Abstract
Chemoresistance is the main cause of treatment failure in advanced colorectal cancer (CRC). However, molecular mechanisms underlying this phenomenon remain to be elucidated. In a previous work we identified low levels of PKM2 as a putative oxaliplatin-resistance marker in HT29 CRC cell lines and also in patients. In order to assess how PKM2 influences oxaliplatin response in CRC cells, we silenced PKM2 using specific siRNAs in HT29, SW480 and HCT116 cells. MTT test demonstrated that PKM2 silencing induced resistance in HT29 and SW480 cells and sensitivity in HCT116 cells. Same experiments in isogenic HCT116 p53 null cells and double silencing of p53 and PKM2 in HT29 cells failed to show an influence of p53. By using trypan blue stain and FITC-Annexin V/PI tests we detected that PKM2 knockdown was associated with an increase in cell viability but not with a decrease in apoptosis activation in HT29 cells. Fluorescence microscopy revealed PKM2 nuclear translocation in response to oxaliplatin in HCT116 and HT29 cells but not in OXA-resistant HTOXAR3 cells. Finally, by using a qPCR Array we demonstrated that oxaliplatin and PKM2 silencing altered cell death gene expression patterns including those of BMF, which was significantly increased in HT29 cells in response to oxaliplatin, in a dose and time-dependent manner, but not in siPKM2-HT29 and HTOXAR3 cells. BMF gene silencing in HT29 cells lead to a decrease in oxaliplatin-induced cell death. In conclusion, our data report new non-glycolytic roles of PKM2 in response to genotoxic damage and proposes BMF as a possible target gene of PKM2 to be involved in oxaliplatin response and resistance in CRC cells.
Highlights
Colorectal cancer (CRC) remains one of the most frequent causes of cancer-related death worldwide
These results were validated in SW480 cells but not in HCT116 where PKM2 knockdown was associated with higher sensitivity to OXA (Fig 1)
In order to emulate the low levels of PKM2 found in OXA resistant HTOXAR3 cells [8], we silenced PKM2 gene expression with the use of specific siRNAs in the parental cell line HT29 and assessed the effect on OXA sensitivity
Summary
Colorectal cancer (CRC) remains one of the most frequent causes of cancer-related death worldwide. It activates several signaling pathways leading to DNA damage repair and/or the activation of cell death programs [3] which in turn depends, among other factors, on the mutational status of the tumor suppressor gene p53 [4,5,6]. Chemoresistance to platinum agents is a complex and multifactorial process in which several mechanisms such as drug influx/efflux modifications, alterations in DNA damage repair, decrease of cell death activation, autocrine survival signaling or high detoxification activity could take part [7,8,9,10]. Most of the studies concerning platinum drugs resistance have focused on cisplatin and the real biological behavior and mechanisms of response to OXA in colorectal cells is mostly unknown
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
