fumonisin-b1 and Head-and-Neck-Neoplasms

Combining an anticancer agent fenretinide (HPR) or C6-pyridinium ceramide (LCL29) with Foscan-mediated photodynamic therapy (FoscanPDT) is expected to augment anticancer benefits of each substance. We showed that treatment with FoscanPDT+HPR enhanced accumulation of C16-dihydroceramide, and that fumonisin B1 (FB), an inhibitor of ceramide synthase, counteracted caspase-3 activation and colony-forming ability of head and neck squamous cell carcinoma (HNSCC) cells. Because cancer cells appear to be more susceptible to increased levels of the endoplasmic reticulum (ER) stress than normal cells, herein we tested the hypothesis that FoscanPDT combined with HPR or LCL29 induces FB-sensitive ER stress-associated apoptosis that affects cell survival.. Using an HNSCC cell line, we determined: cell survival by clonogenic assay, caspase-3 activity by spectrofluorometry, the expression of the ER markers BiP and CHOP by quantitative real-time polymerase chain reaction and western immunoblotting, and sphingolipid levels by mass spectrometry.. Similar to HPR+FoscanPDT, LCL29+FoscanPDT induced enhanced loss of clonogenicity and caspase-3 activation, that were both inhibited by FB. Our additional pharmacological evidence showed that the enhanced loss of clonogenicity after the combined treatments was singlet oxygen-, ER stress- and apoptosis-dependent. The combined treatments induced enhanced, FB-sensitive, up-regulation of BiP and CHOP, as well as enhanced accumulation of sphingolipids.. Our data suggest that enhanced clonogenic cell killing after the combined treatments is dependent on oxidative- and ER-stress, apoptosis, and FB-sensitive sphingolipid production, and should help develop more effective mechanism-based therapeutic strategies.

Topics: Apoptosis; Carcinoma, Squamous Cell; Caspase 3; Caspase Inhibitors; Cell Line, Tumor; Ceramides; Combined Modality Therapy; Endoplasmic Reticulum Stress; Fenretinide; Fumonisins; Head and Neck Neoplasms; Humans; Mesoporphyrins; Photochemotherapy; Pyridinium Compounds; Radiation-Sensitizing Agents; Squamous Cell Carcinoma of Head and Neck

Combining photodynamic therapy (PDT) with another anticancer treatment modality is an important strategy for improved efficacy. PDT with Pc4, a silicon phthalocyanine photosensitizer, was combined with C6-pyridinium ceramide (LCL29) to determine their potential to promote death of SCC17B human head and neck squamous cell carcinoma cells. PDT+LCL29-induced enhanced cell death was inhibited by zVAD-fmk, a pan-caspase inhibitor, and fumonisin B1 (FB), a ceramide synthase inhibitor. Quantitative confocal microscopy showed that combining PDT with LCL29 enhanced FB-sensitive ceramide accumulation in the mitochondria. Furthermore, PDT+LCL29 induced enhanced FB-sensitive redistribution of cytochrome c and caspase-3 activation. Overall, the data indicate that PDT+LCL29 enhanced cell death via FB-sensitive, mitochondrial ceramide accumulation and apoptosis.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Carcinoma, Squamous Cell; Caspase 3; Cell Line, Tumor; Ceramides; Cytochromes c; Drug Synergism; Enzyme Activation; Fumonisins; Head and Neck Neoplasms; Humans; Indoles; Mitochondria; Organosilicon Compounds; Photochemotherapy; Photosensitizing Agents; Protein Transport; Pyridinium Compounds

The sphingolipid ceramide modulates stress-induced cell death and apoptosis. We have shown that ceramide generated via de novo sphingolipid biosynthesis is required to initiate apoptosis after photodynamic therapy (PDT). The objective of this study was to define the role of ceramide synthase (CERS) in PDT-induced cell death and apoptosis using fumonisin B1 (FB), a CERS inhibitor. We used the silicon phthalocyanine Pc4 for PDT, and SCC17B cells, as a clinically-relevant model of human head and neck squamous carcinoma. zVAD-fmk, a pan-caspase inhibitor, as well as FB, protected cells from death after PDT. In contrast, ABT199, an inhibitor of the anti-apoptotic protein Bcl2, enhanced cell killing after PDT. PDT-induced accumulation of ceramide in the endoplasmic reticulum and mitochondria was inhibited by FB. PDT-induced Bax translocation to the mitochondria and cytochrome c release were also inhibited by FB. These novel data suggest that PDT-induced cell death via apoptosis is CERS/ceramide-dependent.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; bcl-2-Associated X Protein; Carcinoma, Squamous Cell; Cell Line, Tumor; Ceramides; Cytochromes c; Endoplasmic Reticulum; Enzyme Inhibitors; Fumonisins; Head and Neck Neoplasms; Humans; Indoles; Mass Spectrometry; Mitochondria; Organosilicon Compounds; Oxidoreductases; Photochemotherapy