Unraveling the interplay between RAS/RAF/MEK/ERK signaling pathway and autophagy in cancer: From molecular mechanisms to targeted therapy.

RAS/RAF/MEK/ERK signaling pathway is one of the most important pathways of Mitogen-activated protein kinases (MAPK), which widely participate in regulating cell proliferation, differentiation, apoptosis and signaling transduction. Autophagy is an essential mechanism that maintains cellular homeostasis by degrading aged and damaged organelles. Recently, some studies revealed RAS/RAF/MEK/ERK signaling pathway is closely related to autophagy regulation and has a dual effect in tumor cells. However, the specific mechanism by which RAS/RAF/MEK/ERK signaling pathway participates in autophagy regulation is not fully understood. This article provides a comprehensive review of the research progress with regard to the RAS/RAF/MEK/ERK signaling pathway and autophagy, as well as their interplay in cancer therapy. The impact of small molecule inhibitors that target the RAS/RAF/MEK/ERK signaling pathway on autophagy is discussed in this study. The advantages and limitations of the clinical combination of these small molecule inhibitors with autophagy inhibitors are also explored. The findings from this study may provide additional perspectives for future cancer treatment strategies.

Multi-omics analysis of pyroptosis regulation patterns and characterization of tumor microenvironment in patients with hepatocellular carcinoma.

Background: Hepatocellular carcinoma (HCC) is a primary malignant tumor of the liver, and pyroptosis has been identified as a novel cellular program that plays a role in numerous diseases including cancer. However, the functional role of pyroptosis in HCC remains unclear. The purpose of this study is to explore the relationship between the two found hub genes and provide targets for clinical treatment. Methods: The Cancer Genome Atlas (TCGA) database was used to collect the gene data and clinically-related information of patients with HCC. After the differentially expressed genes (DEGs) were identified, they were intersected with the genes related to pyroptosis, and a risk prediction model was established to predict the overall survival (OS). Subsequently, drug sensitivity analysis, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Set Enrichment Analysis (GSEA), and Gene Set Variation Analysis (GSVA) was used to analyze the biological characteristics of the DEGs. Different immune cell infiltration and related pathways were analyzed, and hub genes were identified by protein-protein interaction (PPI). Finally, the expression of hub genes was verified by real-time quantitative PCR (qRT-PCR) and immunohistochemistry. Results: We conducted a comprehensive bioinformatics analysis to investigate the molecular mechanisms of pyroptosis in hepatocellular carcinoma (HCC). A total of 8,958 differentially expressed genes were identified, and 37 differentially expressed genes were associated with pyroptosis through intersection. Moreover, we developed an OS model with excellent predictive ability and discovered the differences in biological function, drug sensitivity, and immune microenvironment between high-risk and low-risk groups. Through enrichment analysis, we found that the differentially expressed genes are related to various biological processes. Then, 10 hub genes were identified from protein-protein interaction networks. Finally, midkine (MDK) was screened from the 10 hub genes and further verified by PCR and immunohistochemistry, which revealed its high expression in HCC. Conclusion: We have developed a reliable and consistent predictive model based on the identification of potential hub genes, which can be used to accurately forecast the prognosis of patients, thus providing direction for further clinical research and treatment.

Protein O-mannosyltransferase Rv1002c contributes to low cell permeability, biofilm formation in vitro, and mycobacterial survival in mice.

Mycobacterium tuberculosis (M. tuberculosis) Rv1002c encodes the protein O-mannosyltransferase (PMT), which catalyzes the transfer of mannose to serine or threonine residues of proteins. We explored the function of PMT in vitro and in vivo. Rv1002c protein was heterogeneously overexpressed in nonpathogenic Mycobacterium smegmatis (named as MS_Rv1002c). A series of trials including mass spectrometry, transmission electron microscope, biofilm formation and antibiotics susceptibility were performed to explore the function of PMT on bacterial survival in vitro. Mouse experiments were carried out to evaluate the virulence of PMT in vivo. PMT decreased the cell envelope permeability and promoted microbial biofilm formation. PMT enhanced the mycobacterial survival in vivo and inhibited the release of pro-inflammatory cytokines in serum. The function might be associated with an increased abundance of some mannoproteins in culture filtrate (CF). PMT is likely to be involved in mycobacterial survival both in vivo and in vitro due to increasing the mannoproteins abundance in CF.

Resveratrol inhibited the progression of human hepatocellular carcinoma by inducing autophagy via regulating p53 and the phosphoinositide 3­kinase/protein kinase B pathway.

Resveratrol, a natural product, has been revealed to exert antitumor effects in multiple types of tumors. However, the antitumor effects of resveratrol on hepatocellular carcinoma (HCC) and its potential underlying mechanisms have not yet been elucidated. The present study demonstrated that resveratrol inhibited viability, proliferation, invasion and migration of HCC cells significantly in a time­ and dose­dependent manner, indicating that resveratrol exerted antitumor effects in HCC. Furthermore, relative expression of autophagy­related proteins Beclin1 and LC3 II/I ratio was increased while p62 expression was decreased by resveratrol treatment dose­dependently. The LC3+ puncta formation, which represented autophagosome formation was also markedly dose­dependently upregulated by resveratrol treatment, suggesting that resveratrol induced autophagy in HCC cells. In addition, treatment with autophagy inhibitor 3­methyladenine (3­MA) counteracted the inhibitory effect of resveratrol on HCC cell proliferation, invasion and migration, indicating that suppressing autophagy may hamper the antitumor effect of resveratrol in HCC. It was revealed that resveratrol upregulated the expression of p53 while decreasing the ratio of phosphorylated protein kinase B (p­Akt)/Akt in HCC cells. Treatment with p53 inhibitor pifithrin­α and Akt activator insulin­like growth factor­1 decreased the expression of Beclin1 while significantly promoting cell proliferation, invasion and migration compared with the resveratrol treatment group. Taken together, the results of the present study revealed that resveratrol inhibited the proliferation and mobility of HCC cells through inducing autophagy via activating p53 and inhibiting phosphoinositide 3­kinase/Akt. Enhancing autophagy can augment the antitumor effects of resveratrol in HCC. Therefore, combining resveratrol with an autophagy inducer may be a viable option for treating HCC.

Salvianolic acid B protects against acute lung injury by decreasing TRPM6 and TRPM7 expressions in a rat model of sepsis.

This study aimed to investigate the protective effects of salvianolic acid B (SA-B) on acute lung injury (ALI) through decreasing the expressions of channel kinase's TRPM6 and TRPM7. Wistar Septic rat models were established by lipopolysaccharide (LPS), which were separated into the control, lipopolysaccharide (LPS), SA-B, SA-B + si-TRPM6, SA-B + si-TRPM7, si-TRPM6, and si-TRPM7 groups. Arterial blood gas, protein content, total white blood cell (WBC) count and the percentage of polymorphonuclear neutrophils (PMN%) were measured. Levels of TNF-α and IL-6 levels in bronchoalveolar lavage fluid (BALF) were monitored. Lung coefficient, myeloperoxidase (MPO) and superoxide dismutase (SOD) activity were conducted by MPO and SOD kit. The mRNA expressions of TRPM6 and TRPM7 were detected by qRT-PCR. Compared with the control group, the PaO2 and PaO2 /FiO2 values exhibited decreases in other group, while the PaCO2 value, protein content, total WBC, PMN%, TNF-α, IL-6 levels and lung coefficient values all increased. MPO activity in lung tissue increased, while SOD activity decreased. TRPM6 and TRPM7 expressions increased significantly. Compared with the LPS group, the SA-B, SA-B + si-TRPM6, SA-B + si-TRPM7, si-TRPM6, and si-TRPM7 groups had increased PaO2 and the PaO2 /FiO2 , while decreased PaCO2, protein content, total WBC, PMN%, TNF-α, IL-6 levels, and lung coefficient. MPO activity in lung tissue decreased while SOD activity increased. Decreased mRNA expressions of TRPM6 and TRPM7 in the SA-B, SA-B + si-TRPM6, and SA-B + si-TRPM6 groups were observed. Through decreasing the expressions of the channel kinase TRPM6 and TRPM7, SA-B protects against ALI in septic rats.

Protective effect of recombinant Trichinella 53-kDa protein in sepsis and the effect on macrophages.

The survival rate of the recombinant Trichinella 53-kDa protein infected by the cecal ligation and puncture (CLP) model of sepsis in rats and the expression difference of macrophages were analyzed. Eighteen clean SD rats were selected for the present study. The rats were divided into the sham operation (n=5), control (n=5) and experimental (n=8) groups. The rats in the sham operation group underwent cecum division and suture with routine therapy for cure. The rats in the control and experimental groups were placed in the CLP model of sepsis in rats. The experimental group was administered recombinant Trichinella 53-kDa protein in advance, and the control group was administered the same dose of placebo. The survival rate of the rats within 6 and 12 h, the macrophage expression ratio, and the differences of the expression levels Th1-type cytokines IFN-γ and tumor necrosis factor (TNF)-α, and the Th2 type cytokines interleukin-4 (IL-4) and IL-13 were analyzed. The survival rate of rats in the experimental group was higher than that of the control group with a statistically significant difference (P<0.05). The expression ratio of the macrophages received from the different handling methods of the rats in the experimental group was higher than that of the control group. The difference was statistically significant (P<0.05). The expression levels of the Th1-type cytokines IFN-γ and TNF-α of the rats in the experimental group was higher than that of the control group, while the expression level of the Th2-type cytokines IL-4 and IL-13 was higher than that of the control group. The difference was statistically significant (P<0.05). In conclusion, recombinant Trichinella 53-kDa protein can increase the survival rate following infection with CLP sepsis, which may be associated with the improvement of the macrophages and the adjustment of the expression of Th2 cytokines.

Preservation solutions alter Mrp2-dependent bile flow in cold ischemic rat livers.

BACKGROUND: Previously, decreased organic anion transport through multidrug resistance protein 2 (Mrp2) was observed without any notable cell lysis, even when the livers were stored for 8 hours in University of Wisconsin solution (UW). The aim of this study was to examine the bile flow and its constituents, markers of graft dysfunction without necrosis in cold ischemic livers, using the following preservation media: UW, ET-Kyoto solution (ET-K) and histidine-tryptophan-ketoglutarate solution (HTK). MATERIALS AND METHODS: Rat livers were stored at 4 degrees C for 8 hours in the preservation media, and reperfused to collect the bile and determine their constituents. Glycyrrhizin (GL) and/or glutathione (GSH) were added to the media as necessary. The transport efficiency of Mrp2 was assessed by the biliary excretion of 5-carboxyfluorescein (CF), a fluoroprobe excreted from Mrp2. The Intracellular distribution of Mrp2 was determined by immunostaining. RESULTS: Livers stored for 8 hours exhibited significantly decreased bile production and biliary glutathione (GSH) levels without notable cell lysis. CF excretion was significantly delayed in all solutions. However, these markers were remarkably improved by the redistribution of Mrp2 from the cytoplasm to the canalicular membrane, when the livers were exposed to UW in the presence of GL. Moreover, livers exposed to the Kyoto and HTK solutions increased their bile production and organic anion transport in the presence of GL and GSH. CONCLUSION: These results suggest that the addition of GL and GSH to preservation solutions improves bile production and biliary organic anion transport by increasing Mrp2 localization to the bile canaliculi in post-cold ischemic livers. (248 words).

Decreased Mrp2-dependent bile flow in the post-warm ischemic rat liver.

BACKGROUND: The link between microcirculatory disturbance and hepatocellular dysfunction remains unknown. The present study was designed to examine the key event of warm ischemia reperfusion (WIR) injury with subsequent cholestasis. METHODS: A left lobar 70% ischemia and reperfusion rat model was used in this study. The portal vein and hepatic artery to the left lateral lobe of the liver were subjected to 20 min of warm ischemia followed by 60 min of reperfusion to collect bile and to measure its constituents. RESULTS: The hepatocellular injury was increased significantly in livers exposed to WIR, as judged by serum alanine aminotransferase. This event coincided with decreased bile production and biliary concentration of glutathione (GSH), suggesting impaired bile salts-independent bile flow, while biliary phospholipids and bile salts were not decreased. Additionally, hepatic adenosine triphosphate and GSH were not decreased after WIR. Since the biliary GSH, which is a major driving force for bile salts-independent bile flow, is excreted from hepatocytes into the bile via multidrug resistance protein 2 (Mrp2), we examined whether intracellular localization of Mrp2 occurred. Immunohistochemical analyses revealed hepatocellular Mrp2 was retrieved from bile canalicular membrane into the pericanalicular cytoplasm in the post-warm ischemic livers. Microcirculatory disturbance in livers exposed to 20 min of warm ischemia improved to levels comparable to controls. CONCLUSION: Mrp2 internalization, observed in this study, may play an important determinant of cholestasis in the post-warm ischemic livers.