The study on the role of KLF4 in NSCLC cell invasiveness

• Main Authors: Chieh-Ju Ma, 馬潔如
• Other Authors: Chia-Che Chang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/39651592285498052049

碩士 === 國立中興大學 === 生物醫學研究所 === 94 === Non-small cell lung carcinoma (NSCLC) is the most predominant type of lung cancer and one of the leading causes of lethal malignancies in Taiwan. Widespread metastasis is common in NSCLC and accounts for high mortality and low cure rate. Nevertheless, the molecular mechanisms underlying the metastasis of NSCLC remain unclear. KLF4 (a.k.a. GKLF, Gut-enriched Krüppel-like factor) is a newly identified transcription factor which is expressed mainly in the epithelial cells of the gastrointestinal tract. Deregulation of KLF4 expression has been linked to several types of cancer, including gastric cancer, colon cancer and breast cancer. Its role in the tumorigenesis and progression of NSCLC, however, has never been examined and is therefore the subject of this study. We first unraveled that KLF4 expression is selectively increased in the highly invasive NSCLC cell line CL1-5, while nearly no expression of KLF4 was observed in its parental, low invasive cell line CL1-0. KLF4-stably expressing cell lines were subsequently established in CL1-0 cells to analyze the effect of KLF4 on the growth and invasion of NSCLC cells. Our results indicated that KLF4 overexpression suppressed cell proliferation, likely associated with p21 upregulation in these cells. Furthermore, serum starvation treatment and colony formation in soft agar demonstrated that KLF4 expression promotes cell survival. Moreover, by means of wound healing assay and BoydenTM chamber migration assay, we found that KLF4 expression increased cell migration, but this effect is not statistically significant. In addition, the effect of KLF4 on NSCLC cell invasion was further examined by cell adhesion assay and Transwell-based cell invasion assay. Our results indicated that KLF4 promotes the interaction of cells with ECM. Importantly, Transwell-based cell invasion assay indicated that KLF4 is a potential invasion-promoting gene. Mechanistic study revealed that KLF4 expression suppressed E-cadherin and CRMP-1 protein expression as well as the promoter activity of E-cadherin and CRMP1 genes, consistent with its role in promoting invasion. In summary, our studies clearly demonstrated, for the first time, the promoting role of KLF4 in NSCLC invasiveness, and this effect is likely associated with the suppression of E-cadherin and CRMP1 expression by KLF4. Furthermore, the anchorage-independent growth and the resistance to serum starvation in KLF4-stable cells suggested the oncogenic function of KLF4.