The RNA-binding protein QKI suppresses tumorigenesis of clear cell renal cell carcinoma by regulating the expression of HIF-1α

Hypoxia-induced miR-5100 promotes exosome-mediated activation of cancer-associated fibroblasts and metastasis of head and neck squamous cell carcinoma

The invasion-metastasis cascade in head and neck squamous cell carcinoma (HNSCC) is predominantly caused by the interaction between tumor cells and tumor microenvironment, including hypoxia as well as stromal cells. However, the mechanism of hypoxia-activated tumor-stroma crosstalk in HNSCC metastasis remains to be deciphered. Here, we demonstrated that HIF1α was upregulated in HNSCC specimens compared with adjacent normal tissues, whose overexpression was associated with lymph node metastasis and predicted unfavorable prognosis. HIF1α expression correlated positively with the levels of miR-5100 as well as α-SMA, the marker of CAFs. Hypoxia/HIF1α regulated transcriptionally miR-5100 to promote the degradation of its target gene QKI, which acts as a tumor suppressor in HNSCC. Hypoxic HNSCC-derived exosomal miR-5100 promoted the activation of CAFs by orchestrating QKI/AKT/STAT3 axis, which further facilitated HNSCC metastasis. Additionally, miR-5100 derived from plasma exosomes indicated HNSCC malignant progression. In conclusion, our findings illuminate a novel HIF1α/miR-5100/QKI pathway in HNSCC metastasis, and suggest that miR-5100 might be a potential biomarker and therapeutic target for HNSCC.

Non-adherent culture method affects the proliferation and apoptosis of mesenchymal stem cells through inhibiting LINC00707 to promote RNF6-mediated QKI ubiquitination

Exploration of the molecular mechanisms of mesenchymal stem cell (MSC) growth has significant clinical benefits. Long non-coding RNAs (lncRNAs) have been reported to play vital roles in the regulation of the osteogenic differentiation of MSCs. However, the mechanism by which lncRNA affects the proliferation and apoptosis of MSCs is unclear. In this study, sequencing analysis revealed that LINC00707 was significantly decreased in non-adherent human MSCs (non-AC-hMSCs) compared to adherent human MSCs. Moreover, LINC00707 overexpression promoted non-AChMSC proliferation, cell cycle progression from the G0/G1 phase to the S phase and inhibited apoptosis, whereas LINC00707 silencing had the opposite effect. Furthermore, LINC00707 interacted directly with the quaking (QKI) protein and enhanced the E3 ubiquitin-protein ligase ring finger protein 6 (RNF6)-mediated ubiquitination of the QKI protein. Additionally, the overexpression of QKI rescued the promotive effects on proliferation and inhibitory effects on apoptosis in non-AC-hMSCs induced by the ectopic expression of LINC00707. Thus, LINC00707 contributes to the proliferation and apoptosis in non-AChMSCs by regulating the ubiquitination and degradation of the QKI protein.

FOXP3-regulated lncRNA NONHSAT136151 promotes colorectal cancer progression by disrupting QKI interaction with target mRNAs

The role of lncRNAs in the pathogenesis of cancer, including colorectal cancer (CRC), has repeatedly been demonstrated. However, very few lncRNAs have been well annotated functionally. Our study identified a novel lncRNA upregulated in CRC, NONHSAT136151, which was correlated with clinical progression. In functional assays, NONHSAT136151 significantly enhanced CRC cell proliferation, migration and invasion. Mechanistically, NONHSAT136151 interacted with RNA-binding protein (RBP) QKI (Quaking) to interfere with QKI binding to target mRNAs and regulate their expression. As well, FOXP3 may be causally related to the dysregulation of NONHSAT136151 in CRC cells through its transcriptional activity. In conclusion, our findings identified a novel lncRNA regulated by FOXP3 participates in CRC progression through interacting with QKI, indicating a novel lncRNA-RBP interaction mechanism is involved in CRC pathogenesis.

Epigenetic Regulation in Chromium-, Nickel- and Cadmium-Induced Carcinogenesis

Environmental and occupational exposure to heavy metals, such as hexavalent chromium, nickel, and cadmium, are major health concerns worldwide. Some heavy metals are well-documented human carcinogens. Multiple mechanisms, including DNA damage, dysregulated gene expression, and aberrant cancer-related signaling, have been shown to contribute to metal-induced carcinogenesis. However, the molecular mechanisms accounting for heavy metal-induced carcinogenesis and angiogenesis are still not fully understood. In recent years, an increasing number of studies have indicated that in addition to genotoxicity and genetic mutations, epigenetic mechanisms play critical roles in metal-induced cancers. Epigenetics refers to the reversible modification of genomes without changing DNA sequences; epigenetic modifications generally involve DNA methylation, histone modification, chromatin remodeling, and non-coding RNAs. Epigenetic regulation is essential for maintaining normal gene expression patterns; the disruption of epigenetic modifications may lead to altered cellular function and even malignant transformation. Therefore, aberrant epigenetic modifications are widely involved in metal-induced cancer formation, development, and angiogenesis. Notably, the role of epigenetic mechanisms in heavy metal-induced carcinogenesis and angiogenesis remains largely unknown, and further studies are urgently required. In this review, we highlight the current advances in understanding the roles of epigenetic mechanisms in heavy metal-induced carcinogenesis, cancer progression, and angiogenesis.

Increased expression of the RNA-binding protein Musashi-2 is associated with immune infiltration and predicts better outcomes in ccRCC patients

RNA-binding proteins (RBPs) mainly contribute to abnormalities in posttranscriptional gene regulation. The RBP Musashi-2, an evolutionarily conserved protein, has been characterized as an oncoprotein in various tumors. However, the prognostic value and potential roles of Musashi-2 in clear cell renal cell carcinoma (ccRCC) have not yet been elucidated. In this study, we found that Musashi-2 was mainly expressed in the normal distal tubular cells and collecting duct cells of the kidneys, while its expression was significantly decreased in ccRCC. And higher expression levels of Musashi-2 indicated better overall survival (OS) in ccRCC. Furthermore, immunohistochemistry demonstrated that PD-L1 expression was negatively correlated with Musashi-2 expression, and Musashi-2 was found to be remarkably correlated with multiple immune cells and immune inhibitors, including CD8+ T cells, CD4+ T cells, regulatory T (Treg) cells, PDCD1, CTLA4, Foxp3, and LAG3. Functional enrichment analysis revealed that Musashi-2 might be involved in ccRCC metabolic reprogramming and immune infiltration and further predicted the therapeutic sensitivity of ccRCC. Taken together, Musashi-2 is a prognostic biomarker for ccRCC patients that may provide novel insights into individualized treatment strategies and guide effective immunotherapy.

QKI-6 Suppresses Cell Proliferation, Migration, and EMT in Non-Small Cell Lung Cancer

The RNA-binding protein quaking homolog 6 (QKI-6) is a tumor-suppressor gene in several cancers. However, its role in non-small cell lung cancer (NSCLC) is unclear. In this study, we aimed to determine the association between QKI-6 expression and survival and clinicopathological features in patients with NSCLC and identify the related mechanisms. Western blot and immunohistochemistry (IHC) were used to detect QKI-6 expression in NSCLC. The effect of QKI-6 on NSCLC cells was determined by overexpression and knockdown assays, and label-free quantitative proteomics and Western blot were used to identify the underlying mechanisms. Low QKI-6 expression level was positively correlated with poor overall survival in patients with NSCLC. Furthermore, QKI-6 overexpression inhibited NSCLC cell proliferation and migration and induced a block in the G0/G1 phase, and QKI-6 downregulation increased proliferation and migration. QKI-6 inhibited EMT processes via EGFR/SRC/STAT3 signaling by upregulating AGR2. In conclusion, QKI-6 could be used to develop novel strategies for the treatment of NSCLC.

Dysregulated expression and functions of microRNA-330 in cancers: A potential therapeutic target

As small non-coding RNAs, MicroRNAs (miRNAs) bind to the 3' untranslated region (3'-UTR) of mRNA targets to control gene transcription and translation. The gene of miR-330 has two miRNA products, including miR-330-3p and miR-330-5p, which exhibit anti-tumorigenesis and/or pro-tumorigenesis effects in many kinds of malignancies. In cancers, miR-330-3p and miR-330-5p aberrant expression can influence many malignancy-related processes such as cell proliferation, migration, invasion, apoptosis and epithelial-mesenchymal transition, as well as angiogenesis and responsiveness to treatment. In many cancer types (such as lung, prostate, gastric, breast, bladder, ovarian, colorectal, and pancreatic cancer, and osteosarcoma), miR-330-5p acts as an anti-tumor agent. These cancers have low levels of miR-330-5p that leads to the upregulation of the tumor promotor target genes leading to tumor progression. Here, overexpression of miR-330-5p using miRNA inducers can prevent tumor development. Dual roles of miR-330-5p have been also indicated in the thyroid, liver and cervical cancers. Moreover, miR-330-3p exhibits pro-tumorigenesis effects in lung cancer, pancreatic cancer, osteosarcoma, bladder cancer, and cervical cancer. Here, downregulation of miR-330-3p using miRNA inhibitors can prevent tumor development. Demonstrated in breast and liver cancers, miR-330-3p also has dual roles. Importantly, the activities of miR-330-3p and/or miR-330-5p are regulated by upstream regulators long non-coding RNAs (lncRNAs), including circular and linear lncRNAs. This review comprehensively explained miR-330-3p and miR-330-5p role in development of cancers, while highlighting their downstream target genes and upstream regulators as well as possible therapeutic strategies.

QKI-Regulated Alternative Splicing Events in Cervical Cancer: Pivotal Mechanism and Potential Therapeutic Strategy

QKI is a vital regulator in RNA splicing and maturation, but its role in cervical cancer (CC) is little known. In this study, we found that QKI is decreased in human CC, and overexpression of QKI inhibits HeLa cell proliferation and promotes the apoptosis of cancer cells. We identified hundreds of endogenous QKI-regulated alternative splicing events (ASEs) and differentially expressed genes (DEGs) in QKI-overexpressed HeLa cells by RNA-seq and selectively validated their expression by quantitative reverse-transcription polymerase chain reaction. The gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis showed that QKI-regulated ASEs and DEGs were closely related to cancer, apoptosis, and transcriptional regulatory functions. In short, QKI may affect the occurrence and development of CC by regulating gene expression through AS.

NRP1 and MMP9 are dual targets of RNA-binding protein QKI5 to alter VEGF-R/ NRP1 signalling in trophoblasts in preeclampsia

Preeclampsia (PE) is characterized by placental ischemia and hypoxia, resulting in abnormal casting of the uterine spiral artery, which is mainly caused by insufficient trophoblastic cell infiltration. A reduction in levels of growth factor-based signalling via Neuropilin-1 (NRP1) has been shown to contribute to dysfunctional trophoblast development. In this study, we showed that the RNA-binding protein, QKI5, regulated NRP1 expression and significantly improved trophoblast proliferation in vitro and in vivo. QKI5 and NRP1 expressions were significantly reduced in human PE placentas and in trophoblasts during hypoxia. Overexpression of these factors significantly improved cell proliferation and migration in vitro, in contrast to a decrease upon siRNA knockdown of QKI5 and NRP1 in HTR-8/SVneo cells. Using RIP and RNA pull-down assays, we further showed that QKI5 directly interacted with the 3'-UTR region of NRP1, to mediate cell proliferation and migration via matrix metalloprotease-9. Further, similar to NRP1, QKI5 also targets matrix metalloproteinase 9 (MMP9) involved in secretion of growth factors and its effects can be counteracted by NRP1 overexpression. In vivo studies using a PE mouse model revealed that QKI5 overexpression alleviated PE-related symptoms such as elevated blood pressure and proteinuria. Taken together, we found that QKI5 was a novel regulator, of VEGF-R/NRP1 signalling pathway functioning in trophoblast proliferation and migration, resulting in major contributors to the pathogenesis of PE. While careful evaluation of the broad implications of QKI5 expression is still necessary, this study identified QKI5 as a promising target for treatment strategies in acute PE patients.

Dyregulation of the lncRNA TPT1-AS1 positively regulates QKI expression and predicts a poor prognosis for patients with breast cancer

The long noncoding RNA (lncRNA) TPT1-AS1 has been reported to be involved in the development of multiple cancers. However, its clinical value, biological function, and underlying molecular mechanism in breast cancer (BC) remain unclear. In the present study, TPT1-AS1 expression was decreased in BC tissues, based on RNA-seq data download from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and the qRT-PCR results confirmed the above findings. Otherwise, low TPT1-AS1 expression was significantly associated with some clinical features of malignancy, such as high TNM stage, lymph node metastasis, a Her-2-negative status, and shorter overall survival. More importantly, univariate and multivariate Cox regression analyses indicated that TPT1-AS1 is an independent prognostic factor for patients with BC. Overexpression and knockdown of TPT1-AS1 in BC cell lines altered their proliferation, metastasis and invasion, as measured using the cell counting kit-8 (CCK-8) assay, wound-healing assay and transwell assay, respectively. In addition, a dual luciferase activity reporter assay validated that TPT1-AS1 and QKI shared a binding site in miR-330-3p. Based on these findings, TPT1-AS1 potentially represents a prognostic biomarker for patients with BC and participates in the development of BC through the TPT1-AS1/miR-330-3p/QKI axis.

Integrated analysis of the functions of RNA binding proteins in clear cell renal cell carcinoma

RNA binding proteins (RBPs) dysregulation is involved in the processes of various tumors. However, the roles of RBPs in clear cell renal cell carcinoma (ccRCC) remain poorly understand. In present study, we first performed consensus clustering and identified two clusters, of which cluster 2 was closely correlated with the malignancy of ccRCC. Differentially expressed RBPs between normal and tumor tissues were obtained, comprising 71 up-regulated and 44 down-regulated ones. Then, ten hub genes were selected and validated using The Human Protein Atlas database and receiver operating characteristic curves, showing good diagnostic value for cancers. Besides, we identified ten RBPs with the most useful prognostic values, and were used to construct a risk score model. The model could be used to stratify patients with different prognosis and phenotype distributions. The model showed good performance and can be used as a complementation for clinical factors to guide clinical practice in the future.

CAFs-derived MFAP5 promotes bladder cancer malignant behavior through NOTCH2/HEY1 signaling

Cancer-associated fibroblasts (CAFs) are an important component of the tumor microenvironment and contribute to tumor cell proliferation and metastasis. Microfibrillar-associated protein 5 (MFAP5), a component of elastic microfibers and an oncogenic protein in several types of tumors, is secreted by CAFs. However, the role of MFAP5 in the bladder cancer remains unclear. Here, we report that MFAP5 is upregulated in bladder cancer and is associated with poor patient survival. Downregulation of MFAP5 in CAFs led to an impairment in proliferation and invasion of bladder cancer cells. Luciferase reporter assays and electrophoretic mobility shift assays (EMSA) showed QKI directly downregulates MFAP5 in CAFs. In addition, CAFs-derived MFAP5 led to an activation of the NOTCH2/HEY1 signaling pathway through direct interaction with the NOTCH2 receptor, thereby stimulating the N2ICD release. RNA-sequencing revealed that MFAP5-mediated PI3K-AKT signaling activated the DLL4/NOTCH2 pathway axis in bladder cancer. Moreover, downregulation of NOTCH2 by short hairpin RNA or the inactivating anti-body NRR2Mab was able to reverse the adverse effects of MFAP5 stimulation in vitro and in vivo. Together, these results demonstrate CAFs-derived MFAP5 promotes the bladder cancer proliferation and metastasis and provides new insight for targeting CAFs as novel diagnostic and therapeutic strategy.