Poly(adenosine diphosphate‑ribose) polymerase (PARP)‑1 is the prototypical PARP enzyme well known for its role in DNA repair and as a pro‑inflammatory protein. Since PARP1 is an important co‑factor of several other pro‑inflammatory proteins, in the present study the possible changes in microbial flora of PARP1 knockout mice were investigated. Samples from the duodenum, cecum and feces from wild type and PARP1 knockout C57BL/6J male mice were collected and 16S ribosomal RNA genes were sequenced. Based on the sequencing results, the microbiome and compared samples throughout the lower part of the gastrointestinal system were reconstructed. The present results demonstrated that the lack of PARP1 enzyme only disturbed the microbial flora of the duodenum, where the biodiversity increased in the knockout animals on the species level but decreased on the order level. The most prominent change was the overwhelming abundance of the family Porphyromonadaceae in the duodenum of PARP1‑/‑ animals, which disappeared in the cecum and feces where families were spread out more evenly than in the wild type animals. The findings of the present study may improve current understanding of the role of PARP1 in chronic inflammatory diseases.

The role of ginsenoside in the prevention of cancer has been well established. Ginsenoside Rg5 is one of the main components isolated from red ginseng, which has been demonstrated to have anti‑tumor effects by inhibiting cell proliferation and causing DNA damage. However, the role of ginsenoside Rg5 and its molecular mechanisms remain unclear in human esophageal cancer. In the present study, Rg5 was investigated as a novel drug for the chemotherapy of esophageal cancer in in vitro experiments. Esophageal cancer Eca109 cells were exposed to various concentrations of ginsenoside Rg5 (0‑32 µΜ) for 24 h. Subsequent cell proliferation assays demonstrated that treatment with ginsenoside Rg5 resulted in the dose‑dependent inhibition of proliferation, while a significant increase in apoptotic rate and increased activities of caspase‑3, ‑8 and ‑9 were observed. In addition, the mitochondrial membrane potential was decreased and the cytoplasmic free calcium level increased following treatment with ginsenoside Rg5. Furthermore, the expression of B‑cell lymphoma 2 and phosphorylated‑protein kinase B (p‑Akt) decreased. The specific phosphoinositide‑3 kinase (PI3K) inhibitor LY294002 promoted this effect, while insulin‑like growth factor‑1, a specific PI3K activator, inhibited this action. Taken together, the results suggested that ginsenoside Rg5 may have a tumor‑suppressive effect on esophageal cancer by promoting apoptosis and may be associated with the downregulation of the PI3K/Akt signaling pathway.

As one of the most recognized and well‑known drugs for hepatocellular carcinoma (HCC), the antitumor effect of sorafenib against HCC remains to be improved. Bufalin has displayed an antitumor effect in HCC; however, whether the enhanced antitumor effect may be generated with their combined treatment remains unclear. Therefore, in the present study, their combined effects on HCC proliferation and apoptosis were investigated. It was revealed that either bufalin or sorafenib suppressed PLC/PRF/5 and SMMC‑7721 cell proliferation in a concentration‑dependent manner following incubation for 24 h, and the inhibitory effect was augmented with their combined treatment. The synergistic effect peaked in HCC cells treated with 20 nM bufalin and 10 µM sorafenib. In addition, cell cycle and terminal deoxynucleotidyl transferase dUTP nick‑end labelling assays revealed that bufalin also enhanced sorafenib‑induced apoptosis. Colony formation assay demonstrated that combined treatment significantly suppressed HCC proliferation compared with treatment with either of them alone. Furthermore, B‑cell lymphoma 2‑associated X protein, caspase 7 and poly‑(adenosine diphosphate‑ribose) polymerase were upregulated in HCC cells with combined treatment. Taken together, the results of the present study revealed that the treatment of sorafenib combined with bufalin synergistically suppressed HCC proliferation and induced apoptosis. Therefore, bufalin combined with sorafenib may be a favorable treatment strategy for patients with HCC.

Brain‑type glycogen phosphorylase (PYGB) is an enzyme that metabolizes glycogen, whose function is to provide energy for an organism in an emergency state. The present study purposed to investigate the role and mechanism of PYGB silencing on the growth and apoptosis of prostate cancer cells. A cell counting kit‑8 assay and flow cytometry were performed to determine the cell viability, apoptosis and reactive oxygen species (ROS) content, respectively. Colorimetry was performed to analyze the activity of caspase‑3. Western blotting and reverse transcription‑quantitative polymerase chain reaction were used to evaluate the associated mRNA and protein expression levels. The results revealed that PYGB was upregulated in prostate cancer tissues and was associated with disease progression. In addition, PYGB silencing suppressed the cell viability of PC3 cells. PYGB silencing promoted apoptosis of PC3 cells via the regulation of the expression levels of cleaved‑poly (adenosine diphosphate‑ribose) polymerase, cleaved‑caspase‑3, B‑cell lymphoma‑2 (Bcl‑2) and Bcl‑2‑associated X protein. PYGB silencing increased the ROS content in PC3 cells, and affected nuclear factor (NF)‑κB/nuclear factor‑erythroid 2‑related factor 2 (Nrf2) signaling pathways in PC3 cells. In conclusion, PYGB silencing suppressed the growth and promoted the apoptosis of prostate cancer cells by affecting the NF‑κB/Nrf2 signaling pathway. The present study provided evidence that may lead to the development of a potential therapeutic strategy for prostate cancer.

Ovarian cancer is one of the most common causes of female mortalities from gynecological tumors. An ent‑kaurane diterpenoid compound CRT1 (ent‑18‑acetoxy‑7β‑hydroxy kaur‑15‑oxo‑16‑ene), mainly isolated from the Vietnamese herb Croton tonkinesis has been used in folk medicine in Vietnam for cancer treatment. However, the effect of this compound on human ovarian cancer cells has not yet been reported. The objective of the present study was to determine the effect of CRT1 on the cell viability, apoptosis and metastasis of SKOV3 human ovarian cancer cells using a Cell Counting Kit‑8 assay, flow cytometric analysis of Annexin V‑fluorescein isothiocyanate/propidium iodide staining, western blot analysis, soft agar colony forming assay, wound healing assay and Matrigel invasion assay. The results revealed that CRT1 possessed significant anti‑proliferative effects on SKOV3 cells. CRT1 treatment at 25 and 50 µM induced apoptosis, enhanced the percentage of Annexin V‑positive cells, increased the expression of pro‑apoptotic protein B‑cell lymphoma 2 (Bcl‑2)‑associated X protein, cytochrome c release from the mitochondria to the cytosol, cleaved caspase‑3, caspase‑7, caspase‑9, and poly (adenosine diphosphate‑ribose) polymerase. However, it decreased the expression of Bcl‑2 in a dose‑dependent manner. The percentage of necrotic cells increased following CRT1 treatment at <10 µM. CRT1 at 50 µM significantly induced the phosphorylation of extracellular signal‑regulated kinase (ERK). Growth inhibition and the apoptotic effects of CRT1 could be reversed by PD98059, an ERK inhibitor. Additionally, CRT1 inhibited cell migration and invasion via ERK1/2 activation in SKOV3 cells. These results indicated that CRT1, an ent‑kaurane diterpenoid, may be a potential inhibitor of ovarian cancer by the activating ERK1/2/p90 ribosomal S6 kinase signaling pathway.

Colorectal cancer (CRC) is a major cause of mortality and morbidity. Chronic inflammation is closely associated with the development, progression and prognosis of the majority of intestinal malignancies. In recent years, targeting the nuclear factor (NF)‑κB signaling pathway for CRC therapy has become an attractive strategy. Riccardin D, a novel macrocyclicbis (bibenzyl) compound, was isolated from the Chinese liverwort plant. Previous studies have suggested that Riccardin D exerted chemo‑preventative effects against the intestinal malignancy formation. In the present study, cell counting kit‑8, Hochest 33258 staining, mitochondria membrane permeability assay, western blotting analysis, reverse transcription‑polymerase chain reaction, luciferase reporter gene assay and molecular modeling analysis were performed to detect the effect and mechanisms of Riccardin D on human colon cancer cells. The results demonstrated that Riccardin D significantly inhibited the growth of HT‑29 cells. In addition, the cDNA expression of cyclooxygenase‑2, and the protein expression and activity of NF‑κB and tumor necrosis factor‑α were downregulated; however, the protein expression of cleaved caspase‑3 and ‑9, and cleaved poly (adenosine diphosphate‑ribose) polymerase, and the B‑cell lymphoma (Bcl)‑2: Bcl‑2‑associated X protein ratio were upregulated. Furthermore, Auto Dock analysis identified binding sites between Riccardin D and NF‑κB. These results indicated that Riccardin D may inhibit cell proliferation and induce apoptosis in HT‑29 cells, which may be associated with the blocking of the NF‑κB signaling pathway. Thus, Riccardin D should be investigated as an NF‑κB inhibitor in cancer therapy.

Resistance to Adriamycin (ADR) is an increasing problem in the treatment of leukemia and the development of novel therapeutic strategies is becoming increasingly important. Olaparib is a poly (adenosine diphosphate‑ribose) polymerase (PARP) 1 inhibitor, which has promising antitumor activity in patients with metastatic breast cancer and germline BRCA mutations. Previously published studies have indicated that Olaparib is able to overcome drug resistance in cancer; however, its underlying mechanism of action is yet to be elucidated. The aim of the present study was to explore the mechanism underlying re‑sensitization. Annexin V‑propidium iodide staining indicated that the percentage of apoptotic ADR resistant cells was markedly increased and the cell cycle was blocked at the G2/M‑phase following treatment with ADR combined with Olaparib, when compared with the control group. The alkaline comet assay demonstrated that ADR combined with Olaparib significantly upregulated the induction of the DNA damage response in ADR‑resistant cells. Western blot analysis revealed that the protein expression of γ‑H2A histone family member X, cleaved PARP, caspase 3 and cleaved caspase 3 was markedly enhanced, while the cell cycle‑associated protein cyclin B1 was downregulated in K562/ADR cells following treatment with a combination of ADR and Olaparib. Similar synergistic cytotoxicity was observed in blood mononuclear cells, which were isolated from patients with chemotherapy‑resistant leukemia. As Olaparib is available for clinical use, the results of the present study provide a rationale for the development of Olaparib combinational therapies for cases of ADR resistant leukemia.

Oxidative stress is implicated in the pathophysiology of vascular diseases, including atherosclerosis, aneurysm and arteriovenous fistula. A previous study from our lab suggested that microRNA (miR)‑4463 may be involved in the pathogenesis of vascular disease; however, the roles of oxidative stress in the molecular mechanisms underlying the actions of miR‑4463 in vascular disease have yet to be elucidated. The aim of the present study was to investigate the role of miR‑4463 in hydrogen peroxide (H2O2)‑induced oxidative stress in human umbilical vein endothelial cells (HUVECs). Reverse transcription‑quantitative polymerase chain reaction was used to assess the expression levels of miR‑4463 in HUVECs treated with various concentrations of H2O2. Flow cytometry was used to evaluate the percentage of apoptotic cells, and the protein expression levels of the apoptotic markers cleaved (C)‑caspase3, poly (adenosine diphosphate‑ribose) polymerase 1 (PARP1), B cell lymphoma‑2 (Bcl‑2), Bcl‑2‑associated X protein (Bax) and X‑linked inhibitor of apoptosis protein (XIAP) were determined using western blot analysis. The results demonstrated that the apoptotic rate of HUVECs was increased following treatment with H2O2 in a concentration‑dependent manner, and the expression of miR‑4463 was also upregulated in a dose‑dependent manner. Following transfection with miR‑4463 mimics, the levels of malondialdehyde and reactive oxygen species were increased in HUVECs, with a corresponding increase in the apoptotic rate. Furthermore, western blot analysis revealed that the protein expression levels of C‑caspase3, PARP1 and Bax were upregulated, whereas the levels of Bcl‑2 and XIAP were downregulated. In conclusion, the present findings suggested that the upregulation of miR‑4463 may enhance H2O2‑induced oxidative stress and promote apoptosis in HUVECs in vitro.

Erastin, a classical inducer of non‑apoptotic cell death, exerts cytotoxicity in several types of cancer cells, including gastric cancer cells, by depleting glutathione, which is a primary cellular antioxidant, thus causing reactive oxygen species (ROS) accumulation. Although numerous studies have focused on the non‑apoptotic cell death induced by erastin, whether erastin induces apoptosis remains unknown. The present study confirmed the cytotoxicity of erastin in HGC‑27 cells and used a 30% inhibitory concentration (IC30, approximately 6.23 µM) for further analysis. The cell cycle analysis revealed that 6.23 µM of erastin inhibited proliferation by blocking the cell cycle at the G1/G0 phase. Further analysis also showed that 6.23 µM of erastin clearly inhibited HGC‑27 malignant behaviors, including migration, invasion, colony formation and tumor formation in soft agar. The observation of ROS accumulation due to erastin treatment led to determination of the effects of erastin on mitochondrial function and, as expected, erastin treatment decreased transcriptional activity and ATP production in mitochondria and disrupted the mitochondrial potential; these effects were reversed by the addition of the ROS scavenger NAC. To evaluate the effect of erastin in inducing apoptosis, HGC‑27 cells were treated with 6.23 µM of erastin for 7 days and then analyzed. Evident apoptotic cell death was induced by erastin and this apoptosis was reversed by the addition of an apoptosis inhibitor (zVAD) or NAC but not by the addition of a ferroptosis inhibitor (ferrostatin‑1). Furthermore, the detection of caspase‑3 and poly (adenosine diphosphate‑ribose) polymerase (PARP) also confirmed that treatment with erastin promoted the cleavage of caspase‑3 and PARP, which are hallmarks of apoptosis. Taken together, the present study revealed that a low dose of erastin inhibited malignant behavior and induced apoptosis by causing mitochondrial dysfunction.

It was previously reported that poly-(adenosine diphosphate-ribose) polymerase-1 (PARP-1) regulated ionizing radiation (IR)-induced autophagy in CNE-2 human nasopharyngeal carcinoma cells. The present study aimed to investigate whether PARP-1-mediated IR-induced autophagy occurred via activation of the liver kinase B1 (LKB1)/adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway in CNE-2 cells. In addition, the effect of PARP-1 and AMPK inhibition on the radiation sensitization of CNE-2 cells was investigated. CNE-2 cells were treated with 10 Gy IR in the presence or absence of the AMPK activator 5-amino-1-β-D-ribofuranosyl-1H-imid-azole-4-carboxamide (AICAR). In addition, IR-treated CNE-2 cells were transfected with lentivirus-delivered small-hairpin RNA or treated with the AMPK inhibitor Compound C. Western blot analysis was used to assess the protein expression of PARP-1, phosphorylated (p)-AMPK, microtubule-associated protein 1 light chain 3 (LC3)-II and p-P70S6K. Cell viability and clone formation assays were performed to determine the effect of PARP-1 silencing and AMPK inhibition on the radiation sensitization of CNE-2 cells. The results showed that IR promoted PARP-1, p-AMPK and LC3-II protein expression as well as decreased p-P70S6K expression compared with that of the untreated cells. In addition, AICAR increased the expression of p-AMPK and LC3-II as well as decreased p-P70S6K expression compared with that of the IR-only group; however, AICAR did not increase PARP-1 expression. Furthermore, PARP-1 gene silencing decreased the expression of PARP-1, p-AMPK and LC3-II as well as increased p-P70S6K expression. Compound C decreased p-AMPK and LC3-Ⅱ expression as well as increased p-P70S6K expression; however, Compound C did not increase PARP-1 expression. Western blot analysis detected limited expression of p-LKB1 in all treatment groups. Cell viability and clone formation assays revealed that PARP-1 or AMPK inhibition reduced the proliferation of CNE-2 cells following IR. In conclusion, the present study demonstrated that PARP-1 promoted autophagy via the AMPK/mTOR pathway; in addition, PARP-1 or AMPK inhibition contributed to the radiation sensitization of CNE-2 cells following IR. However, it remains to be elucidated whether PARP-1 is an upstream mediator of the LKB1 pathway in CNE‑2 cells following IR.

Endothelial cells are an important component of the heart and vasculature and form a crucial link between the cardiovascular system and the immune system. Sestrin 1 (SESN1) has an important role in atherosclerosis by inhibiting NOD‑like receptor family pyrin domain containing 3 inflammasome activation. However, whether SESN1 is involved in human umbilical vein endothelial cell (HUVEC) injury caused by atherosclerosis has remained to be elucidated. The present study aimed to investigate the functions of SESN1 in the inflammatory response, apoptosis and endothelial‑mesenchymal transition (EndMT) of HUVECs following stimulation with oxidized low‑density lipoprotein (Ox‑LDL). SESN1 expression at the mRNA and protein levels was detected using reverse transcription‑quantitative PCR (RT‑qPCR) and western blot analysis. Following SESN1 overexpression in Ox‑LDL‑stimulated HUVECs, cell viability was determined using a Cell Counting Kit‑8 assay. Terminal deoxynucleotidyl transferase‑mediated nick‑end labeling staining was employed to detect cell apoptosis and western blot analysis was used to determine the levels of apoptosis‑related proteins. RT‑qPCR, ELISA and western blot were utilized to determine the levels of inflammatory factors. Immunofluorescence staining, RT‑qPCR and western blot analysis were employed to assess the EndMT of Ox‑LDL‑stimulated HUVECs. The results revealed that SESN1 exhibited a low expression in HUVECs following Ox‑LDL stimulation. SESN1 overexpression suppressed inflammation, apoptosis and EndMT in Ox‑LDL‑induced HUVECs. In addition, SESN1 stimulated adenosine monophosphate‑activated protein kinase catalytic subunit α1/sirtuin 1 signaling to suppress Ox‑LDL receptor‑1 expression. An AMPK and SIRT1 inhibitor reversed the effects of SESN1 overexpression on the inflammatory response, apoptosis and EndMT of HUVECs exposed to Ox‑LDL. Taken together, the present study demonstrated that SENS1 exerts a suppressive effect on Ox‑LDL‑induced inflammation, apoptosis and EndMT of HUVECs, suggesting that SENS1 may be used as a novel biomarker for endothelial injury‑related disorders.

Derivatives of 1,4‑naphthoquinone have excellent anti‑cancer effects, but their use has been greatly limited due to their serious side effects. To develop compounds with decreased side effects and improved anti‑cancer activity, two novel types of 1,4‑naphthoquinone derivatives, 2,3‑dihydro‑2,3‑epoxy‑2‑propylsulfonyl‑5,8‑dimethoxy‑1,4‑naphthoquinone (EPDMNQ) and 2,3‑dihydro‑2,3‑epoxy‑2‑nonylsulfonyl‑5,8‑dimethoxy‑1,4‑naphthoquinone (ENDMNQ) were synthesized and their anti‑tumor activities were investigated. The effects of EPDMNQ and ENDMNQ on cell viability, apoptosis and accumulation of reactive oxygen species (ROS) in liver cancer cells were determined by MTT cell viability assay and flow cytometry. The expression levels of mitochondrial, mitogen activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) signaling pathway‑associated proteins in Hep3B liver cancer cells were analyzed by western blot analysis. The results demonstrated that EPDMNQ and ENDMNQ inhibited the proliferation of liver cancer Hep3B, HepG2, and Huh7 cell lines but not that of normal liver L‑02, normal lung IMR‑90 and stomach GES‑1 cell lines. The number of apoptotic cells and ROS levels were significantly increased following treatment with EPDMNQ and ENDMNQ, and these effects were blocked by the ROS inhibitor N‑acetyl‑L‑cysteine (NAC) in Hep3B cells. EPDMNQ and ENDMNQ induced apoptosis by upregulating the protein expression of p38 MAPK and c‑Jun N‑terminal kinase and downregulating extracellular signal‑regulated kinase and STAT3; these effects were inhibited by NAC. The results of the present study demonstrated that EPDMNQ and ENDMNQ induced apoptosis through ROS‑modulated MAPK and STAT3 signaling pathways in Hep3B cells. Therefore, these novel 1,4‑naphthoquinone derivatives may be useful as anticancer agents for the treatment of liver cancer.