Serglycin (SRGN) is a pro-tumorigenic proteoglycan expressed and secreted by various aggressive tumors including glioblastoma (GBM). In our study, we investigated the interplay and biological outcomes of SRGN with TGFβRI, CXCR-2 and inflammatory mediators in GBM cells and fibroblasts. SRGN overexpression is associated with poor survival in GBM patients. High SRGN levels also exhibit a positive correlation with increased levels of various inflammatory mediators including members of TGFβ signaling pathway, cytokines and receptors including CXCR-2 and proteolytic enzymes in GBM patients. SRGN-suppressed GBM cells show decreased expressions of TGFβRI associated with lower responsiveness to the manipulation of TGFβ/TGFβRI pathway and the regulation of pro-tumorigenic properties. Active TGFβRI signaling in control GBM cells promotes their proliferation, invasion, proteolytic and inflammatory potential. Fibroblasts cultured with culture media derived by control SRGN-expressing GBM cells exhibit increased proliferation, migration and overexpression of cytokines and proteolytic enzymes including CXCL-1, IL-8, IL-6, IL-1β, CCL-20, CCL-2, and MMP-9. Culture media derived by SRGN-suppressed GBM cells fail to induce the above properties to fibroblasts. Importantly, the activation of fibroblasts by GBM cells not only relies on the expression of SRGN in GBM cells but also on active CXCR-2 signaling both in GBM cells and fibroblasts.

Alkaloids have garnered significant interest as potential anticancer agents. Vitamin D receptor (VDR) plays a role in preventing the progression of colorectal cancer (CRC) and may be a crucial mediator of the anticancer effects produced by certain alkaloids. The search for novel anticancer drugs that induce VDR expression and act through the VDR could improve the clinical outcomes of CRC patients. The anticancer and pro-apoptotic effects of coclaurine and reticuline were investigated using CRISPR/Cas9-edited VDR/knockout (KO) and wild-type (WT) CRC HCT116 cell lines. Western blotting, RT-qPCR, confocal microscopy, cell viability, scratch assays, and flow cytometry were employed to assess VDR expression and cellular localization, cell growth, wound-healing, cytotoxicity, apoptotic status, cell cycle progression, and VDR-mediated gene expression. Coclaurine and reticuline dose-dependently inhibited HCT116-WT cell viability, decreased wound-healing, and increased VDR nuclear localization and gene expression while downregulating the oncogenic genes SNAIL1 and SNAIL2. Both alkaloids induced late apoptosis in HCT116-WT cells, increased the cleavage of PARP and caspase-3, and upregulated Bax and TP53 while decreasing BCL-2. Both alkaloids caused HCT116-WT cell growth arrest in the S-phase, which is associated with cyclin A1 overexpression. Coclaurine and reticuline lost their anticancer effects in HCT116-VDR/KO cells. Docking studies revealed that both alkaloids occupied the VDR’s active site. These findings demonstrate that coclaurine and reticuline exert anti-CRC and pro-apoptotic activities via the VDR, suggesting them as natural therapeutic candidates. The use of in vivo CRC models is needed to validate the anticancer activities of coclaurine and reticuline.