Research in practice: Therapeutic targeting of oncogenic GNAQ mutations in uveal melanoma

Integration analysis of microRNAs as potential biomarkers in early-stage lung adenocarcinoma: the diagnostic and therapeutic significance of miR-183-3p

Introduction

Lung adenocarcinoma (LUAD) poses a significant therapeutic challenge, primarily due to delayed diagnosis and the limited efficacy of existing treatments.

Methods

To understand the pathogenesis and identify diagnostic biomarkers for LUAD in the early stage, we investigated differential miRNA expression in 33 stage I LUAD patients between tumor and matched paracancerous tissues by Illumina Sequencing. Target genes of differentially expressed miRNAs were predicted using TargetScan and miRDB databases and further analyzed by GO and KEGG pathway enrichment analysis. The miRNAs expression results were verified using qRT-PCR. Additionally, we evaluated the clinical significance of miRNAs by the TCGA database. miR-183-3p was chosen for subsequent biological functional studies by cell proliferation assays, cell migration and cell invasion assays, cell apoptosis and cell cycle assays in LUAD cells. The clinical relevance target genes of miR-183-3p were predicted by TargetScan databases and bioinformatics assays. Gene-specific experimental validation was performed using qRT-PCR, western blotting and luciferase reporter assays.

Results

We identified 36 differentially expressed miRNAs between LUAD tissues and matched paracancerous tissues. Target genes for these miRNAs revealed associations with processes and pathways such as RNA biosynthesis, intracellular signaling, protein transport, and the Ras, MAPK, and PI3K-AKT pathways. The qRT-PCR results were in alignment with the sequencing data for 19 out of these 21 miRNAs which not yet implicated in LUAD, 13 were up-regulated, 6 were down-regulated. The clinical relevance assays showed that 5 up-regulated miRNAs have diagnostic value for LUAD. miR-183-3p showed significant advantages in the result of sequencing, qRT-PCR, and clinical relevance assay. Biological functional assays showed that miR-183-3p emerged as a key regulator, promoting LUAD cell proliferation, decreasing apoptosis, and augmenting migration and invasion capabilities. The clinical relevance assays and experimental validation showed SESN1 as a clinical significance target of miR-183-3p.

Discussion

Our study lays the foundation for investigating miRNAs with diagnostic significance in early-stage LUAD, pointing out that inhibition of miR-183-3p may serve as a novel therapeutic in LUAD.

Arginine Depletion in Human Cancers

Arginine is encoded by six different codons. Base pair changes in any of these codons can have a broad spectrum of effects including substitutions to twelve different amino acids, eighteen synonymous changes, and two stop codons. Four amino acids (histidine, cysteine, glutamine, and tryptophan) account for over 75% of amino acid substitutions of arginine. This suggests that a mutational bias, or "purifying selection", mechanism is at work. This bias appears to be driven by C > T and G > A transitions in four of the six arginine codons, a signature that is universal and independent of cancer tissue of origin or histology. Here, we provide a review of the available literature and reanalyze publicly available data from the Catalogue of Somatic Mutations in Cancer (COSMIC). Our analysis identifies several genes with an arginine substitution bias. These include known factors such as IDH1, as well as previously unreported genes, including four cancer driver genes (FGFR3, PPP6C, MAX, GNAQ). We propose that base pair substitution bias and amino acid physiology both play a role in purifying selection. This model may explain the documented arginine substitution bias in cancers.

The Impact of Ultraviolet Radiation on the Aetiology and Development of Uveal Melanoma

Uveal melanoma (UM) is currently classified by the World Health Organisation as a melanoma caused by risk factors other than cumulative solar damage. However, factors relating to ultraviolet radiation (UVR) susceptibility such as light-coloured skin and eyes, propensity to burn, and proximity to the equator, frequently correlate with higher risk of UM. These risk factors echo those of the far more common cutaneous melanoma (CM), which is widely accepted to be caused by excessive UVR exposure, suggesting a role of UVR in the development and progression of a proportion of UM. Indeed, this could mean that countries, such as Australia, with high UVR exposure and the highest incidences of CM would represent a similarly high incidence of UM if UVR exposure is truly involved. Most cases of UM lack the typical genetic mutations that are related to UVR damage, although recent evidence in a small minority of cases has shown otherwise. This review therefore reassesses statistical, environmental, anatomical, and physiological evidence for and against the role of UVR in the aetiology of UM.

An experimental strategy to probe Gq contribution to signal transduction in living cells

Heterotrimeric G protein subunits Gαq and Gα11 are inhibited by two cyclic depsipeptides, FR900359 (FR) and YM-254890 (YM), both of which are being used widely to implicate Gq/11 proteins in the regulation of diverse biological processes. An emerging major research question therefore is whether the cellular effects of both inhibitors are on-target, that is, mediated via specific inhibition of Gq/11 proteins, or off-target, that is, the result of nonspecific interactions with other proteins. Here we introduce a versatile experimental strategy to discriminate between these possibilities. We developed a Gαq variant with preserved catalytic activity, but refractory to FR/YM inhibition. A minimum of two amino acid changes were required and sufficient to achieve complete inhibitor resistance. We characterized the novel mutant in HEK293 cells depleted by CRISPR–Cas9 of endogenous Gαq and Gα11 to ensure precise control over the Gα-dependent cellular signaling route. Using a battery of cellular outcomes with known and concealed Gq contribution, we found that FR/YM specifically inhibited cellular signals after Gαq introduction via transient transfection. Conversely, both inhibitors were inert across all assays in cells expressing the drug-resistant variant. These findings eliminate the possibility that inhibition of non-Gq proteins contributes to the cellular effects of the two depsipeptides. We conclude that combined application of FR or YM along with the drug-resistant Gαq variant is a powerful in vitro strategy to discern on-target Gq against off-target non-Gq action. Consequently, it should be of high value for uncovering Gq input to complex biological processes with high accuracy and the requisite specificity.