Chemotherapy enhances TNF-related apoptosis-inducing ligand DISC assembly in HT29 human colon cancer cells

Abstract

Cytokines such as Fas-ligand (Fas-L) and Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) can induce human colon cancer cell apoptosis through engagement of their death domain receptors. All the cancer cells are not sensitive to these cytokines. We have shown recently that low doses of cytotoxic drugs could restore TRAIL-induced cell death in resistant colon cancer cell lines. The present work further explores the death pathway triggered by the cytotoxic drug/TRAIL combination in HT-29 colon cancer cells (www.alexis-corp.com). Clinically relevant concentrations of cisplatin, doxorubicin and 5-fluorouracil synergize with TRAIL to trigger HT-29 cell death. Activation of this pathway leads to apoptosis that involves both caspases and the mitochondria. An increased recruitment of Fas-associated death domain (FADD) and procaspase-8 to the TRAIL-induced death-inducing signaling complex (DISC) was shown in cells exposed to anticancer drugs. Following caspase-8 activation at the DISC level, the mitochondria-dependent death pathway is activated, as demonstrated by the cleavage of Bid, the dissipation of DeltaPsi(m), the release of mitochondrial proteins in the cytosol and the inhibitory effect of Bcl-2 expression. Importantly, besides mitochondrial potentiation, we show here that cytotoxic drugs sensitize HT-29 colon cancer cells to TRAIL-induced cell death by enhancing FADD and procaspase-8 recruitment to the DISC, a novel mechanism whose efficacy could depend partly on Bcl-2 expression level.

Ionizing radiation modulates the TRAIL death-inducing signaling complex, allowing bypass of the mitochondrial apoptosis pathway

“…This concerns HT-29 colon carcinoma cells, treated with cisplatin, doxorubicin or 5-fluorouracil (5-FU) (Lacour et al, 2003) and hepatocellular carcinoma, treated with 5-FU (Ganten et al, 2004). These authors found, in common with our study, increased FADD and pro-Caspase-8/10, but not c-FLIP L content in the DISC, as well as increased Caspase-8/10 activity.…”

“…In addition, DNA damage can transcriptionally upregulate TRAIL-R1, TRAIL-R2 (Wu et al, 1997;Guan et al, 2001) and CD95 (Mu¨ller et al, 1998) and stimulate CD95 transport to the cell surface (Bennett et al, 1998), which may explain synergistic combined effects. However, combined effects are also observed without death receptor upregulation at the cell surface (Kim et al, 2001;Lacour et al, 2003;Vivo et al, 2003;Ganten et al, 2004).…”

Mitochondria in hematopoiesis and hematological diseases

“…Classical anticancer agents all induce apoptosis when tested on cell lines in vitro. They usually activate the intrinsic pathway to death that involves the mitochondria and downstream caspase activation, although a ligand-independent role for death receptors was also suggested (Micheau et al, 1999;Lacour et al, 2003). In multiple myeloma cells exposed to cytotoxic drugs, Mcl-1 expression specifically decreases through either synthesis blockade (Raje et al, 2005) or proteasome degradation (Zhong et al, 2005) or caspase-mediated cleavage (Gomez-Bougie et al, 2005a), depending on the stimulus, whereas Bcl-2 expression remains unchanged (Michels et al, 2005).…”

Increased sensitivity to TRAIL-induced apoptosis occurs during the adenoma to carcinoma transition of colorectal carcinogenesis

“…The potential of TRAIL for colorectal cancer treatment is highlighted by the ability of TRAIL to inhibit growth of xenografts of several colon carcinoma cell lines in mouse models and to cooperate with chemotherapeutic agents such as 5-fluorouracil (5-FU), cisplatin, doxorubicin and camptothecin analogue CPT-11 (Ashkenazi et al, 1999;Gliniak and Le, 1999;Lacour et al, 2001Lacour et al, , 2003Shimoyama et al, 2002). In the carcinoma cell line HT29, chemotherapeutic agents, as well as potentiating the mitochondrial amplification of the caspase cascade, enhance recruitment of the adapter protein FADD and caspase-8 to the death-inducing signal complex (DISC) (Lacour et al, 2003).…”