The inhibition of circular RNA circNOLC1 by propofol/STAT3 attenuates breast cancer stem cells function via miR-365a-3p/STAT3 signaling

Background Breast cancer remains one of the most dreadful female malignancies globally, in which cancer stem cells (CSCs) play crucial functions. Circular RNAs have drawn great attention in cancer research area and propofol is a widely applied intravenous anesthetic agent. Methods: In the current study, we explored the function of circular RNA nucleolar and coiled-body phosphoprotein 1 (circNOLC1) in CSCs of breast cancer and the inhibitory impact of propofol on circNOLC1. Results The expression of circNOLC1 was induced in breast cancer tissues compared with the non-tumor tissues. The silencing of circNOLC1 was able to repress the viability of breast cancer cells. Meanwhile, the numbers of colony formation were suppressed by circNOLC1 knockdown in breast cancer cells. The inhibition of circNOLC1 reduced the invasion and migration ability of breast cancer cells. The mRNA and protein levels of E-cadherin were enhanced but Vimentin levels were reduced by the silencing of circNOLC1. The repression of circNOLC1 decreased the side population (SP) ratio in breast cancer cells. Meanwhile, the sphere formation ability of breast cancer cells was attenuated by the silencing of circNOLC1. The levels of ATP-binding cassette (ABC) superfamily G member 2 (ABCG2), c-Myc, B cell-specific Moloney murine leukemia virus integration site 1 (Bmi1), and SRY-box transcription factor 2 (Sox2) were repressed by the depletion of circNOLC1 in the cells. Regarding to the mechanism, circNOLC1 functioned as a competing endogenous RNAs (ceRNAs) for microRNA-365a-3p (miR-365a-3p) and the inhibition of miR-365a-3p rescued circNOLC1 depletion-repressed proliferation and cancer stem cell activity of breast cancer. MiR-365a-3p targeted signal transducer and activator of transcription 3 (STAT3) in breast cancer cells and circNOLC1 enhanced STAT3 expression by sponging miR-365a-3p. The overexpression of STAT3 could reverse miR-365a-3p or circNOLC1 depletion-inhibited proliferation and cancer stem cell properties of breast cancer. Interestingly, the expression of circNOLC1 and STAT3 was repressed by the treatment of propofol. The enrichment of STAT3 on circNOLC1 promoter was inhibited by propofol. The expression of circNOLC1 was suppressed by the silencing of STAT3 in the cells. The inhibition of circNOLC1 expression by propofol was rescued under the co-treatment of STAT3 overexpression. The overexpression of circNOLC1 rescued propofol-attenuated proliferation and cancer stem cell functions in vitro and in vivo. Conclusions Thus, we concluded that circNOLC1 contributes to CSCs properties and progression of breast cancer by targeting miR-365a-3p /STAT3 axis and propofol inhibited circNOLC1 by repressing STAT3 in a feedback mechanism.

Atypical chemokine receptor 3 (ACKR3) induces the perturbation of rRNA biogenesis in colonic cells: a novel mechanism of colorectal tumorigenesis

Background Atypical chemokine receptor 3 (ACKR3) has emerged as a key player in several biologic processes. Its atypical “intercepting receptor” signaling properties have established ACKR3 as the main regulator in many pathophysiological processes. In this study, we investigated the mechanisms of ACKR3 in promoting Colitis and colorectal tumorigenesis. Methods ACKR3 and clinically relevant was evaluated in human colonic cancer specimens. The mechanism of ACKR3-induced perturbation of rRNA biogenesis was performed in Villin-ACKR3-IREF mice specifically expressed ACKR3 in intestines. Nuclear β-arr1 and the interaction of NOLC1 to Fibrillarin were analyzed in vitro and in vivo assays. Results Activation of ACKR3 promotes Colitis and colorectal tumorigenesis, in human and animal model, through NOLC1-induced perturbations of rRNA biogenesis. Human colonic cancer tissues demonstrated higher expression of ACKR3, and high ACKR3 expression was associated with the increased severity of Colitis and colorectal tumorigenesis. Villin-ACKR3 transgenic mice demonstrated the characteristics of ACKR3-induced colorectal cancer, showing the nuclear β-arrestin-1-activated perturbation of rRNA biogenesis. Activation of ACKR3 induced nuclear translocation of β-arrestin-1 (β-arr1), leading to the interaction of β-arr1 with nucleolar and coiled-body phosphoprotein 1 (NOLC1). As the highly phosphorylated protein in the nucleolus, NOLC1 further interacted with Fibrillarin, a conserved nucleolar methyltransferase responsible for ribosomal RNA methylation, leading to the increase of methylation in Histone H2A, resulting in the promotion of rRNA transcription of ribosome biogenesis. Conclusion ACKR3 promotes Colitis and colorectal tumorigenesis through the perturbation of rRNA biogenesis by nuclear β-arr1-induced interaction of NOLC1 with Fibrillarin.

ACKR3 induces the perturbation of rRNA biogenesis: a novel mechanism of colorectal tumorigenesis

Atypical chemokine receptor 3 (ACKR3) has emerged as a key player in several biologic processes. However, much less is known the underlying mechanisms of ACKR3 in promoting tumorigenesis. We found, in human and animal model, that activation of ACKR3 promotes colorectal tumorigenesis through the NOLC1-induced perturbations of rRNA biogenesis. As compared with non-neoplastic tissue, human colonic cancer tissues demonstrated higher expression of ACKR3, and high ACKR3 expression was associated with increased severity of colonic cancer. Villin-ACKR3 transgenic mice demonstrated the characteristics of ACKR3-induced colorectal cancer, showing nuclear β-arrestin-1-activated perturbation of rRNA biogenesis. Activation of ACKR3 induced nuclear translocation of β-arrestin-1 (β-arr1), leading to the interaction of β-arr1 with nucleolar and coiled-body phosphoprotein 1 (NOLC1). As the highly phosphorylated protein in the nucleolus, NOLC1 further interacted with Fibrillarin, a highly conserved nucleolar methyltransferase responsible for ribosomal RNA methylation, leading to the increase of methylation in Histone H2A, resulting in the promotion of rRNA transcription of ribosome biogenesis. Conclusion: ACKR3 promotes colorectal tumorigenesis through the perturbation of rRNA biogenesis by nuclear β-arr1-induced interaction of NOLC1 with Fibrillarin.

A Zic2/Runx2/NOLC1 signaling axis mediates tumor growth and metastasis in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignancies with rapid growth and high metastasis, but lacks effective therapeutic targets. Here, using public sequencing data analyses, quantitative real-time PCR assay, western blotting, and IHC staining, we characterized that runt-related transcription factor 2 (Runx2) was significantly upregulated in ccRCC tissues than that in normal renal tissues, which was associated with the worse survival of ccRCC patients. Overexpression of Runx2 promoted malignant proliferation and migration of ccRCC cells, and inversely, interfering Runx2 with siRNA attenuates its oncogenic ability. RNA sequencing and functional studies revealed that Runx2 enhanced ccRCC cell growth and metastasis via downregulation of tumor suppressor nucleolar and coiled-body phosphoprotein 1 (NOLC1). Moreover, increased Zic family member 2 (Zic2) was responsible for the upregulation of Runx2 and its oncogenic functions in ccRCC. Kaplan–Meier survival analyses indicated that ccRCC patients with high Zic2/Runx2 and low NOLC1 had the worst outcome. Therefore, our study demonstrates that Zic2/Runx2/NOLC1 signaling axis promotes ccRCC progression, providing a set of potential targets and prognostic indicators for patients with ccRCC.

CircNOLC1 promotes epithelial ovarian cancer tumorigenesis and progression by binding ESRP1 and modulating CDK1 and RhoA expression

Background: Circular RNAs (circRNAs) play important roles in cancer tumorigenesis and progression, and could represent prognostic biomarkers and therapeutic targets. Herein, we demonstrated the role of circNOLC1 in epithelial ovarian cancer (EOC). Methods: CircNOLC1 expression was quantified in ovarian cancer tissues and normal ovarian tissues using quantitative real-time reverse transcriptase. After circNOLC1 overexpression or downregulation using a circNOLC1 overexpression plasmid or circNOLC1 short hairpin RNA (shRNA) transfection, respectively, ovarian cancer cell phenotypes and molecular mechanisms were examined in vivo and in vitro. Results: Circ-NOLC1 expression was higher in EOC tissues than in normal tissues, and was positively associated with FIGO stage, differentiation. Among ovarian cancer cell lines, circ-NOLC1 expression was highest in A2780, and lowest in CAOV3. Overexpression of circ-NOLC1 in CAOV3 cells increased cell proliferation, migration, and invasion, while silencing of circ-NOLC1 in A2780 cells had the opposite effect: however, neither circ-NOLC1 downregulation nor overexpression influenced nucleolar and coiled-body phosphoprotein 1 ( NOLC1 ) mRNA expression. In nude mice with subcutaneous tumors, circ-NOLC1 downregulation decreased tumor growth . Bioinformatic analysis and RNA binding protein immunoprecipitation showed that circNOLC1 could bind to epithelial splicing regulatory protein 1 (ESRP1). In addition, circ-NOLC1 overexpression significantly increased ESRP1 protein levels, and those of ras homolog family member A (RhoA) and cyclin dependent kinase 1 (CDK1); circNOLC1 downregulation had the opposite effects. The tumor-promoting effect of circNOLC1 was inhibited by knockdown of ESRP1 expression in circ-NOLC1 overexpressing cells, which might act by modulating RhoA and CDK1 expression. Conclusion: CircNOLC1 might promote EOC tumorigenesis and development by binding ESRP1 and modulating CDK1 and RhoA expression.