title: TGF-β1 conjugated to gold nanoparticles results in protein conformational changes and attenuates the biological function.
abstract: Gold nanoparticles (AuNPs) are widely used as carriers or therapeutic agents due to their great biocompatibility and unique physical properties. Transforming growth factor-beta 1 (TGF-β1), a member of the cysteine-knot structural superfamily, plays a pivotal role in many diseases and is known as an immunosuppressive agent that attenuates immune response resulting in tumor growth. The results reported herein reflect strong interactions between TGF-β1 and the surface of AuNPs when incubated with serum-containing medium, and demonstrate a time- and dose-dependent pattern. Compared with other serum proteins that can also bind to the AuNP surface, AuNP-TGFβ1 conjugate is a thermodynamically favored compound. Epithelial cells undergo epithelial-mesenchymal transition (EMT) upon treatment with TGF-β1; however, treatment with AuNPs reverses this effect, as detected by cell morphology and expression levels of EMT markers. TGF-β1 is found to bind to AuNPs through S-Au bonds by X-ray photoelectron spectroscopy. Fourier transform infrared spectroscopy is employed to analyze the conformational changes of TGF-β1 on the surface of AuNPs. The results indicate that TGF-β1 undergoes significant conformational changes at both secondary and tertiary structural levels after conjugation to the AuNP surface, which results in the deactivation of TGF-β1 protein. An in vivo experiment also shows that addition of AuNPs attenuates the growth of TGF-β1-secreting murine bladder tumor 2 cells in syngeneic C3H/HeN mice, but not in immunocompromised NOD-SCID mice, and this is associated with an increase in the number of tumor-infiltrating CD4⁺ and CD8⁺ T lymphocytes and a decrease in the number of intrasplenic Foxp3(+) lymphocytes. The findings demonstrate that AuNPs may be a promising agent for modulating tumor immunity through inhibiting immunosuppressive TGF-β1 signaling.
authors: Department of Urology, National Cheng Kung University Medical College, 1 University Road, Tainan 70101, Taiwan.
authors: Yuh-Shyan
authors: YS
authors: Tsai
authors: Yu-Hung
authors: YH
authors: Chen
authors: Pai-Chiao
authors: PC
authors: Cheng
authors: Hsin-Tzu
authors: HT
authors: Tsai
authors: Ai-Li
authors: AL
authors: Shiau
authors: Tzong-Shin
authors: TS
authors: Tzai
authors: Chao-Liang
authors: CL
authors: Wu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004586:Electrophoresis; D004797:Enzyme-Linked Immunosorbent Assay; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D006046:Gold / Q000737:chemistry*; D007150:Immunohistochemistry; D016753:Interleukin-10 / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry*; D051379:Mice; D056951:Photoelectron Spectroscopy; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D013329:Structure-Activity Relationship; D053773:Transforming Growth Factor beta1 / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D053773:Transforming Growth Factor beta1; D016753:Interleukin-10; D006046:Gold