title: The effect of focal adhesion kinase gene silencing on 5-fluorouracil chemosensitivity involves an Akt/NF-kappaB signaling pathway in colorectal carcinomas.
abstract: Multicellular resistance (MCR) is produced because multicellular spheroids (MCSs) are formed with a broad cell-cell connection when cultured in three-dimensions, which limits the clinical treatment efficacy in solid tumors. Focal adhesion kinase (FAK) plays an important role in apoptosis, survival and cell adhesion between cells and their extracellular matrix. In this study, we investigated the expressions of FAK, Akt and NF-kappaB in human colorectal cancer (CRC), and the effects of FAK gene silencing on MCSs formation and 5-fluorouracil (5-FU) chemosensitivity in colon carcinoma MCSs culture cells. In CRC samples, FAK, Akt and NF-kappaB were overexpressed. The positive expression of FAK correlated notably with lymph node metastasis and cellular differentiation. Positive expressions of Akt and NF-kappaB were significantly related to cellular differentiation and lymph node metastasis, respectively. Furthermore, positive expression of FAK correlated with that of Akt and NF-kappaB. The expression of FAK was inhibited significantly by a small hairpin RNA targeting FAK. Knockdown of FAK reversed the formation and aggregation of MCSs, significantly decreased the 50% inhibitory concentration of 5-FU, and markedly increased MCS culture cells apoptosis. These effects were associated with reduced levels of Akt and NF-kappaB. These results indicate that suppressing FAK expression potentiated 5-FU-induced cytotoxicity and contributed to its chemosensitizing effect by suppressing Akt/NF-kappaB signaling in colon carcinoma MCS culture cells. These data also imply that FAK mediates MCR of CRC through the survival signaling pathway FAK/Akt/NF-kappaB.
authors.affiliation: Department of Oncology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
authors.forename: Yuying
authors.initials: Y
authors.lastname: Chen
authors.forename: Zhanxiang
authors.initials: Z
authors.lastname: Wang
authors.forename: Pingan
authors.initials: P
authors.lastname: Chang
authors.forename: Liuxin
authors.initials: L
authors.lastname: Xiang
authors.forename: Feng
authors.initials: F
authors.lastname: Pan
authors.forename: Jianjun
authors.initials: J
authors.lastname: Li
authors.forename: Jinyan
authors.initials: J
authors.lastname: Jiang
authors.forename: Lan
authors.initials: L
authors.lastname: Zou
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Zhiheng
authors.initials: Z
authors.lastname: Bian
authors.forename: Houjie
authors.initials: H
authors.lastname: Liang
mesh_terms: D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D017209:Apoptosis; D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D017931:DNA Primers; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000235:genetics*; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D000964:Antimetabolites, Antineoplastic; D017931:DNA Primers; D016328:NF-kappa B; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D005472:Fluorouracil