Cucurbitacin B suppresses hepatocellular carcinoma progression through inducing DNA damage-dependent cell cycle arrest.

BACKGROUND: The mortality rate of liver cancer ranks third in the world, and hepatocellular carcinoma (HCC) is a malignant tumor of the digestive tract. Cucurbitacin B (CuB), a natural compound extracted from Cucurbitaceae spp., is the main active component of Chinese patent medicine the Cucurbitacin Tablet, which has been widely used in the treatment of various malignant tumors in clinics, especially HCC. PURPOSE: This study explored the role and mechanism of CuB in the suppression of liver cancer progression. METHODS: Cell Counting Kit-8 (CCK-8) and colony formation assays were used to detect the inhibitory function of CuB in Huh7, Hep3B, and Hepa1/6 hepatoma cells. Calcein-AM/propidium iodide (PI) staining and lactate dehydrogenase (LDH) measurement assays were performed to determine cell death. Mitochondrial membrane potential (Δψm) was measured, and flow cytometry was performed to evaluate cell apoptosis and cell cycle. Several techniques, such as proteomics, Western blotting (WB), and ribonucleic acid (RNA) interference, were utilized to explore the potential mechanism. The animal experiment was performed to verify the results of in vitro experiments. RESULTS: CuB significantly inhibited the growth of Huh7, Hep3B, and Hepa1/6 cells and triggered the cell cycle arrest in G2/M phage without leading to cell death, especially apoptosis. Knockdown of insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), a target of CuB, did not reverse CuB elicited cell cycle arrest. CuB enhanced phosphorylated ataxia telangiectasia mutated (p-ATM) and phosphorylated H2A histone family member X (γ-H2AX) levels. Moreover, CuB increased p53 and p21 levels and decreased cyclin-dependent kinase 1 (CDK1) expression, accompanied by improving phosphorylated checkpoint kinase 1 (p-CHK1) level and suppressing cell division cycle 25C (CDC25C) protein level. Interestingly, these phenomena were partly abolished by a deoxyribonucleic acid (DNA) protector methylproamine (MPA). Animal studies showed that CuB also significantly suppressed tumor growth in BALB/c mice bearing Hepa1/6 cells. In tumor tissues, CuB reduced the expression levels of proliferating cell nuclear antigen (PCNA) and γ-H2AX but did not change the terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) level. CONCLUSION: This study demonstrated for the first time that CuB could effectively impede HCC progression by inducing DNA damage-dependent cell cycle arrest without directly triggering cell death, such as necrosis and apoptosis. The effect was achieved through ataxia telangiectasia mutated (ATM)-dependent p53-p21-CDK1 and checkpoint kinase 1 (CHK1)-CDC25C signaling pathways. These findings indicate that CuB may be used as an anti-HCC drug, when the current findings are confirmed by independent studies and after many more clinical phase 1, 2, 3, and 4 testings have been done.

Veratramine Inhibits the Cell Cycle Progression, Migration, and Invasion via ATM/ATR Pathway in Androgen-Independent Prostate Cancer.

Prostate cancer (PC) is the second leading cause of cancer-related death among men. Treatment of PC becomes difficult after progression because PC that used to be androgen-dependent becomes androgen-independent prostate cancer (AIPC). Veratramine, an alkaloid extracted from the root of the Veratrum genus, has recently been reported to have anticancer effects that work against various cancers; however, its anticancer effects and the underlying mechanism of action in PC remain unknown. We investigated the anticancer effects of veratramine on AIPC using PC3 and DU145 cell lines, as well as a xenograft mouse model. The antitumor effects of veratramine were evaluated using the CCK-8, anchorage-independent colony formation, trans-well, wound healing assays, and flow cytometry in AIPC cell lines. Microarray and proteomics analyses were performed to investigate the differentially expressed genes and proteins induced by veratramine in AIPC cells. A xenograft mouse model was used to confirm the therapeutic response and in vivo efficacy of veratramine. Veratramine dose dependently reduced the proliferation of cancer cells both in vitro and in vivo. Moreover, veratramine treatment effectively suppressed the migration and invasion of PC cells. The immunoblot analysis revealed that veratramine significantly downregulated Cdk4/6 and cyclin D1 via the ATM/ATR and Akt pathways, both of which induce a DNA damage response that eventually leads to G1 phase arrest. In this study, we discovered that veratramine exerted antitumor effects on AIPC cells. We demonstrated that veratramine significantly inhibited the proliferation of cancer cells via G0/G1 phase arrest induced by the ATM/ATR and Akt pathways. These results suggest that veratramine is a promising natural therapeutic agent for AIPC.

Nuclear ATR lysine-tyrosylation protects against heart failure by activating DNA damage response.

Dysregulated amino acid increases the risk for heart failure (HF) via unclear mechanisms. Here, we find that increased plasma tyrosine and phenylalanine levels are associated with HF. Increasing tyrosine or phenylalanine by high-tyrosine or high-phenylalanine chow feeding exacerbates HF phenotypes in transverse aortic constriction and isoproterenol infusion mice models. Knocking down phenylalanine dehydrogenase abolishes the effect of phenylalanine, indicating that phenylalanine functions by converting to tyrosine. Mechanistically, tyrosyl-tRNA synthetase (YARS) binds to ataxia telangiectasia and Rad3-related gene (ATR), catalyzes lysine tyrosylation (K-Tyr) of ATR, and activates the DNA damage response (DDR) in the nucleus. Increased tyrosine inhibits the nuclear localization of YARS, inhibits the ATR-mediated DDR, accumulates DNA damage, and elevates cardiomyocyte apoptosis. Enhancing ATR K-Tyr by overexpressing YARS, restricting tyrosine, or supplementing tyrosinol, a structural analog of tyrosine, promotes YARS nuclear localization and alleviates HF in mice. Our findings implicate facilitating YARS nuclear translocation as a potential preventive and/or interfering measure against HF.

ATM/IKK alpha axis regulates the crosstalk between autophagy and apoptosis in selenite-treated Jurkat cells.

Selenium is an essential trace element. High dosage of selenite exhibits a great potential in treating leukemia. Previous study discovered selenite could promote leukemia cells apoptosis through inducing DNA damage and cell cycle arrest, while the switch mechanisms of these events and autophagy were still unclear. Current study discovered selenite promoted autophagy and apoptosis of leukemia Jurkat cells. In this process, DNA damage related ATM/IKK alpha axis was activated. This axis could stabilize pro-apoptotic P73, and promote autophagy through regulating NF-kappaB signaling pathway. Moreover, survivin-2B was also confirmed to be necessary for the ATM-induced nuclear location of IKK alpha, and therefore stood at the node position of apoptosis and autophagy cascades inside Jurkat cells. Finally, our in vivo experiments proved that selenite exhibited some anti-tumor effects on Jurkat cells-bearing mice. Moreover, alterations of ATM and IKK alpha expression observed in vivo were similar to that identified in vitro. Therefore, our findings had fully confirmed survivin-2B dependent activation of ATM/IKK alpha axis might be another crosstalk between autophagy and apoptosis of selenite-treated leukemia cells.

Activation of ATM/Chk2 by Zanthoxylum armatum DC extract induces DNA damage and G1/S phase arrest in BRL 3A cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Zanthoxylum armatum DC is a traditional medicinal plant. It is widely used in clinical treatment and disease prevention in China, India and other regions. Modern studies have reported the phytotoxicity, cytotoxicity and the animal toxicity of Zanthoxylum armatum DC, and the damage of genetic material has been observed in plants, but the detailed mechanism has not been explored. Besides, the toxicity of normal mammalian cells has not been evaluated. AIM OF THE STUDY: To evaluate the effects and underlying mechanism of genetic material damage in BRL 3A cells induced by Zanthoxylum armatum DC. MATERIALS AND METHODS: Ultra-High Performance Liquid Chromatography and Orbitrap High-Resolution Mass Spectrometry was used for identification of compounds in methanol extract of Zanthoxylum armatum DC. BRL 3A cells were incubated with different concentrations of methanol extract of Zanthoxylum armatum DC (24 h). The cytotoxicity of extract was assessed with cell viability, LDH release rate, and ROS production. The damage of genetic material was assessed with OTM value of comet cells, cell cycle and the expression levels of p-ATM, p- Chk2, Cdc25A, and CDK2. RESULTS: Ultra-High Performance Liquid Chromatography and Orbitrap High-Resolution Mass Spectrometry investigation revealed the presence of compounds belonging to flavonoid, fatty acid and alkaloid groups. The viability of BRL 3A cells was reduced in a time-dose dependent manner treated by methanol extract of Zanthoxylum armatum DC. It increased LDH release rate and ROS production, activated the DNA double strand damage marker of γH2AX and produced comet cells. In addition, methanol extract of Zanthoxylum armatum DC caused ATM-mediated DNA damage, further phosphorylated Chk2, inhibited cell cycle related proteins, and arrested the G1/S cycle. CONCLUSIONS: Methanol extract of Zanthoxylum armatum DC induces DNA damage and further leads G1/S cell cycle arrest by triggering oxidative stress in the BRL 3A cells. This study provides some useful evidences for its development as an antitumor drug via activation of ATM/Chk2.

High-throughput drug screening identifies the ATR-CHK1 pathway as a therapeutic vulnerability of CALR mutated hematopoietic cells.

Mutations of calreticulin (CALR) are the second most prevalent driver mutations in essential thrombocythemia and primary myelofibrosis. To identify potential targeted therapies for CALR mutated myeloproliferative neoplasms, we searched for small molecules that selectively inhibit the growth of CALR mutated cells using high-throughput drug screening. We investigated 89 172 compounds using isogenic cell lines carrying CALR mutations and identified synthetic lethality with compounds targeting the ATR-CHK1 pathway. The selective inhibitory effect of these compounds was validated in a co-culture assay of CALR mutated and wild-type cells. Of the tested compounds, CHK1 inhibitors potently depleted CALR mutated cells, allowing wild-type cell dominance in the co-culture over time. Neither CALR deficient cells nor JAK2V617F mutated cells showed hypersensitivity to ATR-CHK1 inhibition, thus suggesting specificity for the oncogenic activation by the mutant CALR. CHK1 inhibitors induced replication stress in CALR mutated cells revealed by elevated pan-nuclear staining for γH2AX and hyperphosphorylation of RPA2. This was accompanied by S-phase cell cycle arrest due to incomplete DNA replication. Transcriptomic and phosphoproteomic analyses revealed a replication stress signature caused by oncogenic CALR, suggesting an intrinsic vulnerability to CHK1 perturbation. This study reveals the ATR-CHK1 pathway as a potential therapeutic target in CALR mutated hematopoietic cells.

Circadian Rhythm of NER and ATR Pathways.

Genomic integrity is constantly insulted by solar ultraviolet (UV) radiation. Adaptative cellular mechanisms called DNA damage responses comprising DNA repair, cell cycle checkpoint, and apoptosis, are believed to be evolved to limit genomic instability according to the photoperiod during a day. As seen in many other key cellular metabolisms, genome surveillance mechanisms against genotoxic UV radiation are under the control of circadian clock systems, thereby exhibiting daily oscillations in their catalytic activities. Indeed, it has been demonstrated that nucleotide excision repair (NER), the sole DNA repair mechanism correcting UV-induced DNA photolesions, and ataxia-telangiectasia-mutated and Rad3-related (ATR)-mediated cell cycle checkpoint kinase are subjected to the robust control of the circadian clock. The molecular foundation for the circadian rhythm of UV-induced DNA damage responses in mammalian cells will be discussed.

ATR Inhibition as an Attractive Therapeutic Resource against Cancer.

In this issue of Cancer Discovery, Yap and colleagues demonstrate in a phase I trial enrolling 22 patients diagnosed with advanced solid tumors that BAY 1895344, a new potent and specific ATR inhibitor, is safe and able to induce durable responses in ATM-deficient tumors. This compelling clinical activity paves the way for innovative combination regimens that rely on exploitation of DNA damage response defects in cancer.See related article by Yap et al., p. 80.

Theasaponin E1 Inhibits Platinum-Resistant Ovarian Cancer Cells through Activating Apoptosis and Suppressing Angiogenesis.

Novel therapeutic strategies for ovarian cancer treatment are in critical need due to the chemoresistance and adverse side effects of platinum-based chemotherapy. Theasaponin E1 (TSE1) is an oleanane-type saponin from Camellia sinensis seeds. Its apoptosis-inducing, cell cycle arresting and antiangiogenesis activities against platinum-resistant ovarian cancer cells were elucidated in vitro and using the chicken chorioallantoic membrane (CAM) assay. The results showed that TSE1 had more potent cell growth inhibitory effects on ovarian cancer OVCAR-3 and A2780/CP70 cells than cisplatin and was lower in cytotoxicity to normal ovarian IOSE-364 cells. TSE1 significantly induced OVCAR-3 cell apoptosis via the intrinsic and extrinsic apoptotic pathways, slightly arresting cell cycle at the G2/M phase, and obviously inhibited OVCAR-3 cell migration and angiogenesis with reducing the protein secretion and expression of vascular endothelial growth factor (VEGF). Western bolt assay showed that Serine/threonine Kinase (Akt) signaling related proteins including Ataxia telangiectasia mutated kinase (ATM), Phosphatase and tensin homolog (PTEN), Akt, Mammalian target of rapamycin (mTOR), Ribosome S6 protein kinase (p70S6K) and e IF4E-binding protein 1(4E-BP1) were regulated, and Hypoxia inducible factor-1α (HIF-1α) protein expression was decreased by TSE1 in OVCAR-3 cells. Moreover, TSE1 treatment potently downregulated protein expression of the Notch ligands including Delta-like protein 4 (Dll4) and Jagged1, and reduced the protein level of the intracellular domain (NICD) of Notch1. Combination treatment of TSE1 with the Notch1 signaling inhibitor tert-butyl (2S)-2-[[(2S)-2-[[2-(3,5-difluorophenyl)acetyl]amino]propanoyl]amino]-2-phenylacetate (DAPT), or the Akt signaling inhibitor wortmannin, showed a stronger inhibition toward HIF-1α activation compared with single compound treatment. Taken together, TSE1 might be a potential candidate compound for improving platinum-resistant ovarian cancer treatment via Dll4/Jagged1-Notch1-Akt-HIF-1α axis.

NAD+ supplementation prevents STING-induced senescence in ataxia telangiectasia by improving mitophagy.

Senescence phenotypes and mitochondrial dysfunction are implicated in aging and in premature aging diseases, including ataxia telangiectasia (A-T). Loss of mitochondrial function can drive age-related decline in the brain, but little is known about whether improving mitochondrial homeostasis alleviates senescence phenotypes. We demonstrate here that mitochondrial dysfunction and cellular senescence with a senescence-associated secretory phenotype (SASP) occur in A-T patient fibroblasts, and in ATM-deficient cells and mice. Senescence is mediated by stimulator of interferon genes (STING) and involves ectopic cytoplasmic DNA. We further show that boosting intracellular NAD+ levels with nicotinamide riboside (NR) prevents senescence and SASP by promoting mitophagy in a PINK1-dependent manner. NR treatment also prevents neurodegeneration, suppresses senescence and neuroinflammation, and improves motor function in Atm-/- mice. Our findings suggest a central role for mitochondrial dysfunction-induced senescence in A-T pathogenesis, and that enhancing mitophagy as a potential therapeutic intervention.

Inhibition of miR-1193 leads to synthetic lethality in glioblastoma multiforme cells deficient of DNA-PKcs.

Glioblastoma multiforme (GBM) is the most malignant primary brain tumor and has the highest mortality rate among cancers and high resistance to radiation and cytotoxic chemotherapy. Although some targeted therapies can partially inhibit oncogenic mutation-driven proliferation of GBM cells, therapies harnessing synthetic lethality are 'coincidental' treatments with high effectiveness in cancers with gene mutations, such as GBM, which frequently exhibits DNA-PKcs mutation. By implementing a highly efficient high-throughput screening (HTS) platform using an in-house-constructed genome-wide human microRNA inhibitor library, we demonstrated that miR-1193 inhibition sensitized GBM tumor cells with DNA-PKcs deficiency. Furthermore, we found that miR-1193 directly targets YY1AP1, leading to subsequent inhibition of FEN1, an important factor in DNA damage repair. Inhibition of miR-1193 resulted in accumulation of DNA double-strand breaks and thus increased genomic instability. RPA-coated ssDNA structures enhanced ATR checkpoint kinase activity, subsequently activating the CHK1/p53/apoptosis axis. These data provide a preclinical theory for the application of miR-1193 inhibition as a potential synthetic lethal approach targeting GBM cancer cells with DNA-PKcs deficiency.

Targeting the NPL4 Adaptor of p97/VCP Segregase by Disulfiram as an Emerging Cancer Vulnerability Evokes Replication Stress and DNA Damage while Silencing the ATR Pathway.

Research on repurposing the old alcohol-aversion drug disulfiram (DSF) for cancer treatment has identified inhibition of NPL4, an adaptor of the p97/VCP segregase essential for turnover of proteins involved in multiple pathways, as an unsuspected cancer cell vulnerability. While we reported that NPL4 is targeted by the anticancer metabolite of DSF, the bis-diethyldithiocarbamate-copper complex (CuET), the exact, apparently multifaceted mechanism(s) through which the CuET-induced aggregation of NPL4 kills cancer cells remains to be fully elucidated. Given the pronounced sensitivity to CuET in tumor cell lines lacking the genome integrity caretaker proteins BRCA1 and BRCA2, here we investigated the impact of NPL4 targeting by CuET on DNA replication dynamics and DNA damage response pathways in human cancer cell models. Our results show that CuET treatment interferes with DNA replication, slows down replication fork progression and causes accumulation of single-stranded DNA (ssDNA). Such a replication stress (RS) scenario is associated with DNA damage, preferentially in the S phase, and activates the homologous recombination (HR) DNA repair pathway. At the same time, we find that cellular responses to the CuET-triggered RS are seriously impaired due to concomitant malfunction of the ATRIP-ATR-CHK1 signaling pathway that reflects an unorthodox checkpoint silencing mode through ATR (Ataxia telangiectasia and Rad3 related) kinase sequestration within the CuET-evoked NPL4 protein aggregates.

Folate deficiency induced H2A ubiquitination to lead to downregulated expression of genes involved in neural tube defects.

BACKGROUND: Neural tube defects (NTDs) are common congenital malformations resulting in failure of the neural tube closure during early embryonic development. Although it is known that maternal folate deficiency increases the risk of NTDs, the mechanism remains elusive. RESULTS: Herein, we report that histone H2A monoubiquitination (H2AK119ub1) plays a role in neural tube closure. We found that the folate antagonist methotrexate induced H2AK119ub1 in mouse embryonic stem cells. We demonstrated that an increase in H2AK119ub1 downregulated expression of the neural tube closure-related genes Cdx2, Nes, Pax6, and Gata4 in mouse embryonic stem cells under folate deficiency conditions. We also determined that the E3 ligase Mdm2 was responsible for the methotrexate-induced increase in H2AK119ub1 and downregulation of neural tube closure-related genes. Surprisingly, we found that Mdm2 is required for MTX-induced H2A ubiquitination and is recruited to the sites of DSB, which is dependent on DNA damage signaling kinase ATM. Furthermore, folic acid supplementation restored H2AK119ub1 binding to neural tube closure-related genes. Downregulation of these genes was also observed in both brain tissue of mouse and human NTD cases, and high levels of H2AK119ub1 were found in the corresponding NTDs samples with their maternal serum folate under low levels. Pearson correlation analysis showed a significant negative correlation between expression of the neural precursor genes and H2AK119ub1. CONCLUSION: Our results indicate that folate deficiency contributes to the onset of NTDs by altering H2AK119ub1 and subsequently affecting expression of neural tube closure-related genes. This may be a potential risk factor for NTDs in response to folate deficiency.

Jingfukang induces anti-cancer activity through oxidative stress-mediated DNA damage in circulating human lung cancer cells.

BACKGROUND: Metastasis is the main cause of lung cancer death. As a seed of metastasis, circulating tumor cells are an important target for metastasis intervention. The traditional Chinese medicine, Jinfukang, has been clinically available for the treatment of non-small cell lung cancer (NSCLC). In this study, we investigated the action and underlying mechanisms of Jinfukang against circulating lung tumor cells. METHODS: The cell counting kit-8 (CCK-8), colony formation and cell cycle assays were used to study the cell proliferation ability. Flow cytometry was used to detect the apoptosis and the expression level of ROS and Caspase-3. Comet and TUNEL assays were used to detect DNA damage. DNA damage related pathway protein was detected by western blot. RESULTS: Jinfukang significantly inhibits the proliferation of CTC-TJH-01 cells by inducing G1 phase arrest and inhibits their colony formation in a dose-dependent manner. Moreover, Jinfukang induces apoptosis in CTC-TJH-01 cells through the ROS-mediated ATM/ATR-p53 pathway and DNA damage. CONCLUSIONS: Our findings suggest that Jinfukang may be a potential drug for lung cancer metastasis.

Bergapten alleviates osteoarthritis by regulating the ANP32A/ATM signaling pathway.

Osteoarthritis (OA) is a chronic degenerative disease that commonly affects the elderly. Current drug therapies for treating OA may cause adverse side effects, and so there remains a need to develop alternative treatments. Bergapten (BG) is a coumarin phytohormone that is widely found in fruits and has antioxidative and anti-inflammatory effects. Here, we tested the hypothesis that BG may restrict the progression of OA by examining its effect on OA chondrocytes. We observed that BG significantly ameliorated interleukin (IL)-1ß-induced expression of inflammatory cytokines and mediators, including interleukin 1 (Il-1), interleukin 6 (Il-6), tumor necrosis factor α (Tnf-α), cyclooxygenase 2 (Cox-2) and matrix metalloproteinase 13 (Mmp-13), maintained chondrocyte phenotype, and promoted the secretion of cartilage-specific extracellular matrix. We provide evidence that BG exerts its anti-inflammatory effect by activating the ANP32A/ATM signaling pathway, which was recently verified to be associated with OA. In conclusion, these findings indicate that BG may be a potential candidate for treatment of OA.

Rotundic acid enhances the impact of radiological toxicity on MCF-7 cells through the ATM/p53 pathway.

Although radiation therapy is a powerful anticancer modality, radiation- induced stress response and gene expression with adaptive resistance may severely compromise the effectiveness of radiation. The function of rotundic acid (RA) on inducing apoptosis in the human breast cancer cell line MCF-7 has been investigated in a previous study. In the present study, the combined effect of chemotherapy and radiotherapy on reducing side effects was examined. The results of an MTT assay revealed that radiation (0.5, 2 and 10 Gy) effectively inhibit MCF-7 cell viability in a dose-dependent manner, consistent with the effects of RA (2, 5 and 12.5 µM). Interestingly, a lower dose of radiation (1 Gy) combined with RA (5 µM) exhibited a greater inhibition efficiency compared with a high dose of radiation alone. Flow cytometry revealed that radiation combined with RA induced the apoptosis of MCF-7 cells. Using western blotting, it was demonstrated that radiation induced the expression of ataxia-telangiectasia mutated (ATM) and p53 protein, and that RA enhanced this effect. On examining the potential underlying mechanism, it was revealed that radiation and RA combined induce Bcl-2-associated X protein expression and cell apoptosis in MCF-7 cells. An ATM inhibitor was able to restore the effect of radiation and RA on inducing MCF-7 cell apoptosis. These results suggest that the ATM/p53 pathway directly participates in radiation and RA-induced apoptosis in MCF-7 cells. RA has the potential for development as a novel drug for the treatment of human breast cancer combined with radiation therapy, given that the combined side effects are reduced.

Osthole enhances antitumor activity and irradiation sensitivity of cervical cancer cells by suppressing ATM/NF­κB signaling.

Osthole (7­methoxy­8­isopentenoxycoumarin) is an O­methylated coumarin, originally extracted from Chinese herbal medicine. It has been demonstrated that osthole has antitumor effects in various cancer cells in vitro. The present study assessed the effects of osthole on the regulation of cervical cancer cell viability, apoptosis, and radiation sensitization. HeLa, SiHa, C­33A and CaSki cervical cancer cell lines were cultured and treated with osthole and/or irradiation and then subjected to 3­(4,5­dimethylthiazol­2­yl)­2,5­-diphenyl­tetrazolium bromide cell viability, colony formation, apoptosis, acridine orange/ethidium bromide fluorescence staining, wound­healing, Transwell migration and invasion, immunofluorescence, Comet and western blot assays. The data showed that osthole dose­dependently reduced cervical cancer cell viability, proliferation, and migration and invasion, but induced apoptosis. At the protein level, osthole affected the expression of cervical cancer cell epithelial­mesenchymal transition markers, which showed that the expression of E­cadherin was increased, whereas that of vimentin was decreased. Osthole treatment also sensitized cervical cancer cells to irradiation, showing increased DNA damage as assessed by the Comet assay, and inhibited nuclear factor­κB signaling. In conclusion, osthole is an herbal agent that may offer potential for used as an adjuvant treatment for cervical cancer.

Escin-induced DNA damage promotes escin-induced apoptosis in human colorectal cancer cells via p62 regulation of the ATM/γH2AX pathway.

Escin, a triterpene saponin isolated from horse chestnut seed, has been used to treat encephaledema, tissue swelling and chronic venous insufficiency. Recent studies show that escin induces cell cycle arrest, tumor proliferation inhibition and tumor cell apoptosis. But the relationship between escin-induced DNA damage and cell apoptosis in tumor cells remains unclear. In this study, we investigated whether and how escin-induced DNA damage contributed to escin-induced apoptosis in human colorectal cancer cells. Escin (5-80 µg/mL) dose-dependently inhibited the cell viability and colony formation in HCT116 and HCT8 cells. Escin treatment induced DNA damage, leading to p-ATM and γH2AX upregulation. Meanwhile, escin treatment increased the expression of p62, an adaptor protein, which played a crucial role in controlling cell survival and tumorigenesis, and had a protective effect against escin-induced DNA damage: knockdown of p62 apparently enhanced escin-induced DNA damage, whereas overexpression of p62 reduced escin-induced DNA damage. In addition, escin treatment induced concentration- and time-dependent apoptosis. Similarly, knockdown of p62 significantly increased escin-induced apoptosis in vitro and produced en escin-like antitumor effect in vivo. Overexpression of p62 decreased the rate of apoptosis. Further studies revealed that the functions of p62 in escin-induced DNA damage were associated with escin-induced apoptosis, and p62 knockdown combined with the ATM inhibitor KU55933 augmented escin-induced DNA damage and further increased escin-induced apoptosis. In conclusion, our results demonstrate that p62 regulates ATM/γH2AX pathway-mediated escin-induced DNA damage and apoptosis.

Anti-Tumorigenic Activity of Chrysin from Oroxylum indicum via Non-Genotoxic p53 Activation through the ATM-Chk2 Pathway.

The p53 tumor suppressor plays critical roles in cell cycle regulation and apoptotic cell death in response to various cellular stresses, thereby preventing cancer development. Therefore, the activation of p53 through small molecules is an attractive therapeutic strategy for the treatment of cancers retaining wild-type p53. We used a library of 700 Myanmar wild plant extracts to identify small molecules that induce p53 transcriptional activity. A cell-based screening method with a p53-responsive luciferase-reporter assay system revealed that an ethanol extract of Oroxylum indicum bark increased p53 transcriptional activity. Chrysin was isolated and identified as the active ingredient in the O. indicum bark extract. A treatment with chrysin increased p53 protein expression and the p53-mediated expression of downstream target genes, and decreased cell viability in MCF7 cells, but not in p53-knockdown MCF7 cells. We also found that chrysin activated the ATM-Chk2 pathway in the absence of DNA damage. Hence, the inactivation of the ATM-Chk2 pathway suppressed p53 activation induced by chrysin. These results suggest the potential of chrysin as an anti-cancer drug through the activation of p53 without DNA damage.

Photobiomodulation effects on mRNA levels from genomic and chromosome stabilization genes in injured muscle.

Muscle injuries are the most prevalent type of injury in sports. A great number of athletes have relapsed in muscle injuries not being treated properly. Photobiomodulation therapy is an inexpensive and safe technique with many benefits in muscle injury treatment. However, little has been explored about the infrared laser effects on DNA and telomeres in muscle injuries. Thus, the aim of this study was to evaluate photobiomodulation effects on mRNA relative levels from genes related to telomere and genomic stabilization in injured muscle. Wistar male rats were randomly divided into six groups: control, laser 25 mW, laser 75 mW, injury, injury laser 25 mW, and injury laser 75 mW. Photobiomodulation was performed with 904 nm, 3 J/cm2 at 25 or 75 mW. Cryoinjury was induced by two applications of a metal probe cooled in liquid nitrogen directly on the tibialis anterior muscle. After euthanasia, skeletal muscle samples were withdrawn and total RNA extracted for evaluation of mRNA levels from genomic (ATM and p53) and chromosome stabilization (TRF1 and TRF2) genes by real-time quantitative polymerization chain reaction. Data show that photobiomodulation reduces the mRNA levels from ATM and p53, as well reduces mRNA levels from TRF1 and TRF2 at 25 and 75 mW in injured skeletal muscle. In conclusion, photobiomodulation alters mRNA relative levels from genes related to genomic and telomere stabilization in injured skeletal muscle.