Mutational profiling of mitochondrial DNA reveals an epithelial ovarian cancer-specific evolutionary pattern contributing to high oxidative metabolism.

BACKGROUND: Epithelial ovarian cancer (EOC) heavily relies on oxidative phosphorylation (OXPHOS) and exhibits distinct mitochondrial metabolic reprogramming. Up to now, the evolutionary pattern of somatic mitochondrial DNA (mtDNA) mutations in EOC tissues and their potential roles in metabolic remodelling have not been systematically elucidated. METHODS: Based on a large somatic mtDNA mutation dataset from private and public EOC cohorts (239 and 118 patients, respectively), we most comprehensively characterised the EOC-specific evolutionary pattern of mtDNA mutations and investigated its biological implication. RESULTS: Mutational profiling revealed that the mitochondrial genome of EOC tissues was highly unstable compared with non-cancerous ovary tissues. Furthermore, our data indicated the delayed heteroplasmy accumulation of mtDNA control region (mtCTR) mutations and near-complete absence of mtCTR non-hypervariable segment (non-HVS) mutations in EOC tissues, which is consistent with stringent negative selection against mtCTR mutation. Additionally, we observed a bidirectional and region-specific evolutionary pattern of mtDNA coding region mutations, manifested as significant negative selection against mutations in complex V (ATP6/ATP8) and tRNA loop regions, and potential positive selection on mutations in complex III (MT-CYB). Meanwhile, EOC tissues showed higher mitochondrial biogenesis compared with non-cancerous ovary tissues. Further analysis revealed the significant association between mtDNA mutations and both mitochondrial biogenesis and overall survival of EOC patients. CONCLUSIONS: Our study presents a comprehensive delineation of EOC-specific evolutionary patterns of mtDNA mutations that aligned well with the specific mitochondrial metabolic remodelling, conferring novel insights into the functional roles of mtDNA mutations in EOC tumourigenesis and progression.

miR-145-5p Modulates Gefitinib Resistance by Targeting NRAS and MEST in Non-Small Cell Lung Cancer.

OBJECTIVE: microRNAs may play essential roles in the development and drug resistance of non-small cell lung cancer (NSCLC). However, their functions and mechanisms are not fully understood. Our goal was to define the role of miR-145-5p in the gefitinib resistance of NSCLC. MATERIALS AND METHODS: An A549 gefitinib-resistant cell line and xenograft nude mice were used in this study. The expression of miR-145-5p and its targets, NRAS and MEST, were detected and measured by qPCR, Western blot, RNA-FISH, or immunofluorescence analysis. RESULTS: miR-145-5p was downregulated in gefitinib-resistant A549 cells (A549/Gef R). Overexpression of miR-145-5p enhanced the sensitivity to gefitinib and inhibited cell proliferation and invasion in A549/Gef R. miR-145-5p was also significantly reduced in LUAD and LUSC clinical samples and closely associated with a favorable prognosis, according to the UALCAN and TCGA databases. Moreover, NRAS and MEST were found to be downstream target genes of miR-145-5p and to function as oncogenes in NSCLC samples, and gefitinib resistance could be improved following the interference of these two molecules. CONCLUSION: miR-145-5p improves the sensitivity of acquired gefitinib-resistant cells to gefitinib via inhibiting NRAS and MEST expression. The miR 145-5p-NRAS/MEST axis in NSCLC provides insights for the development of a NRAS/MEST targeting therapeutic approach to overcome gefitinib resistance in NSCLC patients.

[Preparation of a novel chiral stationary phase based on library of small peptides obtained by digestion of bovine serum albumin with trypsin].

A novel chiral stationary phase (CSP) based on library of small peptides for high performance liquid chromatography (HPLC) is described. The conditions for digestion of bovine serum albumin (BSA) with trypsin were optimized, and the results of which were: enzymolysis time 6 h, enzymolysis pH 8.2, enzymolysis temperature 37 degrees C. The obtained library of small peptides, which held many chiral recognition sites, could enhance the interaction between enantiomers and CSP. Then it was ultrafiltrated with membrane (Mr =6000) to discard Mr >6000 molecules, and was bonded to aminopropyl-silica gel activated with 1,1'-carbonyldiimidazole. The proposed CSP held higher density of peptides' ligand and was more steady than intact BSA-CSP. D,L-Tryptophan and D,L-tyrosine were well chiral separated on the novel peptides-CSP. The resolution (Rs) for D,L-tryptophan reached 10.48 with gradient pH buffer from 4.0 to 7.5. The Rs for D,L-tyrosine reached 13.50 with gradient pH buffer from 5.6 to 6.3. In the enantioseparation procedure of D,L-tryptophan and D,L-tyrosine, pH gradient elution was applied. The results could be ascribable to that the variation in pH of mobile phase can change dissociation of both enantiomers and peptides on CSP, which influenced the interaction between them by the conformation of peptides and/or the electrostatic situation and the hydrophobicity of solutes.