Targeting KPNB1 with genkwadaphnin suppresses gastric cancer progression through the Nur77-mediated signaling pathway.

Gastric cancer (GC) remains a global challenge due to the lack of early detection and precision therapies. Genkwadaphnin (DD1), a natural diterpene isolated from the bud of Flos GenkWa (Thymelaeaceae), serves as a Karyopherin ß1 (KPNB1) inhibitor. In this study, we investigated the anti-tumor effect of DD1 in both cell culture and animal models. Our findings reveal that KPNB1, a protein involved in nuclear import, was highly expressed in GC tissues and associated with a poor prognosis in patients. We demonstrated that DD1, alongside the established KPNB1 inhibitor importazole (IPZ), inhibited GC cell proliferation and tumor growth by enhancing both genomic and non-genomic activity of Nur77. DD1 and IPZ reduced the interaction between KPNB1 and Nur77, resulting in Nur77 cytoplasmic accumulation and triggering mitochondrial apoptosis. The inhibitors also increased the expression of the Nur77 target apoptotic genes ATF3, RB1CC1 and PMAIP1, inducing apoptosis in GC cell. More importantly, loss of Nur77 effectively rescued the inhibitory effect of DD1 and IPZ on GC cells in both in vitro and in vivo experiments. In this study, we for the first time explored the relationship between KPNB1 and Nur77, and found KPNB1 inhibition could significantly increase the expression of Nur77. Moreover, we investigated the function of KPNB1 in GC for the first time, and the results suggested that KPNB1 could be a potential target for cancer therapy, and DD1 might be a prospective therapeutic candidate.

Genkwadaphnin promotes leukocyte migration by increasing CD44 expression via PKD1/NF-κB signaling pathway.

Genkwadaphnin (GD), an extract from the flower buds of Daphne genkwa Siebold & Zucc. (Thymelaeaceae) has been reported a significant anti-leukemic activity. However, its functional mechanism has not been defined well. To study the biological mechanism of GD function, we have investigated whether GD affects CD44 expression, which has a role in the regulation of immune cell motilities, and identified the related signaling pathways. GD treatment induced the increase of CD44 expression in a time- and concentration-dependent manner, which was specific for immune cells. GD activated PKD1/NF-κB signaling to induce CD44 expression, and resulted in the increased migration of K562 cells. In invasion assay, cell migratory ability was induced by GD and the transfection with CD44-specific short hairpin RNA resulted in reduction of its cell migration. GD treated human peripheral blood mononuclear cell (PBMC) were also shown the increased CD44 expression and migration. These data suggest that the induction of CD44 expression by GD treatment promotes immune cell transmigration resulting in the enhanced innate immunity.

PRDM1, a Tumor-Suppressor Gene, is Induced by Genkwadaphnin in Human Colon Cancer SW620 Cells.

Genkwadaphnin (GD-1) is isolated from the flower buds of Daphne genkwa Siebold et Zuccarini (Thymelaeaceae), and it has been used as a traditional Korean and Chinese medicine. In this study, the authors observe that GD-1 inhibits the growth of the colon cancer cell line, SW620, through the up-regulation of p21 expression in a PRDM1-dependent manner. After treatment with GD-1, the transcriptional repressor PRDM1 is prominently induced in SW620 cells. Furthermore, GD-1 induce the phosphorylation of PKD1 and MEK and subsequently provide PRDM1 enhancement, resulting in the suppression of c-Myc expression and the up-regulation of p21. PKD1 knockdown using siRNA abrogates PRDM1 expression by GD-1 and subsequently disrupts the regulation of c-Myc and p21 expression. Treating SW620 cells with GD-1 inhibits cell-cycle progression and is characterized by the down-regulation of c-Myc followed by the up-regulation of p21 expression. The up-regulation of p21 by GD-1 induces the growth arrest of the SW620 colon cancer cell line. Based on these data, the authors propose that GD-1 has tumor-suppressor activity that may contribute to the anti-tumor effects of PRDM1 in colon cancer.

Genkwadaphnin induces reactive oxygen species (ROS)-mediated apoptosis of squamous cell carcinoma (SCC) cells.

Genkwadaphnin is a daphnane diterpene ester molecule isolated from the flower buds of Daphne genkwa. In the present study, we investigated the apoptosis-inducing effect of genkwadaphnin in squamous cell carcinoma (SCC) cells. Apoptosis was triggered in SCC12 cells following genkwadaphnin treatment in a time- and concentration-dependent manner. Genkwadaphnin treatment increased phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Knockdown of JNK and p38 MAPK by recombinant adenovirus expressing microRNA (miR) resulted in significant inhibition of genkwadaphnin-induced apoptosis in SCC12 cells. Finally, pretreatment with the reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) markedly reduced SCC12 cell apoptosis, concomitant with significant inhibition of MAPK activation. These results indicate that genkwadaphnin has the potential to induce apoptosis in SCC cells, providing information on which to base further research with the aim of developing a cure for SCC.