Elizabeth E. Miller

Host‐tumor interaction and nutrient supply

Adequate parenteral nutritional support improves nutritional status in cancer patients, but its effect on tumor growth remains controversial. Using a transplantable mammary adenocarcinoma in a rat‐TPN model, the relative effect of different exogenous intravenous nutrients on tumor growth and host maintenance was studied. Relative to chow controls, starvation increased host depletion without reducing tumor growth. Adequate carbohydrate calories alone neither improved host maintenance nor stimulated tumor growth, yet adequate amino acids alone did improve host maintenance but also stimulated tumor growth. Adequate amino acids and carbohydrates given simultaneously maximized both host maintenance and tumor growth. In contrast, an isocaloric, isonitrogenous, intravenous diet providing non‐nitrogenous calories as fat promoted host maintenance equivalent to carbohydrate‐based TPN with no tumor stimulation. This apparent differential utilization of fat calories by normal and malignant cells may permit manipulation of the relative benefit of parenteral nutrition to host or to tumor, permitting host repletion without tumor stimulation or alternatively tumor stimulation at appropriate times to increase sensitivity to phase‐specific antineoplastic therapy.

Alteration of tumor cell kinetics by pulse total parenteral nutrition. Potential therapeutic implications.

Previous work has demonstrated that substrate‐induced alterations of tumor metabolism can be exploited to potentiate tumor response to cycle‐specific chemotherapy (methotrexate, Adriamycin (doxorubicinl). This study was performed to investigate the biologic mechanism responsible for this phenomenon by determining the effect of short‐term total parenteral nutrition (TPN) on tumor cytokinetics. Forty‐two female Lewis/Wistar rats with subcutaneous mammary tumor implants (AC‐33) underwent superior vena caval cannulation, and were randomized to receive either TPN or normal saline intravenously. Animals receiving TPN were killed at 2, 6, 12, 24, and 48 hours after initiating TPN; control animals given normal saline were killed at 0, 24, and 48 hours after randomization. At the time the animals were killed tumor cytokinetic analysis was performed by flow cytophotometry. The percentage of tumor cells in S‐phase was significantly increased in animals after only 2 hours of TPN (55.5 ± 9.1%) compared with the control group (43.7 ± 7.7%) (P < 0.01). The ratio of sensitive/resistant tumor cells to S‐phase‐specific chemotherapy was effectively increased in animals receiving adjuvant TPN (1.31 ± 0.43) compared with control animals (0.80 ± 0.25) (P < 0.015). This alteration in tumor cytokinetics provides one explanation for the enhanced tumor response to cycle‐specific chemotherapy previously observed with pulse TPN administration. Cancer 53:1409‐1415, 1984.

Enhanced Tumor Response to Cycle-Specific Chemotherapy by Parenteral Amino Acid Administration

Forced feeding has been shown to effectively stimulate tumor metabolism in numerous animal models. Significant acceleration of tumor growth by exogenous nutrient administration is generally considered to be detrimental to the host. The present study was performed to determine if substrate-induced alterations in tumor metabolism could be exploited to enhance tumor response to cycle-specific chemotherapy. Following subcutaneous mammary tumor implantation (AC-33) and protein depletion, 39 female Lewis/Wistar rats were randomly assigned to one of four nutritional regimens for 48 hr: (1) protein-depleted food (0.03% protein) ad libitum po, (2) parenteral carbohydrate (18.6% dextrose), (3) parenteral amino acids (2.8% amino acids), or (4) total parenteral nutrition (18.6% dextrose/2.8% amino acids). Methotrexate (5 mg/kg im) was administered to all animals 2 hr after initiating these nutritional regimens. Tumor volume and host toxicity were monitored throughout the study. At sacrifice, significant reduction in tumor volume was observed in animals receiving parenteral amino acids (0.37 +/- 0.24 cm3) and total parenteral nutrition (0.25 +/- 0.18 cm3) compared to the group receiving protein-depleted food po (0.70 +/- 0.22 cm3) (p less than 0.01). In this animal model, the parenteral administration of amino acids with or without the addition of hypertonic dextrose was found to effectively potentiate tumor response to methotrexate without increasing host toxicity.

Reduction of methotrexate toxicity with improved nutritional status in tumor-bearing animals

The administration of chemotherapy in clinical situations is limited frequently because of the associated toxicity to normal bone marrow cells, gastrointestinal epithelium, and other host tissues. Although nutritional support has been advocated to reduce chemotherapy‐related toxicity in cancer patients, few studies substantiate this clinical impression. The current study was performed to determine the role of nutritional status and enteral nutrient intake as determinants of methotrexate (MTX) toxicity in a well‐controlled, tumor‐bearing animal model. After subcutaneous mammary tumor (AC‐33) inoculation, 56 female Lewis/Wistar rats were assigned randomly to one of the following two nutritional regimens for 14 days: (1) protein‐depleted chow (PC) (0.03% protein; 4.27 kcal/g) or (2) standard chow (RC) (22.0% protein; 3.50 kcal/g). After 7 days of dietary control, all animals received one of three weight‐adjusted doses of MTX (5, 10, or 20 mg/kg intramuscularly [IM]) or placebo. All animals received leucovorin rescue (0.6 mg IM) at 6 and 24 hours after MTX injection. Improved nutritional status was associated with a significant reduction in objective measures of MTX‐related morbidity and mortality. At low doses of MTX (5 and 10 mg/kg), the mean duration of clinical signs of toxicity (i.e., hair loss, lethargy, and diarrhea) and severity of leukopenia were greater in protein‐depleted (PD) animals. With high‐dose MTX (20 mg/kg), mortality was increased significantly in PD animals (100%) compared with well‐nourished animals (0%). Equivalent tumor response was observed in PD and well‐nourished animals. Thus, improved nutritional status by enteral nutrition reduced the morbidity and mortality associated with MTX significantly in this tumor‐bearing animal model.

Enhanced tumor response to cycle-specific chemotherapy by pulse total parenteral nutrition

Exogenous nutrient administration has been shown to significantly stimulate tumor growth in numerous animal models. The present study was performed to determine if substrate-induced alterations in tumor metabolism could be exploited to potentiate tumor response to cycle-specific chemotherapy. Following subcutaneous mammary tumor (AC-33) implantation, 55 female Lewis/Wistar rats were randomly assigned to one of three nutritional regimens for 48 hr: (1) protein-depleted chow (0.03% protein) ad lib per os, (2) standard rat chow (22.0% protein) ad lib per os, or (3) total parenteral nutrition (TPN; 18.6% dextrose/2.8% amino acids). One-half of the animals in each group received a single dose of methotrexate (5 mg/kg im) while the remaining animals received placebo (saline) injections. At sacrifice, methotrexate-treated animals receiving TPN demonstrated a significantly smaller tumor volume (0.47 +/- 0.44 cm3) compared to animals given either protein depleted chow (1.30 +/- 0.76 cm3) or standard rat chow (1.34 +/- 0.83 cm3) (P less than 0.01). In this animal model, adjuvant TPN was found to significantly potentiate tumor response to cycle-specific chemotherapy with no detectable exacerbation of host toxicity.

Myosin preparations from the rabbit, rat and mouse.

Abstract Myosin was prepared from the leg muscle of the rabbit, rat, and mouse. The preparations from the different species were found to be practically indistinguishable in yield, electrophoretic mobility, sedimentation rate, specific refractive increment, and viscosity. They were found to contain actomyosin and γ-myosin in addition to myosin proper. The identification and correlation of the three components in the electrophoretic and sedimentation diagrams were worked out. After removal of actomyosin from the myosin preparations by reduction of ionic strength, the actin-free fractions which remain contained γ-myosin as a contaminant. About 20% of the myosin proper appeared to be inhomogeneous on sedimentation. Evidence was also obtained which indicates that strong salt can cause a partial dissociation of actomyosin, and that actomyosin may exist, in part, in a form whose sedimentation properties do not differ appreciably from those of myosin proper.

Stability of 111In-bleomycin in vivo-properties compared with 57Co-bleomycin

Abstract111Indium-bleomycin (111In-BLM) and 57Co-bleomycin (57Co-BLM) were prepared and their distributions were compared in the tissues, blood, and urine in tumor-bearing and in untreated mice and rats. Autoradiographs of electrophoresis gels showed that patterns for urine from untreated and tumor-bearing animals, collected 1–3 h or 48 h after injection of 111In-BLM were similar to those for in vitro mixtures of urine and 111In-BLM, but differed from the patterns obtained with 111InCl3 under in vivo or in vitro conditions. In rats bearing mammary adenocarcinoma, 48 h after administration of the radio-pharmaceutical, the activity ratio of tumor to eleven different tissues was 1.2–4.6 times higher for injected 111In-BLM than for 111InCl3 (P≦0.001 or P≦0.05). Imaging with a gamma camera depicted tumors in mice more distinctly with 111In-BLM than with 111InCl3. These findings were interpreted as reflecting the stability of 111In-BLM in vivo. The tumor concentration (%dose/g) was higher for the viable area than for the necrotic area for 111In-BLM, but the reverse was true for 57Co-BLM.

Tumor Effects on Gluconeogenesis in the Isolated Perfused Rat Liver

Alterations in metabolism in the tumor-bearing host can be explained by: 1) alterations of metabolic processes in the tumor itself, and/or 2) tumor effects on host metabolism. Tumor effects on host liver metabolism were studied using an isolated perfused rat liver preparation. The livers of fasted female Lewis Wistar rats with and without transplanted subcutaneous mammary tumors were perfused for 1 hr with medium containing 5 mM glucose and physiological levels of amino acids. The rate of gluconeogenesis, as measured by conversion of 14C-lactate to 14C-glucose, showed a significant increase in the rate of glucose production from lactate in tumor-bearing rats (2.40 vs 2.00 mumol/min/100 gm). Hepatic glycogen and 14C-glycogen content were not significantly different between the two groups. In order to evaluate whether this tumor model exhibits characteristic changes in metabolism previously reported in other animal tumor models, serum lactate, triglyceride, glucose, and blood urea nitrogen were measured in non-perfused animals. The serum concentration of lactate and triglycerides were significantly higher in tumor-bearing rats (0.9 mM vs 2.7 mM lactate; 244 mg % vs 365.5 mg % triglycerides). Serum glucose and blood urea nitrogen were not significantly different in the two groups. An effect of tumor on host energy metabolism and serum metabolite levels is demonstrated. A method for the study of host-tumor metabolic interactions is described.

Nonabsorbable radioactive material in the treatment of carcinomas by local injections

Nonabsorbable radioactive material was used in treating malignant lesions by local injection. One hundred thirty‐five Lewis Wistar rats were inoculated subcutaneously with tumor cells. After 7 days, the rats grew tumors of approximately 1 × 1 × 1 cm at the injection site. The rats then were divided into two groups; 50% were kept as a contol group while the other 50% received single injections of 1 mCi yttrium 90 (90Y) microspheres directly into the center of the tumor. This study shows a significant reduction of the tumor growth rate in treated animals. Tumor sizes after 4 days averaged 1.31 ml in the treated rats and 9.74 ml in the control group. Excluding animals that had complete regression of the tumor, treated rats lived an average of 30.8 days from the day of treatment compared with the control rats, which lived an average of 17.4 days. Pathology examinations showed no effects from injected radioactive materials in the liver, bone marrow or the kidney. Examination of the injected area after 6 months showed that microspheres remained locally and that the tumor was replaced with collagen tissue.

ACTIVE SPECIFIC IMMUNOTHERAPY OF HUMAN SOLID TUMORS

Active specific immunotherapy of human solid tumors by use of enzyme altered cells appears to be a feasible approach. Our initial results, we believe, warrant continued effort in this area. There seem to be no adverse clinical effects to such treatment. In vitro assay methods, to document enhanced immunity, must be included in any immunotherapy program. Equally importantly, such test methods should be expanded for the earliest detection of adverse effects, such as blocking during the course of immunotherapy. The role of immunotherapy must be that of adjuvant treatment, and its only applicability will be in that role.