Abstract 5214: Tumor cell-derived complement components C1r and C1s promote growth of cutaneous squamous cell carcinoma

Abstract

Abstract The incidence of cutaneous squamous cell carcinoma (cSCC) is increasing worldwide. We have analyzed the role of complement components C1r and C1s in the progression of cSCC. Analysis of cSCC cell lines (n=8) and normal human epidermal keratinocytes (NHEK)(n=11) with oligonucleotide arrays, RNA-seq and quantitative RT-PCR revealed significantly elevated C1r and C1s mRNA levels in cSCC cell lines. Western blot analysis showed increased production of C1r and C1s in cSCC cells compared to NHEKs. The mRNA levels for C1r and C1s were markedly elevated in cSCC tumors (n=6) compared to normal skin (n=11) in vivo. Immunohistochemical analysis for C1r and C1s revealed strong tumor cell specific expression of C1r and C1s in invasive sporadic cSCCs (n=164) and recessive dystrophic epidermolysis bullosa-associated cSCCs (n=16), whereas the expression of both was clearly lower in cSCC in situ (n=63), in premalignant epidermal lesions (actinic keratoses, n=61), and in normal skin (n=9). Knockdown of C1r and C1s expression with two specific siRNAs inhibited proliferation of cSCC cells and growth of human cSCC xenograft tumors in vivo. These results provide evidence for the role of tumor cell-derived C1r and C1s in the progression of cSCC independently of C1q and identify these serine proteinases as putative therapeutic targets in unresectable and metastatic cSCC. Citation Format: Pilvi Riihilä, Liisa Nissinen, Mehdi Farshchian, Markku Kallajoki, Atte Kivisaari, Seppo Meri, Reidar Grénman, Sirkku Peltonen, Juha Peltonen, Veli-Matti Kähäri. Tumor cell-derived complement components C1r and C1s promote growth of cutaneous squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5214.