Abstract 5099: Large-cell neuroendocrine carcinoma cells of the lung induce a tumor-promoting senescent phenotype in fibroblasts through MMP1 overexpression and TGFβ1
Authors: Gabasa Marta , Ikemori Rafael , Arshakyan Marselina , Radisky Evette , Reguard Noemí , Radisky Derek , Alcaraz Jordi 
Published: September 2020

Abstract
Tumor-associated fibroblasts (TAFs) exhibit an activated/fibrotic phenotype in all subtypes of non-small cell lung cancer. In contrast, we previously reported that lung TAFs exhibit premature senescence selectively in large cell neuroendocrine carcinoma of the lung (LCNEC), which is among the most aggressive subtypes of lung cancer. Moreover, we also reported that senescent fibroblasts enhance the growth and invasion of LCNEC cells in vitro and in vivo, and that the co-culture of LCNEC cells with normal fibroblasts was sufficient to induce fibroblast senescence. Intriguingly, whole-genome transcriptional profiling identified MMP1 as highly overexpressed in a panel of LCNEC cells versus non-LCNEC cell lines. Here we examined the role of MMP1 in LCNEC paracrine induction of fibroblast senescence.
MMP-1 expression was silenced in LCNEC cancer cell lines by shRNA, and common senescent markers were analyzed after co-culture with normal fibroblasts, including β-galactosidase staining, cyclin-dependent kinase Inhibitor 2A expression (CDKN2A) and growth arrest. In addition, the tumor-promoting effects of fibroblast conditioned medium in LCNEC growth and invasion were measured.
We confirmed that the LCNEC cell lines used in this study exhibited an increased expression of 3 neuroendocrine markers (CHGA, NCAM1 and SYP) compared to non-LCNEC cells. Induction of fibroblast senescence was confirmed after coculture with shScramble LCNEC cells. Moreover, knocking-down MMP1 in LCNEC cells was sufficient to abrogate fibroblast induced senescence upon co-culture, as well as the tumor-promoting traits of fibroblast's conditioned medium. The addition of active recombinant MMP1 (rMMP1) partially rescued the fibroblast senescent phenotype in co-culture with knocked-down MMP1 LCNEC cells, yet it was not sufficient to induce senescence when added to fibroblasts cultured alone. In contrast, treating fibroblasts with rMMP1 and the potent pro-fibrotic cytokine TGFβ1 was sufficient to induce both senescence and protumorigenic properties.
Our results unveil a process of “niche construction” by LCNEC cells that is driven by their overexpression of MMP1, which induces senescence in adjacent fibroblasts that secrete factors that enhance the growth and invasion of LCNEC cells, thereby contributing to the aggressive nature of these tumors. In addition, our results reveal a new pathologic synergy between MMP1 and TGFβ1 in eliciting fibroblast senescence and enhancing its tumor-promoting traits. Moreover, our findings support that the aberrant carcinoma cell-fibroblast crosstalk mediated by MMP1 may be a suitable therapeutic target in LCNEC, which currently lacks targeted therapies.
Citation Format: Marta Gabasa, Rafael Ikemori, Marselina Arshakyan, Evette Radisky, Noemí Reguard, Derek Radisky, Jordi Alcaraz. Large-cell neuroendocrine carcinoma cells of the lung induce a tumor-promoting senescent phenotype in fibroblasts through MMP1 overexpression and TGFβ1 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5099.