Down-regulating GRP78 reverses pirarubicin resistance of triple negative breast cancer by miR-495-3p mimics and involves the p-AKT/mTOR pathway

Abstract

Due to the lack of known therapeutic targets for triple-negative breast cancer (TNBC), chemotherapy is the only available pharmacological treatment. Pirarubicin (tetrahydropyranyl Adriamycin, THP) is the most commonly used anthracycline chemotherapy agent. However, TNBC has a high recurrence rate after chemotherapy, and the mechanisms of chemoresistance and recurrence are not entirely understood. To study the chemoresistance mechanisms, we first screened compounds on a pirarubicin-resistant cell line (MDA-MB-231R) derived from MDA-MB-231. The drug resistance index of MDA-MB-231R cells was approximately five times higher than that of MDA-MB-231 cells. MDA-MB-231R cells have higher GRP78 and lower miR-495-3p expression levels than MDA-MB-231 cells. Transfecting MDA-MB-231R cells with a siGRP78 plasmid reduced GRP78 expression, which restored pirarubicin sensitivity. Besides, transfecting MDA-MB-231R cells with miR-495-3p mimics increased miR-495-3p expression, which also reversed pirarubicin chemoresistance. Cell counting kit-8 (CCK-8), EdU, wound healing and Transwell assays showed that the miR-495-3p mimics also inhibited cell proliferation and migration. Based on our results, miR-495-3p mimics could down-regulate GRP78 expression viathe p-AKT/mTOR signaling pathway in TNBC cells. Remarkably, chemo-resistant and chemo-sensitive TNBC tissues had opposite trends in GRP78 and miR-495-3p expressions. The lower the GRP78 and the higher the miR-495-3p expression, the better prognosis in TNBC patients. Therefore, the mechanism of pirarubicin resistance might involve the miR-495-3p/GRP78/Akt axis, which would provide a possible strategy for treating TNBC.

The landscape of exosomal non-coding RNAs in breast cancer drug resistance, focusing on underlying molecular mechanisms

“…MiRNAs are considered to be central to the regulation of genes linked to BC drug resistance ( Fu and Tong, 2020 ; Purwanto et al, 2021 ; Liu et al, 2022 ). Several mechanisms modulated by miRNAs have been recognized in relation to BC chemoresistance; targeting genes involved in drug efflux and metabolism; cellular responses to chemotherapeutics (e.g., apoptosis, cell cycle arrest, and DNA repair); epigenetic alterations (e.g., DNA methylation and histone modifications); and deregulation of drug targets and receptors, which are the best examples in the field ( Kutanzi et al, 2011 ).…”

“…MiR-1246 has been reported to be overexpressed in human BC cells, particularly metastatic BC MDA-MB-231 cells (ER-negative). Exosomes derived from drug-resistant MDA-MB-231 cells can reduce apoptosis and promote the migration, invasion, and resistance to DOC, epirubicin ( Liu et al, 2022 ), and gemcitabine (GEM) in non-malignant cells through transferring the aforementioned miRNA, i.e., miR-1246, leading to suppression of Ccng2 gene expression ( Sakha et al, 2016 ; Zhong et al, 2016 ; Li et al, 2017a ). Ccng2 , as a tumor suppressor gene, has a close relationship with cell cycle, DNA damage, and p53-related pathways ( Bates et al, 1996 ; Montagner et al, 2012 ; Chang et al, 2015 ; Zimmermann et al, 2016 ).…”

New progresses on cell surface protein HSPA5/BiP/GRP78 in cancers and COVID-19

“…Salidroside, an extract from Rhodiola roots (molecular formula: C 14 H 20 O 7 ), was reported to suppress the activation of NPC cells by targeting the axis of miR-4262/HSPA5 ( 43 ). In addition, down-regulating HSPA5 was reported to reverse pirarubicin resistance in TNBC through the pathway of p-AKT/mTOR and the mimics of miR-495-3p ( 44 ).…”

Modulation of AKT Pathway-Targeting miRNAs for Cancer Cell Treatment with Natural Products

“…Several miRNAs show ER stress-modulating effects in cancer cells ( Table 1 ). miR-495-3p mimics suppress the expression of ER chaperone GRP78 and inhibit the proliferation and migration of breast cancer (MDA-MB-231) cells, reducing pirarubicin resistance by inactivating AKT expression, which is reversed by miR-495-3p inhibition [ 56 ]. Although studies on the targeting of ER stress-associated AKT by miRNAs are rare ( Table 1 ), the literature on ER stress-associated AKT effectors targeted by various miRNAs is discussed later ( Section 3.3 ).…”