Bevacizumab is an Efficient Therapeutic Approach with Low Side Effects in Patient-Derived Xenografts of Adenoid Cystic Carcinoma of the Lacrimal Gland

Abstract

Purpose: Adenoid cystic carcinoma (ACC) of the lacrimal gland (LGACC) is an aggressive malignant lacrimal gland tumor with a generally poor prognosis. Survival rates for LGACC are 56% at 5 years and 49% at 10 years. Recent studies have indicated that anti-vascular endothelial growth factor (VEGF) therapy can inhibit angiogenesis in ACC cells. This study was designed to explore the efficacy of the antiangiogenic drug bevacizumab in a LGACC patient-derived xenograft (PDX) animal model.

Methods: The histological structure of PDX was determined by hematoxylin-eosin staining to confirm successful xenografting. Immunohistochemistry (IHC) was used to detect the expression of neovascularization-related genes in LGACC patients and in the PDX model, including VEGF, VEGFR1, and FGFR. In order to compare the efficacy of antiangiogenic drug and traditional chemotherapy drug, PDX models were treated with bevacizumab and cisplatin respectively, and body weight was evaluated. Subsequently, the neovascularization-related proteins VEGF, VEGFR2, and CD34, tumor suppressor P53 and proliferation-related protein Ki67 were analyzed by IHC. Quantitative real-time PCR was employed to examine the mRNA expression of apoptosis-related genes BAD and Caspase 9, and of HIF1α.

Results: VEGF, VEGFR1, and FGFR were highly expressed in patients with LGACC and PDX models. Both bevacizumab and cisplatin treatment inhibited PDX tumor growth. The body weight of PDX models treated with cisplatin significantly decreased from day 15, while those treated with bevacizumab did not markedly change. Bevacizumab reduced the expression of VEGF, CD34, and Ki67 in PDX tumors; whereas, bevacizumab upregulated P53 and downregulated HIF1α levels.

Conclusion: The present study indicates that antiangiogenic drugs may be a promising treatment strategy for LGACC.

Keywords: LGACC; PDX; VEGF; bevacizumab; cisplatin.

Figure 1

Neovascularization related proteins are highly expressed in LGACC tissues. VEGF (A), VEGFR1 (C), VEGFR2 (E), and FGFR1 (G) expression in LGACC and normal tissues detected by immunohistochemistry, and the related statistical analysis (B, D, F and H). ***p < 0.001. n=5.

Figure 2

Patient-derived xenograft (PDX) model characterization. (A) Hematoxylin and Eosin staining of PDX tissue. (B–D) VEGF (B), VEGFR1 (C), and VEGFR2 (D) expression in the PDX model detected by immunohistochemical staining. (E) The statistical analysis of (B–D). n=5.

Figure 3

The efficacy of bevacizumab and cisplatin on patient-derived xenograft (PDX) tumor growth and body weight of mice. (A) Representative images of PDX tumor in vehicle, bevacizumab treatment, and cisplatin treatment groups. (B) PDX tumor weight in vehicle, bevacizumab treatment, and cisplatin treatment groups. **p < 0.01; NS, not significant. (C) PDX tumor growth curves. (D) Body weight of PDX mice following vehicle, bevacizumab, and cisplatin treatment. **p < 0.01; ***p < 0.001. n=7.

Figure 4

Bevacizumab and cisplatin suppress angiogenesis and cell proliferation in patient-derived xenograft (PDX) tumors. (A–E) Expression of Ki-67 (A), CD34 (B), P53 (C), VEGF (D), and VEGFR2 (E) detected by immunohistochemical staining in vehicle, bevacizumab treatment, and cisplatin treatment groups. *p < 0.01; **p < 0.05; ***p < 0.001. n=5.

Figure 5

Cisplatin elevates apoptotic gene expression and bevacizumab suppresses HIF1α expression. (A and B) Proapoptotic-related mRNA expression of genes Bad (A) and Caspase-9 (B) was assessed using quantitative real-time PCR in vehicle, bevacizumab, and cisplatin treatment groups. *p < 0.01. (C) Examination of HIF1α expression using quantitative real-time PCR in vehicle, bevacizumab treatment, and cisplatin treatment groups. *p < 0.01. n=3.