Published online Oct 21, 2023. doi: 10.3748/wjg.v29.i39.5452
Peer-review started: July 3, 2023
First decision: August 25, 2023
Revised: September 14, 2023
Accepted: September 26, 2023
Article in press: September 26, 2023
Published online: October 21, 2023
Processing time: 108 Days and 2.8 Hours
Chemoresistance is a major obstacle in colorectal cancer (CRC) therapy. Therefore, characterizing mechanisms of chemoresistance is beneficial to improve the treatment efficacy and survival rate of CRC patients. In this study, we identify the role and potential mechanism of prostaglandin F2α synthase (PGF2α) (PGFS) in drug resistance to CRC, providing a novel therapeutic target against cancer drug resistance in the treatment of CRC.
The new theory of this study is that PGFS resistance to oxaliplatin (Oxa) has two effects, one is to reduce the production of reactive oxygen species (ROS) through the generation of PGF2α products, and the other is the direct protective effect of PGFS on CRC nucleus. The new method in this study is the application of comet experiment to detect DNA damage, and the other is the application of inductively coupled plasma mass spectrometry (ICP-MS) to directly detect the platinum content of DNA in the nucleus, so as to directly detect the effect of PGFS on the binding of platinum and DNA.
This study was designed to exploit the function and mechanism of PGFS in chemoresistance in CRC. Our study reveals the different ways in which PGFS promotes chemoresistance in CRC, and provides a potential target for predicting and reversing chemoresistance of CRC.
The expression level of PGFS is assessed in 37 pairs of CRC tissues and para-cancer tissues by as detected by quantitative polymerase chain reaction and western blot. We examined the influence of PGFS overexpression or knockdown in acquired Oxa-resistant CRC cell lines (HCT116-OxR and HCT8-OxR) and their parental cell lines (HCT116 and HCT8). In order to analyze how PGFS affects colon cancer cell proliferation, A cholecystokinin octapeptide assay was utilized to determine the half-inhibitory concentration value of the cells, a plate clone formation assay was used to determine the clonogenesis ability, and an analysis of proliferating cell nuclear antigen expression was performed to determine the growth rate. Transferase dUTP nick end labeling and Annexin V/propidium iodide stainings, as well as the apoptotic markers cleaved-poly ADP-ribose polymerase and cleaved-caspase 3, were used to detect apoptosis. Western blot and cellular immunofluorescence were used to detect the expression and morphology of the DNA damage marker γ-H2AX. The DNA damage was detected by single-cell gel electrophoresis. Indomethacin, an inhibitor of prostaglandin synthase of PGFS, was used to elucidate the underlying mechanisms. Rescue experiments were conducted by introducing PGF2α, the product of PGFS, subsequent to the knockdown of PGFS. The platinum-DNA adducts were quantified using ICP-MS, and intracellular ROS levels were measured using a kit for measuring reactive oxygen species.
We found that PGFS reduced the production of ROS through its downstream product PGF2α, and thereby promotes Oxa resistance in CRC, meanwhile, it inhibited the formation of platinum-DNA adducts in a PGF2α-independent manner. The suppressive role of PGFS in the formation of platinum-DNA adducts has never been reported before. However, some questions need to be further clarified, for example, by what mechanism does PGFS suppress the formation of platinum-DNA adducts?
This study aims to explore the relationship between PGFS and the occurrence and development of CRC, and the relationship between PGFS and Oxa resistance in CRC as well as the related mechanisms. In the future, it is hoped to predict whether patients with CRC are resistant to Oxa by detecting PGFS genes.
Further work will be needed to clarify the function of PGFS in the nucleus and its mechanisms of action. Moreover, the inhibition mechanism of PGFS in the formation of platinum-DNA adducts needs to be further elucidated.