Boonyakorn BoonsriKiattawee ChoowongkomonBuabarn KuaprasertThanvarin ThitiphatphuvanonKittiya SupraditApinya SayintaJinchutha DuangdaraTawut RudtanatipKanokpan WongprasertSiam UniversityKasetsart UniversityKhon Kaen UniversityMahidol UniversitySynchrotron Light Research Institute (Public Organization)2022-08-042022-08-042021-05-01Marine Drugs. Vol.19, No.5 (2021)166033972-s2.0-85105526393https://repository.li.mahidol.ac.th/handle/20.500.14594/78963Sulfated 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.Mahidol UniversityPharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.3390/md19050258