Dipeptidyl peptidase-4 inhibitor and sodium-glucose cotransporter 2 inhibitor additively ameliorate hepatic steatosis through different mechanisms of action in high-fat diet-fed mice.

AIM: Dipeptidyl peptidase-4 (DPP-4) inhibitors suppress the inactivation of incretin hormones and lower blood glucose levels by inhibiting DPP-4 function. Sodium-glucose cotransporter 2 (SGLT2) inhibitors lower blood glucose levels in an insulin-independent manner by inhibiting renal reabsorption of glucose. DPP-4 and SGLT2 inhibitors each have the potential to improve hepatic steatosis; however, their combined effects remain unclear. In this study, we examined the effects of the combination of these drugs on hepatic steatosis using high-fat diet-fed mice. METHOD: C57BL/6J male mice were fed a 60% high-fat diet for 2 months to induce hepatic steatosis. Mice were divided into four groups (control; DPP-4 inhibitor anagliptin; SGLT2 inhibitor luseogliflozin; anagliptin and luseogliflozin combination), and the effects of each drug and their combination on hepatic steatosis after a 4-week intervention were evaluated. RESULTS: There were no differences in blood glucose levels among the four groups. Anagliptin suppresses inflammation- and chemokine-related gene expression. It also improved macrophage fractionation in the liver. Luseogliflozin reduced body weight, hepatic gluconeogenesis and blood glucose levels in the oral glucose tolerance test. The combination treatment improved hepatic steatosis without interfering with the effects of anagliptin and luseogliflozin, respectively, and fat content and inflammatory gene expression in the liver were significantly improved in the combination group compared with the other groups. CONCLUSION: The combination therapy with the DPP-4 inhibitor anagliptin and the SGLT2 inhibitor luseogliflozin inhibits fat deposition in the liver via anti-inflammatory effects during the early phase of diet-induced liver steatosis.

Protective effects of imeglimin on the development of atherosclerosis in ApoE KO mice treated with STZ.

BACKGROUND: Imeglimin is a new anti-diabetic drug which promotes insulin secretion from pancreatic ß-cells and reduces insulin resistance in insulin target tissues. However, there have been no reports examining the possible anti-atherosclerotic effects of imeglimin. In this study, we investigated the possible anti-atherosclerotic effects of imeglimin using atherosclerosis model ApoE KO mice treated with streptozotocin (STZ). METHODS: ApoE KO mice were divided into three groups: the first group was a normoglycemic group without injecting STZ (non-DM group, n = 10). In the second group, mice were injected with STZ and treated with 0.5% carboxymethyl cellulose (CMC) (control group, n = 12). In the third group, mice were injected with STZ and treated with imeglimin (200 mg/kg, twice daily oral gavage, n = 12). We observed the mice in the three groups from 10 to 18 weeks of age. Plaque formation in aortic arch and expression levels of various vascular factors in abdominal aorta were evaluated for each group. RESULTS: Imeglimin showed favorable effects on the development of plaque formation in the aortic arch in STZ-induced hyperglycemic ApoE KO mice which was independent of glycemic and lipid control. Migration and proliferation of vascular smooth muscle cells and infiltration of macrophage were observed in atherosclerotic lesions in STZ-induced hyperglycemic ApoE KO mice, however, which were markedly reduced by imeglimin treatment. In addition, imeglimin reduced oxidative stress, inflammation and inflammasome in hyperglycemic ApoE KO mice. Expression levels of macrophage makers were also significantly reduced by imeglimin treatment. CONCLUSIONS: Imeglimin exerts favorable effects on the development of plaque formation and progression of atherosclerosis.

Establishment of biological and pharmacokinetic assays of telomerase-specific replication-selective adenovirus.

The use of replication-selective tumor-specific viruses represents a novel approach for the treatment of neoplastic disease. We constructed an attenuated adenovirus, telomerase-specific replication-selective adenovirus (TRAD), in which the human telomerase reverse transcriptase promoter element drives the expression of the E1A and E1B genes linked with an internal ribosome entry site (IRES). Forty-eight hours after TRAD infection at a multiplicity of infection of 1.0, the cell viability of H1299 human lung cancer cells was consistently less than 50% and therefore this procedure could be used as a potency assay to assess the biological activity of TRAD. We also established a quantitative real-time polymerase chain reaction (PCR) analysis with consensus primers for either the adenovirus E1A or IRES sequence. The linear ranges of quantitation with E1A and IRES primers were 10(3)-10(8) and 10(2)-10(8) plaque-forming units/mL in the plasma, respectively. The PCR analysis demonstrated that the levels of E1A in normal tissues were more than 10(3) lower than in the tumors of A549 human lung tumor xenografts in nu/nmicro mice at 28 days after intratumoral injection. Our results suggest that the cell-killing assay against H1299 cells and real-time PCR can be used to assess the biological activity and biodistribution of TRAD in clinical trials.

Late resistance to adenoviral p53-mediated apoptosis caused by decreased expression of Coxsackie-adenovirus receptors in human lung cancer cells.

Adenovirus-mediated wild-type p53 gene transfer induces apoptosis in a variety of human cancer cells. Although clinical trials have demonstrated that a replication-deficient recombinant adenovirus expressing the wild-type p53 gene (Ad-p53) is effective in suppressing growth of non-small cell lung cancer (NSCLC), we often experienced late resistance to this treatment. To elucidate the mechanism of late resistance to Ad-p53 in human lung cancer cells, we generated 5 different resistant variants from p53-susceptible H1299 NSCLC cells by repeated infections with Ad-p53. We first examined the transduction efficiency of adenoviral vector by Ad-LacZ transduction followed by X-gal staining in parental and 5 resistant H1299 cell lines. Their sensitivity to viral infection decreased in correlation with the magnitude of resistance, and Ad-p53-mediated tumor suppression could be restored by dose escalation of Ad-p53 in the resistant variants. The expression of Coxsackie and adenovirus receptor (CAR) and alphaV integrins, which are cellular receptors for attachment and internalization of the virus, respectively, was next investigated in these cell lines. Flow cytometry revealed that alphaVbeta3 and alphaVbeta5 integrin expression was consistent, while p53-resistant cell lines showed that diminished CAR expression correlated with the magnitude of the resistance. Our results demonstrated that decreased CAR expression could be one of the mechanisms of late resistance to Ad-p53, which may have a significant impact on the outcome of adenovirus-based cancer gene therapy.

Telomerase-specific replication-selective virotherapy for human cancer.

PURPOSE: Replication-selective tumor-specific viruses present a novel approach for treating neoplastic disease. These vectors are designed to induce virus-mediated lysis of tumor cells after selective viral propagation within the tumor. Telomerase activation is considered to be a critical step in carcinogenesis, and its activity is closely correlated with human telomerase reverse transcriptase (hTERT) expression. We investigated the antitumor effect of the hTERT-specific replication-competent adenovirus on human cancer cells. EXPERIMENTAL DESIGN: We constructed an adenovirus 5 vector [tumor- or telomerase-specific replication-competent adenovirus (TRAD)], in which the hTERT promoter element drives expression of E1A and E1B genes linked with an internal ribosome entry site, and we examined the selective replication and antitumor effect in human cancer cells in vitro and in vivo. RESULTS: TRAD induced selective E1A and E1B expression in human cancer cells, but not in normal cells such as human fibroblasts. TRAD replicated efficiently and induced marked cell killing in a panel of human cancer cell lines, whereas replication as well as cytotoxicity was highly attenuated in normal human fibroblasts lacking telomerase activity. In nu/nu mice carrying s.c. human lung tumor xenografts, intratumoral injection of TRAD resulted in a significant inhibition of tumor growth. No evidence of TRAD was identified in tissues outside of the tumors, despite the presence of TRAD in the circulation. Moreover, TRAD replication in the distant, noninjected tumors was demonstrated. CONCLUSIONS: Our results suggest that the hTERT promoter confers competence for selective replication of TRAD in human cancer cells, an outcome that has important implications for the treatment of human cancers.