Long-term second-generation antipsychotics decreases bone formation and resorption in male patients with schizophrenia.

RATIONALE: Patients with schizophrenia with second-generation antipsychotics (SGAs) treatment have shown an increased risk of bone fragility and susceptibility to fracture; however, it is still unclear whether this risk is derived from the effect of antipsychotics on balance of bone metabolism. OBJECTIVES: We investigated the changes of two bone turnover biomarkers (BTMs) concentrations in people with schizophrenia receiving SGAs: procollagen type I aminoterminal propeptide (PINP) and C-terminal telopeptide of type I collagen (CTX-1) as BTMs of osteogenesis and bone resorption, respectively, to explore how antipsychotics contribute to bone fragility. METHODS: We recruited 59 Chinese male patients with schizophrenia (32 drug-naïve first-episode (DNFE) patients and 27 chronic patients) to undergo 8 weeks SGAs treatment. Fasting peripheral blood samples of pre- and posttreatment were collected, plasma levels of PINP and CTX-1 were measured. RESULTS: The interaction effects of group and time on PINP and CTX-1 concentrations were found (P = .016 and P = .008). There was a significant decrease for both BTMs concentrations of the posttreatment compared to the pretreatment (P<.001 and P = .003). Chronic patients had significantly higher changes of BTMs concentrations compared to DNFE patients (P = .048 and P = .024). There was a positive correlation of the two BTMs of pretreatment with disease course in DNFE group (r = .37, P = .039;r = .38, P = .035) and a negative correlation of PINP of pretreatment with age in the chronic group (r=-.40, P = .039). CONCLUSION: Long-term SGAs medication inhibited osteogenesis in a dose- and time-dependent manner and damaged the balance of bone formation and bone resorption.

DH334, a beta-carboline anti-cancer drug, inhibits the CDK activity of budding yeast.

The beta-carboline alkaloids present in medicinal plants, such as Peganum harmala and Eurycoma longifolia, have recently drawn attention due to their antitumor activities. Further mechanistic studies indicate that beta-carboline derivatives inhibit DNA topoisomerases and interfere with DNA synthesis. Moreover, some beta-carboline compounds are specific inhibitors of cyclin dependent kinases (CDKs). In this study we used budding yeast as a model system to investigate the antitumor mechanism of beta-carboline drugs. We found that DH334, a beta-carboline derivative, inhibits the growth of budding yeast. Strikingly, deletion of SIC1, which encodes the budding yeast CDK inhibitor, results in resistance to DH334. In contrast, yeast cells defective for Sic1 degradation exhibit morepronounced sensitivity to DH334. The presence of DH334 causes accumulation of yeast cells in G(1) phase, indicating that DH334 blocks cell cycle initiation. We further demonstrated that DH334 inhibits CDK activity as indicated by the decreased phosphorylation of a CDK substrate. All these data suggest that the inhibition of CDK contributes to the toxicity of beta-carboline derivatives to budding yeast. DH334 also inhibits the kinase activity of Cdk2/CyclinA in vitro. Therefore, we speculate that the antitumor activity of beta-carboline drugs could be attributable to their inhibition of CDK.