New strategies are needed to predict and overcome metastatic progression and therapy resistance in prostate cancer. One potential clinical target is the stem cell transcription factor SOX2, which has a critical role in prostate development and cancer. We thus investigated the impact of SOX2 expression on patient outcomes and its function within prostate cancer cells. Analyses of SOX2 expression among a case-control cohort of 1028 annotated tumor specimens demonstrated that SOX2 expression confers a more rapid time to metastasis and decreased patient survival after biochemical recurrence. SOX2 ChIP-Seq analyses revealed SOX2 binding sites within prostate cancer cells which differ significantly from canonical embryonic SOX2 gene targets, and prostate-specific SOX2 gene targets are associated with multiple oncogenic pathways. Interestingly, phenotypic and gene expression analyses after CRISPR-mediated deletion of SOX2 in castration-resistant prostate cancer cells, as well as ectopic SOX2 expression in androgen-sensitive prostate cancer cells, demonstrated that SOX2 promotes changes in multiple metabolic pathways and metabolites. SOX2 expression in prostate cancer cell lines confers increased glycolysis and glycolytic capacity, as well as increased basal and maximal oxidative respiration and increased spare respiratory capacity. Further, SOX2 expression was associated with increased quantities of mitochondria, and metabolomic analyses revealed SOX2-associated changes in the metabolism of purines, pyrimidines, amino acids and sugars, and the pentose phosphate pathway. Analyses of SOX2 gene targets with central functions metabolism (CERK , ECHS1 , HS6SDT1 , LPCAT4 , PFKP , SLC16A3 , SLC46A1 , and TST) document significant expression correlation with SOX2 among RNA-Seq datasets derived from patient tumors and metastases. These data support a key role for SOX2 in metabolic reprogramming of prostate cancer cells and reveal new mechanisms to understand how SOX2 enables metastatic progression, lineage plasticity, and therapy resistance. Further, our data suggest clinical opportunities to exploit SOX2 as a biomarker for staging and imaging, as well as a potential pharmacologic target.

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Insulin-producing human embryonic stem cell-derived β (SC-β) cells are a promising cell source for diabetes cell replacement therapy. We have recently reported a differentiation strategy that produces SC-β cells in islet organoids that not only undergo glucose-stimulated insulin secretion but also have an islet-like dynamic insulin release profile, displaying both first and second phase insulin secretion. The goal of this study was to further characterize the functional profile of these SC-β cells in vitro. We utilized a Seahorse extracellular flux analyzer to measure mitochondrial respiration of SC-β cells at low and high glucose. We also used photolithography to fabricate a microfluidic device containing microwells to immobilize SC-β cells for perfusional analysis, monitoring cytoplasmic calcium using Fluo-4 AM at low and high glucose. Here we find that in addition to increased insulin secretion, SC-β cells have increased cellular respiration and cytoplasmic calcium ion concentration in response to a high glucose stimulation. Our results indicate that SC-β cells have similar function to that reported for islets, providing further performance characterization that could help with eventual development for diabetes cell therapy and drug screening.3 Diabetes Mellitus (DM) is a group of metabolic disorders that leads to the inability of the body to regulate blood glucose levels. Type 1 diabetes (T1D) involves the autoimmunemediated destruction of the insulin-producing pancreatic β cells located in the islets of Langerhans, leading to insulin deficiency and hyperglycemia. T1D is typically managed by injection of exogenous insulin. However, this clinical intervention does not emulate the normal behavior of the native β cells, making patients at risk for many long term complications 1 . An alternative therapy for T1D is the transplantation of cadaveric human islets, with the hope of reducing hyper-and hypoglycemic episodes. Some patients who were transplanted with islets have remained insulin independent for several years 2 . A major limitation of this approach, however, is the scarcity and quality of islets sourced from cadavers, limiting the widespread application of this therapy. Differentiation of human embryonic stem cells (hESCs) to insulinproducing β (SC-β) cells in islet organoids could serve as an unlimited supply of cells to treat millions of patients 3 , particularly if combined with transplantation strategies that vascularization, allow retrievability, and/or protect the cells from immune attack 4-8 .We recently reported a strategy for making large numbers of SC-β cells from hESCs 9 . This protocol is highly efficient, generating an almost pure population of pancreatic endocrine, of which most cells express insulin. These cells are highly functional, capable of undergoing glucose-stimulated insulin secretion. These cells were capable of restoring glucose tolerance when transplanted into streptozotocin-treated mice. Of particular note was the ability of these cells to display first and second phase insulin s...