Cucurbitacin B enhances apoptosis in gefitinib resistant non‑small cell lung cancer by modulating the miR‑17‑5p/STAT3 axis

Abstract

Tyrosine kinase inhibitors, such as gefitinib, are currently widely used as targeted therapeutics for non-small cell lung cancer (NSCLC). Although drug resistance has become a major obstacle to successful treatment, mechanisms underlying resistance to gefitinib remain unclear. Therefore, the present study aimed to investigate the impact of adjunctive cucurbitacin B (CuB) on gefitinib resistance (GR) in the PC9 cell line, including identifying underlying mechanisms. Reverse transcription-quantitative PCR demonstrated significant downregulation of microRNA (miR)-17-5p expression in GR PC9 cells (PC9/GR), and this could be reversed by CuB. During combination treatment with CuB and gefitinib at IC 25 , PC9/GR cell proliferation was downregulated, and apoptosis was upregulated. The presence of a miR-17-5p inhibitor negated the effects of CuB and gefitinib, whereas the presence of a miR-17-5p mimic enhanced them. Luciferase assays demonstrated that the hypothetical target gene, signal transducer and activator of transcription 3 ( STAT3 ), was directly targeted by miR-17-5p. Moreover, significant elevation of the STAT3 protein and phosphorylation levels in PC9/GR cells was reversed by the addition of CuB, despite a lack of change in STAT3 transcription level. During combined treatment with CuB and gefitinib at IC 25 , the STAT3 protein expression was negatively associated with the expression of miR-17-5p. Overexpression of STAT3 increased proliferation and decreased apoptosis and the protein levels of apoptosis-related factors cleaved caspase-3 and cleaved caspase-9 of PC9/GR cells. Findings indicated that STAT3 protein and phosphorylation levels became elevated in response to gefitinib, and that CuB-induced miR-17-5p expression led to STAT3 degradation, thereby ameliorating GR. In summary, CuB reduced the proliferation of GR PC9 cells by modulating the miR-17-5p/STAT3 axis, and may represent a promising potential novel strategy for the reversal of GR.

A Systematic Review of Progress toward Unlocking the Power of Epigenetics in NSCLC: Latest Updates and Perspectives

“…Liu et al demonstrated that CuB regulated cell proliferation and apoptosis by suppressing the XIST/miR-let-7c/IL-6/STAT3 axis in NSCLC [ 132 ]. Similarly, Yu et al showed that CuB reduced the proliferation of gefitinib-resistant PC9 cells by modulating the miR-175p/STAT3 axis [ 133 ], while Yuan et al highlighted the inhibition of epithelial–mesenchymal transition (EMT) in TGF-β1 -induced A549 cells and gefitinib-resistant A549 cells via a decrease in ROS production and disruption of the PI3K/Akt/mTOR signaling pathway [ 134 ]. Furthermore, Liu et al found that CuB suppressed the growth and invasion of gefitinib-resistant NSCLC cells by inducing lysosomal EGFR degradation and by downregulating the CIP2A/PP2A/Akt signaling axis [ 135 ].…”

Protein phosphatase 2A modulation and connection with miRNAs and natural products

“…Natural products ( 116 Furthermore, sucurbitacin B inhibits proliferation and triggers apoptosis of gefitinib-resistant lung cancer cells by upregulating miR-17-5p. 117 Resveratrol suppresses LPS-triggered injury in keratinocytes by upregulating miR-17-5p. 118 In contrast, miR-17-5p is downregulated by retinoic acid in acute myeloid leukemia cells, 119 promoting the neuronal differentiation of neuroblastoma cells (Table 4).…”

“…Celastrol suppresses vascular endothelial growth factor (VEGF)‐promoted proliferation and migration, and inhibits hypoxia‐triggered angiogenesis in HRMEC cells by upregulating miR‐17‐5p 116 . Furthermore, sucurbitacin B inhibits proliferation and triggers apoptosis of gefitinib‐resistant lung cancer cells by upregulating miR‐17‐5p 117 . Resveratrol suppresses LPS‐triggered injury in keratinocytes by upregulating miR‐17‐5p 118 .…”

“…Some PP2A‐activating natural products, such as arctigenin, forskolin, and rutin, downregulate miR‐21‐5p 132 miR‐142‐3p 107 and miR‐200c‐3p, 128 respectively (Figure 4). Similarly, PP2A‐inhibiting natural product geniposide downregulates miR‐21‐5p 135 For comparison, PP2A‐activating natural product, cucurbitacin B, upregulates miR‐17‐5p 117 and miR‐29b‐3p 139 . PP2A‐inhibiting natural product, ursolic acid, upregulates miR‐141‐3p 106 and let‐7b‐5p 97 …”

The Effect of Terpenoid Natural Chinese Medicine Molecular Compound on Lung Cancer Treatment

“…In addition, the semisynthetic derivative of CuB, DACE (2-deoxy-2-amine-cucurbitacin E), and paclitaxel (PTX) showed potential in vitro synergistic antiproliferative effects in A549 cells [ 99 ]. In addition, CuB can reduce the proliferation of gefitinib-resistant (GR) PC9 cell lines by regulating the miR-17-5p/STAT3 axis [ 100 ].…”