Macrophage Migration Inhibitory Factor Is a Determinant of Hypoxia-Induced Apoptosis in Colon Cancer Cell Lines

Abstract

Hypoxia contributes to cytotoxic chemotherapy and radiation resistance and may play a role in the efficacy of antiangiogenesis cancer therapy. We have generated a series of cell lines derived from the colon adenocarcinoma models HT29 and HCT116 by exposing cells in vitro to repeated sublethal periods of profound hypoxia. These cell lines have altered sensitivity to hypoxia-induced apoptosis: those derived from HT29 are resistant, whereas those from HCT116 are more susceptible. We used cDNA selected subtractive hybridization to identify novel genes mediating sensitivity to hypoxia-induced apoptosis and isolated macrophage migration inhibitory factor (MIF) from the hypoxia-conditioned cell lines. MIF expression correlates with susceptibility of the cell lines to apoptosis. In hypoxia-resistant cells, the induction of apoptosis by hypoxia can be restored by the addition of exogenous recombinant MIF protein, suggesting that resistance may result in part from down-regulation of MIF production possibly through an autocrine loop. Inhibition of MIF using small interfering RNA in the susceptible lines conferred resistance to hypoxia-induced cell death. The relative expression of MIF in the hypoxia-conditioned cells implanted s.c. in severe combined immunodeficient mice in vivo was similar to that observed in vitro. In an analysis of 12 unrelated colon tumor cell lines, MIF expression and response to hypoxia varied widely. Cell lines in which MIF was inducible by hypoxia were more sensitive to oxaliplatin. In human colon tumor specimens analyzed by immunohistochemistry, MIF expression was similarly variable. There was no detectable expression of MIF in normal colon mucosa or adenoma but positive staining in all carcinomas tested. Taken together, these data indicate that MIF may be a determinant of hypoxia-induced apoptosis in vitro and that its variable expression in human colon cancers may indicate a functional role in vivo. We suggest that MIF expression in colorectal cancer may be a marker of susceptibility to therapies that may depend on induction of hypoxia, possibly including antiangiogenic therapy.Colon cancer is characterized by regions of variable hypoxia, known to be a consequence of disordered vasculature (1). Cells in these hypoxic regions are resistant to radiation and to cytotoxic drugs (2). We have shown previously that hypoxia induces increased expression of genes involved in the detoxification of cytotoxic drugs (3), an effect exerted in part by activation of transcription factors, including activator protein-1 and nuclear factor-nB (4, 5). Hurwitz et al. have shown recently that antiangiogenic therapy adds to the efficacy of chemotherapy in colorectal cancer (6), whereas Willett et al. showed that bevacizumab alone in rectal cancer markedly decreased blood flow to the tumor (7). These findings raise the possibility that apoptosis as a result of oxygen or nutrient withdrawal contributes to the therapeutic effect and prompted an investigation of the resistance of hypoxic cancer cells to apoptos...

Macrophage migration inhibitory factor deficiency protects pancreatic islets from palmitic acid‐induced apoptosis

“…[31][32][33] However, MIF acts as a pro-apoptotic molecule as well through engaging mitochondriarelated apoptotic pathway. [25][26][27][28] The initial step in the apoptosis induction is assembling of BAX molecules into large homo-oligomers that damage the outer mitochondrial membrane, consequently becoming permeable to proteins normally constrained within the intermembrane space of the mitochondria. On the other hand, presence of Bcl-2 proteins confronts membrane pore formation.…”

“…23 There is also evidence that MIF promotes apoptotic cell death in primary bladder muscle cells, B lymphocytes, tumor cell lines, cardiomyocytes and neurons. [24][25][26][27] The mechanism of apoptosis induction by MIF is not well understood. There is some circumstantial evidence that suggests the involvement of mitochondrial dysfunction in MIF-mediated apoptosis.…”

Murine Protein Serine/Threonine Kinase 38 Stimulates TGF-β Signaling in a Kinase-dependent Manner via Direct Phosphorylation of Smad Proteins

“…RNA Interference-MPK38-specific siRNA (5Ј-CAGGCA-GACAAUGGAGGAUTT-3Ј) targeting a coding region (amino acids 297-303) of MPK38 (17) and a control scrambled siRNA (5Ј-GCGCGGGGCACGUUGGUGUTT-3Ј) (26) were transfected into HEK293, HepG2, or HaCaT cells using the WelFect-Ex TM Plus method according to the manufacturer's instructions.…”

Expression of Macrophage Migration Inhibitory Factor Relates to Survival in High-grade Osteosarcoma

“…The siRNA sequences used to target MIF were 5 0 -ACACCAAGCUGCCCCGCGCdTdT-3 0 and 5 0 -GCGCGGGGCACGUUGGUGUdTdT-3 0 [30]. A fluorescein double-stranded RNA (BLOCK-iT Fluorescent Oligo; Invitrogen, Carlsbad, CA) was used as a control siRNA.…”