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Abstract
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Abstract
In terms of primary brain tumors, glioblastoma is one of the most aggressive and common brain tumors. The high resistance of
glioblastoma to chemotherapy has made it vital to find alternative treatments and biological mechanisms to reduce the survival
of cancer cells. Given that, the objective of the present research was to explore the potential of let-7a-3p when used in combina-
tion with carmustine in human glioblastoma cancer cells. Based on previous studies, the expression of let-7a is downregulated
in the U87MG cell line. Let-7a-3p transfected into U87MG glioblastoma cells. Cell viability of the cells was assessed by MTT
assay. The apoptotic induction in U87MG cancerous cells was determined through the utilization of DAPI and Annexin V/PI
staining techniques. Moreover, the induction of autophagy and cell cycle arrest was evaluated by flow cytometry. Furthermore,
cell migration was evaluated by the wound healing assay while colony formation assay was conducted to evaluate colony for-
mation. Also, the expression of the relevant genes was evaluated using qRT-PCR. Transfection of let-7a-3p mimic in U87MG
cells increased the expression of the miRNA and also increased the sensitivity of U87MG cells to carmustine. Let-7a-3p and
carmustine induced sub-G1 and S phase cell cycle arrest, respectively. Combination treatment of let-7a-3p and carmustine syner-
gistically increased arrested cells and induced apoptosis through regulating involved genes including P53, caspase-3, Bcl-2, and
Bax. Combined treatment with let-7a-3p and carmustine also induced autophagy and increased the expression of the ATG5 and
Beclin 1 (ATG6). Furthermore, let-7a-3p combined with carmustine inhibited cell migration via decreasing the expression of
MMP-2. Moreover, the combination therapy decreased the ability of U87MG to form colonies through downregulating CD-44.
In conclusion, our work suggests that combining let-7a-3p replacement therapy with carmustine treatment could be considered
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