COX-2 inhibitors sensitize human hepatocellular carcinoma cells to TRAIL-induced apoptosis

Abstract

Cyclooxygenase (COX)-2 is upregulated in a variety of human cancers, including in hepatocellular carcinoma (HCC), whereas it is undetectable in most normal tissue. Evidence suggests that COX-2 is likely to be involved in hepatocarcinogenesis and, thus, COX-2 may be involved in an early process in carcinogenesis, dedifferentiation. To address this possibility, we investigated the effect of COX-2 inhibitors on TNF-related apoptosis, inducing ligand (TRAIL) sensitivity and its molecular mechanisms, with special attention to anti-apoptotic proteins. We used the highly selective COX-2 inhibitors, NS398 and CAY10404. We also used the MTT assay and cytological analysis of DAPI-stained DNA to assess viability and apoptosis in two HCC cells (SK-Hep1 and HLE). In order to ask what led to increased sensitivity to TRAIL in HCC cells, cell surface expression of TRAIL and TRAIL-receptors was investigated using flow cytometry analysis. Expression of survivin, X-chromosomelinked IAP (XIAP), Bcl-xL, AKT and phospho-AKT was also investigated using immunoblotting. COX-2 inhibitors resulted in a concentration-dependent decrease in cell viability in the two HCC cell lines tested. Subtoxic levels of COX-2 inhibitors did not significantly augment TNF•-induced apoptosis but did dramatically enhance TRAIL-induced apoptosis in both cell lines. TRAIL receptor 2/death receptor 5 (TRAIL-R2/DR5) expression was significantly up-regulated in SH-Hep1 and HLE cells. TRAIL receptor 1/death receptor 4 (TRAIL-R1/DR4) expression was up-regulated only in SK-Hep1. Expression of survivin and Bcl-xL was down-regulated in SK-Hep1 and HLE cells in the presence of CAY10404 but XIAP was not affected. Expression of survivin, Bcl-xL and XIAP was down-regulated in SK-Hep1 cells in the presence of NS398. Survivin expression was also down-regulated in the presence of NS398 in HLE cells. Finally, NS398 also decreased phospho-AKT in SK-Hep1 cells. These results demonstrate that COX-2 inhibitors can induce apoptosis and augment TRAIL sensitivity by up-regulation of TRAIL receptors and down-regulation of both survivin and AKT signaling.

Combining kallistatin gene therapy and meloxicam to treat hepatocellular carcinoma in mice

“…However, our previous report (31) showed that Fas, a molecule in the death-receptor extrinsic pathway, was upregulated by meloxicam, suggesting the extrinsic pathway might also participate in the apoptosis induced by meloxicam. In addition, the caspase-independent pathways might be also involved in COX-2-inhibition-induced apoptosis, as Yamanaka et al (45) reported that selective COX-2 inhibitors NS398 and CAY10404 induced apoptosis of human HCC SK-Hep1 cells by upregulating TRAIL receptors and downregulating survivin.…”

Downregulation of SNAIL sensitizes hepatocellular carcinoma cells to TRAIL-induced apoptosis by regulating the NF-κB pathway

“…Similarly, previous studies have shown that the apoptotic inhibitors of cIAP2 and survivin are important factors in determining the apoptosis of HCC cells (3,14). Thus, we investigated the expression of the two proteins.…”

“…However, findings of recent studies (3,12,13,30) have shown that many targeted drugs alter their characteristics by acting on special targets. In the present study, we found that silencing SNAIL can increase the expression of p53, which alters the sensitization of HCC cells to TRAIL.…”

“…However, of these receptors, only TRAIL-R1/DR4 and TRAIL-R2/DR5 induce apoptosis (8,9). Several tumor cell lines exhibiting resistance to TRAIL-mediated apoptosis include HCC cell lines (3,10,11). However, the mechanism involved in the resistance to TRAIL-induced apoptosis in HCC cells is mainly connected with activation of the NF-κB pathway, upregulation of apoptotic inhibitors, such as cFLIP, IAP and anti-apoptotic molecules, such as certain Bcl-family members (12)(13)(14)(15).…”

Targeting of COX-2 Expression by Recombinant Adenovirus shRNA Attenuates the Malignant Biological Behavior of Breast Cancer Cells

“…One of these factors is the oncogene c-myc, which is known to be a positive regulator of cyclin D1 and PCNA transcription (Daksis et al, 1994). C-myc also regulates the expressions of bcl-2 and survivin in hepatic cancer cells (Yamanaka et al, 2006). However, the relation of c-myc and bcl-2, survivin was not still fully clear.…”