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A major reason for colorectal cancer (CRC) chemoresistance is the enhanced migration and invasion of cancer cells, such as the cell acquisition of epithelial-mesenchymal transition (EMT). Long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been considered as a pro-oncogene in multiple cancers. However, the precise functional mechanism of lncRNA MALAT1 in chemoresistance and EMT is not well known. In the present study, we focused on the effect of oxymatrine on CRC cells and further investigated the role of MALAT1 in oxymatrine-induced resistance and EMT process. The human CRC cell line HT29 was exposed to increasing doses of oxymatrine to establish stable cell lines resistant to oxymatrine. The established HT29 oxymatrine resistant cells showed an EMT phenotype including specific morphologic changes, enhanced migratory and invasive capacity, and downregulation of E-cadherin protein expression. Subsequently, high-throughput HiSeq sequencing and RT-qPCR showed that lncRNA MALAT1 was significantly upregulated in the oxymatrine resistant cells (P<0.01), while knockdown of MALAT1 partially reversed the EMT phenotype in HT29 resistant cells. Furthermore, oxymatrine treatment suppressed the migration and invasion ability of CRC cells, however, this effect was significantly reversed by overexpression of MALAT1. Finally, we investigated the clinical role of MALAT1 and found that high lncRNA MALAT1 expression level is associated with poor prognosis in CRC patients receiving oxymatrine treatment (P<0.01). In conclusion, we demonstrate that lncRNA MALAT1 is a stimulator for oxymatrine resistance in CRC and it may provide therapeutic and prognostic information for CRC patients.

The matrix metalloproteinase (MMP) family is widely involved in the destruction of the pulp and apical tissues in the inflammatory process. MMP9 is closely related to oral inflammation. Nevertheless, the specific function of MMP9 during oral inflammation, as well as its mechanism, is not well understood. Our previous studies found that in experimentally induced apical periodontitis, more severe inflammation occurred in MMP9 knockout mice compared with the wild type mice. Moreover, the pathology phenomenon of alveolar bone destruction was even more evident in MMP9 knockout mice compared with the wild type mice. We proposed that MMP9 has “anti-inflammatory” properties. We aimed to study the effects of MMP9 on inflammatory response as well as on bone formation and bone destruction. We found a specific relationship between MMP9 and inflammation. qRT-PCR and Western blot revealed that the production of IL-1β, TNF-α, RANK, RANKL, TLR2, and TLR4 was reduced by MMP9 in LPS-stimulated MC3T3-E1 cells. Meanwhile, the expressions of OPG and OCN were increased by MMP9 in LPS-stimulated cells. MMP9 plays a protective role in LPS-induced inflammation, thereby providing new clues to the prevention and treatment of apical periodontitis.