KRASD13 Promotes Apoptosis of Human Colorectal Tumor Cells by ReovirusT3D and Oxaliplatin but not by Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand

Abstract

Colorectal tumors frequently contain activating mutations in KRAS. ReovirusT3D is an oncolytic virus that preferentially kills tumor cells with an activated Ras pathway. Here we have assessed the contribution of endogenous mutant KRAS in human colorectal cancer cell lines to ReovirusT3D replication and to tumor cell oncolysis. In addition, treatment combinations involving ReovirusT3D, oxaliplatin, and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) were tested for their efficacy in tumor cell killing. The mutation status of KRAS did not predict the sensitivity of a panel of human colorectal cancer cell lines to ReovirusT3D. Virus replication was observed in all cell lines tested regardless of KRAS status and was not affected by deletion of endogenous mutant KRAS D13 . However, deletion of KRAS D13 or p53 did reduce apoptosis induction by ReovirusT3D whereas deletion of Bcatenin #S45 had no effect. Likewise, KRAS D13 -or p53-deficient cells display reduced sensitivity to oxaliplatin but not to death receptor activation by TRAIL. Finally, the treatment of colorectal cancer cells with ReovirusT3D combined with either oxaliplatin or TRAIL resulted in a nonsynergistic increase in tumor cell killing. We conclude that oncolysis of human tumor cells by ReovirusT3D is not determined by the extent of virus replication but by their sensitivity to apoptosis induction. Oncogenic KRAS D13 increases tumor cell sensitivity to activation of the cell-intrinsic apoptosis pathway without affecting ReovirusT3D replication. (Cancer Res 2006; 66(10): 5403-8)

Oncogenic KRAS sensitises colorectal tumour cells to chemotherapy by p53-dependent induction of Noxa

“…We found that KRAS greatly facilitated apoptosis induction by both chemotherapeutics as described previously (Klampfer et al, 2005;Smakman et al, 2006) ( Figure 1A and B). HCT116 cells underwent a bona fide cell-cycle arrest and did not enter mitosis before apoptosis induction ( Figure 1C).…”

“…For instance, the expression of oncogenic N-Ras but not that of oncogenic K-Ras in the colonic epithelium provides protection against enterocyte apoptosis in a colitis model (Haigis et al, 2008). In contrast, we along with others have previously shown that oncogenic KRAS promotes apoptosis of human colorectal tumour cells exposed to either 5-FU or oxaliplatin (Klampfer et al, 2005;Smakman et al, 2006). Although activating mutations in KRAS alone do not reliably predict the response of colorectal tumours to chemotherapy (Loriot et al, 2009), these findings do suggest that the acquisition of KRAS mutations may be associated with an increased propensity to undergo apoptosis.…”

Shp2/MAPK signaling controls goblet/paneth cell fate decisions in the intestine

“…shRNA-mediated knockdown of SHP2 in HT29 cells did not affect MEK1/2 activity (Fig. S4F), which is in line with the fact that HT29 cells harbor an oncogenic B-RAF mutation (38) that activates MAPK signaling downstream of SHP2. Furthermore, shSHP2 interference did not alter the expression of the TCF4 isoforms (Fig.…”

Activated Ras signaling significantly enhances reovirus replication and spread

“…Nonetheless, recent publications show that protein translation is not necessary for the preferential replication of reovirus in Ras-transformed cells, as once hypothesized. [4][5][6][7][8][9] We quantitatively measured the efficiency of every step in the first round of reovirus replication, from binding to release, and identified three replication steps that are significantly augmented in connection with increased Ras activation. Activated Ras signaling promotes uncoating of the incoming virus, infectivity of the progeny virus, and virus-induced apoptosis of the host cell.…”