Involvement of ERK1/2 signaling in proliferation of eight liver cell types during hepatic regeneration in rats

The Synergistic Hepatoprotective Activity of Rosemary Essential Oil and Curcumin: The Role of the MEK/ERK Pathway

BACKGROUND

Curcumin is a natural product obtained from the rhizome of Curcuma longa. Rosemary (Rosmarinus officinalis) is a medicinal and aromatic plant that is widely spread in the Mediterranean region. Both Curcumin and rosemary essential oil are natural products of high medicinal and pharmacological significance. The hepatoprotective effect of both natural products is well-established; however, the mechanism of such action is not fully understood. Thus, this study is an attempt to explore the hepatoprotective mechanism of action of these remedies through their effect on MEK and ERK proteins. Furthermore, the effect of rosemary essential oil on the plasma concentration of curcumin has been scrutinized.

MATERIALS AND METHODS

The major constituents of REO were qualitatively and quantitatively determined by GC/MS and GC/FID, respectively. Curcumin and rosemary essential oil were given to mice in a pre-treatment model, followed by induction of liver injury through a high dose of paracetamol. Serum liver enzymes, lipid peroxidation, antioxidant activities, the inflammatory and apoptotic biomarkers, as well as the MEK and ERK portions, were verified. The plasma levels of curcumin were determined in the presence and absence of rosemary essential oil.

RESULTS

The major constituents of REO were 1,8-cineole (51.52%), camphor (10.52%), and α-pinene (8.41%). The results revealed a superior hepatoprotective activity of the combination when compared to each natural product alone, as demonstrated by the lowered liver enzymes, lipid peroxidation, mitigated inflammatory and apoptotic biomarkers, and enhanced antioxidant activities. Furthermore, the combination induced the overexpression of MEK and ERK proteins, providing evidence for the involvement of this cascade in the hepatoprotective activity of such natural products. The administration of rosemary essential oil with curcumin enhanced the curcuminoid plasma level.

CONCLUSION

The co-administration of both curcumin and rosemary essential oil together enhanced both their hepatoprotective activity and the level of curcumin in plasma, indicating a synergistic activity between both natural products.

Function of the Long Noncoding RNAs in Hepatocellular Carcinoma: Classification, Molecular Mechanisms, and Significant Therapeutic Potentials

Hepatocellular carcinoma (HCC) is the most common and serious type of primary liver cancer. HCC patients have a high death rate and poor prognosis due to the lack of clear signs and inadequate treatment interventions. However, the molecular pathways that underpin HCC pathogenesis remain unclear. Long non-coding RNAs (lncRNAs), a new type of RNAs, have been found to play important roles in HCC. LncRNAs have the ability to influence gene expression and protein activity. Dysregulation of lncRNAs has been linked to a growing number of liver disorders, including HCC. As a result, improved understanding of lncRNAs could lead to new insights into HCC etiology, as well as new approaches for the early detection and treatment of HCC. The latest results with respect to the role of lncRNAs in controlling multiple pathways of HCC were summarized in this study. The processes by which lncRNAs influence HCC advancement by interacting with chromatin, RNAs, and proteins at the epigenetic, transcriptional, and post-transcriptional levels were examined. This critical review also highlights recent breakthroughs in lncRNA signaling pathways in HCC progression, shedding light on the potential applications of lncRNAs for HCC diagnosis and therapy.

A Mesenchymal-Epithelial Transition Factor-Agonistic Antibody Accelerates Cirrhotic Liver Regeneration and Improves Mouse Survival Following Partial Hepatectomy

Small-for-size syndrome (SFSS) is a common complication following partial liver transplantation and extended hepatectomy. SFSS is characterized by postoperative liver dysfunction caused by insufficient regenerative capacity and portal hyperperfusion and is more frequent in patients with preexisting liver disease. We explored the effect of the Mesenchymal-epithelial transition factor (MET)-agonistic antibody 71D6 on liver regeneration and functional recovery in a mouse model of SFSS. Male C57/BL6 mice were exposed to repeated carbon tetrachloride injections for 10 weeks and then randomized into 2 arms receiving 3 mg/kg 71D6 or a control immunoglobulin G (IgG). At 2 days after the randomization, the mice were subjected to 70% hepatectomy. Mouse survival was recorded up to 28 days after hepatectomy. Satellite animals were euthanized at different time points to analyze liver regeneration, fibrosis, and inflammation. Serum 71D6 administration significantly decreased mouse mortality consequent to insufficient regeneration of the cirrhotic liver. Analysis of liver specimens in satellite animals revealed that 71D6 promoted powerful activation of the extracellular signal-regulated kinase pathway and accelerated liver regeneration, characterized by increased liver-to-body weight, augmented mitotic index, and higher serum albumin levels. Moreover, 71D6 accelerated the resolution of hepatic fibrosis as measured by picrosirius red, desmin, and α-smooth muscle actin staining, and suppressed liver infiltration by macrophages as measured by CD68 and F4/80 staining. Analysis of gene expression by reverse-transcription polymerase chain reaction confirmed that 71D6 administration suppressed the expression of key profibrotic genes, including platelet-derived growth factor, tissue inhibitor of metalloproteinase 3, and transforming growth factor-β1, and of key proinflammatory genes, including tumor necrosis factor-α, interleukin-1β, chemokine (C-C motif) ligand 3, and chemokine (C-C motif) ligand 5. These results suggest that activating the MET pathway via an hepatocyte growth factor-mimetic antibody may be beneficial in patients with SFSS and possibly other types of acute and chronic liver disorders.

Protective Effects of Dietary Capsaicin on the Initiation Step of a Two-Stage Hepatocarcinogenesis Rat Model

Capsaicin (CPS), an ingredient of Capsicum plants, has anti-inflammatory, antioxidant and antitumoral properties. The mechanisms of CPS on hepatocarcinogenesis preclinical bioassays are not described. Thus, the protective effects CPS were evaluated in the early stages of chemically-induced hepatocarcinogenesis. Male Wistar rats received diet containing 0.01% or 0.02% CPS for 3 weeks. Afterwards, animals received a dose of hepatocarcinogen diethylnitrosamine (DEN, 100 mg/kg body weight). From weeks 4-12, groups had their diet replaced by a 0.05% phenobarbital supplemented one to promote DEN-induced preneoplastic lesions. Animals were euthanized 24 h after DEN administration (n = 5/group) or at week 12 (n = 9/group). The estimated CPS intake in rats resembled human consumption. At the end of week 3, dietary 0.02% CPS attenuated DEN-induced oxidative damage and, consequently, hepatocyte necrosis by reducing serum alanine aminotransferase levels, liver CD68-positive macrophages, lipid peroxidation, while increasing antioxidant glutathione system. Additionally, 0.02% CPS upregulated vanilloid Trpv1 receptor and anti-inflammatory epoxygenase Cyp2j4 genes in the liver. Ultimately, previous 0.02% CPS intake decreased the number of GST-P-positive preneoplastic lesions at week 12. Thus, CPS attenuated preneoplastic lesion development, primarily by diminishing DEN-induced oxidative liver injury. Findings indicate that CPS is a promising chemopreventive agent when administered after and during the early stages of hepatocarcinogenesis.

RNA-Seq transcriptome profiling in three liver regeneration models in rats: comparative analysis of partial hepatectomy, ALLPS, and PVL

The liver is a unique organ that has a phenomenal capacity to regenerate after injury. Different surgical procedures, including partial hepatectomy (PH), intraoperative portal vein ligation (PVL), and associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) show clinically distinct recovery patterns and regeneration. The observable clinical differences likely mirror some underlying variations in the patterns of gene activation and regeneration pathways. In this study, we provided a comprehensive comparative transcriptomic analysis of gene regulation in regenerating rat livers temporally spaced at 24 h and 96 h after PH, PVL, and ALPPS. The time-dependent factors appear to be the most important determinant of post-injury alterations of gene expression in liver regeneration. Gene expression profile after ALPPS showed more similar expression pattern to the PH than the PVL at the early phase of the regeneration. Early transcriptomic changes and predicted upstream regulators that were found in all three procedures included cell cycle associated genes (E2F1, CCND1, FOXM1, TP53, and RB1), transcription factors (Myc, E2F1, TBX2, FOXM1), DNA replication regulators (CDKN1A, EZH2, RRM2), G1/S-transition regulators (CCNB1, CCND1, RABL6), cytokines and growth factors (CSF2, IL-6, TNF, HGF, VEGF, and EGF), ATM and p53 signaling pathways. The functional pathway, upstream, and network analyses revealed both unique and overlapping molecular mechanisms and pathways for each surgical procedure. Identification of molecular signatures and regenerative signaling pathways for each surgical procedure further our understanding of key regulators of liver regeneration as well as patient populations that are likely to benefit from each procedure.

Osteopontin promotes rat hepatocyte proliferation both in vitro and in vivo

Aim: This study aimed to examine the effects of osteopontin (OPN) on hepatocyte growth and liver regeneration (LR). Methods: A recombinant lentivirus expressing OPN and OPN-siRNAs were used to treat BRL-3A cells, while the adenovirus expressing OPN or OPN-targeted shRNA were applied for rat primary hepatocytes. Moreover, rrOPN and OPN-Ab were added to treat BRL-3A. Next, rrOPN was administrated into rat regenerating livers. Then in vitro and in vivo assays were performed to evaluate the biological function of OPN in hepatocyte growth and LR. Results: OPN overexpression facilitated proliferation and viability of BRL-3A cells and primary hepatocytes, while OPN silencing reversed these effects. Similarly, rrOPN stimulated cell cycle progression and viability, but OPN-Ab led to cell cycle arrest and decreased viability. OPN overexpression induced the expression of p-STAT3, p-AKT and CCND1, and OPN siRNA led to reduction of p-AKT and CCND1. Furthermore, rrOPN promoted the expression of p-STAT3 and p-AKT, while OPN-Ab and PI3K/Akt inhibitor LY294002 both inhibited the expressions of p-AKT and Bcl2. Moreover, LR rate, serum IL-6 and TNF-α, Ki-67⁺ proportion and the phosphorylation of STAT3, AKT and p65 were augmented by rrOPN treatment. Conclusion: OPN promotes hepatocyte proliferation both in vitro and in vivo through STAT3 and AKT signaling pathways.

Platelet and liver regeneration after liver surgery

The success of liver surgery, including resection and transplantation, is largely dependent on the ability of the liver to regenerate. Despite substantial improvement in surgical techniques and perioperative care, one of the main concerns is post-hepatectomy liver failure and early allograft dysfunction, both of which are associated with impaired liver regeneration. Recent studies have demonstrated the positive role of platelets in promoting liver regeneration and protecting hepatocytes; however, the underlying mechanisms responsible for these effects are not fully understood. In this review, we updated the accumulated evidence of the role of platelets in promoting liver regeneration, with a focus on liver resection and liver transplantation. The goal of these studies was to support the clinical implementation of platelet agents, such as thrombopoietin receptor agonists, to augment liver regeneration after liver surgery. This "platelet therapy" may become a treatment choice for post-hepatectomy liver failure and early allograft dysfunction.

How Rap and its GEFs control liver physiology and cancer development. C3G alterations in human hepatocarcinoma

Rap proteins regulate liver physiopathology. For example, Rap2B promotes hepatocarcinoma (HCC) growth, while Rap1 might play a dual role. The RapGEF, Epac1, activates Rap upon cAMP binding, regulating metabolism, survival, and liver regeneration. A liver specific Epac2 isoform lacking cAMP-binding domain also activates Rap1, promoting fibrosis in alcoholic liver disease. C3G (RapGEF1) is also present in the liver, but mainly as shorter isoforms. Its function in the liver remains unknown. Information from different public genetic databases revealed that C3G mRNA levels increase in HCC, although they decrease in metastatic stages. In addition, several mutations in RapGEF1 gene are present, associated with a reduced patient survival. Based on this, C3G might represent a new HCC diagnostic and prognostic marker, and a therapeutic target.

Uncovering the regeneration strategies of zebrafish organs: a comprehensive systems biology study on heart, cerebellum, fin, and retina regeneration

Background

Regeneration is an important biological process for the restoration of organ mass, structure, and function after damage, and involves complex bio-physiological mechanisms including cell differentiation and immune responses. We constructed four regenerative protein-protein interaction (PPI) networks using dynamic models and AIC (Akaike’s Information Criterion), based on time-course microarray data from the regeneration of four zebrafish organs: heart, cerebellum, fin, and retina. We extracted core and organ-specific proteins, and proposed a recalled-blastema-like formation model to uncover regeneration strategies in zebrafish.

Results

It was observed that the core proteins were involved in TGF-β signaling for each step in the recalled-blastema-like formation model and TGF-β signaling may be vital for regeneration. Integrins, FGF, and PDGF accelerate hemostasis during heart injury, while Bdnf shields retinal neurons from secondary damage and augments survival during the injury response. Wnt signaling mediates the growth and differentiation of cerebellum and fin neural stem cells, potentially providing a signal to trigger differentiation.

Conclusion

Through our analysis of all four zebrafish regenerative PPI networks, we provide insights that uncover the underlying strategies of zebrafish organ regeneration.

Autologous serum supplement favours in vitro regenerative paracrine factors synthesis

OBJECTIVES

Foetal bovine serum (FBS) is often the serum supplement of choice for in vitro human cell culture. This study compares the effect of FBS and autologous human serum (AuHS) supplement in human peripheral blood mononuclear cell (PBMC) culture to prepare secretome.

MATERIALS AND METHODS

The PBMC (n = 7) were cultured either in RPMI-1640 containing L-glutamine and 50 units/ml Penicillin-Streptomycin (BM) or in BM with either AuHS or FBS. Viability, proliferation and differentiation of PBMC were evaluated. Paracrine factors present in the secretomes (n = 6) were analysed using ProcartaPlex Human Cytokine panel (17 plex). Ingenuity Pathway Analysis (IPA) was performed to predict activation or inhibition of biological functions related to tissue regeneration.

RESULTS

The viability of PBMC that were cultured with FBS supplement was significantly reduced at 96 h compared to those at 0 and 24 h (P < .05). While the reduction of the viability of PBMC that were cultured with AuHS supplement was not significantly different compared to those at 0 and 24 h. The FBS secretomes prepared at 24 h was found to contain significantly higher amount of EGF (P < .05) compared to that in AuHS or BM secretome. The AuHS secretomes contained significantly higher amount of HGF at 24 (P < .05) and 96 h (P < .01), and VEGF-A at 24 h (P < .05) compared to those in the FBS secretomes. SDF-1 was not detected in the FBS secretomes prepared at either 24 or 96 hours. Double immunocytochemical staining revealed a marked increase in co-localization of SDF-1 and its receptor in PBMC that were cultured with AuHS supplement compared to that cultured with FBS supplement.

CONCLUSION

In secretome preparation, AuHS supplement favours synthesis of paracrine factors that are needed for regenerative therapy.

Current status of research on liver regeneration

The liver has a strong regenerative potential, and liver regeneration shows different ways according to the degree of liver injury. The current research on liver regeneration has achieved some promising results, and the cellular and molecular mechanism of liver regeneration has been deeply studied. Recently, the role of biomechanical factors in liver regeneration is gradually attracting attention. In addition to the proliferation of liver cells, liver regeneration also involves the proliferation and differentiation of hepatic stem cells. However, the exact mechanism of liver regeneration is not fully clear. This review will summarize the relevant studies on liver regeneration to discuss the current research status of liver regeneration, with regard to the liver regeneration model, cellular and molecular mechanism of liver regeneration, the effects of mechanical factors on regeneration, and the role of stem cells in liver regeneration. A better understanding of liver regeneration will provide a new avenue for the clinical diagnosis and treatment of liver related diseases.

Long non-coding RNAs as novel targets for therapy in hepatocellular carcinoma

The recognition of functional roles for transcribed long non-coding RNA (lncRNA) has provided a new dimension to our understanding of cellular physiology and disease pathogenesis. LncRNAs are a large group of structurally complex RNA genes that can interact with DNA, RNA, or protein molecules to modulate gene expression and to exert cellular effects through diverse mechanisms. The emerging knowledge regarding their functional roles and their aberrant expression in disease states emphasizes the potential for lncRNA to serve as targets for therapeutic intervention. In this concise review, we outline the mechanisms of action of lncRNAs, their functional cellular roles, and their involvement in disease. Using liver cancer as an example, we provide an overview of the emerging opportunities and potential approaches to target lncRNA-dependent mechanisms for therapeutic purposes.

Kruppel-like factor 2 inhibit the angiogenesis of cultured human liver sinusoidal endothelial cells through the ERK1/2 signaling pathway

Kruppel-like factor 2 (KLF2) is a crucial anti-angiogenic factor. However, its precise role in hepatic angiogenesis induced by liver sinusoidal endothelial cells (LSECs) remain unclear. This study was aimed to evaluate the effect of KLF2 on angiogenesis of LSECs and to explore the corresponding mechanism. Cultured human LSECs were infected with different lentiviruses to overexpress or suppress KLF2 expression. The CCK-8 assay, transwell migration assay and tube formation test, were used to investigate the roles of KLF2 in the proliferation, migration and vessel tube formation of LSECs, respectively. The expression and phosphorylation of ERK1/2 were detected by western blot. We discovered that the up-regulation of KLF2 expression dramatically inhibited proliferation, migration and tube formation in treated LSECs. Correspondingly, down-regulation of KLF2 expression significantly promoted proliferation, migration and tube formation in treated LSECs. Additionally, KLF2 inhibited the phosphorylation of ERK1/2 pathway, followed by the function of KLF2 in the angiogenesis of LSECs disrupted. In conclusion, KLF2 suppressed the angiogenesis of LSECs through inhibition of cell proliferation, migration, and vessel tube formation. These functions of KLF2 may be mediated through the ERK1/2 signaling pathway.

A Novel Matrine Derivative WM130 Inhibits Activation of Hepatic Stellate Cells and Attenuates Dimethylnitrosamine-Induced Liver Fibrosis in Rats

Activation of hepatic stellate cells (HSCs) is a critical event in process of hepatic fibrogenesis and cirrhosis. Matrine, the active ingredient of Sophora, had been used for clinical treatment of acute/chronic liver disease. However, its potency was low. We prepared a high potency and low toxicity matrine derivate, WM130 (C30N4H40SO5F), which exhibited better pharmacological activities on antihepatic fibrosis. This study demonstrated that WM130 results in a decreased proliferative activity of HSC-T6 cells, with the half inhibitory concentration (IC50) of 68 μM. WM130 can inhibit the migration and induce apoptosis in HSC-T6 cells at both concentrations of 68 μM (IC50) and 34 μM (half IC50). The expression of α-SMA, Collagen I, Collagen III, and TGF-β1 could be downregulated, and the protein phosphorylation levels of EGFR, AKT, ERK, Smad, and Raf (p-EGFR, p-AKT, p-ERK, p-Smad, and p-Raf) were also decreased by WM130. On the DMN-induced rat liver fibrosis model, WM130 can effectively reduce the TGF-β1, AKT, α-SMA, and p-ERK levels, decrease the extracellular matrix (ECM) formation, and inhibit rat liver fibrosis progression. In conclusion, this study demonstrated that WM130 can significantly inhibit the activation of HSC-T6 cells and block the rat liver fibrosis progression by inducing apoptosis, suppressing the deposition of ECM, and inhibiting TGF-β/Smad and Ras/ERK pathways.

CDK-associated Cullin 1 promotes cell proliferation with activation of ERK1/2 in human lung cancer A549 cells

Lung cancer is one of the most common causes of cancer-related death in the world, but the mechanisms remain unknown. In this study, we investigated the expression of CDK-associated Cullin 1 (CAC1) in lung cancer, the effect of CAC1 on the proliferation of human lung cancer A549 cells, and the activation of signaling pathways of mitogen-activated protein kinases (MAPKs). Results showed that CAC1 expression was higher levels in human lung carcinoma than normal lung tissue, and CAC1 siRNA reduced the proliferation of lung cancer A549 cells by decreasing cell activity and cell division in vitro. The proportion of cells treated with CAC1 siRNA increased in the G1 phase and decreased in the S and G2/M phase, indicative of G1 cell cycle arrest. Furthermore, the proportions of early/late apoptosis in lung cancer A549 cells were enhanced with CAC1 siRNA treatment. It was also found that activation of extracellular signal-regulated protein kinase (ERK) and p38 signaling pathways were involved in the proliferation of A549 cells. After CAC1 siRNA treatment, p-ERK1/2 levels decreased, and meanwhile p-p38 level increased, A549 cell proliferation increased when ERK1/2 signaling is activated by PMA. Our findings demonstrated that CAC1 promoted the proliferation of human lung cancer A549 cells with activation of ERK1/2 signaling pathways, suggesting a potential cure target for treatment of human lung cancer.