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Abstract
Long non-coding RNAs (lncRNAs) have been reported to be crucial modulators in various
heart diseases, including myocardial infarction (MI). LncRNA metastasis associated
lung adenocarcinoma transcript 1 (MALAT1) has been reported to be highly expressed
in MI samples. However, the mechanism and biological function of MALAT1 in myocardial
infarction are still marked. Similarly, programmed cell death 4 (PDCD4) was also upregulated
in MI samples. Therefore, MALAT1 and PDCD4 were chosen to do further study. At first,
qRT-PCR was applied to examine the expression patterns of MALAT1 and PDCD4. The results
showed that both MALAT1 and PDCD4 were upregulated in MI mice model and the hypoxia-induced
myocardial cell. Subsequently, loss-of function assays were conducted to examine the
impacts of MALAT1 or PDCD4 on cellular processes. Results of MTT assay and flow cytometry
analyses manifested that knockdown of MALAT1 or PDCD4 enhanced cell viability, promoted
cell cycle progress and suppressed cell apoptosis. Transferase-mediated dUTP nick
end labeling (TUNEL) assay revealed that MALAT1 knockdown or PDCD4 knockdown decreased
cell apoptosis in MI mice model. Subsequently, mechanism experiments revealed that
microRNA-200a-3p (miR-200a-3p) could bind to either MALATA1 or PDCD4. Combining with
the cytoplasmic location of MALAT1, we confirmed that MALAT1 acted as a competing
endogenous RNA (ceRNA) to upregulate PDCD4 by sponging miR-200a-3p. Finally, rescue
assay suggested that MALAT1-miR-200a-3p-PDCD4 axis regulated the proliferation, cell
cycle progression and apoptosis of hypoxia-induced myocardial cells.