Early-stage colon cancer with high MALAT1 expression is associated with the 5-Fluorouracil resistance and future metastasis

Background: This study aimed to investigate the role of long noncoding RNA (LncRNA) expression profiles to predict relapse and 5-FU response in patients with stage I/II colon cancer (CC). Methods and Results: The expression level of 15 LncRNA was analyzed in stage I/II colon tumors of 126 CC patients. To confirm the findings in-vitro, 5FU-resistant HT29 cells were generated by subjecting HT-29 cells to the increasing concentrations of 5FU for 6 months. The 5FU resistance was observed in WST-1 and Annexin V analyses. The colony formation and wound healing assays were assessed to determine the metastatic properties of the cells. Expression levels of LncRNAs and mRNA of EMT-related genes were determined by RT-PCR. The role of LncRNA on metastasis and 5FU sensitivity were confirmed in pcDNA3.0-PTENP1 and si-MALAT1 expressed 5FU-resistant HT29 cell lineages. Results: : High MALAT1 (p=0.0002) and low PTENP1 (p= 0.0044) expressions were significantly associated with 5-FU resistance and tumor relapse in stage I/II CC. The invasiveness and colony-forming characteristics of 5-FU-resistant cell lineages were higher as compared to the parent HT-29. Moreover, the expression of MALAT1 (p=0.0009) was increased while the expression of PTENP1 (p=0.0158) decreased in 5FU-resistant-HT-29 cells. Si-MALAT1 treatment increased cell sensitivity to 5FU, whereas it decreased invasive behaviors of 5 FU-resistant-HT-29 cells. Conclusion: MALAT1 may be a biomarker in predicting recurrence in early-stage CC. Our findings suggest that a cell-based therapy to target MALAT1 could be established for these patients to prevent metastasis and 5-FU resistance.