Oct1/Pou2f1 is selectively required for gut regeneration and regulates gut malignancy

The transcription factor Oct1/Pou2f1 promotes poised gene expression states, mitotic stability, glycolytic metabolism and other characteristics of stem cell potency. To determine the effect of Oct1 loss on stem cell maintenance and malignancy, we deleted Oct1 in two different mouse gut stem cell compartments. Oct1 deletion preserved homeostasis in vivo and the ability to generate cultured organoids in vitro, but blocked the ability to regenerate after treatment with dextran sodium sulfate, and the ability to maintain organoids after passage. In a chemical model of colon cancer, loss of Oct1 in the colon severely restricted tumorigenicity. In contrast, loss of one or both Oct1 alleles progressively increased tumor burden in a colon cancer model driven by loss of heterozygosity of the tumor suppressor gene Apc. The different outcomes are consistent with prior findings that Oct1 promotes mitotic stability, and consistent with different gene expression signatures associated with the two models. These results reveal that Oct1 is selectively required for gut regeneration, and has potent effects in colon malignancy, with outcome (pro-oncogenic or tumor suppressive) dictated by tumor etiology. Author summary Colorectal cancer is the second leading cause of cancer death in the United States. Approximately 35% of diagnosed patients eventually succumb to disease. The high incidence and mortality due to colon cancer demand a better understanding of factors controlling the physiology and pathophysiology of the gastrointestinal tract. Previously, we and others showed that the widely expressed transcription factor is expressed at higher protein levels in stem cells, including intestinal stem cells. In this study we use a conditional mouse Oct1 ( Pou2f1 ) allele deleted in two different intestinal stem cell compartments. The results indicate that Oct1 loss is dispensable for maintenance of the mouse gut, but required for regeneration. We also tested Oct1 loss in the context of two different mouse colon cancer models. We find that Oct1 loss has opposing effects in the two models, and further that the two models are associated with different gene expression signatures. The differentially expressed genes are enriched for previously identified Oct1 targets, suggesting that differential gene control by Oct1 is one mechanism underlying different outcomes.