Actions of a novel therapeutic formulation: Zn, Se and Mn plus Lachesis Muta venom (O-LM) on radiation deleterious immune effects

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Background: We have previously reported that O-LM inhibits malignant cell proliferation and increases survival in rodent tumor models (Int J Cancer S13:183, 2002). Molecular and immunological basis of O-LM action were reported (J Clin Oncol 24:18S, 2006). As O- LM selectively protects normal tissues from high doses of ionizing radiation (Proc Int Cancer Congress,1495–9, 1998), we here investigated O- LM protective action upon radiation effects on immune cells. Methods: Balb/c mice (n=15 each group) were employed: control (C); 2Gy whole body irradiated (IR); treated with O-LM (Zn, Se, Mn 4μg/ml each; L. Muta 4 ng/ml; 0.1 ml/day, sc) for 15 days and 2Gy irradiated (O-LM+IR). Mice were sacrificed at day 3, 7 or 15 post-irradiation (PI). Proliferation was evaluated in lymphocytes by [3H]- Thymidine incorporation after T- or B selective mitogen stimulation. In cell-free supernatants (SN) from mitogen-stimulated cultures cytokines involved in lymphocyte regulation and/or inflammation were determined by ELISA. Results: Irradiation induced a decrease in T lymphocyte proliferation at 3 and 7 days PI (% of decrease in IR: 47.6±9.0, p<0.05; 42.0±7.2, p<0.02 respectively). Pretreatment with O-LM recovered proliferation to basal values (day 3 PI 93.4±10.2%; day 7 PI 130.9±15.3%, O-LM+IR vs. C; p=NS). No modifications were observed in B cells. At day 3 PI, a marked decrease in IFN? levels was obtained in SN of IR mice that was reverted by O-LM treatment (pg/ml: IR 1653±419; C 10884±2783, p<0.02; O-LM+IR 16924±4284, p<0.05 vs C). Also, at day 7 PI, an important increase in TNFa was observed in IR mice, that were reverted by O-LM (pg/ml: IR: 300.7±62.3 vs O-LM+IR: 28.7±2.3, p<0.02). No differences were found in IL-2 levels. Conclusions: The therapeutic action of O-LM is based on its ability of targeting simultaneously multiple pathways involved in cancer development. Present data demonstrate that O-LM protects animals from irradiation by recovering the immune function, improving T lymphocyte activity and modulating the production of key cytokines as IFN? and TNFa. The reported effect may represent a potential benefit for cancer patients undergoing radiotherapy.

No significant financial relationships to disclose.

Molecular and immunologycal basis of a novel therapeutic formulation: Oligoelements Zn, Se and Mn plus Lachesis Muta venom (O-LM)

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Background: We have previously reported that O-LM inhibited malignant cell proliferation in vitro and in vivo, increasing survival in rodent tumor models. We also demonstrated a protective action of O-LM against undesirable effects of chemotherapy and ionizing radiation, enhancing their therapeutic action. Furthermore, O-LM applied to patients with advanced breast, colon and pancreatic cancer resulted in increased survival and better quality of life with no side effects. In this work we further investigated the mechanisms involved in O-LM therapeutic effect. Methods: Two groups of Nude mice, control and O-LM (Zn, Se, Mn 4μ g/ml each; L. Muta 4 ng/ml) treated (0.1 ml/day, sc) were inoculated with PANC-1 cells to evaluate tumor development. PCNA, P53, antioxidant enzymes, apoptosis, microvessels and immune cell markers were studied by immunohistochemistry. In control and O-LM treated BALB/c mice we determined in vitro responses to T and B selective mitogens. Results: O-LM treated tumors showed significant lower growing rate, smaller mass (3,77±0,95 vs 9,75±2,30 cm3) and an important peritumoral lymphoid infiltrate. Apoptotic cells and P53 expression were increased while PCNA was negative and microvessels counts were lower than controls. O-LM produced a 3-fold increase in Superoxide Dismutase activity. The infiltrates showed an important number of CD11 bearing cells and B220 positive but CD3 and CD19 negative cells, suggesting the presence of NK cells. In BALB/c mice T selective mitogen Con A, but not B selective mitogens responses were enhanced, with a maximum after 60 days of O-LM treatment. A 4-fold increase in IFNγ release was observed in cell-free supernatants from lymph node culture stimulated with Con A obtained from 60-days treated mice. Conclusions: Present data demonstrate the capacity of O-LM to modulate free radical production, the expression of tumor markers and suggest an important up-regulation of innate and T-cell mediated immunity induced by in vivo treatment with O-LM. These results reinforce the hypothesis that the effective therapeutic action of O-LM is based on its ability of targeting simultaneously multiple pathways involved in cancer development with the additional advantage of the total absence of adverse effects.

No significant financial relationships to disclose.

Inhibition of human primary melanoma cell proliferation by histamine is enhanced by interleukin-6

BACKGROUND

Interleukin-6 (IL-6) is a bifunctional growth factor in malignant melanoma; its expression increases during the malignant progression of the disease. Histamine, detected in large amounts in normal and pathological proliferating tissues, is an important paracrine and autocrine regulator of normal and tumour cell proliferation as well.

MATERIALS AND METHODS

We investigated the presence and function of IL-6 and histamine in the WM35 primary human melanoma cell line with respect to their direct role in cell proliferation and their regulatory interactions.

RESULTS

IL-6 inhibited the proliferation of WM35 melanoma cells and increased significantly the expression of histidine decarboxylase as well as histamine production. It had dose-dependent effects on the proliferation: high concentration (10-5 M) was inhibitory through H1 histamine receptors while low histamine concentration acting on H2 receptors, with a simultaneous increase of cAMP, enhanced colony formation in the monolayer. Furthermore, IL-6 increased the H1- but decreased the H2-histamine receptor expression of the melanoma cells. On the other hand, histamine was locally synthesized by the WM35 melanoma cells.

CONCLUSION

We suggest that the growth arrest induced by IL-6 is in part mediated by its dual action on histamine: a shift toward H1 receptor predominance and an elevation of locally produced histamine with prevalent action on the inhibitory response triggered through the H1 receptor. These findings suggest a local cross-talk between histamine and IL-6 in the regulation of melanoma growth.

Epidermal growth factor in NMU-induced mammary tumors in rats

In this work we analyze the hypothesis that tumors induced by i.p. N-nitroso-N-methylurea injection express EGF-like peptides and EGF receptors which could be involved in the response to hormone manipulation. EGF receptors (EGFR) were determined in the purified membrane fraction of tumors from control and ovariectomized (OVX) animals and no significant differences were found in either maximal binding capacities (Q) or dissociation constants (Kd) between them. Neither did we observe differences between tumors that regressed (HR) or continued growing (HU) after ovariectomy. In order to test the ability of EGFR to trigger a biological response we measured the production of second messengers inositol triphosphates (IP3) and cAMP levels; we found that EGF increases IP3 production in a dose-dependent way, while cAMP levels were not affected. In addition, EGF was able to induce in vitro cell proliferation in a concentration-dependent manner when tested in primary cultures of tumor cells by the clonogenic soft agar technique. EGF/TGF-alpha activity was determined by a radioreceptor assay in tumor cytosols from control and OVX rats. Results showed a trend to lower values in tumors from OVX rats, but no differences between HR and HU tumors. A positive correlation was found between EGF/TGF-alpha activity and progesterone receptor maximal binding capacity. When we tested the action of estradiol and EGF added together to primary cultures of tumor cells we found an additive effect on cell proliferation. The study of steady state mRNA levels showed that E2 increases PgR and c-myc mRNA levels in HR but not in HU tumors. In conclusion, the autocrine loop EGFR-EGF/TGF-alpha present in all tumors is hormonally regulated, possibly by Pg, but is not related to the tumor response to ovariectomy.

Atypical association of H1 and H2 histamine receptors with signal transduction pathways during multistage mouse skin carcinogenesis

OBJECTIVE

In the present work we studied the association of histamine receptors with second messengers during multistage carcinogenesis in Sencar mice skin.

METHODS

96 Sencar female mouse, divided into six groups were used. Tumors appeared only in the 7, 12-dimethylbenz[a]anthracene-initiated and 12-O-tetradecanoylphorbol-13-acetate-promoted group. Control groups received only TPA, or acetone or no treatment at all. Periodically during the promotion period, cAMP and inositol phosphate production were measured after stimulation with H1 or H2 agonists in samples from all groups.

RESULTS

In non-treated skin, H1 receptors were coupled to phosphatidylinositol hydrolysis and H2 receptors mediated cAMP production. Conversely, in tumors H2 receptors were associated with phosphatidylinositol hydrolysis and H1 mediated a rise in cAMP levels. The skin among tumors and the skin from all control groups maintained the same coupling as non-treated skin. An increase in mast cell number, with a homogeneous subepithelial distribution and marked phenotypic changes, was also observed in promoted skin.

CONCLUSIONS

These findings indicate an atypical association of histamine receptors with second messengers that could be a critical feature for the postulated action of histamine in tumor growth.

Hormone dependence of mammary tumors induced in rats by intraperitoneal NMU injection

The purpose of this work was to determine the hormone dependence of mammary tumors induced in Sprague-Dawley rats by three intraperitoneal injections of N-nitroso-N-methylurea at 50, 80, and 110 days of age. Two experimental designs were carried out: (a) Ten days before the first NMU injection, 130 rats were divided into 13 batches and randomly assigned to the following treatments: control, ovariectomy (OVX), tamoxifen (TAM), bromocriptine (BROM), haloperidol (HAL), estradiol (E2), progesterone (Pg), OVX + BROM, TAM + BROM, OVX + HAL, TAM + HAL, OVX + TAM, and E2 + BROM. After 150 days of treatment the following growth parameters were determined: latency period (LP), mean tumor number per rat (n/t), and tumor incidence (TI). LP was significantly increased (p < 0.05) only by Pg and TAM + BROM. The n/t was significantly decreased (p < 0.05) by all treatments except HAL. TI was significantly reduced by OVX, TAM, BROM, and their combinations, (b) Rats bearing ip-NMU-induced mammary tumors were divided into 7 batches and assigned to the following treatments: control, OVX, TAM, BROM, HAL, OVX + BROM, and TAM + BROM. Tumor growth was assessed up to 60 days of treatment; only OVX, TAM and their combination with BROM were able to produce tumor regression. These results support the essential role of E2 and prolactin in the promotion stage of carcinogenesis. However, for established tumors, growth becomes more independent from hormone influence, in particular from prolactin deprivation. We conclude that this model seems suitable for studying the mechanisms underlying the evasion of hormonal control of tumor growth.

Effect of tamoxifen on intraperitoneal N-nitroso-N-methylurea induced tumors

The effect of tamoxifen (TAM) was evaluated on a mammary tumor model induced in Sprague-Dawley rats by intraperitoneal administration of three N-nitroso-N-methylurea (NMU) doses. Animals received TAM (1 mg/kg per day) from 10 days before the first NMU dose up to 140 days later. Thereafter, treatment was discontinued and the observation period was extended 60 days longer. Mean overall latency period, tumor number per rat and tumor incidence were recorded. Significant differences between treated and control batches were observed in tumor number per rat (1.8 +/- 1.1 versus 5.2 +/- 1.6; P < 0.05) and in tumor incidence (50% versus 100%; P < 0.05), respectively. No significant difference in latency period between both batches was recorded. All lesions induced in the control batch were malignant, whereas only 45% of those induced in TAM-treated animals were malignant and the remaining 55% were preneoplastic. At 60 days after treatment discontinuance, tumor incidence increased to 90% and also tumor number per rat increased to 4.6 +/- 1.5. TAM effect was also evaluated in rats with NMU-induced tumors by treatment with 1 mg/kg per day during 60 days starting when tumors reached a 1.5-cm diameter. Regression to less than 80% of initial size in 49% of the tumors was observed, while in ovariectomized rats, 33% of tumors regressed. Estrogen receptor content, ER (fmol/mg protein) and Kd (nM) in control tumors were: 56 +/- 10 and 0.5 +/- 0.1. In tumors of TAM-treated animals, ER was less than 5 fmol/mg protein. Findings demonstrate that TAM significantly decreased the appearance of tumors induced in rats by i.p. injection of NMU and when TAM treatment was initiated after tumor induction, some tumors failed to respond to hormonal manipulation. Differential tumor growth response after TAM or oophorectomy in each tumor indicates that in the same rat it is possible to distinguish hormone-dependent and hormone-autonomous tumor populations. Hormonal regulation of tumor growth can be under intrinsic control, regardless of the hormonal status of the whole organism.

Synergistic effect of mammary tumors on hexachlorobenzene-induced porphyria in rats

The response of animals bearing N-nitroso-N-methylurea (NMU)-induced mammary tumors to the porphyrinogenic action of hexachlorobenzene (HCB) was studied. delta-Aminolevulinic acid (ALA), porphobilinogen and porphyrins in urine, ALA-synthase and porphyrinogen carboxylase activities and porphyrin content in liver and tumor were measured. The results obtained indicate that the metabolic heme pathway operates in mammary tumors but tumor response to HCB treatment could not be detected. HCB administration produced an earlier and greater hepatic porphyria in tumor-bearing rats than in healthy rats suggesting that the presence of tumors exacerbates the action of HCB.