title: Matrix stiffening and β1 integrin drive subtype-specific fibroblast accumulation in lung cancer.
abstract: The crucial role of tumor-associated fibroblasts (TAF) in cancer progression is now clear in non-small cell lung cancer (NSCLC). However, therapies against TAFs are limited due to a lack of understanding in the subtype-specific mechanisms underlying their accumulation. Here, the mechanical (i.e., matrix rigidity) and soluble mitogenic cues that drive the accumulation of TAFs from major NSCLC subtypes: adenocarcinoma (ADC) and squamous cell carcinoma (SCC) were dissected. Fibroblasts were cultured on substrata engineered to exhibit normal- or tumor-like stiffnesses at different serum concentrations, and critical regulatory processes were elucidated. In control fibroblasts from nonmalignant tissue, matrix stiffening alone increased fibroblast accumulation, and this mechanical effect was dominant or comparable with that of soluble growth factors up to 0.5% serum. The stimulatory cues of matrix rigidity were driven by β1 integrin mechano-sensing through FAK (pY397), and were associated with a posttranscriptionally driven rise in β1 integrin expression. The latter mechano-regulatory circuit was also observed in TAFs but in a subtype-specific fashion, because SCC-TAFs exhibited higher FAK (pY397), β1 expression, and ERK1/2 (pT202/Y204) than ADC-TAFs. Moreover, matrix stiffening induced a larger TAF accumulation in SCC-TAFs (>50%) compared with ADC-TAFs (10%-20%). In contrast, SCC-TAFs were largely serum desensitized, whereas ADC-TAFs responded to high serum concentration only. These findings provide the first evidence of subtype-specific regulation of NSCLC-TAF accumulation. Furthermore, these data support that therapies aiming to restore normal lung elasticity and/or β1 integrin-dependent mechano regulation may be effective against SCC-TAFs, whereas inhibiting stromal growth factor signaling may be effective against ADC-TAFs.
  
  
  CONCLUSIONS
  This study reveals distinct mechanisms underlying the abnormal accumulation of tumor-supporting fibroblasts in two major subtypes of lung cancer, which will assist the development of personalized therapies against these cells.
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain. Medical Oncology Department, Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Puig
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Lugo
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Gabasa
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Alícia
authors.initials: A
authors.lastname: Giménez
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Adriana
authors.initials: A
authors.lastname: Velásquez
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Roland
authors.initials: R
authors.lastname: Galgoczy
authors.affiliation: Servei d'Anatomia Patològica, Hospital Clínic de Barcelona, Barcelona, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Ramírez
authors.affiliation: Servei de Cirurgia Toràcica, Hospital Clínic de Barcelona, Barcelona, Spain.
authors.forename: Abel
authors.initials: A
authors.lastname: Gómez-Caro
authors.affiliation: Centro de Biología Molecular "Severo Ochoa," CSIC, Madrid, Spain.
authors.forename: Óscar
authors.initials: Ó
authors.lastname: Busnadiego
authors.affiliation: Centro de Biología Molecular "Severo Ochoa," CSIC, Madrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Rodríguez-Pascual
authors.affiliation: Medical Oncology Department, Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.
authors.forename: Pere
authors.initials: P
authors.lastname: Gascón
authors.affiliation: Medical Oncology Department, Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain. jalcaraz@ub.edu nreguart@clinic.ub.es.
authors.forename: Noemí
authors.initials: N
authors.lastname: Reguart
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain. CIBER de Enfermedades Respiratorias, Bunyola, Spain. jalcaraz@ub.edu nreguart@clinic.ub.es.
authors.forename: Jordi
authors.initials: J
authors.lastname: Alcaraz
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000473:pathology*; D018929:Cell Culture Techniques; D003470:Culture Media / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects; D051417:Focal Adhesion Kinase 1 / Q000096:biosynthesis; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D019012:Integrin beta1 / Q000096:biosynthesis* / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000187:drug effects
chemical_list: D003470:Culture Media; D019012:Integrin beta1; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human