title: Specific upregulation of RHOA and RAC1 in cancer-associated fibroblasts found at primary tumor and lymph node metastatic sites in breast cancer.
abstract: The importance of tumor-stromal cell interactions in breast tumor progression and invasion is well established. Here, an evaluation of differential genomic profiles of carcinoma-associated fibroblasts (CAFs) compared to fibroblasts derived from tissues adjacent to fibroadenomas (NAFs) revealed altered focal adhesion pathways. These data were validated through confocal assays. To verify the possible role of fibroblasts in lymph node invasion, we constructed a tissue microarray consisting of primary breast cancer samples and corresponding lymph node metastasis and compared the expression of adhesion markers RhoA and Rac1 in fibroblasts located at these different locations. Two distinct tissue microarrays were constructed from the stromal component of 43 primary tumors and matched lymph node samples, respectively. Fibroblasts were characterized for their expression of α-smooth muscle actin (α-SMA) and vimentin. Moreover, we verified the level of these proteins in the stromal compartment from normal adjacent tissue and in non-compromised lymph nodes. Our immunohistochemistry revealed that 59 % of fibroblasts associated with primary tumors and 41 % of the respective metastatic lymph nodes (p = 0.271) displayed positive staining for RhoA. In line with this, 57.1 % of fibroblasts associated with primary tumors presented Rac1-positive staining, and the frequency of co-positivity within the lymph nodes was 42.9 % (p = 0.16). Expression of RhoA and Rac1 was absent in fibroblasts of adjacent normal tissue and in compromised lymph nodes. Based on our findings that no significant changes were observed between primary and metastatic lymph nodes, we suggest that fibroblasts are active participants in the invasion of cancer cells to lymph nodes and support the hypothesis that metastatic tumor cells continue to depend on their microenvironment.
authors.affiliation: Radiology and Oncology Department, School of Medicine of São Paulo University, Av. Dr. Arnaldo, 455, sala 4112, São Paulo, SP, CEP 01246-903, Brazil. pbrozenchan@hotmail.com.|Colsan-Blood Bank Beneficent Association, São Paulo, SP, Brazil. pbrozenchan@hotmail.com.|Gynecological Department, School of Medicine of São Paulo Federal University, São Paulo, SP, Brazil. pbrozenchan@hotmail.com.
authors.forename: Patricia Bortman
authors.initials: PB
authors.lastname: Rozenchan
authors.affiliation: Radiology and Oncology Department, School of Medicine of São Paulo University, Av. Dr. Arnaldo, 455, sala 4112, São Paulo, SP, CEP 01246-903, Brazil.
authors.forename: Fatima Solange
authors.initials: FS
authors.lastname: Pasini
authors.affiliation: Radiology and Oncology Department, School of Medicine of São Paulo University, Av. Dr. Arnaldo, 455, sala 4112, São Paulo, SP, CEP 01246-903, Brazil.
authors.forename: Rosimeire A
authors.initials: RA
authors.lastname: Roela
authors.affiliation: Radiology and Oncology Department, School of Medicine of São Paulo University, Av. Dr. Arnaldo, 455, sala 4112, São Paulo, SP, CEP 01246-903, Brazil.
authors.forename: Maria Lúcia Hirata
authors.initials: ML
authors.lastname: Katayama
authors.affiliation: Pathology Department, Vale do Sapucaí University, Pouso Alegre, MG, Brazil.
authors.forename: Fiorita Gonzáles Lopes
authors.initials: FG
authors.lastname: Mundim
authors.affiliation: Psychiatric Department, School of Medicine of São Paulo University (USP), Rua Ovideo Pires de Campos S/N, São Paulo, SP, Brazil.
authors.forename: Helena
authors.initials: H
authors.lastname: Brentani
authors.affiliation: Brazilian Institute of Cancer Control, Av. Alcântara Machado 2576, São Paulo, SP, CEP 03102-002, Brazil.
authors.forename: Eduardo C
authors.initials: EC
authors.lastname: Lyra
authors.affiliation: Radiology and Oncology Department, School of Medicine of São Paulo University, Av. Dr. Arnaldo, 455, sala 4112, São Paulo, SP, CEP 01246-903, Brazil.
authors.forename: Maria Mitzi
authors.initials: MM
authors.lastname: Brentani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008198:Lymph Nodes / Q000378:metabolism / Q000473:pathology; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000235:genetics* / Q000473:pathology; D020830:rac1 GTP-Binding Protein / Q000096:biosynthesis* / Q000235:genetics; D020742:rhoA GTP-Binding Protein / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C107953:RAC1 protein, human; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein
keywords: Breast cancer; Carcinoma-associated fibroblasts; Metastasis; Rho GTPases; Tumor microenvironment