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Background & Aims Circular RNAs (circRNAs) are a class of endogenous noncoding RNAs that form covalently closed circles. Although circRNAs influence many biological processes, little is known about their role in intestinal epithelium homeostasis. We surveyed circRNAs required to maintain intestinal epithelial integrity and identified circular homeodomain-interacting protein kinase 3 (circHIPK3) as a major regulator of intestinal epithelial repair after acute injury. Methods Intestinal mucosal tissues were collected from mice exposed to cecal ligation and puncture for 48 hours and patients with inflammatory bowel diseases and sepsis. We isolated primary enterocytes from the small intestine of mice and derived intestinal organoids. The levels of circHIPK3 were silenced in intestinal epithelial cells (IECs) by transfection with small interfering RNAs targeting the circularization junction of circHIPK3 or elevated using a plasmid vector that overexpressed circHIPK3. Intestinal epithelial repair was examined in an in vitro injury model by removing part of the monolayer. The association of circHIPK3 with microRNA 29b (miR-29b) was determined by biotinylated RNA pull-down assays. Results Genome-wide profile analyses identified ∼300 circRNAs, including circHIPK3, differentially expressed in the intestinal mucosa of mice after cecal ligation and puncture relative to sham mice. Intestinal mucosa from patients with inflammatory bowel diseases and sepsis had reduced levels of circHIPK3. Increasing the levels of circHIPK3 enhanced intestinal epithelium repair after wounding, whereas circHIPK3 silencing repressed epithelial recovery. CircHIPK3 silencing also inhibited growth of IECs and intestinal organoids, and circHIPK3 overexpression promoted intestinal epithelium renewal in mice. Mechanistic studies revealed that circHIPK3 directly bound to miR-29b and inhibited miR-29 activity, thus increasing expression of Rac1, Cdc42, and cyclin B1 in IECs after wounding. Conclusions In studies of mice, IECs, and human tissues, our results indicate that circHIPK3 improves repair of the intestinal epithelium at least in part by reducing miR-29b availability.

Cancer-associated fibroblasts (CAFs) are the most abundant stromal cell type in the tumor microenvironment. CAFs orchestrate tumor-stromal interactions, and contribute to cancer cell growth, metastasis, extracellular matrix (ECM) remodeling, angiogenesis, immunomodulation, and chemoresistance. However, CAFs have not been successfully targeted for the treatment of cancer. The current study elucidates the significance of glypican-1 (GPC-1), a heparan sulfate proteoglycan, in regulating the activation of human bone marrow-derived stromal cells (BSCs) of fibroblast lineage (HS-5). GPC-1 inhibition changed HS-5 cellular and nuclear morphology, and increased cell migration and contractility. GPC-1 inhibition also increased pro-inflammatory signaling and CAF marker expression. GPC-1 induced an activated fibroblast phenotype when HS-5 cells were exposed to prostate cancer cell conditioned media (CCM). Further, treatment of human bone-derived prostate cancer cells (PC-3) with CCM from HS-5 cells exhibiting GPC-1 loss increased prostate cancer cell aggressiveness. Finally, GPC-1 was expressed in mouse tibia bone cells and present during bone loss induced by mouse prostate cancer cells in a murine prostate cancer bone model. These data demonstrate that GPC-1 partially regulates the intrinsic and extrinsic phenotype of human BSCs and transformation into activated fibroblasts, identify novel functions of GPC-1, and suggest that GPC-1 expression in BSCs exerts inhibitory paracrine effects on the prostate cancer cells. This supports the hypothesis that GPC-1 may be a novel pharmacological target for developing anti-CAF therapeutics to control cancer.

Homeostasis of the intestinal epithelium is tightly regulated by numerous extracellular and intracellular factors including vitamin D and the vitamin D receptor (VDR). VDR is highly expressed in the intestinal epithelium and is implicated in many aspects of gut mucosal pathophysiology, but the exact mechanism that controls VDR expression remains largely unknown. The RNA-binding protein human antigen R (HuR) regulates the stability and translation of target mRNAs and thus modulates various cellular processes and functions. Here we report a novel role of HuR in the posttranscriptional control of VDR expression in the intestinal epithelium. The levels of VDR in the intestinal mucosa decreased significantly in mice with ablated HuR, compared with control mice. HuR silencing in cultured intestinal epithelial cells (IECs) also reduced VDR levels, whereas HuR overexpression increased VDR abundance; neither intervention changed cellular Vdr mRNA content. Mechanistically, HuR bound to Vdr mRNA via its 3′-untranslated region (UTR) and enhanced VDR translation in IECs. Moreover, VDR silencing not only inhibited IEC migration over the wounded area in control cells but also prevented the increased migration in cells overexpressing HuR, although it did not alter IEC proliferation in vitro and growth of intestinal organoids ex vivo. The human intestinal mucosa from patients with inflammatory bowel diseases exhibited decreased levels of both HuR and VDR. These results indicate that HuR enhances VDR translation by directly interacting with its mRNA via 3′-UTR and that induced VDR by HuR is crucial for rapid intestinal epithelial restitution after wounding.

Thyroid cancer incidence is rising worldwide. Although fine-needle aspiration biopsy (FNAB) is an accurate modality for evaluating thyroid nodules, up to 25% of FNABs still yield indeterminate results. There is a considerable number of diagnostic thyroidectomies for benign disease as a result of indeterminate FNAB. A more accurate and time-efficient diagnostic approach for analyzing indeterminate thyroid nodules may reduce diagnostic thyroidectomy. Recently, the osteogenic protein, Enigma, has been associated with different cancer types, including thyroid cancer progression and calcification through its interaction with bone morphogenic protein-1 (BMP-1), and tyrosine kinases linked to mitogenic signaling pathways [1, 2]. Our published data on Enigma protein analysis with immunohistochemistry showed promising results in discriminating between malignant versus benign thyroid nodules and demonstrated a correlation with thyroid cancer staging [3]. In this study, we are investigating Enigma at a gene expression level by real-time (RT-qPCR), which is a quantitative and more time-efficient method that requires smaller samples (FNA) than immunohistochemistry. We analyzed Enigma mRNA expression levels to determine if Enigma-qPCR could be used as a diagnostic tool to improve the accuracy of FNAB in both malignant and benign thyroid tissues. We extracted mRNA/DNA/proteins from fresh malignant and benign thyroid nodules using a QIAGEN DNA/RNA/Protein Kit. We ran isolated pure mRNA through Enigma-qPCR. The results showed that the Enigma-mRNA expression was 3-fold higher in malignant as compared to benign thyroid tissues. This finding supports our previous Enigma immunohistochemistry data and shows a relative quantitative difference in Enigma-mRNA expression level between malignant and benign thyroid nodules. We conclude that Enigma-RT-qPCR can be used to effectively determine malignancies in FNAB samples derived from thyroid nodules. This method could potentially enhance the diagnostic accuracy of indeterminate nodules and decrease diagnostic thyroidectomies and associated morbidity. [1] C.R. Jung, J.H. Lim, Y. Choi, D.G. Kim, K.J. Kang, S.M. Noh, D.S. Im, Enigma negatively regulates p53 through MDM2 and promotes tumor cell survival in mice, The Journal of clinical investigation 120(12) (2010) 4493-506. [2] Y.J. Kim, H.J. Hwang, J.G. Kang, C.S. Kim, S.H. Ihm, M.G. Choi, S.J. Lee, Enigma Plays Roles in Survival of Thyroid Carcinoma Cells through PI3K/AKT Signaling and Survivin, Anticancer research 38(6) (2018) 3515-3525. [3] A.A. Firek, M.C. Perez, A. Gonda, L. Lei, I. Munir, A.A. Simental, F.E. Carr, B.J. Becerra, M. De Leon, S. Khan, Pathologic significance of a novel oncoprotein in thyroid cancer progression, Head & neck 39(12) (2017) 2459-2469.

Charcot-Marie-Tooth 1A (CMT1A) is the most common inherited neuropathy without a known therapy, which is caused by a 1.4 Mb duplication on human chromosome 17, which includes the gene encoding the peripheral myelin protein of 22 kDa (PMP22). Overexpressed PMP22 protein from its gene duplication is thought to cause demyelination and subsequently axonal degeneration in the peripheral nervous system (PNS). Here, we targeted TATA-box of human PMP22 promoter to normalize overexpressed PMP22 level in C22 mice, a mouse model of CMT1A harboring multiple copies of human PMP22. Direct local intraneural delivery of CRISPR/Cas9 designed to target TATA-box of PMP22 before the onset of disease, downregulates gene expression of PMP22 and preserves both myelin and axons. Notably, the same approach was effective in partial rescue of demyelination even after the onset of disease. Collectively, our data present a proof-of-concept that CRISPR/Cas9-mediated targeting of TATA-box can be utilized to treat CMT1A.

Paneth cells are specialized intestinal epithelial cells that are located at the base of small intestinal crypts and play a vital role in preserving the gut epithelium homeostasis. Paneth cells act as a safeguard from bacterial translocation across the epithelium and constitute the niche for intestinal stem cells in the small intestine by providing multiple niche signals. Recently, Paneth cells have become the focal point of investigations defining the mechanisms underlying the epithelium-microbiome interactions and pathogenesis of chronic gut mucosal inflammation and bacterial infection. Function of Paneth cells is tightly regulated by numerous factors at different levels, while Paneth cell defects have been widely documented in various gut mucosal diseases in humans. The post-transcription events, specific change in mRNA stability and translation by RNA-binding proteins (RBPs) and noncoding RNAs (ncRNAs) are implicated in many aspects of gut mucosal physiology by modulating Paneth cell function. Deregulation of RBPs and ncRNAs and subsequent Paneth cell defects are identified as crucial elements of gut mucosal pathologies. Here, we overview the posttranscriptional regulation of Paneth cells by RBPs and ncRNAs, with a particular focus on the increasing evidence of RBP HuR and long ncRNA H19 in this process. We also discuss the involvement of Paneth cell dysfunction in altered susceptibility of the intestinal epithelium to chronic inflammation and bacterial infection following disrupted expression of HuR and H19.