Objectives: In a mouse model, aldehyde dehydrogenase 2 (ALDH2) knockout resulted in lower bone mineral density; however, higher parathyroid hormone receptor expression than wild-type mice. This study aimed to investigate whether ALDH2 polymorphisms influence efficacy of intermittent parathyroid hormone therapy and bone mineral density changes in humans. Methods: Eighty-two patients with primary osteoporosis treated with parathyroid hormone for > 1 year were divided into wild-type ALDH2 (ALDH2*1) and variant (ALDH2*2) groups. Bone mineral densities were measured by dual-energy X-ray absorptiometry. Changes in bone mineral density, treatment response, bone turnover markers, and new fracture incidence were evaluated. Furthermore, bone mineral density was analyzed using a mixed-effects model. Results: Femoral neck bone mineral density increased by 1.0 ± 7.4% in the ALDH2*1 group and 4.3 ± 8.1% in the ALDH2*2 group (P < 0.05), whereas lumbar spine bone mineral density increased by 5.7 ± 8.2% and 9.4 ± 9.1% without significance. Treatment success rates were higher in ALDH2*2 group (femoral neck 38.7%, lumbar spine 68.8%) compared with ALDH2*1 (16.3%, 51.0%). Statistical significance was observed only at the femoral neck. Bone turnover markers and fracture incidence were comparable between groups. Mixed-effects analysis adjusting for confounders showed a significant ALDH2 genotype × duration interaction for femoral neck, indicating genotype-related differences in the rate of bone mineral density increase over time. For lumbar spine, the genotype main effect was significant, whereas the interaction was not. Conclusions These findings suggest that ALDH2 polymorphisms may influence the therapeutic response to PTH treatment and highlight the need for larger future studies.

In this study, we examined the molecular and functional characterization of choline uptake in the human esophageal cancer cells. In addition, we examined the influence of various drugs on the transport of [3H]choline, and explored the possible correlation between the inhibition of choline uptake and apoptotic cell death. We found that both choline transporter-like protein 1 (CTL1) and CTL2 mRNAs and proteins were highly expressed in esophageal cancer cell lines (KYSE series). CTL1 and CTL2 were located in the plasma membrane and mitochondria, respectively. Choline uptake was saturable and mediated by a single transport system, which is both Na+-independent and pH-dependent. Choline uptake and cell viability were inhibited by various cationic drugs. Furthermore, a correlation analysis of the potencies of 47 drugs for the inhibition of choline uptake and cell viability showed a strong correlation. Choline uptake inhibitors and choline deficiency each inhibited cell viability and increased caspase-3/7 activity. We conclude that extracellular choline is mainly transported via a CTL1. The functional inhibition of CTL1 by cationic drugs could promote apoptotic cell death. Furthermore, CTL2 may be involved in choline uptake in mitochondria, which is the rate-limiting step in S-adenosylmethionine (SAM) synthesis and DNA methylation. Identification of this CTL1- and CTL2-mediated choline transport system provides a potential new target for esophageal cancer therapy.
Cell Death ; Cell Line ; Cell Membrane ; Cell Survival ; Choline Deficiency ; Choline* ; DNA Methylation ; Esophageal Neoplasms* ; Humans ; Mitochondria ; RNA, Messenger ; S-Adenosylmethionine