Faculty Bibliography

INTRODUCTION/BACKGROUND:Gastric cancer is the third most common cancer worldwide and the second leading cause of cancer deaths. Appropriate staging and treatment options relate to the stage of disease and performance status of the patient. CASE REPORT/METHODS:Here we present the case of a 72 year old male, with an initial presentation of apparently locally advanced gastric cancer. On discovery of metastatic disease, the utility of palliative gastrectomy, and first and second line chemotherapy are discussed. DISCUSSION/CONCLUSIONS:This case demonstrates the potential value of sequential lines of chemotherapy in good performance status patients with advanced gastric cancer. Further research will be necessary in order to assess the utility of newer targeted agents in this setting.

The truncated glucocorticoid receptor mutant gene 465* codes for a protein that is interrupted by a frame-shift mutation in the second zinc finger of the natural DNA binding domain. Thus, 465* represents the natural amino acid sequence 1-465 followed by 21 novel amino acids starting at position 466. The entire ligand binding domain is missing. Prior studies have shown that transient transfection of the glucocorticoid-resistant leukemic T-cell clone ICR-27 with a plasmid expressing 465* rapidly reduces the number of viable cells. This response does not require activation by a steroid, and a hybrid protein consisting of green fluorescent protein fused to 465* is found primarily in the cytoplasm. In the present study, we present evidence that the decrease in cell number is due to a form of cell death that bears many of the classic characteristics of apoptosis. Expression of the 465* protein can be detected a few hours after electroporation and is followed by activation of caspase-3 as well as reduction of the mitochondrial inner transmembrane potential. The caspase-3 inhibitor ZVAD-fmk blocks 465*-dependent cell death when added acutely after electroporation, but fails to do so later. We conclude that the novel 465* gene causes cell death by apoptosis.

Both glucocorticoids and oxysterols, steroids with quite different known transduction pathways, cause the death of lymphoid cells. Dual TUNEL/propidium iodide assays on sensitive human leukemic CEM-C7 clones treated with either steroid were clearly positive by 48 h, consistent with apoptosis. Both steroids evoked two distinctive types of DNA lysis: cleavage into large fragments of several different sizes and the classic "ladders", multiples of approximately 200 base pairs. Conventional gel electrophoresis showed that a small proportion of total DNA had undergone laddering 36-48 h after treatment with glucocorticoid or 24 h after oxysterol exposure. On field inversion gel electrophoresis of cellular DNA both steroids caused an increase in an array of large DNA fragments <50 kb in size. A 50 kb fragment appeared 36 h after treatment with either steroid, but only oxysterol treatment caused a significant increase in a 300 kb fragment. Oxysterol treatment did not result in DNA fragmentation in the resistant M10R5 subclone, which retained sensitivity to glucocorticoids. We conclude that glucocorticoids and oxysterols kill these cells with similar, but not identical, patterns of DNA lysis which occur just before or concomitant with the onset of cell death.