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[Antitumor effect in mice of an organic germanium compound (Ge-132) when different administration methods are used]
Abstract:
The antitumor effect of an organic germanium compound, carboxyethylgermanium sesquioxide (Ge-132), was examined in mice using two systems: one, the ascitic form of Ehrlich carcinoma in DDI mice, and the other, the solid form of Meth-A fibrosarcoma in BALB/c mice. In the mice with Ehrlich ascitic tumors, a remarkable prolongation in life span was observed after intraperitoneal (i.p.) or per oral (p.o.) administration of Ge-132 (300 mg/kg), but not after intravenous (i.v.) injection of the same compound. Following i.p. or p.o. administration, cytotoxic macrophages (Mø) were induced in the peritoneal cavity after 48 h. although this was not the case after i.v. injections. When the in vivo effect of these in vitro active Mø was examined after adoptive transfer to mice bearing Ehrlich ascitic tumor cells, a significant antitumor effect was noted. In the mice bearing solid Meth-A tumors, i.v. injections of Ge-132 (100 mg/kg) were found to inhibit tumor growth remarkably, although i.p. and p.o. administrations did not have the same result. This inhibitory effect of Ge-132 by i.v. administration was explained by the continued augmentation of NK activity in peripheral blood, which was followed by the induction of specific killer cells appearing in the spleen. When the mice which had recovered from Meth-A tumor growth, following i.v. injections of Ge-132, were challenged with the same tumor on day 30, all mice were able to tolerate the challenge, but not a challenge of RL male 1 tumor cells. These observations may indicate that the differing antitumor effects of Ge-132 produced when different administration methods are used can be explained by the variation in effector cells induced by such different administration routes.
Insights
The organic germanium compound carboxyethylgermanium sesquioxide (Ge-132) shows antitumor effects in mice, with efficacy varying by administration route. Intraperitoneal or oral Ge-132 boosts cytotoxic macrophages, while intravenous Ge-132 enhances NK cell activity for tumor inhibition.
Area of Science:
- Immunology
- Pharmacology
- Oncology
Background:
- Organic germanium compounds, like carboxyethylgermanium sesquioxide (Ge-132), are investigated for potential therapeutic applications.
- Understanding the immunomodulatory effects of Ge-132 is crucial for its development as an antitumor agent.
Purpose of the Study:
- To investigate the antitumor effects of Ge-132 in mouse models.
- To determine how different administration routes (intraperitoneal, oral, intravenous) influence Ge-132's efficacy and the underlying immune mechanisms.
Main Methods:
- Two mouse tumor models were used: Ehrlich ascites carcinoma (DDI mice) and Meth-A fibrosarcoma (BALB/c mice).
- Ge-132 was administered via intraperitoneal (i.p.), oral (p.o.), and intravenous (i.v.) routes at specific dosages.
- Immune cell activity, including cytotoxic macrophages and Natural Killer (NK) cells, was assessed.
- Adoptive transfer of immune cells and tumor challenge experiments were conducted.
Main Results:
- Intraperitoneal or oral Ge-132 significantly prolonged survival in Ehrlich ascites tumor-bearing mice by inducing cytotoxic macrophages.
- Intravenous Ge-132 inhibited Meth-A solid tumor growth by augmenting NK cell activity and inducing specific killer cells.
- Mice that recovered from Meth-A tumors after i.v. Ge-132 treatment showed specific immunity against rechallenge.
Conclusions:
- The antitumor efficacy of Ge-132 is dependent on the administration route.
- Different administration routes elicit distinct immune responses, involving either macrophages or NK cells.
- Ge-132 demonstrates potential as an immunomodulatory agent with route-dependent antitumor activity.