Anti-cancer drug 3,3'-diindolylmethane activates Wnt4 signaling to enhance gastric cancer cell stemness and tumorigenesis.

As a natural health supplement, 3,3'-diindolylmethane (DIM) is proposed as a preventive and chemotherapeutic agent for cancer by inhibiting cell proliferation and inducing cell apoptosis. However, we found that in contrary to high level of DIM (30 µM), low level of DIM (1 µM and 10 µM) obviously promoted gastric cancer cell growth and migration. In addition, we found that low level of DIM increased the expression of stemness factors and enhanced the pluripotency of gastric cancer cells. Low level of DIM promoted gastric cancer progression by inducing the PORCN-dependent secretion of Wnt4 and the activation of ß-catenin signaling. Wnt4 knockdown reversed the effects of low level of DIM on gastric cancer cells. The results of in vivo studies showed that gastric cancer cells treated with low level of DIM (1 µM) grew faster and expressed higher level of Wnt4 than control cells. Taken together, our findings indicate that low level of DIM activates autocrine Wnt4 signaling to enhance the progression of gastric cancer, which may suggest an adverse aspect of DIM in cancer therapy. Our findings will provide a new aspect for the safety of DIM in its clinical application.

Photoperiodic and Diurnal Regulation of WNT Signaling in the Arcuate Nucleus of the Female Djungarian Hamster, Phodopus sungorus.

The WNT pathway was shown to play an important role in the adult central nervous system. We previously identified the WNT pathway as a novel integration site of the adipokine leptin in mediating its neuroendocrine control of metabolism in obese mice. Here we investigated the implication of WNT signaling in seasonal body weight regulation exhibited by the Djungarian hamster (Phodopus sungorus), a seasonal mammal that exhibits profound annual changes in leptin sensitivity. We furthermore investigated whether crucial components of the WNT pathway are regulated in a diurnal manner. Gene expression of key components of the WNT pathway in the hypothalamus of hamsters acclimated to either long day (LD) or short day (SD) photoperiod was analyzed by in situ hybridization. We detected elevated expression of the genes WNT-4, Axin-2, Cyclin-D1, and SFRP-2, in the hypothalamic arcuate nucleus, a key energy balance integration site, during LD compared with SD as well as a diurnal regulation of Axin-2, Cyclin-D1, and DKK-3. Investigating the effect of photoperiod as well as leptin on the activation (phosphorylation) of the WNT coreceptor LRP-6-(Ser1490) by immunohistochemistry, we found elevated activity in the arcuate nucleus during LD relative to SD as well as after leptin treatment (2 mg/kg body weight). These findings indicate that differential WNT signaling may be associated with seasonal body weight regulation and is partially regulated in a diurnal manner in the adult brain. Furthermore, they suggest that this pathway plays a key role in the neuroendocrine regulation of body weight and integration of the leptin signal.

Fluocinolone acetonide promotes the proliferation and mineralization of dental pulp cells.

INTRODUCTION: The aim of this study was to investigate the role of the steroid fluocinolone acetonide on the proliferation and mineralization of human dental pulp cells (DPCs). The potential effect of fluocinolone acetonide on reparative dentin formation and the recovery of injured dental pulp were evaluated. METHODS: The proliferative effect of fluocinolone acetonide on DPCs was analyzed by cholecystokinin octapeptide assay and flow cytometry. The mineralized effect of fluocinolone acetonide was investigated by the detection of mineralization-related biomarkers including alkaline phosphatase (ALP), bone sialoprotein, and osteocalcin by using ALP histochemical staining, ALP activity, immunostaining, alizarin red staining, and reverse-transcriptase polymerase chain reaction. The molecules, including dentin sialophosphoprotein and Wnt4, involved in the process of mineralization were detected by real-time polymerase chain reaction and Western blot analysis. RESULTS: Low concentrations of fluocinolone acetonide (0.1-40 µmol/L) promoted the proliferation of DPCs. The flow cytometry results showed that the CD146-positive subpopulation of DPCs was significantly increased after treatment with fluocinolone acetonide at 1 and 10 µmol/L for 48 hours, respectively. The messenger RNA expression and activity of the early-stage mineralization marker ALP were evidently increased in fluocinolone acetonide-treated DPCs compared with the untreated control group, so did the middle-stage mineralization marker bone sialoprotein and the late-stage mineralization marker osteocalcin. Meanwhile, Wnt4 and the dentin-specific marker dentin sialophosphoprotein were obviously up-regulated by fluocinolone acetonide compared with the untreated controls. CONCLUSIONS: Fluocinolone acetonide can promote the proliferation of DPCs, especially for the CD146+ subpopulation. Fluocinolone acetonide can initiate the mineralization of DPCs and has the potential role in repairing injured pulp tissues.