Overexpression of GRK6 associates with the progression and prognosis of colorectal carcinoma

Identification of a venetoclax-resistance prognostic signature base on 6-senescence genes and its clinical significance for acute myeloid leukemia

Background

Satisfactory responses can be obtained for acute myeloid leukemia (AML) treated by Venetoclax (VEN)-based therapy. However, there are still quite a few AML patients (AMLs) resistant to VEN, and it is critical to understand whether VEN-resistance is regulated by senescence.

Methods

Here, we established and validated a signature for predicting AML prognosis based on VEN resistance-related senescence genes (VRSGs). In this study, 51 senescence genes were identified with VEN-resistance in AML. Using LASSO algorithms and multiple AML cohorts, a VEN-resistance senescence prognostic model (VRSP-M) was developed and validated based on 6-senescence genes.

Results

According to the median score of the signature, AMLs were classified into two subtypes. A worse prognosis and more adverse features occurred in the high-risk subtype, including older patients, non-de novo AML, poor cytogenetics, adverse risk of European LeukemiaNet (ELN) 2017 recommendation, and TP53 mutation. Patients in the high-risk subtype were mainly involved in monocyte differentiation, senescence, NADPH oxidases, and PD1 signaling pathway. The model's risk score was significantly associated with VEN-resistance, immune features, and immunotherapy response in AML. In vitro, the IC50 values of ABT-199 (VEN) rose progressively with increasing expression of G6PD and BAG3 in AML cell lines.

Conclusions

The 6-senescence genes prognostic model has significant meaning for the prediction of VEN-resistance, guiding personalized molecularly targeted therapies, and improving AML prognosis.

Computational analysis of G-protein-coupled receptor kinase family members as potential targets for colorectal cancer therapy

Background

G-protein-coupled receptor (GPCR) kinases (GRKs) interact with ligand-activated GPCR, causing intracellular phosphorylation and interfering with the intracellular signal transduction associated with the development of cancer. Colorectal cancer (CRC) is a fast-growing disease, and its molecular mechanism involves various regulatory proteins, including kinases. However, the GRK mechanism in CRC has not been explored.

Methods

We used an integrated computational approach to investigate the potential of GRK family members as targeted proteins in CRC. The GRK expression levels in tumor and normal tissues, colon adenocarcinoma samples, and metastatic colon adenocarcinoma were analyzed using ONCOMINE, GEPIA, and UALCAN, as well as TNM plots. Genetic changes in the GRK family genes were investigated using cBioportal. The prognostic value related to the gene expression of the GRK family was examined using GEPIA and UALCAN. Co-expression analysis of the GRK family was conducted using COXPRESdb. Association analysis of the Gene Ontology, KEGG pathway enrichment, and drug-gene analyses were performed using the over-representation analysis (ORA) in WebGestalt.

Results

GRK2, GRK3, and GRK5 mRNA levels increased significantly in patients with CRC and metastatic CRC. Genetic changes were detected in patients with CRC, including GRK7 (1.1%), GRK2 (1.7%), GRK4 (2.3%), GRK5 (2.5%), GRK6 (2.5%), GRK3 (2.9%), and GRK1 (4%). CRC patients with low mRNA of GRK7 levels had better disease-free and overall survival than those with high GRK7 levels. Hierarchical clustering analysis revealed significant positive correlations between GRK5 and GRK2 and between GRK2 and GRK6. KEGG pathway enrichment analysis showed that the gene network (GN) regulated several cellular pathways, such as the morphine addiction signaling and chemokine signaling pathways in cancer. The drug-gene association analysis indicated that the GN was associated with several drugs, including reboxetine, pindolol, beta-blocking agents, and protein kinase inhibitors.

Conclusion

No research has been conducted on the relation of GRK1 and GRK7 to cancer, particularly CRC. In this work, genes GRK2, GRK3, GRK5, and GRK6 were found to be oncogenes in CRC. Although inhibitors against GRK2, GRK5, and GRK6 have previously been developed, further research, particularly preclinical and clinical studies, is needed before these agents may be used to treat CRC.

GRK6 Depletion Induces HIF Activity in Lung Adenocarcinoma

G protein-coupled receptor kinase 6 (GRK6) is expressed in various tissues and is involved in the development of several diseases including lung cancer. We previously reported that GRK6 is down-regulated in lung adenocarcinoma patients, which induces cell invasion and metastasis. However, further understanding of the role of GRK6 in lung adenocarcinoma is required. Here we explored the functional consequence of GRK6 inhibition in lung epithelial cells. Analysis of TCGA data was coupled with RNA sequencing (RNA-seq) in alveolar epithelial type II (ATII) cells following depletion of GRK6 with RNA interference (RNAi). Findings were validated in ATII cells followed by tissue microarray analysis. Pathway analysis suggested that one of the Hallmark pathways enriched upon GRK6 inhibition is 'Hallmark_Hypoxia' (FDR = 0.014). We demonstrated that GRK6 depletion induces HIF1α (hypoxia-inducible factor 1 alpha) levels and activity in ATII cells. The findings were further confirmed in lung adenocarcinoma samples, in which GRK6 expression levels negatively and positively correlate with HIF1α expression (P = 0.015) and VHL expression (P < 0.0001), respectively. Mechanistically, we showed the impact of GRK6 on HIF activity could be achieved via regulation of VHL levels. Taken together, targeting the HIF pathway may provide new strategies for therapy in GRK6-depleted lung adenocarcinoma patients.

Unraveling the Molecular Nexus between GPCRs, ERS, and EMT

G protein-coupled receptors (GPCRs) represent a large family of transmembrane proteins that transduce an external stimulus into a variety of cellular responses. They play a critical role in various pathological conditions in humans, including cancer, by regulating a number of key processes involved in tumor formation and progression. The epithelial-mesenchymal transition (EMT) is a fundamental process in promoting cancer cell invasion and tumor dissemination leading to metastasis, an often intractable state of the disease. Uncontrolled proliferation and persistent metabolism of cancer cells also induce oxidative stress, hypoxia, and depletion of growth factors and nutrients. These disturbances lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and induce a cellular condition called ER stress (ERS) which is counteracted by activation of the unfolded protein response (UPR). Many GPCRs modulate ERS and UPR signaling via ERS sensors, IRE1α, PERK, and ATF6, to support cancer cell survival and inhibit cell death. By regulating downstream signaling pathways such as NF-κB, MAPK/ERK, PI3K/AKT, TGF-β, and Wnt/β-catenin, GPCRs also upregulate mesenchymal transcription factors including Snail, ZEB, and Twist superfamilies which regulate cell polarity, cytoskeleton remodeling, migration, and invasion. Likewise, ERS-induced UPR upregulates gene transcription and expression of proteins related to EMT enhancing tumor aggressiveness. Though GPCRs are attractive therapeutic targets in cancer biology, much less is known about their roles in regulating ERS and EMT. Here, we will discuss the interplay in GPCR-ERS linked to the EMT process of cancer cells, with a particular focus on oncogenes and molecular signaling pathways.

Decreased Cytoplasmic Expression of ADAMTS14 Is Correlated with Reduced Survival Rates in Oral Squamous Cell Carcinoma Patients

A disintegrin and metalloproteinase with thrombospondin motif 14 (ADAMTS14) is a member of the zinc-dependent protease family that is implicated in the occurrence and progression of tumors. Oral cancer (OC) is a common cancer worldwide, but it is particularly prevalent in Taiwan. However, whether the expression of ADAMTS14 is correlated with the carcinogenesis and progression of oral squamous cell carcinoma (OSCC) has not yet been investigated. In this study, we used immunohistochemistry (IHC) to examine 250 OSCC specimens in order to identify correlations between the cytoplasmic expression of ADAMTS14 and (1) clinicopathological features of OSCC as well as (2) clinical outcomes of OSCC. Our results indicate that cytoplasmic expression of ADAMTS14 was lower in OSCC tissues than in normal tissues. In analyzing correlations between ADAMTS14 expression and clinicopathological features, we found that negative cytoplasmic expression of ADAMTS14 was significantly associated with higher frequencies of lymph node metastasis and more advanced AJCC stages (III/IV). Kaplan-Meier survival analysis revealed that negative cytoplasmic expression of ADAMTS14 was also associated with significantly worse OSCC survival. Univariate and multivariate analyses confirmed that cytoplasmic expression of ADAMTS14 was associated with lymph node metastasis, tumor stage, and tumor grade and also indicated that cytoplasmic ADAMTS14 expression may be an independent prognostic factor for OSCC. This is the first study to report that the cytoplasmic expression level of ADAMTS14 is associated with OSCC prognosis and tumor progression. Our data indicate that ADAMTS14 can serve as a prognostic marker and a potential therapeutic target for OSCC.

Hypermethylation of the G protein-coupled receptor kinase 6 (GRK6) promoter inhibits binding of C/EBPα, and GRK6 knockdown promotes cell migration and invasion in lung adenocarcinoma cells

We previously reported that the expression of G protein-coupled receptor kinase 6 (GRK6) is significantly downregulated in lung adenocarcinoma (LADC) tissues, and low expression levels of GRK6 are correlated with poor survival prognosis. However, the specific regulatory mechanisms and functions of GRK6 in LADC remain unknown. Here, we report that GRK6 mRNA expression levels are downregulated in LADC tissues compared to those in matched adjacent non-tumor tissues (P < 0.001). The promoter of the GRK6 gene was found to be hypermethylated in LADC tissues, and its methylation was correlated with both GRK6 expression and pathology grade. GRK6 promoter hypermethylation may predict shorter overall survival. Treatment with 5-aza-2'-deoxycytidine significantly enhanced GRK6 gene expression. Four binding sites of CCAAT/enhancer-binding protein-α (C/EBPα) in the CpG island of the GRK6 gene promoter were predicted in silico, of which three sites were further confirmed by ChIP. Decreased binding of C/EBPα to binding sites 1, 3 and 4 of the GRK6 gene promoter was observed in LADC tissues. Inhibition of C/EBPα significantly inhibited GRK6 expression, while overexpression of C/EBPα significantly promoted GRK6 expression. In addition, overexpression of GRK6 significantly suppressed, while GRK6 knockdown promoted cell migration and invasion. Overexpression of GRK6 enhanced E-cadherin expression and suppressed vimentin expression, and silencing of GRK6 had the opposite effects. Furthermore, ectopic expression of GRK6 significantly decreased matrix metalloproteinase (MMP) 2 and MMP7 protein expression levels. Our findings suggest that hypermethylation of the GRK6 gene promoter suppressed binding of C/EBPα, thereby contributing to the promotion of cell migration and invasion. The methylation status of the GRK6 promoter might be suitable for use as an epigenetic biomarker, and the C/EBPα-GRK6 signaling pathway may be a potential target for LADC.