Cancer-associated fibroblasts enact field cancerization by promoting extratumoral oxidative stress.

Abstract

Histological inspection of visually normal tissue adjacent to neoplastic lesions often reveals multiple foci of cellular abnormalities. This suggests the presence of a regional carcinogenic signal that spreads oncogenic transformation and field cancerization. We observed an abundance of mutagenic reactive oxygen species in the stroma of cryosectioned patient tumor biopsies, indicative of extratumoral oxidative stress. Diffusible hydrogen peroxide (H2O2) was elevated in the conditioned medium of cultured skin epithelia at various stages of oncogenic transformation, and H2O2 production increased with greater tumor-forming and metastatic capacity of the studied cell lines. Explanted cancer-associated fibroblasts (CAFs) also had higher levels of H2O2 secretion compared with normal fibroblasts (FIBs). These results suggest that extracellular H2O2 acts as a field effect carcinogen. Indeed, H2O2-treated keratinocytes displayed decreased phosphatase and tensin homolog (PTEN) and increased Src activities because of oxidative modification. Furthermore, treating FIBs with CAF-conditioned medium or exogenous H2O2 resulted in the acquisition of an oxidative, CAF-like state. In vivo, the proliferative potential and invasiveness of composite tumor xenografts comprising cancerous or non-tumor-forming epithelia with CAFs and FIBs could be attenuated by the presence of catalase. Importantly, we showed that oxidatively transformed FIBs isolated from composite tumor xenografts retained their ability to promote tumor growth and aggressiveness when adoptively transferred into new xenografts. Higher H2O2 production by CAFs was contingent on impaired TGFβ signaling leading to the suppression of the antioxidant enzyme glutathione peroxidase 1 (GPX1). Finally, we detected a reduction in Smad3, TAK1 and TGFβRII expression in a cohort of 197 clinical squamous cell carcinoma (SCC) CAFs, suggesting that impaired stromal TGFβ signaling may be a clinical feature of SCC. Our study indicated that CAFs and cancer cells engage redox signaling circuitries and mitogenic signaling to reinforce their reciprocal relationship, suggesting that future anticancer approaches should simultaneously target ligand receptor and redox-mediated pathways.

• Authors: Jeremy Soon Kiat Chan, Ming Jie Tan, Ming Keat Sng, Ziqiang Teo, Terri Phua, Chee Chong Choo, Liang Li, Pengcheng Zhu, Nguan Soon Tan
• Journal: Cell death & disease (Cell Death Dis) Vol. 8 Issue 1 Pg. e2562 (01 19 2017) ISSN: 2041-4889 [Electronic] England
• PMID: 28102840 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Reactive Oxygen Species
• Transforming Growth Factor beta
• Hydrogen Peroxide
• PTEN Phosphohydrolase
• PTEN protein, human

Topics

• Breast Neoplasms (genetics, metabolism, pathology)
• Cancer-Associated Fibroblasts (metabolism, pathology)
• Carcinoma, Squamous Cell (genetics, metabolism, pathology)
• Cell Line, Tumor
• Cell Transformation, Neoplastic (genetics)
• Female
• Gene Expression Regulation, Neoplastic
• Humans
• Hydrogen Peroxide (metabolism)
• Oxidative Stress (genetics)
• PTEN Phosphohydrolase (biosynthesis, genetics)
• Reactive Oxygen Species (metabolism)
• Signal Transduction (drug effects)
• Transforming Growth Factor beta (biosynthesis, genetics)
• Xenograft Model Antitumor Assays