miR-31-NUMB Cascade Modulates Monocarboxylate Transporters to Increase Oncogenicity and Lactate Production of Oral Carcinoma Cells

Abstract

Oral squamous cell carcinoma (OSCC) is among the leading causes of cancer-associated death worldwide. miR-31 is an oncogenic miRNA in OSCC. NUMB is an adaptor protein capable of suppressing malignant transformation. Disruption of the miR-31-NUMB regulatory axis has been demonstrated in malignancies. Mitochondrial dysfunction and adaptation to glycolytic respiration are frequent events in malignancies. Monocarboxylate transporters (MCTs) function to facilitate lactate flux in highly glycolytic cells. Upregulation of MCT1 and MCT4 has been shown to be a prognostic factor of OSCC. Here, we reported that miR-31-NUMB can modulate glycolysis in OSCC. Using the CRISPR/Cas9 gene editing strategy, we identified increases in oncogenic phenotypes, MCT1 and MCT4 expression, lactate production, and glycolytic respiration in NUMB-deleted OSCC subclones. Transfection of the Numb1 or Numb4 isoform reversed the oncogenic induction elicited by NUMB deletion. This study also showed, for the first time, that NUMB4 binds MCT1 and MCT4 and that this binding increases their ubiquitination, which may decrease their abundance in cell lysates. The disruptions in oncogenicity and metabolism associated with miR-31 deletion and NUMB deletion were partially rescued by MCT1/MCT4 expression or knockdown. This study demonstrated that NUMB is a novel binding partner of MCT1 and MCT4 and that the miR-31-NUMB-MCT1/MCT4 regulatory cascade is present in oral carcinoma.

A new insight into the diverse facets of microRNA-31 in oral squamous cell carcinoma

“…MCT1 and/or MCT4 expression upregulation has also been demonstrated to be a prospective indicator of HNSCC. NUMB binds MCT1/MCT4 in OSCC cells, causing MCT1/MCT4 degradation, decreasing oncogenicity, and increasing glycolytic metabolism [33]. NUMB had an effect on lactate synthesis and glycolytic respiration in OSCC cells.…”

“…Ectopic expression of miR-31 is remarkably upregulated in OSCC [33], which is consistently expressed in saliva and serum or plasma of OSCC patients [34]. miR-31 may bind to the 3′ untranslated region (UTR) of factor-inhibiting hypoxia-inducible factor (FIH), a hypoxia-inducible factor (HIF) regulatory factor that prevents HIF from functioning as a transcriptional regulator under normal environments [33]. Monocarboxylate Transporter (MCT) family members are responsible for metabolite transport in metabolic activities.…”

“…NUMB can suppress NOTCH signaling by directly attaching to the NOTCH intracellular domain (NICD), preventing it from accessing the nucleus. NUMB can also directly inhibit NOTCH by recruiting Itch to polyubiquitinate and degrade Notch proteins [33]. Ectopic expression of miR-31 is remarkably upregulated in OSCC [33], which is consistently expressed in saliva and serum or plasma of OSCC patients [34].…”

“…NUMB can also directly inhibit NOTCH by recruiting Itch to polyubiquitinate and degrade Notch proteins [33]. Ectopic expression of miR-31 is remarkably upregulated in OSCC [33], which is consistently expressed in saliva and serum or plasma of OSCC patients [34]. miR-31 may bind to the 3′ untranslated region (UTR) of factor-inhibiting hypoxia-inducible factor (FIH), a hypoxia-inducible factor (HIF) regulatory factor that prevents HIF from functioning as a transcriptional regulator under normal environments [33].…”

“…MiR-31 has been demonstrated to target SIRT3 to impair mitochondrial function and ACOX1 to modify the lipidome profile in OSCC. The inhibition of NUMB by miR-31 has both proliferative and metabolic consequences [33]. Overall, Chou et al [33] identified that the existence of the miR-31-NUMB-MCT1/MCT4 axis in modulating oncogenesis and metabolic switching, implying that disrupting this cascade may prevent tumor pathogenesis and aerobic glycolysis.…”