545 Shedding of collagen XVII accelerates tumor growth and invasion in skin carcinogenesis

Abstract

The incidence of cutaneous squamous cell carcinoma (cSCC) and its precancerous forms is increasing worldwide. Here, we analyzed the role of complement classical pathway components C1q, C1r and C1s in the progression of cSCC. Analysis of cSCC cell lines (n¼8) and normal human epidermal keratinocytes (n¼11) with oligonucleotide arrays, RNA-seq and quantitative RT-PCR showed significantly elevated C1r and C1s mRNA levels in cSCC cell lines, whereas the expression of C1q was low. Western blotting analysis showed increased production of C1r (n¼8) and C1s (n¼ 7) in cSCC cells compared to NHEKs. The mRNA levels for C1r and C1s were markedly elevated in cSCC tumors (n¼6) compared to normal skin (n¼11) in vivo. Immunohistochemical analysis revealed strong tumor cell specific expression of C1r and C1s in invasive sporadic cSCCs (n¼164) and recessive dystrophic epidermolysis bullosa-associated cSCCs (n¼16), whereas the expression of both C1r and C1s was clearly lower in cSCC in situ (n¼63), in premalignant epidermal lesions (actinic keratoses, n¼61), and in normal skin (n¼9). The expression of C1r was up-regulated by IFN-g and the expression of C1s was up-regulated by IFN-g and TNF-a in cSCC cells. Knockdown of C1r and C1s expression with two specific siRNAs inhibited proliferation of cSCC cells. Moreover, growth of human cSCC xenograft tumors in vivo was significantly inhibited by knockdown of C1r and C1s. These results provide evidence for the role of tumor cell-derived C1r and C1s in the progression of cSCC and identify them as putative therapeutic targets in cSCC.