Interplay between Endoplasmic Reticular Stress and Survivin in Colonic Epithelial Cells

Sustained endoplasmic reticular stress (ERS) is implicated in aggressive metastasis ofcancer cells and increased tumor cell proliferation. Cancer cells activate the unfolded proteinresponse (UPR), which aids in cellular survival and adaptation to harsh conditions. Inhibition ofapoptosis, in contrast, is a mechanism adopted by cancer cells with the help of the inhibitor of anapoptosis (IAP) class of proteins such as Survivin to evade cell death and gain a proliferativeadvantage. In this study, we aimed to reveal the interrelation between ERS and Survivin. Weinitially verified the expression of Survivin in Winnie (a mouse model of chronic ERS) colon tissuesby using immunohistochemistry (IHC) and immunofluorescence (IF) in comparison with wild typeBlk6 mice. Additionally, we isolated the goblet cells and determined the expression of Survivin byIF and protein validation. Tunicamycin was utilized at a concentration of 10 µg/mL to induce ERSin the LS174T cell line and the gene expression of the ERS markers was measured. This was followedby determination of inflammatory cytokines. Inhibition of ERS was carried out by 4Phenyl Butyricacid (4PBA) at a concentration of 10 mM to assess whether there was a reciprocation effect. Thedownstream cell death assays including caspase 3/7, Annexin V, and poly(ADP-ribose) polymerase(PARP) cleavage were evaluated in the presence of ERS and absence of ERS, which was followed bya proliferative assay (EdU click) with and without ERS. Correspondingly, we inhibited Survivin byYM155 at a concentration of 100 nM and observed the succeeding ERS markers and inflammatorymarkers. We also verified the caspase 3/7 assay. Our results demonstrate that ERS inhibition notonly significantly reduced the UPR genes (Grp78, ATF6, PERKandXBP1) along with Survivin butalso downregulated the inflammatory markers such as IL8, IL4, and IL6, which suggests a positivecorrelation between ERS and the inhibition of apoptosis. Furthermore, we provided evidence thatERS inhibition promoted apoptosis in LS174T cells and shortened the proliferation rate. Moreover,Survivin inhibition by YM155 led to a comparable effect as that of ERS inhibition, which includesattenuation of ERS genes and inflammatory markers as well as the promotion of programmed celldeath via the caspase 3/7 pathway. Together, our results propose the interrelation between ERS andinhibition of apoptosis assigning a molecular and therapeutic target for cancer treatment