Knockdown of Latent Transforming Growth Factor-β (TGF-β)-Binding Protein 2 (LTBP2) Inhibits Invasion and Tumorigenesis in Thyroid Carcinoma Cells

Abstract

Latent transforming growth factor-β (TGF-β)-binding protein 2 (LTBP2) is one of four proteins in the LTBP family of proteins (LTBP1-4) and was shown to play a vital role in tumorigenesis. However, little is known regarding the functional role of LTBP2 in thyroid carcinoma. Therefore, the current study aimed to evaluate the effect of LTBP2 expression on the proliferation, invasion, and tumorigenesis in thyroid carcinoma cells and to explore the molecular mechanism of LTBP2 in tumor progression. Our results showed that the expression of LTBP2 is upregulated in human thyroid carcinoma and cell lines. Knockdown of LTBP2 inhibits the proliferation, invasion, and EMT phenotype in thyroid carcinoma cells. Furthermore, knockdown of LTBP2 attenuates thyroid carcinoma growth in nude mice. Finally, knockdown of LTBP2 inhibits activation of the PI3K/Akt pathway in thyroid carcinoma cells. In summary, the present study has provided further evidence that knockdown of LTBP2 inhibits invasion and tumorigenesis in thyroid carcinoma cells. Our findings may help to further elucidate the molecular mechanisms underlying thyroid carcinoma progression and provide candidate targets for the prevention and treatment of thyroid carcinoma.

Figure 1

LTBP2 is highly expressed in human thyroid carcinoma tissues and cell lines. The mRNA expression of LTBP2 in human thyroid carcinoma tissues (A) and cell lines (C) was analyzed by RT-qPCR. The protein expression of LTBP2 in human thyroid carcinoma tissues (B) and cell lines (D) was analyzed by Western blotting. Experiments were performed in triplicate. *p < 0.05 versus control.

Figure 2

Knockdown of LTBP2 inhibits the proliferation in thyroid carcinoma cells. FTC133 cells were transfected with sh-LTBP2 or mock for 24 h. The corresponding transfection efficiency was detected by RT-qPCR (A) and Western blotting (B). The effect of LTBP2 on thyroid carcinoma cell proliferation was measured by the CCK-8 assay (C). Experiments were performed in triplicate. *p < 0.05 versus the mock group.

Figure 3

Knockdown of LTBP2 inhibits migration and invasion in thyroid carcinoma cells. FTC133 cells were transfected with sh-LTBP2 or mock for 24 h. (A) Transwell assay showing that sh-LTBP2 suppressed the migration in FTC133 cells compared to control cells. (B) Matrigel invasion assay showing that sh-LTBP2 reduced the invasion in FTC133 cells compared to control cells. Experiments were performed in triplicate. *p < 0.05 versus the mock group.

Figure 4

Knockdown of LTBP2 inhibits the EMT phenotype in thyroid carcinoma cells. FTC133 cells were transfected with sh-LTBP2 or mock for 24 h. (A) The levels of E-cadherin, N-cadherin, and vimentin were detected by Western blot analysis. (B) Quantification of E-cadherin, N-cadherin, and vimentin. Experiments were performed in triplicate. *p < 0.05 versus the mock group.

Figure 5

Knockdown of LTBP2 inhibits the growth of thyroid carcinoma in vivo. FTC133 cells (1 × 10⁶ cells/0.1 ml) transduced with sh-LTBP2 or mock were injected subcutaneously into the flank of nude mice. (A) The volume of tumors was monitored every 5 days. (B) The mice were sacrificed 25 days after inoculation, and tumors were excised, measured, and weighed. Experiments were performed in triplicate. *p < 0.05 versus the mock group.

Figure 6

Knockdown of LTBP2 inhibits the activation of the PI3K/Akt pathway in thyroid carcinoma cells. FTC133 cells were transfected with sh-LTBP2 or mock for 24 h. (A) The levels of phosphorylated PI3K, total PI3K, phosphorylated Akt, and total Akt were detected using Western blot analysis. Quantification of (B) p-PI3K/PI3K and (C) p-Akt/Akt. Experiments were performed in triplicate. *p < 0.05 versus the mock group.