Resistance to death pathway induction as a potential targeted therapy in CRISPR/Cas-9 knock-out colorectal cancer cell lines.

Regulated cell death is a fundamental biological process that plays a crucial role in maintaining tissue homeostasis and eliminating damaged or unnecessary cells. Ferroptosis is an iron-dependent process, characterized by the accumulation of oxidized and damaged lipids, which leads to programmed cell death. Among the ferroptotic pathway genes regulating this process, GPX4, TFRC, ACSL4, FSP1, SLC7A11, and PROM2 could be considered. There are many well-known ferroptotic pathway regulators, which are discussed in this compact review. Cells with tissues of different origin display sensitive or resistant phenotypes to such regulators. In some cases, unexpected changes during cell treatment occurred, suggesting the possibility of regulating the death pathway. We assumed that possible changing of ferro-sensitivity to ferro-resistance in cells, especially in colorectal cancer cell lines, is responded for induced chemoresistance. Using novel techniques, such as CRISPR/Cas-9 genome editing, an induced phenotype "switching" is possible.

Compensative Resistance to Erastin-Induced Ferroptosis in GPX4 Knock-Out Mutants in HCT116 Cell Lines.

Ferroptosis results from the accumulation of oxidized and damaged lipids which then leads to programmed cell death. This programmed process is iron-dependent, and as a fundamental biological process, plays a crucial role in tissue homeostasis. The ferroptosis molecular pathway depends on self-regulatory genes: GPX4; TFRC; ACSL4; FSP1; SLC7A11, and PROM2. Some of them were considered here as ferro-sensitive or ferro-resistance markers. We examined the impact of GPX4 gene knock-out, using the CRISPR/Cas-9 technique, on ferroptosis induction in the HCT116 colorectal cancer cell line. The results confirmed that cells lacking the GPX4 gene (GPX4 KO) should be more susceptible to ferroptosis after erastin treatment. However, the decrease in cell viability was not as significant as we initially assumed. Based on the lipid peroxidation markers profile and RT-qPCR gene expression analysis, we revealed the activation of an alternative antioxidant system supporting GPX4 KO cells, mostly for cellular ferroptotic death avoidance. Increased expression of FSP1 and PRDX1 genes in knock-out mutants was associated with their function-recognized here as ferroptosis suppressors. For such reasons, studies on the role of GPX4 and other crucial genes from the ferroptotic pathway should be explored. Despite promising prospects, the utilization of ferroptosis mechanisms in cancer therapy remains at the stage of experimental and in vitro preclinical studies.