CD95 ligand induces senescence in mismatch repair-deficient human colon cancer via chronic caspase-mediated induction of DNA damage

Abstract

CD95 is best known for its ability to induce apoptosis via a well-characterized pathway involving caspase-mediated proteolytic events. However, in apoptosis-resistant cell lines of diverse cancer types stimulation of CD95 primarily has pro-tumorigenic effects that affect many of the hallmarks of cancer. For instance, in colon cancer cells with a mutant KRAS gene CD95 primarily promotes invasion and metastasis. In the current study, we further investigated the context dependency of the consequences of CD95 activation in colon cancer. We used a series of patient-derived three-dimensional colon cancer cultures and studied their response to stimulation with CD95 ligand (CD95L). CD95L had a strong inhibitory effect on the clone-forming capacity of five out of nine cultures. In line with previous work, these cultures all had a wild-type KRAS gene and expressed high levels of CD95. Furthermore, the most sensitive cultures were characterized by microsatellite instability (MSI) and deficient mismatch repair. The reduced clonogenic growth of MSI-type colonospheres resulting from chronic CD95 stimulation was only partly due to apoptosis as many tumor cells survived treatment, yet were unable to regenerate clones. CD95 stimulation caused an irreversible cell cycle arrest, which was associated with cytokine secretion, similar to the senescence-associated secretory phenotype (SASP), and expression of senescence-associated β-galactosidase. In human colon cancer cohorts, CD95 expression was strongly correlated with the recently identified consensus molecular subtype 1 (CMS1), which mainly consists of MSI-high tumors, and with two independent SASP signatures. Mechanistically, CD95-induced senescence was caused by chronic DNA damage via caspase-activated DNAse resulting in p53 activation and p21 expression, with a minor contribution of the SASP. We conclude that induction of senescence is a hitherto unrecognized consequence of high CD95 expression, which appears to be most relevant for CMS1.

FasR and FasL in colorectal cancer

“…During SC with anti-Fas antibodies no substantial apoptosis rate increase was observed, similarly to data obtained during adherent cultures. Our results are in line with findings of other groups suggesting that the Fas pathway have rather pro-survival activity inducing growth, invasion and metastasis of cancer cells, especially CSCs (16,25,32,40). The increased sphere sizes following 2-week incubation with anti-FasR antibodies agreed with mentioned tumor-promoting activity of Fas signaling (Fig.…”

“…6A). That seems to proof the engagement of FasR in the senescence induction accompanied by the cell cycle arrest as was suggested earlier by Raats et al (32). Surprisingly, the Raats group (32) correlated the presence of wild kRAS gene with FasR inhibitory effects.…”

“…We hoped to add to the knowledge concerning the usefulness of cancer cell lines for chemotherapeutics activity/effectiveness analysis for potential clinical applications. FasR/FasL activity is still highly controversial since it is suspected to be engaged in the regulation of apoptosis, senescence and survival depending on the entire niche environment (6,15,32). Further studies are, however, needed to clarify the detailed signaling relationships between proteins from FasR/FasL-induced pathways.…”

Distinguishable Prognostic Signatures of Left- and Right-Sided Colon Cancer: a Study Based on Sequencing Data

“…CD95L is a critical survival factor for cancer cells and protects and promotes cancer stem cells [43]. Raats DA et al concluded that FASLG prompts senescence in mismatch repair-deficient human colon cancer through chronic caspase-mediated induction of DNA damage [44]. Therefore, these core genes play different roles in the occurrence and development of colon cancer through different mechanisms.…”

Stress Management: Death Receptor Signalling and Cross-Talks with the Unfolded Protein Response in Cancer

“…Mechanistically, CD95 cooperates with PDGFRβ to activate a phospholipase Cγ1/PIP2/cofilin pathway, which is not counteracted by LIM-Kinase LIMK in a K-Ras mutated context, thus stimulating the formation of cell protrusions [125]. It is worth noting that, in K-Ras wildtype colon cancer cells, CD95L can mediate senescence, in a caspase-dependent manner [126]. In primary glioma cells and glioblastoma cell lines CD95 induces migration by recruiting Yes in a caspase-independent manner, forming a protein complex initiating a PI3K/Akt/GSK3β pathway, which promotes Matrix MetealloProteinases (MMPs) up-regulation.…”