Silencing LINC00987 ameliorates adriamycin resistance of acute myeloid leukemia via miR-4458/HMGA2 axis.

BACKGROUND: Most patients with acute myeloid leukemia (AML) eventually develop drug resistance, leading to a poor prognosis. Dysregulated long gene non coding RNAs (lincRNAs) have been implicated in chemoresistance in AML. Unfortunately, the effects of lincRNAs which participate in regulating the Adriamycin (ADR) resistance in AML cells remain unclear. Thus, the purpose of this study is to determine LINC00987 function in ADR-resistant AML. METHODS: In this study, ADR-resistant cells were constructed. LINC00987, miRNAs, and HMGA2 mRNA expression were measured by qRT-PCR. P-GP, BCRP, and HMGA2 protein were measured by Western blot. The proliferation was analyzed by MTS and calculated IC50. Soft agar colony formation assay and TUNEL staining were used to analyze cell colony formation and apoptosis. Xenograft tumor experiment was used to analyze the xenograft tumor growth of ADR-resistant AML. RESULTS: We found that higher expression of LINC00987 was observed in AML patients and associated with poor overall survival in AML patients. LINC00987 expression was increased in ADR-resistant AML cells, including ADR/MOLM13 and ADR/HL-60 cells. LINC00987 downregulation reduces ADR resistance in ADR/MOLM13 and ADR/HL-60 cells in vitro and in vivo, while LINC00987 overexpression enhanced ADR resistance in MOLM13 and HL-60 cells. Additionally, LINC00987 functions as a competing endogenous RNA for miR-4458 to affect ADR resistance in ADR/MOLM13 and ADR/HL-60 cells. HMGA2 is a target of miR-4458. LINC00987 knockdown and miR-4458 overexpression reduced HMGA2 expression. HMGA2 overexpression enhanced ADR resistance, which reversed the function of LINC00987 silencing in suppressing ADR resistance of ADR/MOLM13 and ADR/HL-60 cells. CONCLUSIONS: Downregulation of LINC00987 weakens ADR resistance by releasing miR-4458 to deplete HMGA2 in ADR/MOLM13 and ADR/HL-60. Therefore, LINC00987 may act as the therapeutic target for treating chemoresistant AML.

FDXR variants cause adrenal insufficiency and atypical sexual development.

Genetic defects affecting steroid biosynthesis cause cortisol deficiency and differences of sex development; among these defects are recessive mutations in the steroidogenic enzymes CYP11A1 and CYP11B, whose function is supported by reducing equivalents donated by ferredoxin reductase (FDXR) and ferredoxin. So far, mutations in the mitochondrial flavoprotein FDXR have been associated with a progressive neuropathic mitochondriopathy named FDXR-related mitochondriopathy (FRM), but cortisol insufficiency has not been documented. However, patients with FRM often experience worsening or demise following stress associated with infections. We investigated 2 female patients with FRM carrying the potentially novel homozygous FDXR mutation p.G437R with ambiguous genitalia at birth and sudden death in the first year of life; they presented with cortisol deficiency and androgen excess compatible with 11-hydroxylase deficiency. In addition, steroidogenic FDXR-variant cell lines reprogrammed from 3 patients with FRM fibroblasts displayed deficient mineralocorticoid and glucocorticoid production. Finally, Fdxr-mutant mice allelic to the severe p.R386W human variant showed reduced progesterone and corticosterone production. Therefore, our comprehensive studies show that human FDXR variants may cause compensated but possibly life-threatening adrenocortical insufficiency in stress by affecting adrenal glucocorticoid and mineralocorticoid synthesis through direct enzyme inhibition, most likely in combination with disturbed mitochondrial redox balance.