Dysregulated Krüppel-like factor 4 and vitamin D receptor signaling contribute to progression of hepatocellular carcinoma.
OBJECTIVE
Krüppel-like factor 4 (KLF4) is a transcription factor and putative tumor suppressor. However, little is known about its effects in hepatocellular carcinogenesis. We investigated the clinical significance, biologic effects, and mechanisms of dysregulated KLF4 signaling.


METHODS
We performed microarray analysis of hepatocellular carcinoma (HCC) tissues. We used molecular biology analyses and animal models to evaluate activation and function of KLF4-vitamin D receptor (VDR) pathway.


RESULTS
Expression of KLF4 protein was decreased or lost in primary HCC samples, in particular, lymph node metastases, compared with normal liver tissues. Loss of KLF4 from primary tumors was significantly associated with reduced survival time and was identified as a prognostic marker. Most human HCC cell lines had losses or substantial decreases in levels of KLF4. Exogenous expression of KLF4 in HCC cells upregulated expression of mesenchymal-epithelial transition (MET) and inhibited their migration, invasion, and proliferation in vitro. When these cells were injected into mice, tumors grew more slowly and metastasis was inhibited, compared with HCC cells that did not express KLF4. VDR is a direct transcriptional target of KLF4; we identified 2 sites in the VDR promoter that bound specifically to KLF4. Increased expression of VDR sensitized tumor cells to the inhibitory effects of vitamin D.


CONCLUSIONS
KLF4 binds to the promoter of VDR to regulate its expression; levels of KLF4 are reduced and levels of VDR are increased in HCC cell lines and primary tumor samples. Expression of KLF4 in HCC cells sensitizes them to the anti-proliferative effects of VD3. This pathway might be manipulated to prevent or treat liver cancer.
Tumor Institute, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China; Department of Oncology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China; Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Qi
Q
Li
Tumor Institute, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China; Department of Oncology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China. Electronic address: gaoyon@hotmail.com.
Yong
Y
Gao
Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Zhiliang
Z
Jia
Department of Gastroenterology and Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Lopa
L
Mishra
Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Kun
K
Guo
Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, Texas; Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Zhiwei
Z
Li
Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Xiangdong
X
Le
Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Daoyan
D
Wei
Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, Texas; Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Suyun
S
Huang
Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas. Electronic address: kepxie@mdanderson.org.
Keping
K
Xie
D000818:Animals; D001665:Binding Sites; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000556:secondary; D002465:Cell Movement; D049109:Cell Proliferation; D018450:Disease Progression; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D006801:Humans; D007150:Immunohistochemistry; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D008207:Lymphatic Metastasis; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D020411:Oligonucleotide Array Sequence Analysis; D011379:Prognosis; D011401:Promoter Regions, Genetic; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D046888:Tissue Array Analysis / Q000379:methods; D014162:Transfection; D047368:Tumor Burden
C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D018167:Receptors, Calcitriol