SIRT1 Controls Enteroendocrine Progenitor Cell Proliferation in High-Fat Diet-Fed Mice.

BACKGROUND & AIMS: We aimed to investigate how sirtuin 1 (SIRT1), a conserved mammalian Nicotinamide adenine dinucleotide+-dependent protein deacetylase, regulates the number of enteroendocrine cells (EECs). EECs benefit metabolism, and their increase potentially could treat type 2 diabetes and obesity. METHODS: We used mice with specific Sirt1 disruption in the intestinal epithelium (VilKO, villin-Cre+, and Sirt1flox/flox mice) or enteroendocrine progenitor cells (EEPCs) (NgnKO, neurogenin 3-Cre+, Sirt1flox/flox mice) and mice with increased SIRT1 activity owing to overexpression (Sir2d mice) or 24-hour fasting. Mice were fed a high-fat diet (HFD), and blood glucagon-like peptide 1 (GLP-1) and glucose levels were measured. Intestinal tissues, EECs, and formed organoids were analyzed using quantitative polymerase chain reaction, immunoblotting, and immunohistochemistry. RESULTS: In HFD-fed VilKO and NgnKO mice, an increase in EECs (42.3% and 37.2%), GLP-1- or GLP-2-producing L cells (93.0% and 61.4%), and GLP-1 (85.7% and 109.6%) was observed after glucose loading, explaining the improved metabolic phenotype of HFD-VilKO mice. These increases were associated with up-regulated expression of neurogenin 3 (EEPC marker) in crypts of HFD-VilKO and HFD-NgnKO mice, respectively. Conversely, Sir2d or 24-hour fasted mice showed a decrease in EECs (21.6%), L cells (41.6%), and proliferative progenitor cells. SIRT1 overexpression- or knockdown-mediated change in the progenitor cell proliferation was associated with Wnt/ß-catenin activity changes. Notably, Wnt/ß-catenin inhibitor completely suppressed EEC and L-cell increases in HFD-VilKO mice or organoids from HFD-VilKO and HFD-NgnKO mice. CONCLUSIONS: Intestinal SIRT1 in EECs modulates the EEPC cycle by regulating ß-catenin activity and can control the number of EECs in HFD-fed mice, which is a previously unknown role.

Src kinase-associated phosphoprotein2 expression is associated with poor prognosis in non-small cell lung cancer.

BACKGROUND/AIM: Non-small cell lung cancer (NSCLC) is among the leading causes of cancer-related deaths worldwide. In certain human cancer types, Src is associated with cancer progression and refractory cancer. To improve the prognoses of NSCLC patients, we evaluated Src kinase-associated phosphoprotein 2 (SKAP2), a factor associated with integrin-stimulated cytoskeletal rearrangement, as a new therapeutic target. MATERIALS AND METHODS: We performed immunohistochemistry for SKAP2 in 99 NSCLC samples and evaluated the relationship between SKAP2 expression, clinicopathological factors and prognosis. RESULTS: Higher SKAP2 expression was detected in cancerous tissues and was predominantly expressed in the cytoplasm. Elevated SKAP2 expression levels were associated with poor prognosis (p=0.007) and shorter survival time after recurrence (p=0.035). High SKAP2 expression was an independent prognostic factor in NSCLC patients (p=0.027). CONCLUSION: High SKAP2 expression levels in NSCLC tissues could be a powerful biomarker of poor prognosis. Therefore, SKAP2 is a promising candidate molecular target for NSCLC treatment.