Fibulin-3 Has Anti-Tumorigenic Activities in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer. Several previous studies have shown that fibulin-3 participates in the occurrence and development of various tumors; however, its role in cSCC remains unknown. In the present study, we observed that the expression of fibulin-3 was downregulated in cSCC tissues compared with normal skin tissues, which was due to fibulin-3 promoter methylation. In vitro, knockdown of fibulin-3 in cSCC cell lines A431 and SCL-1 cells promoted cell proliferation, protected cells against apoptosis and enhanced migration and invasion abilities. Conversely, overexpression of fibulin-3 inhibited cell proliferation by promoting growth arrest during the G1/S phase transition, induced apoptosis, and reduced migration and invasion abilities. These anticarcinogenic effects of fibulin-3 were associated with inhibition of the AKT signaling pathway. Through a mouse xenograft model, we found that fibulin-3 overexpression inhibited the cSCC tumor growth in vivo. Our results suggest that fibulin-3 has anti-tumorigenic activities in cSCC. Downregulation of fibulin-3 is involved in cSCC development and it may serve as a novel therapeutic target of this disease.