Yaqi Wang,1,2 Hui Su,1 Xiaopeng Wang,1 Chen Tu,1 Tong Xiao,1 Bincheng Ren,3 Shuang Wang1 

1Department of Dermatology, Xi’an Jiaotong University The Second Affiliated Hospital, Xi’an, Shaanxi, People’s Republic of China; 2Department of Dermatology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China; 3Department of Rheumatology and Immunology, Xi’an Jiaotong University The Second Affiliated Hospital, Xi’an, Shaanxi, People’s Republic of China

Correspondence: Shuang Wang, Department of Dermatology, Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, 710004, People’s Republic of China, Email 13571864159@163.com Bincheng Ren, Department of Rheumatology and Immunology, Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, 710004, People’s Republic of China, Email renbincheng7@163.com

Background: The forkhead box (FOX) family member FOXN3 has been reported to inhibit transcriptional activity associated with regulating tumor development. However, the role of FOXN3 in the pathogenesis of melanoma is not well understood.
Objective: To investigate the biological functions of FOXN3 in drug resistance of melanoma.
Materials and Methods: The expression of FOXN3 in melanoma was investigated using Gene Expression profiling interactive analysis (GEPIA) and Linkedomics databases. Melanoma cell proliferation, invasion, and migration were assessed using the colony formation assay, the scratch wound healing test, the Transwell invasion assay, and the nude mice xenograft to determine the effects of FOXN3 over-expression and depletion. The functional role of the transcriptional regulator in melanoma cells was tested through chromatin immunoprecipitation, immunofluorescence.
Results: FOXN3 was downregulated in melanoma. Over-expression of FOXN3 inhibited the proliferation and motility of melanoma cells, whereas FOXN3 knockdown significantly enhanced the proliferation and motility of melanoma cells. Overexpression of FOXN3 reduced autophagic activity in melanoma cells. Enhanced autophagic activity in drug-resistant melanoma cell lines is related to drug-sensitive cells, and significant differences in FOXN3 localization were observed when comparing melanoma cells that were sensitive and resistant to Vemurafenib. Additionally, FOXN3 has been identified as binding to the promoter region of the cancer antigen Fibrous Sheath Interacting Protein 1 (FSIP1), thereby regulating the expression of this gene.
Conclusion: FOXN3 functions as an important regulator of the development and progression of Vemurafenib-resistant melanoma cells, partly owing to its binding to the FISP1. As such, FOXN3 may represent a relevant target for therapeutic interventions in patients suffering from drug-resistant melanoma.
Plain language summary: FOXN3, a member of the forkhead box (FOX) family, plays a role in inhibiting transcriptional activity linked to tumor development. However, its involvement in melanoma pathogenesis remains unclear. Our study explores FOXN3’s functions in melanoma drug resistance, revealing reduced FOXN3 expression in melanoma tissue compared to normal skin. FOXN3 inhibits melanoma cell proliferation, invasion, and migration, leading to in vivo growth retardation. Overexpression of FOXN3 suppresses autophagy in drug-resistant melanoma cells, making it a key regulator in Vemurafenib-resistant melanoma progression. This suggests FOXN3 as a potential therapeutic target for drug-resistant melanoma patients.

Keywords: melanoma, FOXN3, autophagy, Vemurafenib, drug resistance