Investigation Of Warning Genes Involved In Hepatic Metastasis Of Rectal Carcinoma Based On RNA-Seq

Objective: To investigate the whole-transcriptome difference in primary focal tumortissues of rectal carcinoma with and without heterochrony hepatic metastasis，and thenidentify the putative warning genes involved in hepatic metastasis of rectal carcinoma.Method：The total12primary focal tumor tissues of rectal carcinoma were split into twogroups， based on the patients with heterochrony hepatic metastasis or not afterlong-term follow-up. The next generation sequencing (NGS)–based RNA-seqtechnology was employed to characterize the whole-transcriptome of primary focaltumor tissues of rectal carcinoma in the two groups, and the the mathematical statisticsmodel of poissonian distribution was used to filter differentially expressed genes(DEGs)between two groups. Also, bioinformatic approaches (GO and KEGG analysis) wereperformed to further filtered the DEGs with biological significance. Combined theextracted DEGs from RNA-seq and bioinformatics analysis，the most related warninggenes, which might predict the heterochrony hepatic metastasis of rectal carcinoma,were further verified by qRT-PCR.Result：Based on the analysis of transcriptome data from RNA-seq,93DEGs weredetected between the two libraries of metastatic and non-metastatic rectal carcinomas,among which were26up-regulated genes and67down-regulated gene respectively.Based on the results of bioinformatic analysis, we found that epithelial–mesenchymaltransition (EMT), cell migration, locomotion and localization processes could bemeaningfully related to heterochrony hepatic metastasis happened in rectal carcinoma.And the alternation in TGF-βpathway and the phagosome or focal adhesion inducedpathway might be the most meaningful cellular network interaction involved inheterochrony hepatic metastasis of rectal carcinoma. Combined all of above, we selected13significant heterochrony hepatic metastasis associated genes(SPP1、PDGFB、FSTL3、MME、MMP3、VANGL2、CTNNA2、SMOC1、LEFTY1、SMAD9、REG1A、REG3A、REG1B) and then compared the candidate genes in two new primary focal tumor tissues of rectal carcinoma, one of which was from metastatic patient, and the other fromnon-metastatic. Interestingly, the REG family showed the most significant difference inmRNA expression between the liver metastatic and non-metastatic primary focal tumortissues of rectal carcinoma (p-value was REG1A：3.08×10-5；REG1B：0.00322；REG3A：0.0127,respectively). The loss or decline of REG1A、REG1B and REG3A expression wasonly appeared in liver metastatic primary focal tumor tissues of rectal carcinoma.Concussion: The down-regulation of REG family (also known as Regeneratingislet-derived family) in primary focal tumor tissues of rectal carcinoma could be one ofthe most meaningful warning events in heterochrony hepatic metastasis of rectalcarcinoma. The loss or decrease expression of REG1A、REG3A and REG1B could havepossibility as a putative biomarker for predicting the heterochrony hepatic metastasis ofrectal carcinoma.