Colorectal cancer has a significant morbidity and mortality, being the fourth most common cancer worldwide [15
]. Defining the pathways that drive colorectal cancer will provide a better understanding of neoplastic progression, and may potentially identify targets for therapeutic intervention. Myeov expression has previously been shown to be enhanced in myeloma as well as breast, esophageal and gastric cancers [7
]. We have employed Digital Differential Display (DDD) a bioinformatic tool, to identify Myeov as a novel colorectal cancer associated gene [3
]. Briefly, we used DDD to compare expressed sequence tags (ESTs) between normal colorectal and cancer tissue, thereby identifying differentially expressed genes. Myeov was shortlisted for further investigation and we demonstrated enhanced Myeov expression in colorectal cancer and that it promotes tumour proliferation and invasion [3
], key hallmarks of metastatic cancer. These datasets support the important role of Myeov in this disease.
Gene knockdown using siRNA represents an excellent tool to assess the functional importance of cancer related genes in vitro. We have previously employed siRNA to knockdown Myeov in colorectal and gastric cancer cell lines and have shown knockdown to result in decreased cell proliferation and invasion [3
]. Using this technology, the current study further supports the functional importance of Myeov in CRC by showing that it drives colorectal cancer cell migration, a key process in the malignant phenotype. This data consolidates our previous reports that Myeov drives both proliferation and invasion. This new data illustrates a further role for Myeov in the motility of colorectal cancer cell and key hallmark of metastatic tumour cells.
Having established Myeov as a key player in CRC cell biology, we investigated whether Myeov was a downstream effector of COX/PGE 2
bioactivity. PGE 2
is a well established player in the progression of CRC and has been shown to induce increased proliferation, migration, and invasiveness of CRC cells [16
]. We hypothesise that enhanced COX/PGE 2
bioactivity in CRC leads to increased levels of Myeov and therefore increased invasion and migration. We have demonstrated in this study that treatment with PGE 2
enhances the expression of Myeov. Although the signalling mechanisms connecting PGE 2
signalling and Myeov transcription remain unknown, our findings support the hypothesis that Myeov is in part PGE 2
regulated and contributes to the downstream oncogenic activity of COX. PGE 2
has been shown to drive CRC cell migration and enhanced Myeov expression may at least in part mediate this process [16
]. The precise signalling and transcriptional mechanisms at play here need to be further deciphered. It has been shown that PGE 2
-mediated CRC cell migration is related to the intracellular activation of EGFR by PGE 2
]. Further work will clarify if Myeov expression is regulated by PGE 2
in a similar manner. Interestingly, we also quantitated the levels of secreted PGE 2
in Myeov knockdown and control cells however no significant difference was observed, confirming that the regulation of PGE 2
expression is not downstream of Myeov bioactivity (data not shown).
These findings further define the role for Myeov bioactivity in colorectal carcinogenesis. Ongoing studies into Myeov expression will expand this pathway to reveal newer insights into colorectal cancer progression and possibly enable a potential therapeutic based on targeting Myeov.