BCN057 induces intestinal stem cell repair and mitigates radiation-induced intestinal injury

Abstract

BackgroundRadiation-induced gastrointestinal syndrome (RIGS) results from the acute loss of intestinal stem cells (ISC), impaired epithelial regeneration, and subsequent loss of the mucosal barrier, resulting in electrolyte imbalance, diarrhea, weight loss, sepsis, and mortality. The high radiosensitivity of the intestinal epithelium limits effective radiotherapy against abdominal malignancies and limits the survival of victims of nuclear accidents or terrorism. Currently, there is no approved therapy to mitigate radiation toxicity in the intestine. Here we demonstrate that BCN057, an anti-neoplastic small molecular agent, induces ISC proliferation and promotes intestinal epithelial repair against radiation injury.MethodsBCN057 (90 mg/kg body weight, subcutaneously) was injected into C57Bl6 male mice (JAX) at 24 h following abdominal irradiation (AIR) and was continued for 8 days post-irradiation. BCN057-mediated rescue of Lgr5-positive ISC was validated in Lgr5-EGFP-Cre-ERT2 mice exposed to AIR. The regenerative response of Lgr5-positive ISC was examined by lineage tracing assay using Lgr5-EGFP-ires-CreERT2-TdT mice with tamoxifen administration to activate Cre recombinase and thereby marking the ISC and their respective progeny. Ex vivo three-dimensional organoid cultures were developed from surgical specimens of human colon or from mice jejunum and were used to examine the radio-mitigating role of BCN057 on ISC ex vivo. Organoid growth was determined by quantifying the budding crypt/total crypt ratio. Statistical analysis was performed using Log-rank (Mantel-Cox) test and paired two-tail t test.ResultsTreatment with BCN057 24 h after a lethal dose of AIR rescues ISC, promotes regeneration of the intestinal epithelium, and thereby mitigates RIGS. Irradiated mice without BCN057 treatment suffered from RIGS, resulting in 100% mortality within 15 days post-radiation. Intestinal organoids developed from mice jejunum or human colon demonstrated a regenerative response with BCN057 treatment and mitigated radiation toxicity. However, BCN057 did not deliver radio-protection to mouse or human colon tumor tissue.ConclusionBCN057 is a potential mitigator against RIGS and may be useful for improving the therapeutic ratio of abdominal radiotherapy. This is the first report demonstrating that a small molecular agent mitigates radiation-induced intestinal injury by inducing ISC self-renewal and proliferation.Electronic supplementary materialThe online version of this article (10.1186/s13287-017-0763-3) contains supplementary material, which is available to authorized users.

A Novel Organoid Model of Damage and Repair Identifies HNF4α as a Critical Regulator of Intestinal Epithelial Regeneration

“…There are currently no useful in vitro models of intestinal epithelial damage and repair that use primary epithelial cells. An organoid model of irradiation-induced epithelial damage and repair was used previously, [14][15][16][17] however, a careful transcriptional analysis of the repair process has not been performed previously. Here, we describe a model of epithelial regeneration using sublethally irradiated smallintestinal organoids that recapitulates key aspects of epithelial repair after irradiation in vivo.…”

“…Damage models using organoid culture exposed to irradiation have been developed previously, however, the recovery phase after induction of damage was not characterized extensively. [14][15][16][17] Here, we performed a dose range of g-radiation on intestinal epithelial organoids to identify a sublethal dose that results in a cycle of damage and repair, as measured by the loss and resurgence of expression of intestinal epithelial stem cell markers such as leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) and olfactomedin 4 (Olfm4), as well as morphologic characteristics. Transcriptomic analysis of different time points identified hepatocyte nuclear factor 4a (HNF4a) as one of the upstream regulators of the epithelial response to damage.…”

Transient enhancement of p53 activity protects from radiation-induced gastrointestinal toxicity

“…Developing novel compounds that can mitigate radiation effects is a growing research field. Many different cytokines, growth factors, and inhibitors have been proposed for this function (32)(33)(34)(35)(36)(37)(38). These agents either act on the Wnt pathway necessary for CBC function or otherwise, affect the overall health of intestine after radiation exposure.…”

Radiation induced toxicity in rectal epithelial stem cell contributes to acute radiation injury in rectum

“…Currently there are no FDA-approved treatments that can be used to protect against radiation induced damage to the rectal epithelium. Previous research on radiation induced toxicity in small bowel demonstrated that radiation induced loss of intestinal stem cell is the major cause of mucosal damage [4][5][6]. Unlike radiation induced small bowel toxicity majority of the reports on radiation induced rectal injury described radiation induced proctitis /fibrosis [7,8].…”

“…These Bmi1+ve ISCs interconvert with more rapidly proliferating LRG5+ve stem cells known as CBCs that express markers including Lgr5, Olfm4, Lrig1 and Ascl2 [10][11][12][13][14][15]. Both in vivo mice model and ex-vivo organoid model it has been demonstrated that sensitivity of these stem cell are the determining factor for mucosal epithelial response to radiation exposure [4,6]. In small intestine it has been reported that label-retaining stem cells present at the +4 position are more radioresistant than CBCs and functions as a reserve stem cell pool.…”