Molecular Investigation of KRAS Gene in Breast Cancer Patients

AIMP2-DX2 provides therapeutic interface to control KRAS-driven tumorigenesis

Recent development of the chemical inhibitors specific to oncogenic KRAS (Kirsten Rat Sarcoma 2 Viral Oncogene Homolog) mutants revives much interest to control KRAS-driven cancers. Here, we report that AIMP2-DX2, a variant of the tumor suppressor AIMP2 (aminoacyl-tRNA synthetase-interacting multi-functional protein 2), acts as a cancer-specific regulator of KRAS stability, augmenting KRAS-driven tumorigenesis. AIMP2-DX2 specifically binds to the hypervariable region and G-domain of KRAS in the cytosol prior to farnesylation. Then, AIMP2-DX2 competitively blocks the access of Smurf2 (SMAD Ubiquitination Regulatory Factor 2) to KRAS, thus preventing ubiquitin-mediated degradation. Moreover, AIMP2-DX2 levels are positively correlated with KRAS levels in colon and lung cancer cell lines and tissues. We also identified a small molecule that specifically bound to the KRAS-binding region of AIMP2-DX2 and inhibited the interaction between these two factors. Treatment with this compound reduces the cellular levels of KRAS, leading to the suppression of KRAS-dependent cancer cell growth in vitro and in vivo. These results suggest the interface of AIMP2-DX2 and KRAS as a route to control KRAS-driven cancers.

Direct targeting of oncogenic KRAS activity is a challenge. Here the authors report that a splice variant of AIMP2, AIMP2-DX2, enhances KRAS stability by blocking ubiquitin-mediated degradation of KRAS via the E3 ligase, Smurf2, and identify a chemical that can hinder AIMP2-DX2 from interacting with KRAS.

The Relevance of SNPs at 3'UTR Region of CASP7 and miR-371b-5p Associated Diseases: A Computational Analysis

The process of genetically programmed cell death, or apoptosis, plays a crucialrolein cellular homeostasis and gene expression. Disruption of apoptosis may lead to aberrant immune responses, cancer, and neurodegenerative diseases. Single nucleotide polymorphisms (SNPs) present in various microRNA (miRNA) genes and targets being an alteration of miRNA activity resulting in human diseases. Evidence reported that SNPs increase/decrease the effectiveness of the interaction between miRNAs and their target genes associated with diseases. The primary purpose of this study is not only to identify miRSNPs on the CASP7 gene (caspase-7) and SNPs in miRNA genes targeting 3'UTR but also to evaluate the effect of thesegene variations in apoptosis and their associated diseases. We detected 120 miRNAs binding sites and 27 different SNPs in binding sites of miRNA in 3'UTR of the CASP7 gene by ten different online softwares. Interestingly, miR-371b-5p's binding site on CASP7 has an SNP (rs576198588, G/T) on CASP7 3'UTR, and its genomic sequence has an SNP (rs751339395, G/T) at the same nucleotide with rs576198588. Similarly, two other SNPs (rs774879764, C/G rs750389063, C/T) were identified at the first position binding site of miR-371b-5p. Here, miRSNP (rs576198588) at CASP7 3'UTR and SNP (rs751339395) at miR-371b-5p genomic sequence cross-matches at the same site of binding region. Besides, miR-371b-5p targets many apoptosis-related genes (HIP1, TRIAP1, GSKIP, NIN, DAP, CAAP1, XIAP, TMBIM1, TMBIM4, TNFRSF10A, RAD21, AKT1, BAG1, BAG4) even though it had no apoptosis correlated interaction demonstrated formerly. It assures that CASP7 could have a significant consequence on apoptosis through different pathways. Henceforth, this study was representing and signifying an influential connotation among miR-371b-5p and apoptosis via computational exploration and recommended to have better insight.