restore ovulation and meiotic spindle configuration in mature oocytes exposed at the primordial stage. LH improved the cumulative pregnancy rate and litter size in six consecutive breeding rounds, confirming the potential of LH treatment to preserve fertility. This protective effect appeared to be mediated by an enhanced early DNA repair response, via homologous recombination, and generation of anti-apoptotic signals in the ovary a few hours after injury with chemotherapy. This response ameliorated the chemotherapy-induced increase in DNA-damaged oocytes and apoptotic granulosa cells. LH treatment also protected growing follicles from chemotherapy. LH reversed the chemotherapy-induced depletion of primordial and primary follicular subpopulations, reduced oocyte DNA damage and granulosa cell apoptosis, restored mature oocyte cohort size, and improved meiotic spindle properties.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This was a preliminary study performed with mouse ovarian samples. Therefore, preclinical research with human samples is required for validation.

WIDER IMPLICATIONS OF THE FINDINGS

The current study tested if LH could protect the adult mouse ovarian reserve and reproductive lifespan from alkylating chemotherapy. These findings highlight the therapeutic potential of LH as a complementary non-surgical strategy for preserving fertility in female cancer patients.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Regional Valencian Ministry of Education (PROMETEO/2018/137), the Spanish Ministry of Science and Innovation (CP19/00141), and the Spanish Ministry of Education, Culture and Sports (FPU16/05264). The authors declare no conflict of interest.

SOX4-induced upregulation of ARHGAP9 promotes the progression of acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common acute leukemia. Rho GTPase activating protein 9 (ARHGAP9) has been reported to be positively correlated with overall survival of AML patients, but the specific molecular function remains unclear. This study aims to further explore the functional role and the molecular mechanism of ARHGAP9 in AML cells. The expression level of ARHGAP9 in AML cells was measured using quantitative real-time PCR (qRT-PCR) and western blot. Cell transfection was performed to interfere ARHGAP9. CCK-8, flow cytometry and TUNEL assays were conducted to detect cell viability, cell cycle distribution and apoptosis, respectively. The binding relationship between SOX4 and ARHGAP9 promoter was verified using luciferase reporter assay and chromatin immunoprecipitation. The results showed that ARHGAP9 was upregulated in AML cells. Interference of ARHGAP9 greatly reduced cell viability and induced cell cycle arrest in G1 phase, accompanied with the reduction of Ki67, PCNA, cyclin D1, cyclin E1, CDK4 and CDK6. In addition, Interference of ARHGAP9 greatly promoted cell apoptosis, accompanied with the decreased protein expression of Bcl-2 and the increased protein expression of Bax, cleaved caspase 3 and cleaved caspase 9. Furthermore, SOX4 directly bound to ARHGAP9 promoter and regulated ARHGAP9 expression. In conclusion, this study suggested that ARHGAP9 interference exerted an anti-tumor effect through inhibiting cell proliferation, blocking cell cycle progression, and promoting cell apoptosis in AML cells. ARHGAP9 may serve as a novel therapeutic target for AML.

Toxic Prediction of Pyrrolizidine Alkaloids and Structure-Dependent Induction of Apoptosis in HepaRG Cells

Pyrrolizidine alkaloids (PAs) are common phytotoxins and could cause liver genotoxicity/carcinogenicity following metabolic activation. However, the toxicity of different structures remains unclear due to the wide variety of PAs. In this study, the absorption, distribution, metabolism, excretion, and toxicity (ADMET) of 40 PAs were analyzed, and their toxicity was predicted by Komputer Assisted Technology (TOPKAT) using Discovery Studio software. The in silico results showed that all PAs except retronecine had good intestinal absorption, and all PAs were predicted to have different toxicity ranges. To verify the predictive results, 4 PAs were selected to investigate cell injury and possible mechanisms of the differentiation in HepaRG cells, including retronecine type of twelve-membered cyclic diester (retrorsine), eleven-membered cyclic diester (monocrotaline), noncyclic diester (retronecine), and platynecine type (platyphylline). After 24 h exposure, retronecine-type PAs exhibited concentration-dependent cytotoxicity. The high-content screening assay showed that cell oxidative stress, mitochondrial damage, endoplasmic reticulum stress, and the concentration of calcium ions increased, and neutral lipid metabolism was changed notably in HepaRG cells. Induced apoptosis by PAs was indicated by cell cycle arrest in the G2/M phase, disrupting the mitochondrial membrane potential. Overall, our study revealed structure-dependent cytotoxicity and apoptosis after PA exposure, suggesting that the prediction results of in silico have certain reference values for compound toxicity. A 1,2-membered cyclic diester seems to be a more potent apoptosis inducer than other PAs.

Recognition of G-quadruplex topology through hybrid binding with implications in cancer theranostics

The selective recognition and imaging of oncogene specific G-quadruplex (GQ) structures holds great promise in the development of diagnostic therapy (theranostics) for cancer and has been challenging due to their structural dynamics and diversity. We report selective recognition of GQ by a small molecule through unique hybrid loop stacking and groove binding mode with turn on far-red fluorescence response and anticancer activity demonstrating the potential implications for GQ-targeted cancer theranostics.

Methods: Biophysical investigation reveal the turn on far-red emission property of TGP18 for selective recognition of GQ. In cellulo studies including DNA damage and oxidative stress evaluation guided us to perform in vitro (3D spheroid) and in vivo (xenograft mice model) anti-cancer activity, and tumor tissue imaging to assess the theranostic potential of TGP18.

Results: Neocuproine-based far-red turn on fluorescence probe TGP18 shows GQ-to-duplex selectivity and specifically recognizes BCL-2 GQ with high affinity through a unique hybrid binding mode involving loop-stacking and groove interactions. Our study reveals that the selective recognition originating from the distinct loop structure of GQ that alters the overall probe interaction and binding affinity. TGP18 binding to anti-apoptotic BCL-2 GQ ablates the pro-survival function and elicit anti-cancer activity by inducing apoptosis in cancer cells. We deciphered that inhibition of BCL-2 transcription synergized with signaling cascade of nucleolar stress, DNA damage and oxidative stress in triggering apoptosis signaling pathway.

Conclusion: Intervention of GQ mediated lethality by TGP18 has translated into anti-cancer activity in both in vitro 3D spheroid culture and in vivo xenograft models of lung and breast cancer with superior efficacy for the former. In vivo therapeutic efficacy supplemented with tumor 3D spheroid and tissue imaging potential define the role of TGP18 in GQ-targeted cancer theranostics.

Association of IGF1R polymorphisms (rs1546713) with susceptibility to age-related cataract in a Han Chinese population

AIM

To explore the susceptible association between the insulin-like growth factor-1 receptor (IGF1R) single nucleotide polymorphism (SNP) and age-related cataract (ARC), and investigate the underlying mechanisms in human lens epithelium (HLE) cells.

METHODS

Totally 1190 unrelated participants, comprising 690 ARC patients and 500 healthy individuals in Han Chinese population were recruited and genotyped for target SNP. The χ ²-test was used to detect genotypic distribution between the patient and control groups and the logistic regression was performed to adjust the age and gender. Meanwhile, different biological experimental methods, such as cell counting kit 8 (CCK-8) assay, flow cytometry, quantitative real time polymerase chain reaction (Q-PCR) and Western blot, were used to detect cell viability, cell cycle progression and apoptosis in HLE cells or IGF1R knockdown HLE cells.

RESULTS

The rs1546713 in IGF1R gene was identified (P=0.046, OR: 1.606, 95%CI: 1.245-2.071), which shown a significant relevance with ARC risk under the dominant model. The results demonstrated that IGF1R knockdown inhibited cell proliferation by inducing cell cycle arrested at S phase and promoting apoptosis. Mechanistically, the cell cycle blocked at S phase was linked with the alterations of cyclin A, cyclin B, cyclin E and P21. The pro-apoptosis function of IGF1R may related with stimulating the activation of Caspase-3 and altering the expression levels of apoptotic proteins, including Bcl-2, Bax and Caspase-3.

CONCLUSION

This study first report that IGF1R polymorphisms may affect susceptibility to ARCs in Han Chinese population and provide new clues to understand the pathogenic mechanism of ARCs. Notably, IGF1R is likely a potential target for ARC prevention and treatment.

Pyoluteorin induces cell cycle arrest and apoptosis in human triple-negative breast cancer cells MDA-MB-231

Objectives

To screen the cytotoxic activity of six secondary metabolites isolated from soil fungus Aspergillus niger. Importantly, to investigate the mechanism that pyoluteorin induced human triple-negative breast cancer MDA-MB-231 cells apoptosis in vitro.

Methods

The cell viability assay was tested with CTG assay. Cell cycle, apoptosis and intracellular reactive oxygen species (ROS) production assay were tested with flow cytometry. Additionally, intracellular ROS production assay and mitochondrial membrane potential assay were determined with laser scanning confocal microscopy. The expression of apoptosis-related proteins was determined with Western blot.

Key findings

Pyoluteorin displayed significantly selective cytotoxicity against human triple-negative breast cancer MDA-MB-231 cells (IC50 = 0.97 µm) with low toxicity against human breast epithelial cell MCF-10A. It was found that pyoluteorin could arrest MDA-MB-231 cells cycle at G2/M phase and induce cell apoptosis. Further experiments demonstrated that the apoptosis-inducing effect of pyoluteorin was related to reduction of mitochondrial membrane potential, accumulation of ROS and change of apoptosis-related protein expressions.

Conclusion

Our studies revealed that pyoluteorin had potent proliferation inhibition against MDA-MB-231 cells through arresting cell cycle at G2/M phase and inducing caspase-3-dependent apoptosis by mitochondrial pathway, implying that pyoluteorin may be a potential lead compound for drug discovery of human triple-negative breast cancer.

Berberine protects Kawasaki disease-induced human coronary artery endothelial cells dysfunction by inhibiting of oxidative and endoplasmic reticulum stress

Kawasaki disease (KD) is an acute febrile illness characterized by systemic vasculitis especially in coronary arteries. Berberine (BBR) shows several beneficial effects on cardiovascular system. The present study is to investigate whether BBR exerts protective effect against KD-induced damage of human coronary artery endothelial cell (HCAECs) and the underlying mechanisms. HCAECs exposed to medium with 15% serum from KD patients or healthy volunteers for 24 h. Stimulated HCAECs were treated with vehicle (without BBR) and BBR (20 μM) for 24 h, the cell apoptosis, cell cycle, induction of intracellular reactive oxygen species (ROS) and protein expression were examined by flow cytometry and western blot. The KD-induced differentially expressed proteins in HCAECs were determined by quantitative proteomics. BBR inhibited HCAECs from apoptosis and arrested cell cycle at G0/G1 stage. BBR protected HCAECs from injury by inhibiting expression of THBD, vWF and EDN1. Bioinformatics analysis suggested that the oxidative and ER stress were involved in KD-induced damage in HCAECs. ROS production and the protein expression of ATF4, p-EIF2α, p-PERK, XBP1, p-IRE1, HSP90B1, HSPG2, DNAJC3, P4HB and VCP were increased by serum from KD patients and decreased by BBR treatment. BBR exerts its protective effects on KD-induced damage of HCAECs through its inhibitory effects on oxidative and ER stress indicating BBR as a therapeutic candidate for KD.

The Circadian Gene Per1 Plays an Important Role in Radiation-Induced Apoptosis and DNA Damage in Glioma

Objective:

Period1 (PER1), a core circadian gene, not only modulates circadian rhythm but may also play an important role in other biological processes, including pathways involved in the proliferation and apoptosis of tumor cells. In this study, we investigated the mechanism by which the downregulated expression of PER1 promotes the apoptosis of wild-type P53 human glioma U343 cells exposed to X-rays.

Methods:

U343 cells were exposed to 6 mV 10 Gy X-ray irradiation after infection with an shRNA lentivirus to reduce the expression of PER1 and were analyzed by SCGE analysis, flow cytometry, qRT-PCR, and western blotting.

Result:

SCGE analysis revealed that compared with the controls, U343 cells expressing low levels of PER1 showed minor DNA damage when exposed to X-ray irradiation (P<0.05), and the flow cytometry assay showed lower death rates (P<0.05). RT-PCR and western blot analysis both revealed decreased expression of CHK2 and P53, which regulate DNA damage and repair via the CHK2-P53 pathway, and decreased expression of C-MYC, which is related to cell apoptosis.

Conclusion:

Our research suggests that PER1 may play an important role in tumor radiotherapy, which is attributable to enhanced chk2-P53 signaling and proapoptotic processes. These findings provide a new target for the clinical treatment of glioma and a reliable basis for postradiation therapy and gene therapy for glioma and other cancers.

Biochanin A Induces S Phase Arrest and Apoptosis in Lung Cancer Cells

Lung cancer is among the most common malignancies with a poor 5-year survival rate reaching only 16%. Thus, new effective treatment modalities and drugs are urgently needed for the treatment of this malignancy. In this study, we conducted the first investigation of the effects of Biochanin A on lung cancer and revealed the mechanisms underlying its potential anticancer effects. Biochanin A decreased cell viability in a time-dependent and dose-dependent manner and suppressed colony formation in A549 and 95D cells. In addition, Biochanin A induced S phase arrest and apoptosis and decreased mitochondrial membrane potential (ΔΨm) in A549 and 95D cells in a dose-dependent manner. Our results of subcutaneous xenograft models showed that the growth of Biochanin A group was significantly inhibited compared with that of control groups. Finally, P21, Caspase-3, and Bcl-2 were activated in Biochanin A-treated cells and Biochanin A-treated xenografts which also demonstrated that Biochanin A induced cell cycle arrest and apoptosis in lung cancer cells by regulating expression of cell cycle-related proteins and apoptosis-related proteins. In conclusion, this study suggests that Biochanin A inhibits the proliferation of lung cancer cells and induces cell cycle arrest and apoptosis mainly by regulating cell cycle-related protein expression and activating the Bcl-2 and Caspase-3 pathways, thus suggesting that Biochanin A may be a promising drug to treat lung cancer.

DNA damage-induced replication stress results in PA200-proteasome-mediated degradation of acetylated histones

Histone acetylation influences protein interactions and chromatin accessibility and plays an important role in the regulation of transcription, replication, and DNA repair. Conversely, DNA damage affects these crucial cellular processes and induces changes in histone acetylation. However, a comprehensive overview of the effects of DNA damage on the histone acetylation landscape is currently lacking. To quantify changes in histone acetylation, we developed an unbiased quantitative mass spectrometry analysis on affinity‐purified acetylated histone peptides, generated by differential parallel proteolysis. We identify a large number of histone acetylation sites and observe an overall reduction of acetylated histone residues in response to DNA damage, indicative of a histone‐wide loss of acetyl modifications. This decrease is mainly caused by DNA damage‐induced replication stress coupled to specific proteasome‐dependent loss of acetylated histones. Strikingly, this degradation of acetylated histones is independent of ubiquitylation but requires the PA200‐proteasome activator, a complex that specifically targets acetylated histones for degradation. The uncovered replication stress‐induced degradation of acetylated histones represents an important chromatin‐modifying response to cope with replication stress.

Period2 downregulation inhibits glioma cell apoptosis by activating the MDM2-TP53 pathway

The Period2 (Per2) gene is an essential component of the mammalian circadian clock and is strongly linked to glioma occurrence and its response to radiotherapy. Here, we examined the role of Per2 in the response to X-ray-induced DNA damage in U343 glioma cells and in a mouse cancer model. Following low dose X-ray irradiation, we observed that lowering Per2 expression using RNAi reduces DNA damage and cell death in U343 cells and glioma tissue. Additionally, Per2 was associated with increased TP53 activity and was involved in the DNA damage during TP53-mediated apoptosis. These findings suggest that Per2, a core circadian gene, is not only a tumor suppressor gene but can also be regarded as an upstream regulator of TP53. It thus appears that Per2 is an important inhibitor of tumor growth that acts by increasing TP53 expression, DNA damage repair, and apoptosis.

Effect of norcantharidin on the proliferation, apoptosis, and cell cycle of human mesangial cells

AIMS

Norcantharidin (NCTD) regulates immune system function and reduces proteinuria. We sought to investigate the effect of NCTD on proliferation, apoptosis and cell cycle of cultured human mesangial cells (HMC) in vitro.

METHODS

HMC cells were divided into a normal control group, and various concentrations of NCTD group (2.5, 5, 10, 20, or 40 μg/mL). Cell proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, apoptosis was detected by Annexin V/propidium iodide (PI) assays, and morphological analysis was performed by Hoechest 33258 staining. Finally, cell cycle was analyzed by flow cytometry.

RESULTS

NCTD dose and time dependently inhibits HMC proliferation significantly (p < .05). Apoptosis dose and time dependently increased after NCTD treatment. Cell-cycle analysis revealed that the number of cells in the G2 phase increased significantly, whereas the fraction of cells in the S phase decreased, especially 24 h after 5 μg/ml NCTD treatment.

CONCLUSION

NCTD inhibits HMC cell proliferation, induces apoptosis, and affects the cell cycle.

Effects of purified zearalenone on selected immunological and histopathologic measurements of spleen in post-weanling gilts

The present study was aimed at investigating the adverse effects of dietary zearalenone (ZEA) on the lymphocyte proliferation rate (LPR), interleukin-2 (IL-2), mRNA expressions of pro-inflammatory cytokines, and histopathologic changes of spleen in post-weanling gilts. A total of 20 crossbred piglets (Yorkshire × Landrace × Duroc) with an initial BW of 10.36 ± 1.21 kg (21 d of age) were used in the study. Piglets were fed a basal diet with an addition of 0, 1.1, 2.0, or 3.2 mg/kg purified ZEA for 18 d ad libitum. The results showed that LPR and IL-2 production of spleen decreased linearly (P < 0.05) as dietary ZEA increased. Splenic mRNA expressions of interleukin-1β (IL-1β) and interleukin-6 (IL-6) were linearly up-regulated (P < 0.05) as dietary ZEA increased. On the contrary, linear down-regulation (P < 0.05) of mRNA expression of interferon-γ (IFN-γ) was observed as dietary ZEA increased. Swelling splenocyte in 1.1 mg/kg ZEA treatments, atrophy of white pulp and swelling of red pulp in 2.0 and 3.2 mg/kg ZEA treatments were observed. The cytoplasmic edema in 1.1 mg/kg ZEA treatments, significant chromatin deformation in 2.0 mg/kg ZEA treatment and phagocytosis in 3.2 mg/kg ZEA treatment were observed. Results suggested that dietary ZEA at 1.1 to 3.2 mg/kg can induce splenic damages and negatively affect immune function of spleen in post-weanling gilts.

Anticancer effects of cantharidin in A431 human skin cancer (Epidermoid carcinoma) cells in vitro and in vivo

Cantharidin (CTD), a potential anticancer agent of Traditional Chinese Medicine has cytotxic effects in different human cancer cell lines. The cytotoxic effects of CTD on A431 human skin cancer (epidermoid carcinoma) cells in vitro and in A431 cell xenograft mouse model were examined. In vitro, A431 human skin cell were treated with CTD for 24 and 48 h. Cell phase distribution, ROS production, Ca²⁺ release, Caspase activity and the level of apoptosis associated proteins were measured. In vivo, A431 cell xenograft mouse model were examined. CTD-induced cell morphological changes and decreased percentage of viable A431 cells via G0/G1 phase arrest and induced apoptosis. CTD-induced G0/G1 phase arrest through the reduction of protein levels of cyclin E, CDK6, and cyclin D in A431 cells. CTD-induced cell apoptosis of A431 cells also was confirm by DNA gel electrophoresis showed CTD-induced DNA fragmentation. CTD reduced the mitochondrial membrane potential and stimulated release of cytochrome c, AIF and Endo G in A431 cells. Flow cytometry demonstrated that CTD increased activity of caspase-8, -9 and -3. However, when cells were pretreated with specific caspase inhibitors activity was reduced and cell viability increased. CTD increased protein levels of death receptors such as DR4, DR5, TRAIL and levels of the active form of caspase-8, -9 and -3 in A431 cells. AIF and Endo G proteins levels were also enhanced by CTD. In vivo studies showed that CTD significantly inhibited A431 cell xenograft tumors in mice. Taken together, these in vitro and in vivo results provide insight into the mechanisms of CTD on cell growth and tumor production. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 723-738, 2017.

5‑bromo‑3‑(3‑hydroxyprop‑1‑ynyl)‑2H‑pyran‑2‑one induces apoptosis in T24 human bladder cancer cells through mitochondria-dependent signaling pathways

The present study was performed to investigate the effect of 5-bromo-3-(3-hydroxyprop-1-ynyl)-2H-pyran-2-one (BHP) on the induction of apoptosis and cell cycle arrest in T24 human bladder carcinoma cells. An MTT assay was used to investigate the inhibition of cell proliferation. Flow cytometry was used to observe alterations in the cell cycle, generation of reactive oxygen species (ROS), alterations in mitochondrial membrane potential (MMP) and induction of apoptosis in the T24 cells following BHP treatment. Western blot analysis was performed for the determination of expression levels of apoptotic proteins, and 4,6‑diamidino‑2‑phenylindole dihydrochloride staining was used to observe apoptosis and DNA damage. The results demonstrated that treatment of the bladder cancer cells with BHP enhanced the activation of caspases and increased the production of ROS. It also caused damage to DNA, reduced MMP, and increased the secretion of endonuclease G and apoptosis‑inducing factor from the mitochondria. The expression levels of cyclin E and cell division cycle 25C were reduced, whereas the expression levels of p21 and phosphorylated p53 were increased in the BHP‑treated cells. In addition, treatment with BHP caused cell cycle arrest at the G0/G1 phase, increased the expression levels of B cell lymphoma‑2 (Bcl‑2)‑associated X protein and poly(ADP‑ribose) polymerase, decreased the expression of Bcl‑2 and ultimately induced apoptosis of the T24 cells. Thus, BHP inhibited the proliferation of bladder cancer cells by inducing cell apoptosis through the mitochondrial pathway.

Benzyl isothiocyanate (BITC) induces apoptosis of GBM 8401 human brain glioblastoma multiforms cells via activation of caspase-8/Bid and the reactive oxygen species-dependent mitochondrial pathway

Benzyl isothiocyanate (BITC) is one of member of the isothiocyanate family which has been shown to induce cancer cell apoptosis in many human cancer cells. In the present study, we investigated the effects of BITC on the growth of GBM 8401 human brain glioblastoma multiforms cells. Results indicated that BITC-induced cell morphological changes decreased in the percentage of viable GBM8401 cells and these effects are dose-dependent manners. Results from flow cytometric assay indicated that BITC induced sub-G1 phase and induction of apoptosis of GBM 8401 cells. Furthermore, results also showed that BITC promoted the production of reactive oxygen species (ROS) and Ca²⁺ release, but decreased the mitochondrial membrane potential (ΔΨ_m ) and promoted caspase-8, -9, and -3 activates. After cells were pretreated with Z-IETD-FMK, Z-LEHD-FMK, and Z-DEVD-FMK (caspase-8, -9, and -3 inhibitors, respectively) led to decrease in the activities of caspase-8, -9, and -3 and increased the percentage of viable GBM 8401 cells that indicated which BITC induced cell apoptosis through caspase-dependent pathways. Western blotting indicated that BITC induced Fas, Fas-L, FADD, caspase-8, caspase -3, and pro-apoptotic protein (Bax, Bid, and Bak), but inhibited the ant-apoptotic proteins (Bcl-2 and Bcl-x) in GBM 8401 cells. Furthermore, BITC increased the release of cytochrome c, AIF, and Endo G from mitochondria that led to cell apoptosis. Results also showed that BITC increased GADD153, GRP 78, XBP-1, and ATF-6β, IRE-1α, IRE-1β, Calpain 1 and 2 in GBM 8401 cells, which is associated with ER stress. Based on these observations, we may suggest that BITC-induced apoptosis might be through Fas receptor, ROS induced ER stress, caspase-3, and mitochondrial signaling pathways. Taken together, these molecular alterations and signaling pathways offer an insight into BITC-caused growth inhibition and induced apoptotic cell death of GBM 8401 cells. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1751-1760, 2016.

Effects of purified zearalenone on selected immunological measurements of blood in post-weaning gilts

Zearalenone (ZEA), an estrogenic mycotoxin, is produced mainly by Fusarium fungi. Previous studies have indicated that acute ZEA exposure induced various damages in different species; however, its transparent hematotoxicity in female piglets at dietary levels of 1.1 to 3.2 mg/kg has not been shown. The present study was conducted to investigate the effects of dietary ZEA (1.1–3.2 mg/kg) on hematology, T lymphocyte subset, immunoglobulin, antibody titer, lymphocyte proliferation rate (LPR), and interleukin-2 (IL-2) in peripheral blood of post-weaning gilts. A total of 20 female piglets (Landrace × Yorkshire × Duroc), weaned at 42 d with an average body weight of 10.36 ± 1.21 kg were used in the study. Female piglets were kept in a temperature controlled room, divided into four treatments, and fed a diet based on corn-soybean meal-fishmeal-whey, with an addition of 0, 1.1, 2.0, or 3.2 mg/kg purified ZEA for 18 d ad libitum. Feed intake and refusal were measured daily and individual pigs were weighed weekly. Blood and serum samples were collected for selected immunological measurements. Female piglets fed different levels of dietary ZEA grew similarly with no difference in feed intake. Hematological values including leukocytes, platelets, lymphocytes, hematocrit, and mean corpuscular hemoglobin (MCH) decreased linearly (P < 0.05) as dietary ZEA increased. Female piglets fed diets containing 2.0 mg/kg ZEA or greater showed significantly decreased CD4⁺CD8⁺, CD4⁺, and CD4⁺/CD8⁺ in comparison to the control (P < 0.05), whereas CD8⁺ was significantly increased (P = 0.026) in the gilts which were fed the diet containing 3.2 mg/kg ZEA. Serum immunoglobulin G (IgG) and the antibody titer on d 18 were reduced linearly as dietary ZEA levels increased (P < 0.001). Linear decrease in LPR was observed (P < 0.05). Female piglets fed diets containing 2.0 mg/kg ZEA or more showed significantly decreased IL-2 in comparison to the control (P < 0.05). The results suggested that dietary ZEA at the levels of 1.1 to 3.2 mg/kg can induce different degrees of hematotoxicity and negatively affect immune function in female piglets.

The protective effect of resveratrol against cytotoxicity induced by mycotoxin, zearalenone

Zearalenone (ZEA), a non-steroidal estrogenic mycotoxin, is widely present in cereals and agricultural products.

Rescue of cells from apoptosis increases DNA repair in UVB exposed cells: implications for the DNA damage response

Classically, the nucleotide excision repair (NER) of cyclobutane pyrimidine dimers (CPD) is a lengthy process (t_1/2 > 48 h).

Abieslactone induces cell cycle arrest and apoptosis in human hepatocellular carcinomas through the mitochondrial pathway and the generation of reactive oxygen species

Abieslactone is a triterpenoid lactone isolated from Abies plants. Previous studies have demonstrated that its derivative abiesenonic acid methyl ester possesses anti-tumor-promoting activity in vitro and in vivo. In the present study, cell viability assay demonstrated that abieslactone had selective cytotoxicity against human hepatoma cell lines. Immunostaining experiments revealed that abieslactone induced HepG2 and SMMC7721 cell apoptosis. Flow cytometry and western blot analysis showed that the apoptosis was associated with cell cycle arrest during the G₁ phase, up-regulation of p53 and p21, and down-regulation of CDK2 and cyclin D1. Furthermore, our results revealed that induction of apoptosis through a mitochondrial pathway led to upregulation of Bax, down-regulation of Bcl-2, mitochondrial release of cytochrome c, reduction of mitochondrial membrane potential (MMP), and activation of caspase cascades (Casp-9 and -3). Activation of caspase cascades also resulted in the cleavage of PARP fragment. Involvement of the caspase apoptosis pathway was confirmed using caspase inhibitor Z-VAD-FMK pretreatment. Recent studies have shown that ROS is upstream of Akt signal in mitochondria-mediated hepatoma cell apoptosis. Our results showed that the accumulation of ROS was detected in HepG2 cells when treated with abieslactone, and ROS scavenger partly blocked the effects of abieslactone-induced HepG2 cell death. In addition, inactivation of total and phosphorylated Akt activities was found to be involved in abieslactone-induced HepG2 cell apoptosis. Therefore, our findings suggested that abieslactone induced G₁ cell cycle arrest and caspase-dependent apoptosis via the mitochondrial pathway and the ROS/Akt pathway in HepG2 cells.

Heartwood extract of Acacia catechu induces apoptosis in human breast carcinoma by altering bax/bcl-2 ratio

Background:

The heartwood extract of A. catechu, called pale catechu or “Katha” in Hindi has been widely used in traditional Indian medicinal system. Although various pharmacological properties of this plant had been reported previously, only a few were concerned with the anticancer activity of this plant.

Objective:

The objective was to assess the in vitro anticancer and apoptosis inducing effect of 70% methanolic extract of “Katha” (ACME) on human breast adenocarcinoma cell line (MCF-7).

Materials and Methods:

MCF-7 cell line was treated with increasing concentrations of ACME and cell viability was calculated. Flow cytometric methods were used to confirm the apoptosis promoting role of ACME. Morphological changes were then analysed using confocal microscopy. Western blotting was then performed to investigate the expression of apoptogenic proteins and to analyse the activation of caspases.

Results:

ACME showed significant cytotoxicity to MCF-7 cells with an IC₅₀ value of 288.85 ± 25.79 μg/ml. Flow cytometric analysis and morphological studies confirmed that ACME is able to induce apoptosis in MCF-7 cells. Furthermore, immunoblot results suggested the pathway of apoptosis induction by increasing Bax/Bcl-2 ratio which results in the activation of caspase-cascade and ultimately leads to the cleavage of Poly adeno ribose polymerase (PARP).

Conclusion:

These results provide the evidence that ACME is able to inhibit the proliferation of MCF-7 cells by inducing apoptosis through intrinsic pathway.

The roles of endoplasmic reticulum stress and mitochondrial apoptotic signaling pathway in quercetin-mediated cell death of human prostate cancer PC-3 cells

Prostate cancer has its highest incidence and is becoming a major concern. Many studies have shown that traditional Chinese medicine exhibited antitumor responses. Quercetin, a natural polyphenolic compound, has been shown to induce apoptosis in many human cancer cell lines. Although numerous evidences show multiple possible signaling pathways of quercetin in apoptosis, there is no report to address the role of endoplasmic reticulum (ER) stress in quercetin-induced apoptosis in PC-3 cells. The purpose of this study was to investigate the effects of quercetin on the induction of the apoptotic pathway in human prostate cancer PC-3 cells. Cells were treated with quercetin for 24 and 48 h and at various doses (50-200 μM), and cell morphology and viability decreased significantly in dose-dependent manners. Flow cytometric assay indicated that quercetin at 150 μM caused G0/G1 phase arrest (31.4-49.7%) and sub-G1 phase cells (19.77%) for 36 h treatment and this effect is a time-dependent manner. Western blotting analysis indicated that quercetin induces the G0/G1 phase arrest via decreasing the levels of CDK2, cyclins E, and D proteins. Quercetin also stimulated the protein expression of ATF, GRP78, and GADD153 which is a hall marker of ER stress. Furthermore, PC-3 cells after incubation with quercetin for 48 h showed an apoptotic cell death and DNA damage which are confirmed by DAPI and Comet assays, leading to decrease the antiapoptotic Bcl-2 protein and level of ΔΨm , and increase the proapoptotic Bax protein and the activations of caspase-3, -8, and -9. Moreover, quercetin promoted the trafficking of AIF protein released from mitochondria to nuclei. These data suggest that quercetin may induce apoptosis by direct activation of caspase cascade through mitochondrial pathway and ER stress in PC-3 cells.

Polyphyllin D induces apoptosis in K562/A02 cells through G2/M phase arrest

Objectives

The effect of polyphyllin D on inducing cell death of the K562/A02 human leukaemia drug-resistant cells in vitro was examined.

Methods

The effect of polyphyllin D on K562/A02 cells were analysed by studying their cytotoxicity, apoptosis, cell cycle distribution, caspase-3 activity and disruption of mitochondrial membrane potential (MMP).

Key findings

Polyphyllin D, a small molecular monomer extracted from rhizoma of Paris polyphyllin, exhibited strong anticancer activity in a previous study. Our results demonstrate that polyphyllin D exerts a growth inhibitory effect by arresting cells at G2/M phase and by the induction of apoptosis in K562/A02 human leukaemia drug-resistant cells, G2/M phase arrest was found to be associated with up-regulation of p21 and down-regulation of cyclin B1 and cyclin-dependent protein kinase 1. Polyphyllin D-induced apoptosis via the mitochondrial apoptotic pathway as evidenced by decreased Bcl-2 expression levels, disruption of MMP and increased Bax, cytochrome C and cleaved-caspase-3 levels.

Conclusions

These data suggest that polyphyllin D has a potential as a potent therapeutic agent for chronic myeloid leukaemia.

Effect of a bispidinone analog on mitochondria‑mediated apoptosis in HeLa cells

The present study was carried out to investigate the effect of 2,4,6,8-tetraaryl-3,7-diazabicyclo[3.3.1]nonan-9-one (bispidinone) analogs on the in vitro growth of human cervical carcinoma (HeLa) cells. A series of 11 bispidinone analogs was synthesized with substituents, e.g., fluoro/methyl/ethyl/isopropyl/thiomethyl/methoxy groups, at various positions. These compounds were synthesized to identify which substituent and position induced the strongest cytotoxic effect in cancer cells. Among these synthetics, analog 9, which contains methoxy groups, had the most significant cytotoxic effect on HeLa cells, and its IC50 value was less than 13 µM. A WST-8 assay also showed that analog 9 inhibited the proliferation of HeLa cells. By using DNA content analysis, we found that analog 9 induced sub-G1 and G1 phase arrest in a time-dependent manner. A [3H]-thymidine incorporation assay suggested that analog 9 inhibited DNA replication in HeLa cells. On performing light microscopy, morphological changes such as cellular shrinkage and disruption, which are apoptotic features, were observed in HeLa cells. Annexin V/propidium iodide double staining and rhodamine-123 staining showed that analog 9 induced apoptosis and disrupted the intracellular mitochondrial membrane potential in HeLa cells. The western blot analysis results suggested that analog 9 induced mitochondria-mediated apoptosis. In addition, we have shown that analog 9 may play a role in the Fas signaling apoptotic pathway.

Polysaccharide from Phellinus linteus induces S-phase arrest in HepG2 cells by decreasing calreticulin expression and activating the P27kip1-cyclin A/D1/E-CDK2 pathway

ETHNOPHARMACOLOGY RELEVANCE

Our previous study showed that the proteoglycan P1 from Phellinus linteus (Mesima) exhibits significant anti-tumor activity against human hepatocellular carcinoma cells (HepG2); however, its molecular mechanism remains unknown. This study aims to provide insights into the mechanism of the anti-tumor activity of P1 against HepG2 cells.

METHODS

We examined the effects of P1 on HepG2 cell proliferation in vitro and in vivo. Flow cytometry was used to analyze the cell cycle distribution and apoptosis. Proteomic analysis, real-time (RT)-PCR, and Western blot were carried out to observe the expression of several cell cycle control proteins in HepG2 cells.

RESULTS

Both the volume and the weight of solid tumors were significantly decreased in P1-treated mice (200mg/kg) compared with the control. The HepG2 cells in the P1-treated tumors were significantly decreased, irregularly shaped, and smaller. P1 slightly increased the body weight of the tumor-bearing mice, which indicates that P1 is nontoxic to mammals at 200mg/kg. P1 also caused a significant dose-dependent increase in S phase arrest, but no apoptosis was observed in HepG2 cells. The results of the proteomic analysis, RT-PCR, and Western blot analysis showed that significantly downregulated expression of calreticulin, cyclin D1, cyclin E, and CDK2 and upregulated expression of P27 kip1 and cyclin A in the P1-treated HepG2 cells (200 μg/ml).

CONCLUSION

These results suggest that calreticulin expression and the P27 kip1-cyclin A/D1/E-CDK2 pathway were involved in P1-induced S-phase cell cycle arrest in HepG2 cells.

UVB-induced cell death signaling is associated with G1-S progression and transcription inhibition in primary human fibroblasts

DNA damage induced by ultraviolet (UV) radiation can be removed by nucleotide excision repair through two sub-pathways, one general (GGR) and the other specific for transcribed DNA (TCR), and the processing of unrepaired lesions trigger signals that may lead to cell death. These signals involve the tumor suppressor p53 protein, a central regulator of cell responses to DNA damage, and the E3 ubiquitin ligase Mdm2, that forms a feedback regulatory loop with p53. The involvement of cell cycle and transcription on the signaling to apoptosis was investigated in UVB-irradiated synchronized, DNA repair proficient, CS-B (TCR-deficient) and XP-C (GGR-deficient) primary human fibroblasts. Cells were irradiated in the G1 phase of the cell cycle, with two doses with equivalent levels of apoptosis (low and high), defined for each cell line. In the three cell lines, the low doses of UVB caused only a transient delay in progression to the S phase, whereas the high doses induced permanent cell cycle arrest. However, while accumulation of Mdm2 correlated well with the recovery from transcription inhibition at the low doses for normal and CS-B fibroblasts, for XP-C cells this protein was shown to be accumulated even at UVB doses that induced high levels of apoptosis. Thus, UVB-induced accumulation of Mdm2 is critical for counteracting p53 activation and apoptosis avoidance, but its effect is limited due to transcription inhibition. However, in the case of XP-C cells, an excess of unrepaired DNA damage would be sufficient to block S phase progression, which would signal to apoptosis, independent of Mdm2 accumulation. The data clearly discriminate DNA damage signals that lead to cell death, depending on the presence of UVB-induced DNA damage in replicating or transcribing regions.

Isoalantolactone inhibits UM-SCC-10A cell growth via cell cycle arrest and apoptosis induction

Isoalantolactone is a sesquiterpene lactone compound isolated from the roots of Inula helenium L. Previous studies have demonstrated that isoalantolactone possesses antifungal, anti-bacterial, anti-helminthic and anti-proliferative properties in a variety of cells, but there are no studies concerning its effects on head and neck squamous cell carcinoma (HNSCC). In the present study, an MTT assay demonstrated that isoalantolactone has anti-proliferative activity against the HNSCC cell line (UM-SCC-10A). Immunostaining identified that this compound induced UM-SCC-10A cell apoptosis but not necrosis. To explain the molecular mechanisms underlying its effects, flow cytometry and western blot analysis showed that the apoptosis was associated with cell cycle arrest during the G1 phase, up-regulation of p53 and p21, and down-regulation of cyclin D. Furthermore, our results revealed that induction of apoptosis through a mitochondrial pathway led to up-regulation of pro-apoptotic protein expression (Bax), down-regulation of anti-apoptotic protein expression (Bcl-2), mitochondrial release of cytochrome c (Cyto c), reduction of mitochondrial membrane potential (MMP) and activation of caspase-3 (Casp-3). Involvement of the caspase apoptosis pathway was confirmed using caspase inhibitor Z-VAD-FMK pretreatment. Together, our findings suggest that isoalantolactone induced caspase-dependent apoptosis via a mitochondrial pathway and was associated with cell cycle arrest in the G1 phase in UM-SCC-10A cells. Therefore, isoalantolactone may become a potential drug for treating HNSCC.

A novel trifluoromethyl benzopyran induces G1 cell cycle arrest and apoptosis in HeLa human cervical carcinoma cells

In the present study, a biologically active 4-(trifluoromethyl)phenyl piperazin moiety was linked to a 2,2- dimethyl -2H-benzopyran template to generate (3R,4S)-2,2-dimethyl-6-nitro-4-(4-(3-(trifluoromethyl)phenyl)piperazin-1-yl) chroman -3-ol (C110g), and the cellular and molecular mechanisms by which C110g exerts cytotoxic effects on the HeLa human cervical cancer cell line were further investigated. C110g suppressed the viability of HeLa cells in both concentration- and time-dependent manner (IC50 of 17 µM) by inducing DNA damage and G1 cell cycle arrest. Characteristic changes in nuclear morphology and Annexin V/PI staining pointed to apoptosis as the mode of cell death. The levels of p53 and p21 were increased in the C110g-treated cells, with a corresponding increase in Bax/Bcl-2 protein ratio. Subsequently, C110g induced the cytoplasmic release of cytochrome c from the mitochondria accompanied by a decreased mitochondrial membrane potential and activation of caspase-3 and -9. These results confirmed that the C110g transduced the apoptotic signal via the mitochondrial pathway. Caspase-8, typically associated with the initiation of the death receptor pathway, was activated, suggesting the extrinsic pathway might also be involved. However, C110g did not result in reactive oxygen species (ROS) generation. Taken together, these findings indicate that the DNA damage-dependent p53-regulated mitochondrial pathway as well as the extrinsic pathway play a crucial role in C110g-induced apoptosis, which provide a better understanding of the molecular mechanisms of trifluoromethyl benzopyrans in cervical cancer.

Sterigmatocystin-induced DNA damage triggers G2 arrest via an ATM/p53-related pathway in human gastric epithelium GES-1 cells in vitro

Sterigmatocystin (ST), which is commonly detected in food and feed commodities, is a mutagenic and carcinogenic mycotoxin that has been recognized as a possible human carcinogen. Our previous study showed that ST can induce G2 phase arrest in GES-1 cells in vitro and that the MAPK and PI3K signaling pathways are involved in the ST-induced G2 arrest. It is now widely accepted that DNA damage plays a critical role in the regulation of cell cycle arrest and apoptosis. In response to DNA damage, a complex signaling network is activated in eukaryotic cells to trigger cell cycle arrest and facilitate DNA repair. To further explore the molecular mechanism through which ST induces G2 arrest, the current study was designed to precisely dissect the role of DNA damage and the DNA damage sensor ataxia telangiectasia-mutated (ATM)/p53-dependent pathway in the ST-induced G2 arrest in GES-1 cells. Using the comet assay, we determined that ST induces DNA damage, as evidenced by the formation of DNA comet tails, in GES-1 cells. We also found that ST induces the activation of ATM and its downstream molecules, Chk2 and p53, in GES-1 cells. The ATM pharmacological inhibitor caffeine was found to effectively inhibit the activation of the ATM-dependent pathways and to rescue the ST-induced G2 arrest in GES-1 cells, which indicating its ATM-dependent characteristic. Moreover, the silencing of the p53 expression with siRNA effectively attenuated the ST-induced G2 arrest in GES-1 cells. We also found that ST induces apoptosis in GES-1 cells. Thus, our results show that the ST-induced DNA damage activates the ATM/53-dependent signaling pathway, which contributes to the induction of G2 arrest in GES-1 cells.

In vitro anticancer activity of Spondias pinnata bark on human lung and breast carcinoma

Spondias pinnata, a commonly distributed tree in India, previously proven for various pharmacological properties and also reported for efficient anti-oxidant, free radical scavenging and iron chelating activity, continuing this, the present study is aimed to investigate the role of 70 % methanolic extract of S. pinnata bark (SPME) in promoting apoptosis in human lung adenocarcinoma cell line (A549) and human breast adenocarcinoma cell line (MCF-7). These two malignant cell lines and a normal cell line were treated with increasing concentrations of SPME and cell viability is calculated. SPME showed significant cytotoxicity to both A549 and MCF-7 cells with an IC50 value of 147.84 ± 3.74 and 149.34 ± 13.30 μg/ml, respectively, whereas, comparatively no cytotoxicity was found in normal human lung fibroblast cell line (WI-38): IC50 932.38 ± 84.44 μg/ml. Flow cytometric analysis and confocal microscopic studies confirmed that SPME is able to induce apoptosis in both malignant cell lines. Furthermore, immunoblot result proposed the pathway of apoptosis induction by increasing Bax/Bcl-2 ratio in both cell types, which results in the activation of the caspase-cascade and ultimately leads to the cleavage of Poly adeno ribose polymerase. For the first time this study proved the anticancer potential of SPME against human lung and breast cancer by inducing apoptosis through the modulation of Bcl-2 family proteins. This might take S. pinnata in light to investigate it for further development as therapeutic anticancer source.

Modulation of DNA base excision repair during neuronal differentiation

Neurons are terminally differentiated cells with a high rate of metabolism and multiple biological properties distinct from their undifferentiated precursors. Previous studies showed that nucleotide excision DNA repair is downregulated in postmitotic muscle cells and neurons. Here, we characterize DNA damage susceptibility and base excision DNA repair (BER) capacity in undifferentiated and differentiated human neural cells. The results show that undifferentiated human SH-SY5Y neuroblastoma cells are less sensitive to oxidative damage than their differentiated counterparts, in part because they have robust BER capacity, which is heavily attenuated in postmitotic neurons. The reduction in BER activity in differentiated cells correlates with diminished protein levels of key long patch BER components, flap endonuclease-1, proliferating cell nuclear antigen, and ligase I. Thus, because of their higher BER capacity, proliferative neural progenitor cells are more efficient at repairing DNA damage compared with their neuronally differentiated progeny.

Pseudolaric Acid B induces caspase-dependent and caspase-independent apoptosis in u87 glioblastoma cells

Pseudolaric acid B (PLAB) is one of the major bioactive components of Pseudolarix kaempferi. It has been reported to exhibit inhibitory effect on cell proliferation in several types of cancer cells. However, there is no report elucidating its effect on glioma cells and organ toxicity in vivo. In the present study, we found that PLAB inhibited growth of U87 glioblastoma cells in a dose-dependent manner with IC₅₀~10 μM. Flow cytometry analysis showed that apoptotic cell death mediated by PLAB was accompanied with cell cycle arrest at G2/M phase. Using Western blot, we found that PLAB induced G2/M phase arrest by inhibiting tubulin polymerization in U87 cells. Apoptotic cell death was only partially inhibited by pancaspase inhibitor, z-VAD-fmk, which suggested that PLAB-induced apoptosis in U87 cells is partially caspase-independent. Further mechanistic study demonstrated that PLAB induced caspase-dependent apoptosis via upregulation of p53, increased level of proapoptotic protein Bax, decreased level of antiapoptotic protein Bcl-2, release of cytochrome c from mitochondria, activation of caspase-3 and proteolytic cleavage of poly (ADP-ribose) polymerase (PARP) and caspase-independent apoptosis through apoptosis inducing factor (AIF). Furthermore, in vivo toxicity study demonstrated that PLAB did not induce significant structural and biochemical changes in mouse liver and kidneys at a dose of 25 mg/kg. Therefore, PLAB may become a potential lead compound for future development of antiglioma therapy.

Polyphenolic extract isolated from Korean Lonicera japonica Thunb. induce G2/M cell cycle arrest and apoptosis in HepG2 cells: involvements of PI3K/Akt and MAPKs

Lonicera japonica Thunb. (L. japonica T.) has been used in Korean traditional medicine for long time because of its anti-cancer and hepatic protective effect. In this study, we investigated polyphenolic extract in L. japonica T. using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) and its anti-cancer effect on hepatocarcinoma cells. Human HepG2 cell line was treated with various concentrations of polyphenolic extract. Apoptosis was detective by cell morphology, cell cycle analysis and immunoblot analysis. Polyphenolic extract inhibited cell proliferation at 48h in a dose-dependent manner. Polyphenolic extract affected HepG2 cell viability by inhibiting cell cycle progression at the G2/M transition and inducing apoptosis. Polyphenolic extract also decreased the expression of CDK1, CDC25C, cyclin B1, pro-caspases-3 and -9 and poly ADP ribose polymerase, and affected the levels of mitochondrial apoptotic-related proteins. The phosphorylation of extracellular signal-related kinase ½ (ERK 1/2), c-Jun N-terminal kinase (JNK), and p-38 mitogen-activated protein kinases (MAPKs) were increased in HepG2 cells treated with polyphenolic extract, whereas Akt was dephosphorylated. These results indicate that inhibition of PI3K/Akt and activation of MAPKs are pivotal in G2/M cell cycle arrest and apoptosis of human hepatocarcinoma cells mediated by polyphenolic extract.

Furano-1,2-Naphthoquinone Inhibits Src and PI3K/Akt Signaling Pathways in Ca9-22 Human Oral Squamous Carcinoma Cells

Furano-1,2-naphthoquinone (FNQ), a biologically active component ofAvicennia marina, has been demonstrated to display anticancer activity. FNQ exerted cytotoxicity with the G2/M cell cycle arrest and apoptosis in Ca9-22 cells. FNQ-induced G2/M arrest was correlated with a marked decrease in the expression levels of cyclin A and cyclin B, and their activating partner cyclin-dependent kinases (CDK) 1 and 2 with concomitant induction of p27. FNQ-induced apoptosis was accompanied by Bax and Bad upregulation, and the downregulation of Bcl-2, Bcl-XL, Mcl-1, and X-linked inhibitor of apoptosis (XIAP), resulting in cytochrome C release and sequential activation of caspase-9 and caspase-3. Mechanistic studies showed that FNQ suppressed Src phosphorylation, PI3K, and Akt activation in Ca9-22 cells. Moreover, the Src inhibitor PP2 reduced the phosphorylation of Src and activation of PI3K/Akt, which was comparable with FNQ treatment. The combined treatment of FNQ with PP2 enhanced the cell cycle arrest and apoptosis and also led to the downregulation of Bcl-XL, Mcl-1, XIAP, cyclin A, cyclin B, CDK1, and CDK2 and upregulation of p27, Bax, and Bad. These findings suggest that FNQ-mediated cytotoxicity of Ca9-22 cells is related with the G2/M cell cycle arrest and apoptosis via inactivation of Src and PI3K/Akt-mediated signaling pathways.

Ultraviolet C irradiation induces different expression of cyclooxygenase 2 in NIH 3T3 cells and A431 cells: the roles of COX-2 are different in various cell lines

Ultraviolet C (UVC) is a DNA damage inducer, and 20 J/m² of UVC irradiation caused cell growth inhibition and induced cell death after exposure for 24–36 h. The growth of NIH 3T3 cells was significantly suppressed at 24 h after UVC irradiation whereas the proliferation of A431 cells was inhibited until 36 h after UVC irradiation. UVC irradiation increased COX-2 expression and such up-regulation reached a maximum during 3–6 h in NIH 3T3 cells. In contrast, UVC-induced COX-2 reached a maximum after 24–36 h in A431 cells. Measuring prostaglandin E2 (PGE2) level showed a biphasic profile that PGE2 release was rapidly elevated in 1–12 h after UVC irradiation and increased again at 24 h in both cell lines. Treatment with the selective COX-2 inhibitor, SC-791, during maximum expression of COX-2 induction, attenuated the UVC induced-growth inhibition in NIH 3T3 cells. In contrast, SC-791 treatment after UVC irradiation enhanced death of A431 cells. These data showed that the patterns of UVC-induced PGE2 secretion from NIH 3T3 cells and A431 cells were similar despite the differential profile in UVC-induced COX-2 up-regulation. Besides, COX-2 might play different roles in cellular response to UVC irradiation in various cell lines.

Phytoglycoprotein (38 kDa) induces cell cycle (G₀/G₁) arrest and apoptosis in HepG2 cells

Styrax japonica Siebold et al Zuccarini (SJSZ) has been used to heal inflammation and bronchitis as folk medicine in Korea. Firstly, glycoprotein isolated from SJSZ (SJSZ glycoprotein) has a molecular weight with 38  kDa and consists of carbohydrate (57.64%) and protein (42.35%). In the composition of SJSZ glycoprotein, carbohydrate mostly consists of glucose (28.17%), galactose (21.85%), and mannose (2.62%) out of 52.64%, respectively. The protein consists of Trp (W, 7.01%), Pro (P, 6.72%), and Ile (I, 5.42%) out of 42.35% as three major amino acids, while total amount of other amino acids is 23.20%. The purpose of this study is to know whether the SJSZ glycoprotein (38  kDa) induces the cell cycle arrest and apoptosis in HepG2 cells. Cytotoxicity was evaluated using MTT and lactate dehydrogenase assay and amount of intracellular reactive oxygen species (iROS) and nitric oxide (NO) was measured using fluorescence microplate reader. Activities of cell cycle-related proteins [p53, p21, p27, Cyclin D1, and cyclin-dependent kinase (CDK)4] and apoptosis-related factors [iNOS, Bid, Bcl-2/bax, cytochrome c, caspase-9, caspase-3, and poly-(ADP-ribose) polymerase (PARP)] were assessed by Western blot and fluorescence-activated cell sorter (FACS) analysis. In the cell cycle-related proteins, SJSZ glycoprotein (50  µg/ml) significantly enhances the expression of p53, p21, and p27, whereas it suppressed the activity of cyclin D1/CDK4. In the apoptosis-related factors, SJSZ glycoprotein (50  µg/ml) stimulates to increase iROS, and NO, to activate iNOS, Bid, Bcl-2/bax, cytochrome c, caspase-9, caspase-3, and PARP. SJSZ glycoprotein (50  µg/ml) has potent effect to arrest cell cycle from G(0) /G(1) to S and to induce apoptosis in HepG2 cells.

Induction of G2/M phase arrest and apoptosis by potent antitumor APCA in human cervix carcinoma cells

3-(dimethylamino-ethylamino)-8-oxo-8H-acenaphthol[1, 2-b]pyrrole-9-carboxylic acid (APCA), as a potent antitumor compound, showed anticancer activity on a series of established cancer cells. Meanwhile, the cytotoxic effects of APCA were much smaller on normal human cells than that on cancer cells. This study investigated the molecular mechanisms underlying APCA-induced growth inhibition in HeLa cells. The results showed that the APCA-induced cell cycle arrest at G(2)/M phase correlated with cyclinB1 and cyclin-dependent kinase 1 expression downregulation in a p53-independent manner, and also caused an increase in apoptosis, which was confirmed by characteristic morphological changes and increased apoptotic sub-G(1) population. Furthermore, translocation inhibition of nuclear factor-κB, upregulation of Bax, and downregulation of Bcl-2, caspase-3 and caspase-9 activation, and poly-(ADP-ribose) polymerase cleavage were observed in HeLa cells treated with APCA, which indicated that the mitochondrial pathway was involved in the apoptosis signal pathway. In summary, APCA displayed an antitumor effect through cell cycle arrest and apoptotic induction in HeLa cells, which suggested that APCA might have therapeutic potential against cervix carcinoma as an effective lead compound.

Cucurbitacin E Induces G(2)/M Phase Arrest through STAT3/p53/p21 Signaling and Provokes Apoptosis via Fas/CD95 and Mitochondria-Dependent Pathways in Human Bladder Cancer T24 Cells

Cucurbitacin E, a tetracyclic triterpenes compound extracted from cucurbitaceous plants, has been shown to exhibit anticancer and anti-inflammatory activities. The purpose of this study was to elucidate whether cucurbitacin E promotes cell cycle arrest and induces apoptosis in T24 cells and further to explore the underlying molecular mechanisms. The effects of cucurbitacin E on T24 cell's growth and accompanied morphological changes were examined by MTT assay and a phase-contrast microscope. DNA content, mitochondrial membrane potential (ΔΨ_m) and annexin V/PI staining were determined by flow cytometry. The protein levels were measured by Western blotting. Our results demonstrated that cucurbitacin E-induced G₂/M arrest was associated with a marked increase in the levels of p53, p21 and a decrease in phospho-signal transducer and activator of transcription 3 (STAT3), cyclin-dependent kinase 1 (CDK1) and cyclin B. Cucurbitacin E-triggered apoptosis was accompanied with up-regulation of Fas/CD95, truncated BID (t-BID) and a loss of ΔΨ_m, resulting in the releases of cytochrome c, apoptotic protease activating factor 1 (Apaf-1) and apoptosis-inducing factor (AIF), and sequential activation of caspase-8, caspase-9, and caspase-3. Our findings provided the first evidence that STAT3/p53/p21 signaling, Fas/CD95 and mitochondria-dependent pathways play critical roles in cucurbitacin E-induced G₂/M phase arrest and apoptosis of T24 cells.