Recent data indicate that NAD(P)H: quinone oxidoreductase 1 (NQO1) is important in the activation of mitomycin C. A polymorphism in human NQO1 (609C>T) is associated with diminished NQO1 activity. The purpose of our study was to determine the effect of the 609C>T polymorphism on tumor NQO1 activity and overall survival in patients with disseminated peritoneal cancer receiving intraperitoneal mitomycin C therapy. Patients with disseminated peritoneal cancer of gastrointestinal or other origin were eligible. Following aggressive surgical debulking, patients were administered a 2-h heated (40.5 degrees C) intraperitoneal perfusion with mitomycin C. NQO1 activity was determined in tumor tissue obtained during surgery and patients were genotyped for the NQO1 C609T polymorphism using a polymerase chain reaction-based method. The major response variable monitored during the trial was overall survival. Of the 117 patients genotyped for the NQO1 609C>T polymorphism, 67% were wild-type (WT), 31% were heterozygous (HE), and 2% were homozygous mutant (HM). In tumor tissue, the mean NQO1 activities from WT (n = 14) and HE (n = 5) patients were 794 +/- 603 and 70 +/- 133.1 nmol/min/mg protein respectively (P = 0.006). Significant differences in survival between WT versus HE/HM genotypes were noted in optimally debulked patients (R0/R1) (43.6+ months, median not yet reached versus 23 months respectively, P = 0.037) and in patients with peritoneal carcinomatosis of colonic origin (18.2 versus 11.5 months respectively, P = 0.050). These data indicate that the NQO1 609C>T polymorphism results in significantly reduced tumor NQO1 activity and reduced survival in subsets of patients receiving intraperitoneal hyperthermic mitomycin C therapy.

Despite the proven efficacy of radiosurgery for the treatment of brain tumors, limited histological information is available after treatment that might allow a better understanding of the relationship between radiation dose, the volume treated, and the response of the surrounding brain to the delivered radiation. The use of an animal model could provide the opportunity to clarify these relationships and answer several other key questions arising in clinical practice. We show here that treatment of small animals with radiosurgery is feasible using a robotically controlled linear accelerator, which offers the advantages of radiosurgery and preserves the potential for fractionated regimens without rigid immobilization. Specifically, we demonstrate the use of a robotically driven linear accelerator to provide radiosurgical treatment to a rat brain tumor model.

Therapeutic radiation and subsequent detection of tumor cell death has been performed mainly in vitro systems, making it difficult to accurately characterize the mechanisms of tumor cell death after radiosurgery. To better characterize what occurs to glioma cells after radiation therapy, we developed a rat model using the 9L gliosarcoma cell line implanted reproducibly to the caudate nucleus in rats. After 1 Gy radiation, 9L tumors in vivo induced mainly necrosis (determined by trypan blue exclusion) of 10 - 74 % at 6 - 72 hours post-radiation. This is in contrast to a previous in vitro study which demonstrated that 18 Gy of radiation induces considerably less cell death as determined by trypan blue exclusion (approximately 20 - 25 % at 6 - 72 hours post-radiation). However, significant amounts of apoptosis were detected as early as 6 hours after radiation. Apoptosis determination was by annexin V (marker of early apoptosis) and propidium iodide (marker of membrane stability) staining followed by flow cytometry detection. When caspase 3 and caspase 8 enzymatic activities (mediators of apoptosis) were measured from freshly explanted tumor cells, peak activity was found 6 hours after 1 Gy radiation (p < 0.01). Taken together, these data indicate the presence of apoptosis early after radiation therapy (1 Gy) which progressed to necrosis in a unique in vivo model of gliosarcoma that may prove useful in determining new therapeutic approaches to radiation therapy and tumor cell biology.

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