RESUMO
OBJECTIVE: Cancer-associated fibroblasts (CAFs) are one of the most important components of tumor microenvironment. CAFs are believed to play an important role in tumor invasion and metastasis. Recently, fibroblast activation protein (FAP), a type II integral membrane glycoprotein belonging to the serine protease family, has emerged as a specific marker of CAFs. FAP was overexpressed in stromal fibroblasts of solid malignancies, however, the role of FAP on the process of invasion and metastasis of gastric carcinomas is still unknown. METHODS: Expression of FAP level was detected by immunohistochemistry in 60 gastric cancer surgical specimens (28 with omentum metastasis and 32 without), 20 normal human gastric tissues and omentum of 10 nonneoplastic gastric diseases. Fibroblasts were isolated from patient's tissues in the distal normal zones and tumor zones respectively, which were correspondingly designated as normal zone fibroblasts (NFs) and cancer-associated fibroblasts (CAFs). To explore the effects of FAP on NFs or CAFs, fibroblasts were co-cultured with human gastric cancer cell line MGC-803 cells. The ability of invasion and migration of MGC-803 cells was evaluated after transfecting FAP siRNA into CAFs of gastric carcinomas. RESULTS: We investigated the level of expression of FAP in surgical specimens, and found overexpressed in CAFs and non-expressed in NFs. Expression of FAP level in CAFs is significantly associated with Lauren classification,the degree of differentiation, depth of tumor invasion and TNM stage, but it is not correlated to age and gender in gastric carcinoma patients. There was positive correlation between the FAP level with metastasis to the omentum(p < 0.05, R(2) = 0.2736, p < 0.05, R(2) = 0.1479). In addition, the invasion and migration abilities of MGC-803 cells were significantly increased when cells were co-cultured with CAFs. On the other hand, invasion and migration abilities were significantly decreased by 46.9 and 50.3%, respectively, after knocking down FAP in CAFs.Further, NFs did not have appreciable effect on the invasion and migration of MGC-803 cells. CONCLUSIONS: Our findings showed that FAP was overexpressed in CAFs of gastric carcinomas, and siRNA-mediated knock down of FAP significantly suppressed invasion and migration of MGC-803 cells. FAP may be an important regulator in the invasion and migration of gastric cancer and may provide a novel therapeutic target in gastric carcinomas.
Assuntos
Movimento Celular , Fibroblastos/patologia , Gelatinases/metabolismo , Proteínas de Membrana/metabolismo , Omento/patologia , Serina Endopeptidases/metabolismo , Neoplasias Gástricas/patologia , Estômago/patologia , Western Blotting , Adesão Celular , Proliferação de Células , Células Cultivadas , Endopeptidases , Feminino , Fibroblastos/metabolismo , Mucosa Gástrica/metabolismo , Gelatinases/antagonistas & inibidores , Gelatinases/genética , Humanos , Técnicas Imunoenzimáticas , Metástase Linfática , Masculino , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/genética , Pessoa de Meia-Idade , Invasividade Neoplásica , Estadiamento de Neoplasias , Omento/metabolismo , RNA Interferente Pequeno/genética , Serina Endopeptidases/genética , Neoplasias Gástricas/metabolismo , Células Estromais/metabolismo , Células Estromais/patologiaRESUMO
AIMS: Interface zone fibroblasts (INFs) are very important in the progression and metastasis of tumours but their effect on the invasion and migration of gastric cancer cells is still unclear. METHODS: Primary fibroblasts were isolated from the distal normal zone (normal zone fibroblasts, NFs), interface zone (INFs) and tumour zone (cancer-associated fibroblasts, CAFs) of 60 human gastric carcinoma tissue samples. The crosstalk between these fibroblasts and human gastric cancer MGC-803 cells was evaluated using an indirect co-culture model in vitro. RESULTS: A high level of fibroblast activation protein (FAP) in the invasion front of gastric cancer was found in the gastric cancer tissue samples and no FAP expression was found in 20 normal gastric tissue samples by immunohistochemistry. High FAP expression was associated with Lauren classification, degree of differentiation, tumour node metastasis stage and depth of tumour invasion (p<0.05 or p<0.01). INFs promoted invasion and migration of MGC-803 cells. The number of invasions in INFs, CAFs and NFs were 120.10±27.53 (95% CI 102.12 to 138.10), 63.00±14.80 (95% CI 53.33 to 72.67) and 14.22±6.20 (95% CI 10.17 to 18.27), respectively; the number of invasions in INFs were 8.45-fold and 1.89-fold higher than those in NFs and CAFs, respectively (p<0.05). The number of migrations in INFs, CAFs and NFs were 118.00±16.83 (95% CI 107.00 to 129.00), 61.00±16.36 (95% CI 50.31 to 71.69) and 24.00±11.52 (95% CI 16.47 to 31.53), respectively; the number of migration in INFs were 4.91-fold and 1.92-fold higher than those in NFs and CAFs, respectively (p<0.05). INFs also significantly promoted cell proliferation and inhibited apoptosis in MGC-803 cells compared with NFs and CAFs (p<0.05). CONCLUSIONS: These findings indicate that INFs exhibit a more robust biological modulatory activity than CAFs and NFs. INFs may be a key factor leading to tumour progression and metastasis and may be of use as a tool for post-treatment surveillance.
