Endocrine mediation of psychosocial stressor effects on mouse mammary tumor growth.

We have demonstrated that differential housing alters the growth rate of the androgen-responsive Shionogi mouse mammary carcinoma (SC115). In the present study we wished to determine if changes in plasma levels of hormones or a shift in the responsiveness of the tumor cells to hormones was responsible for the differential tumor growth rates observed. Plasma testosterone and corticosterone levels were assayed 24 h, 3 days and 1 week post tumor cell/vehicle injection. Also 3 weeks post injection androgen and glucocorticoid receptor binding capacity (Bmax) and binding affinity (Kd) and the in vitro responsiveness of tumor cells to dihydrotestosterone and hydrocortisone were measured. At 24 h post injection, plasma testosterone levels were significantly increased in mice with large tumors, but remained low in mice with small tumors. Plasma corticosterone levels were significantly elevated in mice with small tumors compared to those of mice with large tumors at all time points measured. Androgen and glucocorticoid receptor binding capacity and binding affinity of tumor cells did not differ among groups. Further, all groups tested had the ability to respond to dihydrotestosterone and hydrocortisone in vitro. These data indicate that an effect of housing condition on plasma levels of steroid hormones may, in part, mediate the differential tumor growth rates observed in this model.     

Functional characteristics of transplantable rat pituitary tumor MtT SA5 inducing pronounced adrenal hyperplasia

Transplantable rat pituitary tumor MtT SA5 is characterized by the induction of pronounced adrenal enlargement. In spite of remarkable elevation of plasma ACTH levels, serum corticosterone levels in hypophysectomized tumor-bearing rats were lower than those in intact control rats. No immunohistochemical alterations were seen in corticotrophs of the pituitary in tumor-bearing rats. Ratio of bioactive ACTH (Bio-ACTH) to immunoreactive ACTH (Ir-ACTH) in the tumor tissues was 0.2%, being extraordinarily lower than in the pituitary tissues (23%). Gel chromatography of the tumor tissue showed large molecular weight forms of Ir-ACTH, which seem to result from abnormal processing of proopiomelanocortin, and are responsible for the lower levels of Bio-ACTH compared to Ir-ACTH. The MtT SA5 tumor is suggested to secrete ACTH-related peptides which induce pronounced adrenal enlargement with little or no stimulation of glucocorticoid production.     

Gluconeogenesis in the tumor-influenced rat hepatocyte: importance of tumor burden, lactate, insulin, and glucagon

In an attempt to define the relationship between tumor burden (cachexia) and host hepatocyte gluconeogenesis, the following experiments were performed with the use of an F344 male rat bearing a transplantable sarcoma. Food intake of tumor-bearing (TB) rats was constant until day 24 following implant and a tumor burden of 18 +/- 5.2% (mean +/- SD), at which time food intake progressively declined daily. Tumor burden was arbitrarily divided at 12.8% to determine if any measured changes occurred prior to or following the approximate time when a significant decline in food intake occurred. Plasma glucose levels decreased with tumor burden. Whole-blood lactate levels increased with tumor burden. Fasting plasma alanine levels decreased with tumor burden. Plasma 3-methylhistidine levels increased with tumor burden. Plasma glucagon levels increased with tumor burden, whereas plasma insulin levels decreased. Hormone changes were noted at small tumor burdens prior to a decline in food intake. Viable hepatocytes were isolated from 4 groups: non-tumor-bearing (NTB), small tumor burden [(STB) 3.5% total body weight (TBW)], moderate tumor burden [(MTB) 14% TBW], and large tumor burden [(LTB) 23% TBW]. As expected in NTB rats, hepatocytes produced significantly more glucose with 20 mM lactate than 20 mM alanine or than Hanks' balanced salt solution (HBSS) alone. Hepatocytes from STB rats demonstrated the same basic relationship for lactate, alanine, and HBSS, but they produced significantly more glucose from lactate and HBSS alone than NTB hepatocytes. With alanine as substrate, the rates of glucose production by hepatocytes were not affected by the presence or size of tumor. However, with lactate as substrate, hepatocytes from MTB and LTB rats produced progressively less glucose as tumor burden increased (r = -0.85, p less than .001), which may partly explain the reduction in blood glucose and elevation in blood lactate levels observed. Elevated gluconeogenesis in TB rats occurred early prior to a decline in food intake. The key precursor appeared to be lactate. The balance between glucagon and insulin appeared to promote the abnormal host carbohydrate metabolism observed.     

ACTH, ADH, and calcitonin concentrations as markers of response and relapse in small-cell carcinoma of the lung

The ectopically produced polypeptide hormones ACTH, ADH, and calcitonin were investigated as tumor markers in patients with small-cell carcinoma of the lung (SCC). Plasma ADH concentrations were evaluated separately as well as in relation to concomitantly obtained plasma osmolality levels. No significant nor consistent changes of marker concentrations caused by lysis of tumor cells were found immediately after administration of cytotoxic drugs. After tumor regression, plasma ACTH and serum calcitonin concentrations and inappropriate ADH secretion (plasma ADH levels inappropriately high compared with plasma osmolality) became normal in most cases; however, progressive disease was not followed consistently by changes in plasma ACTH concentrations and occurrence of inappropriate ADH secretion. Contrary to this, among 12 patients with disease progression, serum calcitonin levels increased in ten patients and plasma ADH levels increased in 11 patients. In most cases, however, these changes were only moderate, and serum calcitonin concentrations were found to be increased after tumor regression in patients who had normal pretreatment levels. It is concluded that decisions on treatment of patients with SCC cannot exclusively be based on changes in the concentrations of the polypeptide hormones that might be of ectopic origin.     

Reversal of tumor-induced biochemical abnormalities by insulin treatment in rats

In F344 rats bearing transplantable 3-methylcholanthrene (CAS: 56-49-5)-induced sarcomas, plasma concentrations of immunoreactive insulin were decreased following the development of mild or severe anorexia. Plasma levels of immunoreactive glucagon and lactate were elevated in severely anorectic tumor-bearing (TB) rats, while plasma glucose concentrations remained normal. Both groups of TB rats exhibited decreased plasma levels of serine, glutamine, citrulline, and tryptophan and increased concentrations of alanine. Plasma levels of proline and phenylalanine were also elevated in the severely anorectic TB rats. In a second experiment, 7 daily treatments with insulin corrected the anorexia for 6 days and increased body weights of TB rats. Plasma concentrations of lactate and immunoreactive glucagon were decreased, and the abnormal plasma concentrations of glutamine, proline, analine, and phenylalanine were altered toward normal following the insulin treatments. Therefore, these data are consistent with insulin treatments benefiting the TB host by increasing feeding, increasing body weight, reducing tumor glycolysis and metabolism, reducing gluconeogenesis, and reducing host catabolism, while not stimulating tumor growth. Thus insulin therapy may have potential benefits in cancer treatment by shifting glucose metabolism toward the host and away from the tumor.     

Inhibitory effects of combined administration of uft and krestin on intraperitoneal metastases in mice

In this study we investigated the effect of combined administration of UFT and Krestin (PSK) on the growth of intraperitoneal metastasis and temporal changes in the immune-endocrine system under this immunochemotherapy. At 7 days, Plasma ACTH levels of the PSK group were significantly lower than that of the control group (p<0.01). At 14 days, the tumor weight in the combined and the PSK alone group was significantly decreased, compared to the control group (p<0.05). Serum IAP levels of the UFT group were significantly lower than that of the control group (p<0.05). Serum cortisol levels of the combined group were lower than that of the other groups.     

Plasma and tumor ACTH in carcinoma of the lung.

Plasma and tissue contents of immunoreactive ACTH were determined in 100 patients undergoing surgical resection for lung cancer. ACTH was detectable (greater than 1 ng ACTH equivalent/g wet weight) tissue in 47 of 49 specimens of epidermoid carcinoma, in 15 of 17 specimens of adenocarcinoma and in 7 of 8 specimens of large cell carcinoma; the median concentrations in these three tumor types were 8, 3 and 9 ng/g, respectively. Patients with oat cell carcinoma were not considered candidates for curative resection and are not included in this series. ACTH was not detectable in 36 specimens of apparently normal lung tissue from the same lobe but distant from the tumor and ranged up to 6 ng/g in 14 other specimens. One-half of patients with epidermoid carcinoma but only one-quarter of those with adenocarcinoma had preoperative plasma levels exceeding 250 ng/L plasma. About 75% of patients survived for at least one year whether preoperative plasma levels were greater than 400 ng/L or less than 200 ng/L. In only 4 of 21 patients with preoperative levels greater than 300 ng/L did the plasma fall by at least one-half in the immediate postoperative period. It is concluded that measurement of preoperative and postoperative plasma immunoreactive ACTH does not have a prognostic value for remission or long term survival in lung cancer, probably because it is unlikely that the tumor per se is the sole source accounting for the elevated levels generally observed in this condition.     

Effect of energy restriction on cell cycle machinery in 1-methyl-1-nitrosourea-induced mammary carcinomas in rats

Energy restriction (ER) results in a profound inhibition of chemically induced mammary carcinogenesis. The cancer inhibitory activity of ER has been shown to be associated with lower rates of cell proliferation during both premalignant and malignant stages of this disease process. Moreover, inhibition of carcinogenesis and suppression of cell proliferation occur in animals in which plasma concentrations of insulin-like growth factor (IGF)-I are reduced, and plasma corticosterone levels are increased concomitantly. Given the role of both hormones in signal transduction pathways that can modulate cell cycle progression, albeit via different regulatory mechanisms, we report experiments conducted to determine whether hypothesized effects of changes in plasma levels of IGF-I and corticosterone on cell cycle regulation could be detected in mammary carcinomas occurring in 40% ER rats in comparison to ad libitum fed control rats or 40% ER rats that were energy repleted for 7 days (ER-REP). As determined by appropriate combinations of immunoprecipitations, Western blots, and kinase activity assays, it was found that levels of phosphorylated retinoblastoma and E2F-1 were significantly reduced by ER (approximately 40 and 75%, respectively; P < 0.01), an effect that was partially reversed by ER-REP. Reductions in cyclin-dependent kinase (CDK)2 (82%) and CDK4 (77%) kinase activity in ER carcinomas were likely to account for the observed effects on retinoblastoma and E2F-1. Both Cip1/p21 and Kip1/p27 and levels of these proteins complexed with CDK2 were significantly elevated in ER carcinomas (P < 0.01), and levels of cyclin E were reduced. On the other hand, regulation of CDK4 kinase activity by ER was likely attributable to effects on cyclin D1 as well as increased binding of P16 and P19 to CDK4. The majority of changes induced by ER were reversed by ER-REP. These observations are consistent with the hypothesis that ER exerts its profound cancer inhibitory activity, in part, by multifaceted regulation of cell cycle machinery, possibly via concomitant changes in corticosterone and IGF-1 metabolism, although the role of other hormones and growth factors should not be dismissed.     

Hormonal changes following tumor transplantation: factors increasing corticosterone and the relationship of corticosterone to tumor-induced anti-inflammation

EL-4 lymphoma cells transplanted to syngeneic C57BL/6J mice induced a biphasic decrease in inflammation and a bi-phasic increase in serum levels of corticosterone. In addition, this tumor altered serum levels of 3 other hormones, resulting in a biphasic decrease in insulin, an early decrease in prolactin, and a terminal severe deficiency in thyroxine. Early changes occurred 16 to 48 hr after tumor transplantation and were of variable duration, while late-phase defects developed during the last few days of life. Soluble factors associated with tumor growth may mediate certain hormonal changes since serum levels of corticosterone increased and insulin decreased following injection of tumorous ascites into normal mice. Further, injection of cell-free tumor culture supernatants increased corticosterone levels. Hormonal changes following injection of soluble factors occurred after a delay of 16 hr indicating that the factors acted indirectly. Surgical adrenalectomy blocked the corticosterone increase induced by tumor transplantation or ascites injection and eliminated the anti-inflammatory effect of tumor transplantation while significantly decreasing the effect associated with injection of tumorous ascites. Thus, the physiologically induced increase in serum levels of corticosterone reached anti-inflammatory levels. Further, elevated levels of corticosterone are a major contributing factor to anti-inflammation induced by tumorous ascites injection and constitute the principal mechanism of anti-inflammation following tumor transplantation.     

Growth hormone and experimental cancer cachexia

Plasma levels of growth hormone (GH) and the effect of GH treatment have been evaluated in adult nongrowing sarcoma-bearing mice (C57BL/6J). Prepubertal tumor-bearing mice, tumor-bearing hypophysectomized Sprague-Dawley rats, and malnourished non-tumor-bearing animals served as additional groups of study and control animals. Adult sarcoma-bearing mice showed an increase in plasma levels of GH early following tumor implantation. GH levels increased further with tumor progression. The anorexia and the state of malnutrition in sarcoma-bearing mice were the major factors behind increased GH levels. Muscle wasting and body composition in the tumor-bearing host were not improved by GH treatment at doses that increased growth rate in normal growing mice with intact pituitaries or partially normalized growth rate in hypophysectomized rats. Exogenous GH supported tumor growth and host body growth to the same extent in hypophysectomized rats. Exogenous GH in excess of endogenous GH did not stimulate tumor growth further. It is suggested that increased GH production in a tumor-bearing host acts in concert with other hormones to stimulate endogenous substrate mobilization and in tumor-bearing animals to prevent substrate deficiency and hypoglycemia. On the basis of this conclusion, it is unlikely that GH supplementation to a freely eating tumor-bearing host will support replenishment of host tissues.     

Some aspects of pituitary function after neuroadenolysis in patients with metastatic cancer

The effects of neuroadenolysis on plasma titres of beta-endorphin, beta-lipotropin, ACTH, TSH and prolactin have been investigated in five patients with metastatic cancer who responded to the treatment and have been in remission for more than four years and in five others who were undergoing the treatment for the first time for pain due to cancer metastases. beta-Endorphin, beta-lipotropin and ACTH titres were within the normal ranges of values in both categories of patients but post-neuroadenolysis titres of these peptides were higher than those before the treatment. The ability to secrete TSH and prolactin and to respond to thyroid stimulating hormone releasing hormone (TRH) remains intact following the treatment. However, whereas basal TSH titres and response to TRH was lower in the majority of patients, no such effect was observed on prolactin secretion. Plasma titres of prolactin and TSH were below the sensitivity of the method in the five patients who are in remission for more than four years. These preliminary findings suggest that neuroadenolysis probably affects some mechanism(s) associated with the control of beta-endorphin, beta-lipotropin and ACTH synthesis.     

Humoral mediation for cachexia in tumour-bearing rats.

Early and severe loss of body weight associated with pronounced tissue changes developed in rats transplanted with a fast-growing ascites hepatoma (Yoshida AH-130). The protein content showed an early and marked fall in the skeletal muscle, while in the liver it transiently increased 4 days after implantation then declined to values lower than in control animals. Protein loss in gastrocnemius muscle and liver resulted mainly from enhancement of protein catabolism (Tessitore L. et al., Biochem. J., 241: 153-158, 1987). In contrast to the tumour-bearing rats, in the pair-fed animals the initial body weight was maintained, while the protein mass decreased sharply in the liver and moderately in the gastrocnemius muscle. In host animals total plasma protein decreased during the period of tumour growth, while both triglycerides and total cholesterol markedly increased. Glucose remained unchanged even when overt cachexia had developed. The total free amino acid concentration in the plasma of tumour-bearing rats decreased slightly by day 4 and returned to values close to those of controls in the late stages of tumour growth. By contrast, in the pair-fed controls the plasma levels of triglycerides and particularly of total free amino acids and glucose decreased over the whole experimental period, whereas total protein and cholesterol were unchanged. Marked perturbations in the hormonal homeostasis developed early after tumour transplantation. The plasma levels of glucagon, corticosterone and catecholamines rose sharply, while those of insulin and thyroid hormones decreased. Furthermore, high plasma concentrations of prostaglandin E2 (PGE2) and tumour necrosis factor (TNF) were observed over the whole experimental period. IL-1-like activity, TNF and PGE2 were released in vitro from AH-130 cells. These data suggest that the systemic effects of AH-130 tumour on the host rat reflected the interplay of a complex network of factors, including classical hormones and cytokines, all of which likely concur in enhancing tissue protein catabolism.     

Changes in plasma hormone profiles after tumor transplantation into syngeneic and allogeneic rats

Transplantation of 2 chemically (DMBA, MCA)-induced tumors into syngeneic female or male DA strain rats elicited hormonal changes during tumor growth. Plasma levels of 7 different hormones were studied. Tumor cells in syngeneic recipients produced a biphasic decrease in insulin, an early increase in prolactin, and a late-phase decrease in thyroxine. Corticosterone decreased in female tumor bearers but increased in males. This difference may reflect differences in the tumors transplanted. Male rats had a decrease in testosterone during the late phase of tumor growth, while females had a biphasic decrease in progesterone and a late-phase increase in growth hormone. The tumors used were moderately immunogenic in syngeneic recipients. However, tumor transplantation to allogeneic recipients produced an early decrease in growth hormone and no change in insulin, corticosterone or thyroxine. Further, transplantation of normal liver cells to syngeneic or allogeneic recipients produced no hormonal abnormalities. This study demonstrates that hormonal changes which are not observed with normal cells or allogeneic tumor transplantation can occur within 2 days of syngeneic tumor transplantation. Progressive tumor growth is characterized by a worsening endocrine imbalance which involves multiple hormone systems.     

Parous rats regain high susceptibility to chemically induced mammary cancer after treatment with various mammotropic hormones.

Parity in humans and rats provides significant protection against mammary tumor development. This study was carried out to investigate whether treatment of parous rats with mammotropic hormones would affect methyl-nitrosourea (MNU)-induced mammary carcinogenesis. Parous rats were treated with 17beta-estradiol (E2), progesterone (P4) and thyroxine (T4) alone or in combination. E2 (20 microg/60 days) and P4 (20 mg/60 days) were administered by silastic tubing and T4 in the drinking water (3 microg T4/ml). Hormonal treatments commenced 7 days before MNU injection and continued for 33 weeks. Animals were palpated weekly for tumor detection. The effects of the hormonal treatments on the circulating concentrations of E2, P4, growth hormone (GH), prolactin (PRL), T4 and insulin-like growth factor-I (IGF-I) after 7 days of treatment, the time of MNU injection, was assessed. Animals treated with E2 had significantly elevated circulation concentrations of GH, PRL and P4, and serum levels of E2 were more consistent in this group than in the other animal groups. P4 treatment caused elevation in P4 concentration in serum but did not affect the circulating levels of other hormones. The proliferation of the mammary gland at the time of MNU injection was elevated in animal groups treated with E2 either alone or with P4 and T4 and in animals treated with P4 alone, but the mammary gland was most differentiated in untreated parous rats and least in animals treated with E2 either alone or with P4 and T4. Mammary tumor incidence was 10% in parous rats that did not receive any hormonal treatment. Treatments with E2 or P4 alone significantly increased the susceptibility of parous animals to 67 and 50.0%, respectively; a tumor incidence similar to that of untreated AMV rats (64%). Parous rats treated with E2 plus P4 had tumor incidence higher than 90%. T4 administered did not affect mammary carcinogenesis.     

Substituting ornithine for arginine in total parenteral nutrition eliminates enhanced tumor growth.

Total parenteral nutrition (TPN) may enhance the growth of some tumors: this enhanced growth is associated with an increase in the erythrocyte polyamine levels. The effect of arginine in TPN on tumor growth was compared with ornithine using rats with a transplantable Ward colon tumor. The relationship of circulating arginine, ornithine, glutamine, and polyamines with tumor growth was investigated. For rats fed chow ad libitum, increasing tumor weights were associated with a linear decrease in the plasma arginine levels which was consistently lower than that of age-matched non-tumor bearing (NTB) rats; ornithine and lysine levels were not affected. Subsequent experiments suggest that plasma glutamine levels were also lower in tumor bearing rats. Pair-fed NTB rats had reduced arginine but not glutamine levels in plasma. TPN regimens with arginine or with ornithine substituted for arginine at two levels (equimolar [Orn-Em] or isonitrogenous [Orn-IN]) were given to colon tumor bearing rats for 8 days. The final tumor weight of rats which received the arginine-containing regimen (19.8 +/- 5.7 g, n = 4) (P less than 0.05) was significantly greater than the tumor weight of rats fed chow ad libitum (12.1 +/- 3.3 g, n = 6). The final tumor weights of Orn-EM (11.2 +/- 2.6 g, n = 4) or Orn-IN (11.6 +/- 0.8 g, n = 6) were similar to the chow-fed controls. The plasma arginine levels were elevated, compared with the control, when arginine was present in the regimen. The plasma arginine levels of rats which received Orn-EM or Orn-IN were lower than the controls. The plasma ornithine levels were not affected by arginine in the regimen but were elevated with increasing levels of ornithine in TPN. Plasma glutamine levels were decreased when arginine was present in the regimen but were elevated when ornithine was substituted for arginine. Erythrocyte putrescine was increased when either arginine or ornithine was included in the TPN regimens. These results demonstrate that while arginine in a parenteral regimen stimulates tumor growth, substituting ornithine for arginine in TPN does not enhance the growth of a transplantable colon tumor.     

Thyroid hormones and experimental cancer cachexia

The relationship between circulating thyroid hormones and nutritional status was studied in sarcoma-bearing inbred C57BL/6J mice and control mice. Supplementation with exogenous thyroxine (T4) was also evaluated. Tumor-bearing animals had depressed levels of circulating thyroid hormones. This was also found in food-restricted (pair-fed and pair-weighed) controls. Plasma levels of thyroid hormones decreased with increased tumor burden. Thyrotropin-releasing hormone caused an increased response of thyroid-stimulating hormone in tumor-bearing animals. Low levels of thyroid hormones in sarcoma-bearing mice were due to depressed hormone production by the thyroid gland rather than to increased clearance rate of hormones. Plasma levels of triiodothyronine (T3) correlated to the amount of whole-body nitrogen among sarcoma-bearing mice and food-restricted controls. Exogenous T4 increased food intake by 20% in sarcoma-bearing mice. The benefit of this was probably counteracted by an increased metabolic rate, since reversal of plasma levels of T3 and free T4 had no net effect on body composition of freely eating sarcoma-bearing mice, although it had a negative effect on body and muscle composition in food-restricted controls. Exogenous T4 did not stimulate tumor growth. The results indicate that low circulating levels of thyroid hormones in experimental cancer cachexia are probably caused by the reduced food intake (anorexia), which is in agreement with findings in clinical cancer. Depression of thyroid hormones is probably a physiological means to reduce energy expenditure and to preserve substrates in progressive cancer disease.     

Therapeutic efficacy of intracarotid infusion of 20% mannitol with ACNU in Fischer rats with intracerebrally implanted 9L gliosarcoma

The purpose of this study was to investigate the therapeutic effect of intracarotid infusion of 20% mannitol with ACNU chemotherapy in Fischer 344 rats with intracerebrally implanted 9L gliosarcoma, compared with giving them only ACNU intraperitoneally. Thirty 9L gliosarcoma bearing Fischer 344 rats were evaluated in the following 3 groups. Group I: control (no treatment); group II: treated by ACNU 20 mg/kg intraperitoneally on the 7th day after implantation of 9L gliosarcoma cells; group III: treated by intracarotid infusion of 20% mannitol 3.1 ml/min. and with the same dose of ACNU as in group II. Mean survival time after the inoculation of tumor cells into the brain was 15.1 days (group I), 21.8 days (group II) and 27.9 days (group III). In group II all tumor-bearing Fischer rats died within 24 days after inoculation of tumor cells, whereas in group III 5 out of 6 rats survived more than 25 days after them. Group III evidenced necrosis and degenerative findings with vacuole and microcyst without vascular proliferation in tumor tissues more than group II on the 7th day after ACNU treatment for the experimental brain tumor. On the 7th day after ACNU treatment of each group, BrdU labeling index was calculated in order to evaluate tumor proliferation. The Mean BrdU labeling index in tumor cells of group III demonstrated 7.5%, against 14.5% (about one half) in group II. From our experimental study of survival time and BrdU labeling index, it is suggested that osmotic blood brain barrier disruption chemotherapy by intracarotid infusion of 20% mannitol and ACNU was more effective than simple treatment by intraperitoneal injection of ACNU in the Fischer rats with intracerebrally implanted 9L gliosarcoma.     

Suppression of 9L gliosarcoma growth by copper depletion with copper-deficient diet and D-Penicillamine

Summary Trace element such as Cu and Zn have important chemical and biological properties. Recently, tissue Cu and Zn concentrations have been correlated with prognosis in selected malignancies. In addition, depletion of trace metals has suppressive effects on tumor growth in experimental rat models. We measured tissue levels of Cu and Zn and investigated the inhibitory effects on tumor growth in a rat brain tumor model by the Cu-depletion. 9L gliosarcoma cells were injected subcutaneously in 24 anesthetized 5 week old male Fischer-344 rats. Control animals (n = 12) were given a normal diet throughout the experiment and hypocupremic rats (n = 12) were given a Cu-deficient diet beginning 3 weeks before and after tumor implantation, and administered 2 mg of D-Penicillamine peri os., once daily, 3 days before and after implantation. At the time of sacrifice, samples were taken to measure tumor weights. To determine tissue Cu and Zn levels, atomic absorption spectrophotometery was used. Cu, Zn and Cu/Zn ratio were significantly higher in control tumors than brain tissues. Cu levels and Cu/Zn ratio were significantly lower in hypocupremic tumors than those in control tumors. Zn levels in hypocupremic tumors were significantly higher than control tumors. Our study indicated that Cu depletion by a Cu-deficient and D-Penicillamine reduced Cu concentration and Cu/Zn ratio in a tumor model with reduction of tumor weight. A metabolic approach that restricts Cu to alter the microenvironment within the cell must become a new horizon of cancer therapy.     

Estrone sulfate stimulates growth of nitrosomethylurea-induced breast carcinoma in vivo in the rat

Concentrations of estradiol in human breast tumors from pre- and post-menopausal women are similar whereas plasma levels are 5- to 60-fold lower in post-menopausal women. The mechanism for maintaining high tumor tissue estrogen levels in post-menopausal women is unknown but could be related to the ability of plasma estrone sulfate to serve as a precursor for estradiol synthesis in tumor tissue. Estrone sulfate plasma levels are 30-fold higher than free estradiol levels in post-menopausal women and estrone sulfatase is present in many tissues, including breast tumors, supporting this hypothesis. In this study, we examined the ability of exogenously administered estrone sulfate to stimulate growth of a carcinogen-induced, hormone-dependent rat mammary tumor and measured the rate of conversion of estrone sulfate to free estrone and estradiol. Castrate rats bearing nitrosomethylurea-induced mammary tumors were infused with estradiol as a control or estrone sulfate over a 14-day period. Estradiol at low doses significantly increased tumor volume whereas higher amounts paradoxically inhibited growth. By comparison, estrone sulfate infusions significantly increased tumor volume over that observed in castrate animals on both days 7 and 14 of infusion. To determine whether estrone sulfate was converted to free estrone and estradiol during this protocol, 3H-estrone sulfate was substituted for unlabelled steroid and castrate animals were again infused for 14 days. At 7, 10 and 14 days of infusion, 18-26% of estrone sulfate was converted to free estrone and 9-16% to free estradiol. There were no significant differences between the 2 doses used and the rates of conversion were stable over the infusion period. Conversion of estrone sulfate to free estradiol was also demonstrated by radioimmunoassay of free estradiol in plasma during estrone sulfate infusions. These data demonstrate that exogenously administered estrone sulfate can stimulate mammary tumor growth in castrate animals and support the possibility that estrone sulfate may serve as an important source of tumor tissue estradiol.     

Influence of the Walker 256 carcinosarcoma on muscle, tumor, and whole-body protein synthesis and growth rate in the cancer-bearing rat

The in vivo rates of protein synthesis were assessed in tumor tissue, skeletal muscle, and whole body of rats bearing the Walker 256 carcinosarcoma. Estimates of protein synthesis in the nontumorous tissues were compared to tumor-free controls. Changes in size of the whole animal and tumor (i.e., growth) were measured, and fractional rates of growth, synthesis, and breakdown were estimated. Muscle protein synthesis and whole-body growth were significantly reduced in rats bearing larger tumors, and both were negatively correlated with tumor size (r = -0.723 and -0.825, respectively; P less than 0.01). Furthermore, whole-body and muscle protein synthesis were positively correlated with body growth (r = 0.380 and 0.563, respectively; P less than 0.05). Tumor growth followed first-order kinetics between days 7 and 13 following implantation, with a mean rate constant of 34.3%/day for the larger tumors and 27.7%/day for the small tumors. The difference in tumor growth became statistically significant over the final 3 days of tumor volume measurements. Fractional protein synthesis was significantly lower in the larger compared to the smaller tumors (48.6 versus 84.8%/day; P less than 0.05) as measured on day 14. This finding indicates a lower protein breakdown rate for the larger tumors (14.3 versus 59.0%/day; P less than 0.01) and suggests that the process of protein breakdown could play a significant role in determining tumor size, leading support to the theory of tumors acting as nitrogen traps.