TY  - JOUR
A1  - Bensaad, Karim
A1  - Favaro, Elena
A1  - Lewis, Caroline A.
A1  - Peck, Barrie
A1  - Lord, Simon
A1  - Collins, Jennifer M.
A1  - Pinnick, Katherine E.
A1  - Wigfield, Simon
A1  - Buffa, Francesca M.
A1  - Li, Ji-Liang
A1  - Zhang, Qifeng
A1  - Wakelam, Michael J. O.
A1  - Karpe, Fredrik
A1  - Schulze, Almut
A1  - Harris, Adrian L.
T1  - Fatty Acid Uptake and Lipid Storage Induced by HIF-1 alpha Contribute to Cell Growth and Survival after Hypoxia-Reoxygenation
JF  - Cell Reports
N2  - An in vivo model of antiangiogenic therapy allowed us to identify genes upregulated by bevacizumab treatment, including Fatty Acid Binding Protein 3 (FABP3) and FABP7, both of which are involved in fatty acid uptake. In vitro, both were induced by hypoxia in a hypoxia-inducible factor-1 alpha (HIF-1 alpha)-dependent manner. There was a significant lipid droplet (LD) accumulation in hypoxia that was time and O-2 concentration dependent. Knockdown of endogenous expression of FABP3, FABP7, or Adipophilin (an essential LD structural component) significantly impaired LD formation under hypoxia. We showed that LD accumulation is due to FABP3/7-dependent fatty acid uptake while de novo fatty acid synthesis is repressed in hypoxia. We also showed that ATP production occurs via beta-oxidation or glycogen degradation in a cell-type-dependent manner in hypoxia-reoxygenation. Finally, inhibition of lipid storage reduced protection against reactive oxygen species toxicity, decreased the survival of cells subjected to hypoxia-reoxygenation in vitro, and strongly impaired tumorigenesis in vivo.
KW  - inducible factor-I
KW  - binding protein
KW  - triglyceride accumulation
KW  - cancer cell
KW  - complex-III
KW  - beta-oxidation
KW  - metabolism
KW  - lipogenesis
KW  - proliferation
KW  - resistance
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-115162
SN  - 2211-1247
VL  - 9
IS  - 1
ER  - 
TY  - JOUR
A1  - Ehrenschwender, M.
A1  - Bittner, S.
A1  - Seibold, K.
A1  - Wajant, H.
T1  - XIAP-targeting drugs re-sensitize PIK3CA-mutated colorectal cancer cells for death receptor-induced apoptosis
JF  - Cell Death & Disease
N2  - Mutations in the oncogenic PIK3CA gene are found in 10-20% of colorectal cancers (CRCs) and are associated with poor prognosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and agonistic TRAIL death receptor antibodies emerged as promising anti-neoplastic therapeutics, but to date failed to prove their capability in the clinical setting as especially primary tumors exhibit high rates of TRAIL resistance. In our study, we investigated the molecular mechanisms underlying TRAIL resistance in CRC cells with a mutant PIK3CA (PIK3CA-mut) gene. We show that inhibition of the constitutively active phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway only partially overcame TRAIL resistance in PIK3CA-mut-protected HCT116 cells, although synergistic effects of TRAIL plus PI3K, Akt or cyclin-dependent kinase (CDK) inhibitors could be noted. In sharp contrast, TRAIL triggered full-blown cell death induction in HCT116 PIK3CA-mut cells treated with proteasome inhibitors such as bortezomib and MG132. At the molecular level, resistance of HCT116 PIK3CA-mut cells against TRAIL was reflected by impaired caspase-3 activation and we provide evidence for a crucial involvement of the E3-ligase X-linked inhibitor of apoptosis protein (XIAP) therein. Drugs interfering with the activity and/or the expression of XIAP, such as the second mitochondria-derived activator of caspase mimetic BV6 and mithramycin-A, completely restored TRAIL sensitivity in PIK3CA-mut-protected HCT116 cells independent of a functional mitochondrial cell death pathway. Importantly, proteasome inhibitors and XIAP-targeting agents also sensitized other CRC cell lines with mutated PIK3CA for TRAIL-induced cell death. Together, our data suggest that proteasome-or XIAP-targeting drugs offer a novel therapeutic approach to overcome TRAIL resistance in PIK3CA-mutated CRC.
KW  - trail-mediated apoptosis
KW  - ligand trail
KW  - CASPASE-3
KW  - resistance
KW  - BH3-only proteins
KW  - inhibitor
KW  - MCL-1
KW  - degradation
KW  - activation
KW  - carcinoma
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-114374
SN  - 2041-4889
VL  - 5
ER  -