Inhibition of serine/arginine-rich protein kinase-1 (SRPK1) prevents cholangiocarcinoma cells induced angiogenesis.

The serine/arginine-rich protein kinase-1 (SRPK1) is an enzyme that has an essential role in regulating numerous aspects of mRNA splicing. SRPK1 has been reported to be overexpressed in multiple cancers, suggesting it as a promising therapeutic target in oncology. No previous studies reported the role of SRPK1 in cholangiocarcinoma (CCA) cells. This study aimed to examine the expression of SRPK1 and the effects of SRPK1 inhibition on the viability and angiogenesis activity of CCA cells using a selective SRPK1 inhibitor, SPHINX31. Here, we demonstrate that SPHINX31 (0.3-10 µM) had no inhibitory effects on CCA cells' viability and proliferation. However, SPHINX31 decreased the mRNA expression of pro-angiogenic VEGF-A165a isoform. In addition, SPHINX31 attenuated SRSF1 phosphorylation and nuclear localization, and increased the ratio of VEGF-A165b/total VEGF-A proteins. Moreover, when HUVECs were grown in conditioned medium from SPHINX31-treated CCA cells, migration slowed, and tube formation decreased. The present study demonstrates that targeting SRPK1 in CCA cells effectively attenuates angiogenesis by suppressing pro-angiogenic VEGF-A isoform splicing. These findings suggest a potential therapeutic treatment using SRPK1 inhibitors for the inhibition of angiogenesis in cholangiocarcinoma.

Probing the Anti-Cancer Potency of Sulfated Galactans on Cholangiocarcinoma Cells Using Synchrotron FTIR Microspectroscopy, Molecular Docking, and In Vitro Studies.

Sulfated galactans (SG) isolated from red alga Gracilaria fisheri have been reported to inhibit the growth of cholangiocarcinoma (CCA) cells, which was similar to the epidermal growth factor receptor (EGFR)-targeted drug, cetuximab. Herein, we studied the anti-cancer potency of SG compared to cetuximab. Biological studies demonstrated SG and cetuximab had similar inhibition mechanisms in CCA cells by down-regulating EGFR/ERK pathway, and the combined treatment induced a greater inhibition effect. The molecular docking study revealed that SG binds to the dimerization domain of EGFR, and this was confirmed by dimerization assay, which showed that SG inhibited ligand-induced EGFR dimer formation. Synchrotron FTIR microspectroscopy was employed to examine alterations in cellular macromolecules after drug treatment. The SR-FTIR-MS elicited similar spectral signatures of SG and cetuximab, pointing towards the bands of RNA/DNA, lipids, and amide I vibrations, which were inconsistent with the changes of signaling proteins in CCA cells after drug treatment. Thus, this study demonstrates the underlined anti-cancer mechanism of SG by interfering with EGFR dimerization. In addition, we reveal that FTIR signature spectra offer a useful tool for screening anti-cancer drugs' effect.