Toru Yoshimura

Transforming growth factor‐β1‐induced apoptosis is blocked by β1‐integrin‐mediated mitogen‐activated protein kinase activation in human hepatoma cells

Growth factors and extracellular matrices cooperatively regulate cellular behavior. However, the interactions between transforming growth factor‐β1 (TGF‐β1) and integrins in hepatic cells are not fully understood. We investigated the effects of β1‐integrin on TGF‐β1‐regulated growth of hepatoma cells. Human hepatoma cell lines HepG2, Huh7, and Hep3B were stably transfected with β1‐integrin, and the parental, and mock‐ and β1‐integrin‐transfected hepatoma cells were treated with TGF‐β1. Modulation of apoptosis and pathways involved in the process were investigated. TGF‐β1 suppressed the growth of hepatoma cells, and apoptosis was observed in Hep3B and Huh7. Hepatoma cells transfected with β1‐integrin were protected from TGF‐β1‐induced apoptosis. Mitogen‐activated protein (MAP) kinase inhibitors, PD98059, SB203580, and SP600125, abolished this protective effect of β1‐integrin, but herbimycin A and wortmannin were ineffective. Hepatoma cells overexpressing β1‐integrin showed increased activities of MAP kinases, and TGF‐β1 induced sustained activation of MAP kinases in these cells, but only transient activation in mock‐transfected cells. These data suggest that MAP kinases activated by β1‐integrin provide a strong anti‐apoptotic signal during TGF‐β1‐induced apoptosis in human hepatoma cells. Therefore β1‐integrin‐mediated signals may contribute to the development and progression of hepatocellular carcinoma.

Higher arterial stiffness, greater peripheral vascular resistance and lower blood flow in lower-leg arteries are associated with long-term hyperglycaemia in type 2 diabetic patients with normal ankle-brachial index.

Higher arterial stiffness and greater peripheral vascular resistance reduce blood flow in lower‐leg arteries and contribute to the development of ischaemic limb in diabetic patients even without peripheral artery occlusive disease. The aim of this study was to clarify whether these vascular parameters are associated with long‐term hyperglycaemia in diabetic patients.

Impaired peripheral circulation in lower-leg arteries caused by higher arterial stiffness and greater vascular resistance associates with nephropathy in type 2 diabetic patients with normal ankle-brachial indices

Diabetic nephropathy is a major cause of lower-limb amputation. We enrolled 250 type 2 diabetic patients without apparent occlusive peripheral arterial disease (ankle-brachial indices >0.9) and 40 age-matched nondiabetic subjects consecutively admitted to our hospital. Flow volume and resistive index (RI), an index of vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Brachial-ankle pulse wave velocity (baPWV) was measured as an index of arterial distensibility. Flow volume was negatively correlated with both baPWV (p=0.0009) and RI (p<0.0001) among the patients. When the patients were grouped into four subgroups with or without albuminuria and renal insufficiency according to the levels of urinary albumin excretion rate (>or=20 or <20microg/min) and estimated glomerular filtration rate (eGFR) (<60 or >or=60ml/min/1.73m(2)), albuminuric patients with renal insufficiency (n=30) showed the lowest flow volume (p=0.0078) and the highest baPWV (p=0.0006) and RI (p=0.0274) among the groups. Simple linear regression analyses demonstrated that eGFR correlated positively with flow volume (p=0.0020) and negatively with baPWV (p=0.0258) and RI (p=0.0029) in patients with albuminuria (n=92), but not with normoalbuminuria (n=158). Impaired peripheral circulation in lower-leg arteries associates with nephropathy in diabetic patients even though they have normal ankle-brachial indices.

Low Blood Flow Estimates in Lower-Leg Arteries Predict Cardiovascular Events in Japanese Patients With Type 2 Diabetes With Normal Ankle-Brachial Indexes

OBJECTIVE—To examine the association of baseline measures in lower-leg arteries and conventional cardiovascular risk factors with the incidence of cardiovascular disease (CVD) events in type 2 diabetic patients with normal ankle-brachial indexes (ABIs) (>0.9). RESEARCH DESIGN AND METHODS—We studied 129 type 2 diabetic patients and 35 age-matched nondiabetic subjects with no apparent CVD consecutively admitted to our hospital. At baseline, total flow volume and resistive index, as an index of vascular resistance, at the popliteal artery was evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Patients were followed 4.8 ± 1.5 years (range 3.0–8.2) or until their first event of CVD. RESULTS—On follow-up, 16 patients developed primary CVD events. Patients with CVD had lower blood flow (P < 0.01) and higher vascular resistance (P < 0.05) than patients without CVD. When the patients were grouped into tertiles according to their levels of total flow volume (129.6–85.5, 85.3–63.3, and 62.7–23.8 ml/min), Kaplan-Meier analysis showed a higher probability of developing CVD events in patients in the lowest than in patients in the highest (P = 0.0199, log-rank test) tertile. Multivariate Cox proportional hazards analysis revealed that the lowest tertile for flow volume (hazard ratio [HR] 8.60, 95% CI 1.61–45.97, P = 0.012), hypertension (3.99, 1.12–14.25, P = 0.033), and smoking status (12.01, 1.21–119.28, P = 0.034) were significant independent predictors of CVD events. CONCLUSIONS—We have demonstrated that low blood flow estimates in lower-leg arteries may be predictive for CVD events among Japanese patients with type 2 diabetes even though they have a normal ABI.

Serum monomeric laminin‐γ2 as a novel biomarker for hepatocellular carcinoma

The diagnosis of hepatocellular carcinoma (HCC) in the early stages is important for successful clinical management. Laminin (Ln)‐γ2 expression has been reported in various types of malignant carcinomas. We recently developed a highly sensitive method to measure serum monomeric Ln‐γ2 levels using a fully automated chemiluminescent immunoassay (CLIA). Using our CLIA, we evaluated its diagnostic value in sera from patients with chronic liver disease (CLD) and patients with hepatocellular carcinoma (HCC). Serum alpha‐fetoprotein (AFP) and des‐gamma‐carboxy prothrombin (DCP) were also examined in these subjects. Median levels of Ln‐γ2 were significantly higher in patients with HCC (173.2 pg/mL; range: 39.5–986 pg/mL) compared with patients with CLD (76.7 pg/mL; range: 38.7–215.9 pg/mL) and with healthy volunteers (41.1 pg/mL; range: 10.9–79.0 pg/mL). The optimal cutoff value for Ln‐γ2 that allowed us to distinguish between HCC and nonmalignant CLD was 116.6 pg/mL. Elevated Ln‐γ2 levels were observed in 0% of healthy volunteers, 17% of patients with CLD, and 63% of patients with HCC. The positivity rate in patients with HCC for the combination of Ln‐γ2 and DCP was 89.5%, which was better than that for either of the two markers alone (63% and 68%, respectively). Among patients with early‐stage HCC (T1 or T2), the positivity rates for monomeric Ln‐γ2, AFP and DCP were 61%, 39% and 57%, respectively. Serum Ln‐γ2 may be a potential biomarker for HCC surveillance. The combination of Ln‐γ2 and DCP may be more sensitive for laboratory diagnosis of HCC than the combination of AFP and DCP.