m6A RNA methylation regulates the transcription factors JUN and JUNB in TGF-ß-induced epithelial-mesenchymal transition of lung cancer cells.

N6-methyladenosine (m6A) is the most common internal chemical modification of mRNAs involved in many pathological processes including various cancers. In this study, we investigated the m6A-dependent regulation of JUN and JUNB transcription factors (TFs) during transforming growth factor-beta-induced epithelial-mesenchymal transition (EMT) of A549 and LC2/ad lung cancer cell lines, as the function and regulation of these TFs within this process remains to be clarified. We found that JUN and JUNB played an important and nonredundant role in the EMT-inducing gene expression program by regulating different mesenchymal genes and that their expressions were controlled by methyltransferase-like 3 (METTL3) m6A methyltransferase. METTL3-mediated regulation of JUN expression is associated with the translation process of JUN protein but not with the stability of JUN protein or mRNA, which is in contrast with the result of m6A-mediated regulation of JUNB mRNA stability. We identified the specific m6A motifs responsible for the regulation of JUN and JUNB in EMT within 3'UTR of JUN and JUNB. Furthermore, we discovered that different m6A reader proteins interacted with JUN and JUNB mRNA and controlled m6A-dependent expression of JUN protein and JUNB mRNA. These results demonstrate that the different modes of m6A-mediated regulation of JUN and JUNB TFs provide critical input in the gene regulatory network during transforming growth factor-beta-induced EMT of lung cancer cells.

Erratum: TGF-ß1 facilitates MT1-MMP-mediated proMMP-9 activation and invasion in oral squamous cell carcinoma cells (BBREP_101072).

[This corrects the article DOI: 10.1016/j.bbrep.2021.101072.].

TGF-ß1 facilitates MT1-MMP-mediated proMMP-9 activation and invasion in oral squamous cell carcinoma cells.

Matrix metalloproteinase (MMP)-2 and MMP-9, also known as gelatinases or type IV collagenases, are recognized as major contributors to the proteolytic degradation of extracellular matrix during tumor invasion. Latent MMP-2 (proMMP-2) is activated by membrane type 1 MMP (MT1-MMP) on the cell surface of tumor cells. We previously reported that cell-bound proMMP-9 is activated by the MT1-MMP/MMP-2 axis in HT1080 cells treated with concanavalin A in the presence of exogenous proMMP-2. However, the regulatory mechanism of proMMP-9 activation remains largely unknown. Transforming growth factor (TGF)-ß1 is frequently overexpressed in tumor tissues and is associated with tumor aggressiveness and poor prognosis. In this study, we examined the role of TGF-ß1 on MT1-MMP-mediated proMMP-9 activation using human oral squamous cell carcinoma cells. TGF-ß1 significantly increased the expression of MMP-9. By adding exogenous proMMP-2, TGF-ß1-induced proMMP-9 was activated during collagen gel culture, which was suppressed by the inhibition of TGF-ß1 signaling or MT1-MMP activity. This MT1-MMP-mediated proMMP-9 activation was needed to facilitate TGF-ß1-induced cell invasion into collagen gel. Thus, TGF-ß1 may facilitate MT1-MMP-mediated MMP-9 activation and thereby stimulate invasion of tumor cells in collaboration with MT1-MMP and MMP-2.