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The biguanide metformin is widely used for treating diabetes mellitus. We previously showed the chemopreventive effect of metformin in two rodent models of colorectal carcinogenesis. However, besides epidemiologic studies, little is known about the effects of metformin on human colorectal carcinogenesis. The objective of this pilot study was to evaluate the chemopreventive effect of metformin on rectal aberrant crypt foci (ACF), which are an endoscopic surrogate marker of colorectal cancer. We prospectively randomized 26 nondiabetic patients with ACF to treatment with metformin (250 mg/d, n = 12) or no treatment (control, n = 14); 23 patients were evaluable for end point analyses (9 metformin and 14 control); the two groups were similar in ACF number and other baseline clinical characteristics. Magnifying colonoscopy determined the number of rectal ACF in each patient at baseline and after 1 month in a blinded fashion (as were all laboratory end point analyses). We also examined proliferative activity in colonic epithelium (via proliferating cell nuclear antigen labeling index) and apoptotic activity (via terminal deoxynucleotidyl transferase dUTP nick-end labeling). At 1 month, the metformin group had a significant decrease in the mean number of ACF per patient (8.78 ± 6.45 before treatment versus 5.11 ± 4.99 at 1 month, P = 0.007), whereas the mean ACF number did not change significantly in the control group (7.23 ± 6.65 versus 7.56 ± 6.75, P = 0.609). The proliferating cell nuclear antigen index was significantly decreased and the apoptotic cell index remained unaltered in normal rectal epithelium in metformin patients. This first reported trial of metformin for inhibiting colorectal carcinogenesis in humans provides preliminary evidence that metformin suppresses colonic epithelial proliferation and rectal ACF formation in humans, suggesting its promise for the chemoprevention of colorectal cancer. Cancer Prev Res; 3(9);

This is the first report to demonstrate consistent and profound elevation of hs-CRP in cases of NASH compared with in cases of simple nonprogressive steatosis. Our results suggest that hs-CRP may be a clinical feature that not only distinguishes NASH from simple nonprogressive steatosis but also indicates the severity of hepatic fibrosis in cases of NASH.

LETM1 is located in the chromosomal region that is deleted in patients suffering Wolf-Hirschhorn syndrome; it encodes a homolog of the yeast protein Mdm38 that is involved in mitochondrial morphology. Here, we describe the LETM1-mediated regulation of the mitochondrial volume and its interaction with the mitochondrial AAA-ATPase BCS1L that is responsible for three different human disorders. LETM1 is a mitochondrial inner-membrane protein with a large domain extruding to the matrix. The LETM1 homolog LETM2 is a mitochondrial protein that is expressed preferentially in testis and sperm. LETM1 downregulation caused mitochondrial swelling and cristae disorganization, but seemed to have little effect on membrane fusion and fission. Formation of the respiratory-chain complex was impaired by LETM1 knockdown. Cells lacking mitochondrial DNA lost active respiratory chains but maintained mitochondrial tubular networks, indicating that mitochondrial swelling caused by LETM1 knockdown is not caused by the disassembly of the respiratory chains. LETM1 was co-precipitated with BCS1L and formation of the LETM1 complex depended on BCS1L levels, suggesting that BCS1L stimulates the assembly of the LETM1 complex. BCS1L knockdown caused disassembly of the respiratory chains as well as LETM1 downregulation and induced distinct changes in mitochondrial morphology.

Previously, we reported two types of neutral ceramidase in mice, one solubilized by freeze-thawing and one not. The former was purified as a 94-kDa protein from mouse liver, and cloned (Tani, M., Okino, N., Mori, K., Tanigawa, T., Izu, H., and Ito, M. (2000) J. Biol. Chem. 275, 11229 -11234). In this paper, we describe the purification, molecular cloning, and subcellular distribution of a 112-kDa membrane-bound neutral ceramidase of rat kidney, which was completely insoluble by freeze-thawing. The open reading frame of the enzyme encoded a polypeptide of 761 amino acids having nine putative N-glycosylation sites and one possible transmembrane domain. In the ceramidase overexpressing HEK293 cells, 133-kDa (Golgi-form) and 113-kDa (endoplasmic reticulum-form) Myc-tagged ceramidases were detected, whereas these two proteins were converted to a 87-kDa protein concomitantly with loss of activity when expressed in the presence of tunicamycin, indicating that the N-glycosylation process is indispensable for the expression of the enzyme activity. Immunohistochemical analysis clearly showed that the ceramidase was mainly localized at the apical membrane of proximal tubules, distal tubules, and collecting ducts in rat kidney, while in liver the enzyme was distributed with endosome-like organelles in hepatocytes. Interestingly, the kidney ceramidase was found to be enriched in the raft microdomains with cholesterol and GM1 ganglioside.Over the past decade, sphingolipids and their metabolites have emerged as a new class of lipid biomodulators of various cell functions (1, 2). Ceramide (N-acylsphingosine; Cer), 1 a common lipid backbone of sphingolipids, functions as a second messenger in a variety of cellular events including apoptosis and cell differentiation (3, 4). Sphingosine (Sph) has bifunctional effects on cell growth, i.e. it exerts mitogenic (5) and apoptosis inducing (6) activities, depending on the cell type and cell cycle. Sph-1-phosphate (S1P) was found to function as an intra-and intercellular second messenger to regulate cell growth (7), motility (8), and morphology (9). Interestingly, S1P inhibits the apoptosis induced by Cer and Fas ligand (10), indicating that the balance of Cer/Sph/S1P affects cell phenotype. Ceramidase (CDase, EC 3.5.1.23) is an enzyme that catalyzes hydrolysis of the N-acyl linkage of Cer to produce Sph, which can be phosphorylated to S1P by sphingosine kinase (11). Sph is not produced by de novo synthesis (12), and thus the activity of CDase is crucial not only for switching off the Cer-induced signaling but also for generation of Sph and S1P. CDase is classified into two categories: acid and neutral/alkaline enzymes depending on pH optimum. Acid CDase is thought to be a housekeeping enzyme to catabolize Cer in lysosomes. The enzyme was purified from human urine (13), and cDNA encoding the enzyme was isolated from cDNA libraries of human (14) and mouse (15). A deficiency of the enzyme could cause Farber disease in which Cer is accumulated in lysosomes (16). Neutral/alkaline CDase seems...

Co-administration of L. casei is effective for the treatment of aspirin-associated small bowel injury.

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