川平 洋

BACKGROUND: Recent studies reveal that during trogocytosis plasma membranes are frequently transferred upon cell-to-cell contact, and that this phenomenon plays an important role in the modulation of anti-tumor immune response. However, the accompanying physiological roles in the tumor microenvironment are poorly understood. METHODS & RESULTS: Human gastric cancer cell line OCUM-1 was co-cultured with T cells whose plasma membrane was stained with PKH26. Flow-cytometric analysis revealed that OCUM-1 was positive for PKH26 at one hour and the positive rate increased over time. The acquisition of PKH26 was dependent on cell-to-cell contact and suppressed when T cells were fixed. OCUM-1 came to express various immunological synapse molecules after 10 hours of co-culture (positive rate, CD45:73.6±7.9%, CD3: 35.5±10.1%, CD4: 15.3±14.7%, CD8: 7.7±2.4%, CD11a: 8.1±4.3%, CD11b: 3.4±1.9%). We focused on CD11a which belongs to β2 integrins and aids immune cell adherence to endothelial cells. After co-culture with activated T cells (LAK), the expression level of CD11a on OCUM-1 was accelerated (with T cells: 19.1±13.4%, with LAK: 75.2±11.8%) and the adhesion rate on endothelial cells increased in a CD11a dependent manner (adhesion rate, single-culture: 2.0±0.64%, co-culture: 6.3±2.0%, co-culture (pre-treat with CD11a antibody): 2.3±1.4%, n=10, single-culture vs co-culture, p<0.0001; co-culture vs pre-treat with CD11a antibody, p<0.0001). CONCLUSION: These results suggest that acquisition of CD11a from T cells by trogocytosis enables cancer cells to increase adhesive properties towards endothelial cells, which may result in intravenous metastasis promotion.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is frequently associated with diabetes mellitus (DM), and their prognosis remains particularly poor. Metformin, a widely used antidiabetic agent, has demonstrated anti-tumor effects through multiple mechanisms and has been associated with improved outcomes in various malignancies. In this study, we investigated retrospectively survival outcomes and intra-tumoral infiltration patterns of various immune cells in diabetic patients who underwent curative resection of PDAC, comparing those who received metformin with those who did not. METHODS: A total of 65 diabetic patients who underwent curative resection for invasive PDAC were retrospectively analyzed. Among them, 17 patients received metformin, while 48 did not. Recurrence-free survival (RFS) and overall survival (OS) were compared between the two groups. Following propensity score matching, tumor-infiltrating CD3(+) and CD8(+) T cells were assessed by immunohistochemistry (IHC), and their densities were compared between metformin users and non-users. RESULTS: Patients in the metformin group showed significantly prolonged RFS [hazard ratio (HR) =0.42, P=0.03] and OS (HR =0.421, P=0.03) compared to those in the non-metformin group. Multivariate analysis identified metformin use as an independent prognostic factor for both RFS (HR =0.40, P=0.02) and OS (HR =0.21, P=0.02). The survival benefit of metformin was particularly evident in patients who underwent upfront surgery, whereas not significant in those who received neoadjuvant therapy. Immunohistochemical analysis revealed a significantly higher density of CD8(+) T cells (650.7 vs. 269.9/mm2, P<0.001) with an increased CD8/CD3 ratio in resected tumors from metformin-treated patients compared to non-users (58.9% vs. 44.8%, P<0.001). This trend was kept in patients who underwent upfront surgery, while less pronounced in patients treated with neoadjuvant therapy. CONCLUSIONS: Metformin may enhance the infiltration of cytotoxic CD8(+) T cells into the tumor microenvironment and improve the prognosis of diabetic patients with PDAC, particularly in those undergoing upfront surgical resection.

PURPOSE: There is limited awareness of work-related musculoskeletal disorders (MSDs) in Japan, despite the high ergonomic risks for surgeons. We conducted this study to investigate the prevalence, characteristics, and impact of MSDs on Japanese general surgeons. METHODS: An electronic survey of 136 general surgeons at a Japanese university hospital network used a modified Nordic Musculoskeletal Questionnaire to assess demographics, work factors, MSD symptoms, psychological distress, use of nonsteroidal anti-inflammatory drugs (NSAIDs), and their impact. RESULTS: Based on a 56.6% response rate, we found a high prevalence of chronic (37.7%) and acute (51.9%) MSDs. These disorders frequently impacted surgeons' work (30.0%) and daily life (39.0%), leading to time off (5.2%) and medical intervention (28.6%). Both MSD types correlated significantly with the use of NSAIDs and psychological distress. Notably, neck pain was strongly associated with the use of NSAIDs. The proportion of minimally invasive surgical procedures performed each week was associated significantly with acute, but not chronic, MSDs. CONCLUSIONS: MSDs are highly prevalent among Japanese surgeons, impacting their physical and psychological health. The high symptom prevalence and the strong association between neck pain and NSAID reliance underscore the urgent need for ergonomic interventions and preventive strategies in surgical practice to protect this essential workforce.