Silencing of lemur tyrosine kinase 2 restricts the proliferation and invasion of hepatocellular carcinoma through modulation of GSK-3β/Wnt/β-catenin signaling

Lemur tyrosine kinase 2 has a tumor-inhibition function in human glioblastoma by regulating the RUNX3/Notch pathway

Deregulation of lemur tyrosine kinase 2 (LMTK2) is a vital determinant for the onset and progression of malignancies, yet the relationship between LMTK2 and glioblastoma (GBM) is undetermined. This study was carried out to determine the relevance of LMTK2 in GBM. Initiating investigation by assessing The Cancer Genome Atlas (TCGA) data showed LMTK2 mRNA levels were decreased in GBM tissue. Later examination of clinical specimens confirmed low levels of LMTK2 mRNA and protein in GBM tissue. The downregulated level of LMTK2 in patients with GBM was related to poor overall survival. A suppressive function of LMTK2 on the proliferative capability and metastatic potential of GBM cells was demonstrated by overexpressing LMTK2 in GBM cell lines. Moreover, the restoration of LMTK2 augmented the sensitivity of GBM cells to the chemotherapy drug temozolomide. The mechanistic investigation uncovered LMTK2 as a regulator of the runt-related transcription factor 3 (RUNX3)/Notch signaling pathway. The overexpression of LMTK2 increased the expression of RUNX3 while inhibiting the activation of Notch signaling. The silencing of RUNX3 diminished the regulatory role of LMTK2 on Notch signaling. The inhibition of Notch signaling reversed the LMTK2-silencing-elicited protumor effects. Importantly, LMTK2-overexpressed GBM cells displayed weakened tumorigenicity in xenograft models. Our findings illustrate that LMTK2 has a tumor-inhibition function in GBM by constraining Notch signaling via RUNX3. This work indicates the deregulation of the LMTK2-mediated RUNX3/Notch signaling pathway may be a novel molecular mechanism for the malignant transformation of GBMs. This work highlights the interest in LMTK2-related approaches for treating GBM.

hsa_circ_0000285 sponging miR-582-3p promotes neuroblastoma progression by regulating the Wnt/β-catenin signaling pathway

Circular RNA has been reported to play a key role in neuroblastoma (NB); however, the role of circ_0000285 in NB remains unclear. The aim of this study was to elucidate the role of circ_0000285 in NB. We studied the expression patterns of miR-582-3p and circ_0000285 in NB tissues and cells using real-time quantitative polymerase chain reaction. The expression of proteins associated with apoptosis (Bax and Bcl-2) and the proteins associated with Wnt/β-catenin (Wnt, p-Gsk-3β, Gsk-3β, β-catenin, and C-myc) were quantified by western blotting. In vivo animal models were prepared for the functional verification of circ_0000285 on tumor growth. The potential binding of circ_0000285 to miR-582-3p was ascertained using dual-luciferase reporter and RNA-binding protein immunoprecipitation experiments. Noticeable upregulation of circ_0000285 expression was observed in NB tumor samples and cell lines. In vivo and in vitro experiments indicated that the absence of circ_0000285 repressed NB cell proliferation and migration, provoked apoptosis, and impaired the activity of Wnt/β-catenin signaling. miR-582-3p is targeted by circ_0000285 and is poorly expressed in NB cells. The additional repression of miR-582-3p in NB cells after circ_0000285 silencing largely recovered circ_0000285 silencing-suppressed NB cell proliferation and migration and enhanced apoptosis. The absence of miR-582-3p restored Wnt/β-catenin signaling activity impaired by the knockdown of circ_0000285. circ_0000285 functions as an miR-582-3p sponge to strengthen Wnt/β-catenin signaling activity, thus exacerbating NB development.

Role of β-Catenin Activation in the Tumor Immune Microenvironment and Immunotherapy of Hepatocellular Carcinoma

Recently, the therapeutic combination of atezolizumab and bevacizumab was widely used to treat advanced hepatocellular carcinoma (HCC). According to recent clinical trials, immune checkpoint inhibitors (ICIs) and molecular target agents are expected to be key therapeutic strategies in the future. Nonetheless, the mechanisms underlying molecular immune responses and immune evasion remain unclear. The tumor immune microenvironment plays a vital role in HCC progression. The infiltration of CD8-positive cells into tumors and the expression of immune checkpoint molecules are key factors in this immune microenvironment. Specifically, Wnt/β catenin pathway activation causes "immune exclusion", associated with poor infiltration of CD8-positive cells. Some clinical studies suggested an association between ICI resistance and β-catenin activation in HCC. Additionally, several subclassifications of the tumor immune microenvironment were proposed. The HCC immune microenvironment can be broadly divided into inflamed class and non-inflamed class, with several subclasses. β-catenin mutations are important factors in immune subclasses; this may be useful when considering therapeutic strategies as β-catenin activation may serve as a biomarker for ICI. Various types of β-catenin modulators were developed. Several kinases may also be involved in the β-catenin pathway. Therefore, combinations of β-catenin modulators, kinase inhibitors, and ICIs may exert synergistic effects.

Lemur tyrosine kinase 2 silencing inhibits the proliferation of gastric cancer cells by regulating GSK-3β phosphorylation and β-catenin nuclear translocation

Previous studies on the mechanism of proliferation and cell cycle progression of gastric cancer cells have shown promising perspectives for the prevention and treatment of gastric cancer. The aim of the present study was to investigate the role of lemur tyrosine kinase 2 (LMTK2) in gastric cancer cell proliferation and cell cycle progression, as well as in tumor-bearing nude mouse models. The expression levels of LMTK2 were determined in gastric cancer cell lines. In addition, the effects of LMTK2 silencing or overexpression on cell proliferation were measured using Cell Counting Kit-8, BrdU and colony formation assays. Cell cycle progression was analyzed using flow cytometry and western blotting. The expression levels of proteins associated with the β-catenin pathway were assessed using western blot analysis. A tumor-bearing nude mouse model was established by injecting gastric cancer cells, and the effect of LMTK2 knockdown or overexpression on tumor growth was examined. The expression levels of LMTK2 were found to be upregulated in all gastric cancer cell lines. Moreover, LMTK2 knockdown inhibited cell proliferation, colony formation and cell cycle progression. LMTK2 knockdown also inhibited the activation of GSK-3β/β-catenin signaling, as evidenced by reduced GSK-3β phosphorylation and nuclear β-catenin levels. LMTK2 knockdown also suppressed tumor growth, whereas overexpression accelerated this process. In conclusion, LMTK2 silencing can inhibit the proliferation of gastric cancer cells in vitro and tumor growth in vivo by regulating GSK-3β phosphorylation and β-catenin nuclear translocation.

Paeoniflorin Affects Hepatocellular Carcinoma Progression by Inhibiting Wnt/β-Catenin Pathway through Downregulation of 5-HT1D

BACKGROUND

Hepatocellular Carcinoma (HCC) is a primary liver cancer with high mortality. Paeoniflorin is a pinane monoterpene picroside with anti-tumor effect isolated from Chinese peony root and white peony root.

OBJECTIVE

The study was conducted to investigate the underlying mechanism of Paeoniflorin (PF) regulating Hepatocellular Carcinoma (HCC) progression via 5-hydroxytryptamine receptor 1D (5-HT1D).

METHODS

HepG2 and SMMC-7721 hepatoma cells were treated with different concentrations of PF (0, 5, 10, 20 μM). Cell proliferation, apoptosis, migration, and invasion were examined by CCK-8 and colony formation assays, flow cytometry, wound healing assay, and transwell assay, respectively. RTqPCR assay was used to detect the expression level of 5-HT1D, and Western blot assay was used to detect the expressions of 5-HT1D and Wnt/β-catenin pathway-related proteins.

RESULTS

With the increase in PF concentration, the mRNA levels of 5-HT1D in HepG2 and SMMC- 7721 hepatoma cells were decreased in a dose-dependent manner, and the proliferation, colony formation, migration and invasion ability of cells were gradually weakened, while the apoptosis rate was gradually increased. Overexpression of 5-HT1D significantly promoted the proliferation, colony formation, migration and invasion of HepG2 and SMMC-7721 cells, and increased the expression of Wnt/β-catenin pathway-related proteins, β -actenin, survivin, C-myc, and Cyclin D1. Furthermore, 5-HT1D overexpression could reverse the effect of PF on hepatoma cells and inhibit the expressions of Wnt/β-catenin pathway-related proteins.

CONCLUSION

PF may inhibit the progression of HCC by blocking Wnt/β-catenin pathway expression through downregulating 5-HT1D.

Lemur Tyrosine Kinases and Prostate Cancer: A Literature Review

The members of the Lemur Tyrosine Kinases (LMTK1-3) subfamily constitute a group of three membrane-anchored kinases. They are known to influence a wide variety of key cellular events, often affecting cell proliferation and apoptosis. They have been discovered to be involved in cancer, in that they impact various signalling pathways that influence cell proliferation, migration, and invasiveness. Notably, in the context of genome-wide association studies, one member of the LMTK family has been identified as a candidate gene which could contribute to the development of prostate cancer. In this review, of published literature, we present evidence on the role of LMTKs in human prostate cancer and model systems, focusing on the complex network of interacting partners involved in signalling cascades that are frequently activated in prostate cancer malignancy. We speculate that the modulators of LMTK enzyme expression and activity would be of high clinical relevance for the design of innovative prostate cancer treatment.

Differential Gene Expression Analysis Reveals Global LMTK2 Regulatory Network and Its Role in TGF-β1 Signaling

Lemur tyrosine kinase 2 (LMTK2) is a transmembrane Ser/Thr kinase whose role has been increasingly recognized; however, when compared to other kinases, understanding of the LMTK2 networks and biological functions is still limited. Recent data have shown that transforming growth factor (TGF)-β1 plays a role in modulating LMTK2 function by controlling its endocytic trafficking in human bronchial epithelial cells. Here, we aimed to unveil the LMTK2 regulatory network and elucidate how it affects cellular functions and disease pathways in either TGF-β1 dependent or independent manner. To understand how the LMTK2 and TGF-β1 pathways interconnect, we knocked down (KD) LMTK2 using small(si)RNA-mediated silencing in human bronchial epithelial CFBE41o- cells, treated cells with TGF-β1 or vehicle control, and performed differential gene expression analysis by RNA sequencing (RNAseq). In vehicle-treated cells, LMTK2 KD affected expression of 2,506 genes while it affected 4,162 genes after TGF-β1 stimulation. Bioinformatics analysis shows that LMTK2 is involved in diverse cellular functions and disease pathways, such as cell death and survival, cellular development, and cancer susceptibility. In summary, our study increases current knowledge about the LMTK2 network and its intersection with the TGF-β1 signaling pathway. These findings will serve as basis for future exploration of the predicted LMTK2 interactions and signaling pathways.

GSK-3 in liver diseases: Friend or foe?

Liver diseases, including hepatitis due to hepatitis B or C virus infection, non-alcoholic fatty liver disease, and hepatocellular carcinoma pose major challenges for overall health due to limited curative treatment options. Thus, there is an urgent need to develop new therapeutic strategies for the treatment of these diseases. A better understanding of the signaling pathways involved in the pathogenesis of liver diseases can help to improve the efficacy of emerging therapies, mainly based on pharmacological approaches, which influence one or more specific molecules involved in key signal transduction pathways. These emerging therapies are very promising for the prevention and treatment of liver diseases. One promising druggable molecular target is the multifunctional serine/threonine kinase, glycogen synthase kinase 3 (GSK-3). In this review, we discuss conditions in which GSK-3 is implicated in liver diseases. In addition, we explore newly emerging drugs that target GSK-3β, as well as their potential use in and impact on the management of liver diseases.