YBX1/lncRNA SBF2-AS1 interaction regulates proliferation and tamoxifen sensitivity via PI3K/AKT/MTOR signaling in breast cancer cells.

Y-box binding protein 1 (YBX1) is a multifunctional oncoprotein that can interact with several long non-coding RNAs (lncRNAs) to regulate metastasis in malignancies including breast cancer (BC). In the present study, we demonstrated the association of YBX1 with oncogenic lncRNA SBF2-AS1 (SET-binding factor 2 antisense RNA 1) via PI3K/AKT/mTOR signaling to regulate BC cell proliferation. We further explored the involvement of the YBX1/SBF2-AS1/PI3K/AKT/mTOR axis in the restoration of tamoxifen (TAM) sensitivity. YBX1-SBF2-AS1 association was predicted in silico and verified by RNA immunoprecipitation (RIP)-qPCR assay. Transfection experiments, Real-time RT PCR, Western blots, Phospho AKT/mTOR antibody array kit, and cell proliferation/apoptosis assays were employed to detect the YBX1/SBF2-AS1/ PI3K/AKT/mTOR axis and its effects upon TAM treatment in vitro. We identified that the YBX1 protein specifically binds to lncRNA SBF2-AS1. Our transfection experiments in MCF-7 and MDA-MB-468 cells with SBF2-AS1 silenced or overexpressed YBX1 plasmids, and their negative controls revealed that YBX1 regulates the expression of SBF2-AS1 by forming a positive feedback loop for its activation. We further demonstrated YBX1-SBF2-AS1 association exerts its effects on cell proliferation via PI3K/AKT/mTOR signaling pathway. Furthermore, we observed an increase in TAM sensitivity in BC cells after the knockdown of YBX1-SBF2-AS1 marked by decreased cell proliferation through disruption of the PI3K/AKT/mTOR axis. Our study has identified a novel YBX1/SBF2-AS1/PI3K/AKT/mTOR regulatory axis which may serve as a potential target to improve the effectiveness and efficacy of TAM treatment in BC.

Hussain SA ，Venkatesh T 《-》

Inhibitory role of large intergenic noncoding RNA-ROR on tamoxifen resistance in the endocrine therapy of breast cancer by regulating the PI3K/Akt/mTOR signaling pathway.

Breast cancer (BC) is the second-leading cause of central nervous system metastases among severe malignancies. This study aimed at investigating the underlying mechanism by which large intergenic noncoding RNA-regulator of reprogramming (lincRNA-ROR) affects the tamoxifen (TAM) resistance of BC cells by regulating the PI3K/Akt/mTOR signaling pathway. Immortalized human mammary epithelial cell line (MCF10A) and BC cell lines (MCF-7, MDA-MB-231, T47D, BCAP-37, and ZK-75-1) were cultured, and BC tissues and adjacent normal breast tissues were collected from 152 BC patients. LincRNA-ROR expression in tissues and cells were detected using reverse transcription quantitative polymerase chain reaction. RNA interference was used to silence lincRNA-ROR in MDA-MB-231 cells, and then the cell proliferation and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and annexin-V and propidium iodide (PI) double staining respectively. The expression of apoptosis-related proteins and PI3K/Akt/mTOR signaling pathway-related proteins was measured by performing western blot assay. The BC tissues and cells presented a higher expression of lincRNA-ROR. MAD-MB-231 cells exhibited the highest lincRNA-ROR expression. After lincRNA-ROR silencing, MAD-MB-231 cells showed decreased proliferation, and increased sensitivity to TAM. Besides, the apoptosis-promoting effect of TAM on MAN-MB-231 cells significantly increased. The expression of PI3K/Akt/mTOR signaling pathway-related proteins and the PI3K/Akt/mTOR signaling pathway were repressed by TAM after silencing lincRNA-ROR. Our study demonstrated that silencing lincRNA-ROR could increase the sensitivity of BC MAD-MB-231 cells to TAM by suppressing the activation of P13K/Akt/mTOR signaling pathway.

Lu PW ，Li L ，Wang F ，Gu YT ... -  《-》

Downregulation of lncRNA ZEB1-AS1 Represses Cell Proliferation, Migration, and Invasion Through Mediating PI3K/AKT/mTOR Signaling by miR-342-3p/CUL4B Axis in Prostate Cancer.

Ma T ，Chen H ，Wang P ，Yang N ，Bao J ... -  《-》

LncRNA TP73-AS1 Promotes Cell Proliferation and Inhibits Cell Apoptosis in Clear Cell Renal Cell Carcinoma Through Repressing KISS1 Expression and Inactivation of PI3K/Akt/mTOR Signaling Pathway.

Emerging evidence suggests that long non-coding RNAs (lncRNAs) play a vital regulatory role in the pathogenesis and progression of renal cell carcinoma (RCC). We aim to determine lncRNA profiles in clear cell RCC (ccRCC) and investigate key lncRNAs involved in ccRCC tumorigenesis and progression. RNA sequencing technique and qPCR were used to determine the candidate lncRNAs in ccRCC tissues. The correlations between lncRNA P73 antisense RNA 1T (TP73-AS1) levels and survival outcomes were analyzed to elucidate its clinical significance. The underlying mechanisms of TP73-AS1 in ccRCC were analyzed through in vitro functional assays. We found TP73-AS1 was upregulated in 40 ccRCC tissues compared with adjacent normal renal tissues and increased TP73-AS1 was correlated to aggressive clinicopathologic features and unfavorable prognosis. Knockdown of TP73-AS1 suppressed cell proliferation, invasion and induced cell apoptosis. We also identified KISS-1 metastasis-suppressor (KISS1) was significantly upregulated in TP73-AS1 knockdown cells. Further, we revealed that TP73-AS1 suppressed KISS1 expression through the interaction with Enhancer of zeste homolog 2 (EZH2) and the specific binding to KISS1 gene promoter region. Knockdown of KISS1 partly reversed TP73-AS1 knockdown-induced inhibition of cell proliferation and promotion of apoptosis. We further determined that TP73-AS1 knockdown activated PI3K/Akt/mTOR signaling pathway, while overexpression of TP73-AS1 induced inhibition of PI3K/Akt/mTOR pathway and these effects could be partly abolished by overexpression of KISS1. In conclusion, we identified that TP73-AS1 as an oncogenic lncRNA in the development of ccRCC and a potential target for human renal carcinoma treatment.

Liu G ，Zhao X ，Zhou J ，Cheng X ，Ye Z ，Ji Z ... -  《-》

LncRNA MALAT1 Expression Regulates Breast Cancer Progression via PI3K/AKT/mTOR Pathway Modulation.

Naveed M ，Malik A ，Anjum H ，Ijaz B ... -  《-》