Novel MRPS9-ALK Fusion Mutation in a Lung Adenocarcinoma Patient: A Case Report

MRPS9-Mediated Regulation of the PI3K/Akt/mTOR Pathway Inhibits Neuron Apoptosis and Protects Ischemic Stroke

Neuronal apoptosis is crucial in the pathophysiology of ischemic stroke (IS), albeit its underly24ing mechanism remaining elusive. Investigating the mechanism of neuronal apoptosis in the context of IS holds substantial clinical value for enhancing the prognosis of IS patients. Notably, the MRPS9 gene plays a pivotal role in regulating mitochondrial function and maintaining structural integrity. Utilizing bioinformatic tactics and the extant gene expression data related to IS, we conducted differential analysis and weighted correlation network analysis (WGCNA) to select important modules. Subsequent gene interaction analysis via the STRING website facilitated the identification of the key gene-mitochondrial ribosomal protein S9 (MRPS9)-that affects the progression of IS. Moreover, possible downstream signaling pathways, namely PI3K/Akt/mTOR, were elucidated via Kyoto Encyclopedia of Gene and Genomes (KEGG) and Gene Ontology (GO) pathway analysis. Experimental models were established utilizing oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro and middle cerebral artery occlusion/reperfusion (MCAO/R) in mice. Changes in gene and protein expression, as well as cell proliferation and apoptosis, were monitored through qPCR, WB, CCK8, and flow cytometry. An OGD/R cell model was further employed to investigate the role of MRPS9 in IS post transfusion of MRPS9 overexpression plasmids into cells. Further studies were conducted by transfecting overexpressed cells with PI3K/Akt/mTOR signaling pathway inhibitor LY294002 to unveil the mechanism of MRPS9 in IS. Bioinformatic analysis revealed a significant underexpression of MRPS9 in ischemic stroke patients. Correspondingly, in vitro experiments with HN cells subjected to OGD/R treatment demonstrated a marked reduction in MRPS9 expression, accompanied by a decline in cell viability, and an increase cell apoptosis. Notably, the overexpression of MRPS9 mitigated the OGD/R-induced decrease in cell viability and augmentation of apoptosis. In animal models, MRPS9 expression was significantly lower in the MCAO/R group compared to the sham surgery group. Further, the KEGG pathway analysis associated MRPS9 expression with the PI3K/Akt/mTOR signaling pathway. In cells treated with the specific PI3K/Akt/mTOR inhibitor LY294002, phosphorylation levels of Akt and mTOR were decreased, cell viability decreased, and apoptosis increased compared to the MRPS9 overexpression group. These findings collectively indicate that MRPS9 overexpression inhibits PI3K/Akt/mTOR pathway activation, thereby protecting neurons from apoptosis and impeding IS progression. However, the PI3K/Akt/mTOR inhibitor LY294002 is capable of counteracting the protective effect of MRPS9 overexpression on neuronal apoptosis and IS. Our observations underscore the potential protective role of MRPS9 in modulating neuronal apoptosis and in attenuating the pathophysiological developments associated with IS. This is achieved through the regulation of the PI3K/Akt/mTOR pathway. These insights forge new perspectives and propose novel targets for the strategic diagnosis and treatment of IS.

Characterizing kinase intergenic-breakpoint rearrangements in a large-scale lung cancer population and real-world clinical outcomes

BACKGROUND

Kinase gene fusions are strong driver mutations in neoplasia; however, kinase intergenic-breakpoint rearrangements (IGRs) confound the detection of such fusions and of targeted treatments. We aim to provide an overview of kinase IGRs in a large lung cancer cohort and examine real-world survival outcomes of patients with such fusions.

METHODS

Mutational profiles analyzed using targeted next-generation sequencing of 425 cancer-related genes between June 2016 and July 2019 were retrospectively reviewed. Patients' demographic data, clinical characteristics, and survivals were analyzed. RNA sequencing or immunohistochemical assays were carried out to verify chimeric fusion products.

RESULTS

We identified 3411 patients with kinase fusions from a cohort of 30 450 patients with lung cancer, and 624 kinase IGR events were identified in 538 of the 3411 patients. The most frequently identified kinase genes included anaplastic lymphoma kinase (ALK), RET proto-oncogene (RET), ROS proto-oncogene 1 (ROS1), Erb-B2 receptor tyrosine kinase 2/3 (ERBB2/3), and epidermal growth factor receptor (EGFR). Our data showed that most (67%) kinase IGRs occurred on the same chromosome and kinase domains remained intact at the 3'-end. Approximately 3% (19/624) of the kinase IGRs had one genomic breakpoint located in gene promoter regions, including nine fusion events involving ALK, RET, ROS1, EGFR, ERBB2, or fibroblast growth factor receptor 3 (FGFR3). Among the 538 patients with kinase IGRs, 167 (31%) lacked oncogenic driver mutations, among which 28 received targeted therapies in real-world practice. Notably, three ALK IGR patients who harbored no canonical oncogenic aberrations were confirmed with an EML4-ALK chimeric fusion product by RNA sequencing and/or ALK immunohistochemical assays. One patient demonstrated a favorable clinical outcome after 14 months on crizotinib. An additional two patients who had ROS1 IGRs demonstrated a clinical benefit after 13 and 19 months on crizotinib, respectively.

CONCLUSION

A large real-world lung cancer cohort with kinase IGRs was comprehensively analyzed for their molecular characteristics. The data indicated the potential oncogenic function of kinase IGRs and their outcomes following the administration of targeted therapies.