Protein arginine methyltransferase 5 (PRMT5) is the primary methyltransferase generating symmetric-dimethyl-arginine marks on histone and non-histone proteins. PRMT5 dysregulation is implicated in multiple oncogenic processes. Here, we report that PRMT5-mediated methylation of protein kinase B (AKT) is required for its subsequent phosphorylation at Thr308 and Ser473. Moreover, pharmacologic or genetic inhibition of PRMT5 abolishes AKT1 arginine 15 methylation, thereby preventing AKT1 translocation to the plasma membrane and subsequent recruitment of its upstream activating kinases PDK1 and mTOR2. We show that PRMT5/AKT signaling controls the expression of the epithelial-mesenchymal-transition transcription factors ZEB1, SNAIL, and TWIST1. PRMT5 inhibition significantly attenuates primary tumor growth and broadly blocks metastasis in multiple organs in xenograft tumor models of high-risk neuroblastoma. Collectively, our results suggest that PRMT5 inhibition augments anti-AKT or other downstream targeted therapeutics in high-risk metastatic cancers.

Malignant brain tumours are rare but are the most challenging types of cancers to treat. Despite conventional multimodality approaches available for their management, the outlook for most patients remains dismal due to the ability of the tumour cells to invade the normal brain. Attention has now focused on novel therapeutic interventions such as as the use of micronutrients. Both chokeberry extract (Aronia melanocarpa), which is rich in natural pigments such as anthocyanins and curcumin (diferuloylmethane) found in turmeric (Curcuma longa) have been reported to possess anticancer properties in other cancers. The aim of this study was to extend our previous research to evaluate the therapeutic potential of these two agents by testing their ability to induce apoptosis in an established glioblastoma cell line (U373). This was accomplished by treating the cells for 48 h with either chokeberry extract or curcumin, and using the Annexin-V assay. Gene profiles of 8 MMPs (2, 9, 14, 15, 16, 17, 24 and 25) and 4 TIMPs (1, 2, 3 and 4) were analysed for effects of mediators of invasion by quantitative real-time polymerase chain reaction (RT-PCR). The IC50 values determined for curcumin and chokeberry extract were 15 and 200 µg/ml, respectively. Our results also suggest that curcumin induces apoptosis but chokeberry extract is necrotic to this cell line. It is possible that chokeberry extract kills the cells by other non-apoptotic pathways. In addition, the RT-PCR results show downregulation of the gene expression of MMP-2, -14, -16 and -17 for both micronutrients. Taken together, the comparative data suggest that both curcumin and chokeberry extract may exhibit their anticancer potential by inducing apoptosis and inhibiting invasion by reducing MMP gene expression.

Preventing aberrant inflammation is essential to maintaining homeostasis in the mammalian intestine. Although P-glycoprotein (P-gp) expression in the intestine is critical for protecting the intestinal epithelium from toxins and damage due to neutrophil infiltration, its regulation in the intestine is poorly understood.

Protein arginine methyltransferase 5 (PRMT5) generates most of the symmetric di-methyl-arginine marks on histones and non-histone proteins by which it regulates a wide range of physiological processes including cancer cell proliferation and metastasis. Here, we report that PRMT5 directly regulates epidermal growth factor receptor (EGFR) transcription and thus controls EGF stimulated EGFR signaling. PRMT5 modulates protein kinase B (AKT) activation by methylation of AKT1 Arg 15, which is required for its subsequent phosphorylation at AKT1 Thr 308 and Ser 473. The PRMT5/EGFR/AKT axis converges to regulate transcription factors ZEB1, SNAIL, and TWIST1 to promote the epithelial-mesenchymal transition (EMT), which supports tumor cell invasion and metastasis. Inhibiting PRMT5 methyltransferase activity with a small molecule inhibitor attenuated primary tumor growth and prevented hepatic metastasis in aggressive tumor models in vivo. Collectively, our results support the use of PRMT5 based therapies for metastatic cancer.

Ulcerative colitis (UC) is a devastating chronic disease characterized by aberrant colonic inflammation and intestinal dysbiosis. The pathognomonic ulceration as well as intestinal epithelial damage is driven by excess luminal infiltration and activation of neutrophils. Recently our group discovered a system of lipid mediators regulating transmigration of neutrophils from the colonic lamina propria across the epithelial barrier. During homeostasis the multidrug resistance efflux pump p-glycoprotien (P-gp) maintains a gradient of endocannabinoids, which limits neutrophil transmigration. During inflammation however, P-gp is downregulated and Multidrug resistance-associated protein 2 (MRP2), which secretes the neutrophil chemoattractant hepoxilin A3 is upregulated, promoting luminal infiltration of neutrophils. In ulcerative colitis P-gp is significantly downregulated, resulting in the excess luminal accumulation of neutrophils found in ulcer bases. We discovered that the balance of these multidrug resistant efflux pumps is dependent on the microbiome and its secreted metabolites, which is significantly altered in UC. Consequently, we are designing a consortium of bacteria to optimize the expression of P-gp on the host epithelium and thus restrain neutrophil transmigration in UC.Using antibiotic stratification experiments and fecal xenograft models we have identified specific bacterial species that increase P-gp expression, and thus likely restrain neutrophil transmigration. Thus far we have validated the role of 15 candidate bacteria and 78 bacterial metabolites in regulating P-gp expression and function either directly or through interactions with other bacterial species. Leveraging this understanding of microbial regulation of host efflux pumps as well as in-vivo population dynamics data we are developing an algorithm to predict the P-gp induction ability of all possible combinations of candidate microbe. Using this algorithm we will design P-gp high, mid, and low inducing consortia, to study the role of these populations on intestinal inflammation using murine models of ulcerative colitis. The development of such consortia has wide ranging implications for research and clinical practice alike from facilitating further study of the underlying inter-microbial networks regulating key host defense systems in the intestine to the development of a probiotic with the potential to limit colonic neutrophil infiltration in patients with UC. This work is supported by R01DK125407, T32AI132152, and F30DK134110 by National Institutes of Health. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.