Mechanisms of hepatocyte growth factor-mediated signaling in differentiation of pancreatic ductal epithelial cells into insulin-producing cells

MicroRNA-365-3p inhibits bone marrow mesenchymal stem cell differentiation into islet-like cell clusters via targeting Pax6 and inhibiting the MEK/ERK pathway

BACKGROUND

Diabetes has severe impacts on the health of patients. The differentiation of mesenchymal stem cells (MSCs) into islet-like cell clusters (ICCs) is an effective protocol for the treatment of diabetes. microRNAs (miRs) regulate multiple cellular processes including cell differentiation. This study sought to identify the mechanism of miR-365-3p in the differentiation of bone marrow MSCs (bMSCs) into ICCs.

METHODS

Initially, the differentiation of bMSCs into ICCs was induced. Then, the miR-365-3p expression pattern in the bMSCs and ICCs was detected. Next, the miR-365-3p expression pattern was silenced in bMSCs to assess the effect on differentiation efficiency and measure the expressions of ICC marker genes during the differentiation of bMSCs into ICCs. The miR-365-3p downstream target genes were predicted and verified. Paired box protein 6 (Pax6) was downregulated in bMSCs with silenced miR-365-3p to evaluate the differentiation of bMSCs into ICCs. Furthermore, the Pax6 downstream pathway was evaluated.

RESULTS

The differentiation of bMSCs into ICCs was successfully induced. The miR-365-3p expression in bMSCs was higher than that in ICCs. miR-365-3p downregulation in bMSCs facilitated the differentiation of bMSCs into ICCs, as evidenced by elevated releases of insulin and C-peptide in ICCs and elevated expressions of ICC marker genes. Our findings denoted that miR-365-3p targeted Pax6. Inhibition of Pax6 expression annulled the promotion of miR-365-3p downregulation on the differentiation of bMSCs into ICCs. Increased phosphorylation levels of MEK and ERK were identified in ICCs after downregulation of miR-365-3p however they were decreased after downregulation of Pax6.

CONCLUSIONS

This study supported that miR-365-3p inhibited the differentiation of bMSCs into ICCs via targeting Pax6 and inhibiting the MEK/ERK pathway.

Evaluation of in vivo and ex vivo pre-treated bone marrow-derived mesenchymal stem cells with resveratrol in streptozotocin-induced type 1 diabetic rats

OBJECTIVES

To compare the therapeutic potential of rat bone marrow-derived mesenchymal stem cells (BM-MSCs) preconditioned ex-vivo with resveratrol (MCR) and BM-MSCs isolated from resveratrol-pre-treated rats (MTR) in type-1 diabetic rats.

METHODS

Type-1 diabetes was induced by a single streptozotocin injection (50 mg/kg; ip) in 24 rats. Following the confirmation of T1DM, diabetic rats were randomly divided into four groups: diabetic control (DC), diabetic rats treated with insulin subcutaneous (7.5 IU/kg/day), diabetic rats treated with MCR cells (3 × 106cells/rat, intravenous) and diabetic rats treated with MTR cells (3 × 106cells/rat, intravenous). Rats were sacrificed 4 weeks following cellular transplantation.

KEY FINDINGS

Untreated diabetic rats suffered from pancreatic cell damage, had high blood glucose levels, increased apoptotic, fibrosis, and oxidative stress markers and decreased survival and pancreatic regeneration parameters. Both MSCs preconditioned ex-vivo with RES and MSCs isolated from rats pre-treated with RES homed successfully in injured pancreas and showed therapeutic potential in the treatment of STZ-induced T1DM. MCR cells showed better efficiency than MTR cells.

CONCLUSIONS

The pre-conditioning of BM-MSCs with resveratrol may be a promising therapeutic possibility in T1DM. Resveratrol-preconditioned BM-MSCs encouraged effects almost comparable to that of exogenous insulin with the advantages of cured pancreas and restored islets not attained by insulin.

Madecassoside suppresses proliferation and invasiveness of HGF-induced human hepatocellular carcinoma cells via PKC-cMET-ERK1/2-COX-2-PGE2 pathway

Recent studies showed that Madecassoside (MAD), a pentacyclic triterpene isolated from Centella asitica (L.), was used as a therapeutic agent in wound healing and also as an anti-inflammatory, anti-oxidative activities and anti-aging agent. However, its role in cancer has not been elucidated. In our present study, hepatocyte growth factor (HGF) induced the phosphorylation of its corresponding receptor cMET, increased expression of cyclo-oxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in human hepatocellular carcinoma (HCC) cells lines (HepG2 and SMMC-77), and this effect was inhibited by MAD in a dose-dependent manner. In addition, MAD exhibited significant anti-proliferative and anti-invasive effect in HGF-induced HepG2 and SMMC-77 cells. Moreover, MAD inhibited the phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and the protein kinase C (PKC) activity in HGF-induced HepG2 and SMMC-77 cells. This conclusion was consistent with the effect of selective COX-2 inhibitor (NS-398) and knockdown of COX-2 by siRNA on attenuating the proliferation and invasiveness potential, and over-expression of COX-2 on abolishing the effects of MAD on proliferation and invasiveness potential, and was also in parallel with the effect of PKC inhibitor (Bisindolylmaleimide) on inhibiting PKC activity, MEK/ERK1/2 inhibitor (PD98059) inhibited MEK/ERK1/2 pathways in HGF-induced HepG2 and SMMC-77 cells. Collectively, MAD could inhibit the HGF-activated proliferation and invasiveness of HCC cells via regulating the activation of cMET-PKC-ERK1/2-COX-2-PGE2 cascade, which indicated that MAD might help control HGF-linked HCC.

Genetic basis of dyslipidemia in disease precipitation of coronary artery disease (CAD) associated type 2 diabetes mellitus (T2DM)

Type 2 diabetes mellitus (T2DM) and its complications are linked to environmental, clinical, and genetic factors. This review analyses the disorders of lipids and their genetics with respect to coronary artery disease (CAD) associated with T2DM. Cell organelles, hepatitis C-virus infection, reactive oxygen species produced in mitochondria, and defective insulin signaling due to the arrest of G1 phase to S phase transition of β-cells have significant roles in the precipitation of the diseases. Adiponectin is anti-inflammatory and anti-atherosclerotic and improves insulin resistance. Low-density lipoprotein (LDL) is atherosclerotic, and LDL-cholesterol in T2DM is associated with high-cardiovascular risk. Further, LDL cholesterol reduction significantly reduces cardiovascular morbidity and mortality. High-density lipoprotein (HDL) is also anti-atherosclerotic due to HDL associated paraoxonase-1 serum enzyme, which prevents LDL oxidative modifications and the development of CAD. Moreover, elevated apolipoprotein B and apolipoprotein A-I (ApoB/ApoA-I) ratio in plasma is also a risk factor for CAD. LDL receptor, adiponectin, and endocannabinoid receptor-1 genes are independently associated with CAD and T2DM. Polymorphism of Apo E2 (epsilon2) is a positive factor to increase the T2DM risk and Apo E4 (epsilon4) is a negative factor to reduce the disease risk. Taq 1B polymorphism of cholesterol ester transfer protein (CETP) gene contributes to the development of atherosclerosis, whereas haplotypes of APOA5, APOC3, APOC4, and APOC5 genes are in the same cluster and are independently associated with high plasma triglyceride level, CAD and T2DM. In conclusion, because various genes, LDLR, CETP, APOA5, Apo E, Apo B, and Apo A-I, are associated with the precipitation of CAD associated with T2DM, a personalized diet-gene intervention therapy may be advocated to reduce the disease precipitation.

Inhibition of c-Met promoted apoptosis, autophagy and loss of the mitochondrial transmembrane potential in oridonin-induced A549 lung cancer cells

OBJECTIVE

Herein, inhibition of hepatocyte growth factor receptor, c-Met, significantly increased cytochrome c release and Bax/Bcl-2 ratio, indicating that c-Met played an anti-apoptotic role. The following experiments are to elucidate this anti-apoptotic mechanism, then the effect of c-Met on autophagy has also been discussed.

METHODS

Investigated was the influence of c-Met on apoptosis, autophagy and loss of mitochondrial transmembrane potential (Δψm), and the relevant proteins were examined.

KEY FINDINGS

First, we found that activation of extracellular signal-regulated kinase (ERK), p53 was promoted by c-Met interference. Subsequent studies indicated that ERK was the upstream effector of p53, and this ERK-p53 pathway mediated release of cytochrome c and up-regulation of Bax/Bcl-2 ratio. Secondly, the inhibition of c-Met augmented oridonin-induced loss of mitochondrial transmembrane potential (Δψm), resulting apoptosis. Finally, the inhibition of c-Met increased oridonin-induced A549 cell autophagy accompanied by Beclin-1 activation and conversion from microtubule-associated protein light chain 3 (LC3)-I to LC3-II. Activation of ERK-p53 was also detected in autophagy process and could be augmented by inhibition of c-Met. Moreover, suppression of autophagy by 3-methyladenine (3-MA) or small interfering RNA against Beclin-1 or Atg5 decreased oridonin-induced apoptosis. Inhibition of apoptosis by pan-caspase inhibitor (z-VAD-fmk) decreased oridonin-induced autophagy as well and Loss of Δψm also occurred during autophagic process.

CONCLUSION

Thus, inhibiting c-Met enhanced oridonin-induced apoptosis, autophagy and loss of Δψm in A549 cells.

Islet β-Cell Mass Preservation and Regeneration in Diabetes Mellitus: Four Factors with Potential Therapeutic Interest

Islet β-cell replacement and regeneration are two promising approaches for the treatment of Type 1 Diabetes Mellitus. Indeed, the success of islet transplantation in normalizing blood glucose in diabetic patients has provided the proof of principle that cell replacement can be employed as a safe and efficacious treatment. Nonetheless, shortage of organ donors has hampered expansion of this approach. Alternative sources of insulin-producing cells are mandatory to fill this gap. Although great advances have been achieved in generating surrogate β-cells from stem cells, current protocols have yet to produce functionally mature insulin-secreting cells. Recently, the concept of islet regeneration in which new β-cells are formed from either residual β-cell proliferation or transdifferentiation of other endocrine islet cells has gained much interest as an attractive therapeutic alternative to restore β-cell mass. Complementary approaches to cell replacement and regeneration could aim at enhancing β-cell survival and function. Herein, we discuss the value of Hepatocyte Growth Factor (HGF), Glucose-Dependent Insulinotropic Peptide (GIP), Paired box gene 4 (Pax4) and Liver Receptor Homolog-1 (LRH-1) as key players for β-cell replacement and regeneration therapies. These factors convey β-cell protection and enhanced function as well as facilitating proliferation and transdifferentiation of other pancreatic cell types to β-cells, under stressful conditions.

Hepatocyte growth factor upregulation promotes carcinogenesis and epithelial-mesenchymal transition in hepatocellular carcinoma via Akt and COX-2 pathways

Advanced hepatocellular carcinoma (HCC) is an important cause of cancer mortality. Epithelial-mesenchymal transition (EMT) has been shown to be an important biological process in cancer progression and metastasis. We have focused on elucidating factors that induce EMT to promote carcinogenesis and subsequent metastasis in HCC using the BNL CL.2 (BNL) and BNL 1ME A. 7R.1 (1MEA) cell lines. BNL cells are normal hepatocytes whereas the 1MEA cells are HCC cells derived from chemical transformation of the BNL cells. Their morphological characteristics were examined. Expression levels of hepatocyte growth factor (HGF), markers of EMT and mediators of HGF signaling were determined and functional characteristics were compared. BNL cells were treated with HGF and effects on EMT-marker and mediators of HGF signaling were analyzed. BNL cells display characteristic epithelial morphology whereas 1MEA cells display mesenchymal characteristics. 1MEA cells express and secrete more HGF than BNL cells. There was significantly decreased expression of E-cadherin, albumin, AAT and increased expression of fibronectin, collagen-1, vimentin, snail and slug in 1MEA cells. There was also increased expression of cyclooxygenase-2 (COX-2), Akt and phosphorylated Akt (pAkt) in 1MEA cells. Moreover, 1MEA cells had increased migratory capacity inhibited by inhibition of COX-2 and Akt but not extracellular signal regulated kinase (ERK). Molecular mesenchymal characteristics of 1MEA cells were reversed by inhibition of COX-2, Akt and ERK. Treatment of BNL cells with HGF led to decreased expression of E-cadherin and increased expression of fibronectin, vimentin, snail, slug, COX-2, Akt, pAkt and increased migration, invasiveness and clonogenicity. We conclude that development of HCC is associated with upregulation of HGF which promotes EMT and carcinogenesis via upregulation of COX-2 and Akt. Consequently, HGF signaling may be targeted for therapy in advanced and metastatic HCC.