Gene expression profile of human colorectal cancer identified NKTR as a biomarker for liver metastasis.

Liver metastasis is one of the prognostic factors of colorectal cancer (CRC). The aim of this study is to identify biomarkers that facilitate easier detection of liver metastasis. Significance Analysis of Microarrays (SAM) and Array Data Analyzer (ADA) were applied used for the analysis of differentially differently expressed mRNAs. mRNA expression was verified by quantitative real-timer reverse transcriptiontase polymerase chain reaction (qRT-PCR). Immunohistochemistry were was used to show natural killer-tumor recognition (NKTR) expression in CRC. NKTR-knockdown CRC cells were constructed obtained by using short hairpin RNA (shRNA). Followed by CCK-8 assay, plate colony formation test, and transwell assay were used to evaluate the influence of NKTR on cell proliferation, migration, and invasion in vitro. SAM yielded showed 256 up-regulated and 224 down-regulated differentially differently expressed genes. Seven genes were identified by using ADA, tools and four genes were verified by using qRT-PCR. Three genes (metastasis associated lung adenocarcinoma transcript 1 (MALAT1), nuclear factor I/B (NKTR), and nuclear factor I/B (NFIB)) showed a statistically significant considerabley difference between CRC with and liver metastasis and CRC without liver metastasis. Immunohistochemical analysis showed that NKTR expression was much lower in primary CRC with liver metastasis than that in primary CRC without liver metastasis. The NKTR protein plays a role in the lytic function of natural killer (NK) cells and it has been rarely studied in the CRC. The down-regulation of NKTR by shRNA interference in CRC cells increased cell proliferation, migration, and invasion in vitro.