Cytokeratin 18 regulates the transcription and alternative splicing of apoptotic‑related genes and pathways in HeLa cells

Abstract

Cytokeratin 18 (CK18), one of the major components of intermediate filaments (IF) in simple epithelial cells, undergoes caspase-mediated cleavage upon epithelial cell necrosis and apoptosis. CK18 has been used as a biomarker of several cancers and has been reported to be dysregulated in cervical cancers. The effects of dysregulated expression of CK18 at a molecular level are, however, unclear. In the present study, the function of CK18 in HeLa cells, a cell line derived from a cervical cancer cells, was investigated using shRNA knockdown. Reduced levels of CK18 led to a significant decrease in cell apoptosis, compared with control cells. Notably, RNA-seq analysis of the transcriptomes of HeLa cells, with or without CK18 knockdown, revealed that genes in the NF-κB pathway, and certain apoptosis pathways, were under global transcriptional and alternative splicing regulation. Quantitative RT-PCR confirmed the CK18-regulated transcription of apoptotic genes FAS and FADD , as well as immune genes CXCL2 and CD79B , in addition to alternative splicing of FAS and CTNNB1 . Western blot analysis further revealed that CK18 knockdown led to reduced expression of CASP8. In conclusion, the present study indicated that CK18 played a role in apoptosis, which may be mediated via a feed-back regulation loop and may involve regulation of transcription and alternative splicing of a number of genes in apoptotic pathways.

Cytokeratin 18 cell death assays as biomarkers for quantification of apoptosis and necrosis in COVID-19: a prospective, observational study

“… 7 8 During apoptosis, CK-18 is usually cleaved by caspases, resulting in CK-18 fragments. Cell death by necrosis, however, liberates only full-length (non-cleaved) CK-18 9 ( figure 5 ).…”

Honokiol Inhibits Melanoma Growth by Targeting Keratin 18 in vitro and in vivo

“…KRT18 is one of the keratins, also known as cytokeratins (KRTs), the intermediate filament forming proteins in epithelial cells (Cheng et al, 2019). The keratins are not only extensively used as tumor markers in cancer diagnosis, including in the detection of circulating tumor cells in carcinoma patients (Werner et al, 2019), but also their role in tumorigenesis and metastasis has gradually been valued (Dmello et al, 2019;Sharma et al, 2019).…”

Elevated Serum Level of Cytokeratin 18 M65ED Is an Independent Indicator of Cardiometabolic Disorders

“…The pathway in which CK18 is involved in cell death at a molecular level is, however, not very clear. CK18 could regulate the transcription of apoptotic genes FAS and FADD, as well as immune genes CXCL2 and CD79B, in addition to alternative splicing of FAS and CTNNB1 [13]. More precisely designed studies should be conducted to isolate peripheral blood mononuclear cells from the whole blood of the subjects and measure the expression of cell death-related genes and proteins to explore why CK18 M65ED is positively associated with cardiometabolic disorders.…”

“…The cellular content of the soluble fraction of CK18 has been shown to be released into the extracellular space during cell death both in vitro and in vivo [12]. A recent study indicated that CK18 played a role in apoptosis, which may be mediated via a feedback regulation loop and may involve regulation of transcription and alternative splicing of a number of genes in NF-κB pathway and certain apoptosis pathways [13]. In addition to caspase-induced apoptosis, other forms of cell death can lead to the release of CK18.…”