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Experimental intraocular malignancy: the effect of intracameral perfusion
Abstract:
Transplantable Brown-Pearce carcinoma was adapted successfully in the rabbit anterior chamber. Regression of tumor growth was attained on tri-weekly perfusion of the AC with 10 micromolar of methotrexate. Tumor cyclic nucleotide phosphodiesterase (PDE) and protein activator were found to be markedly depressed during the course of chemotherapy and the PDE cAMP/cGMP ratio was similarly altered. Corroborative light and electron-microscopic studies showed specific alterations of intracellular organelles in relation to MTX and tumor cell death. These findings suggest that metabolic pathways of cyclic nucleotides are important biochemical modulators of neoplastic cells. The method of intraocular perfusion precludes systemic toxic effects and avoids compromising the animals' immunocompetence.
Insights
Chemotherapy using methotrexate (MTX) effectively reduced Brown-Pearce carcinoma growth in rabbit eyes. This treatment altered cyclic nucleotide metabolism and organelle structure, suggesting its potential for targeted cancer therapy with minimal systemic toxicity.
Area of Science:
- Oncology
- Pharmacology
- Cell Biology
Background:
- Brown-Pearce carcinoma, a transplantable tumor, was adapted for study in the rabbit anterior chamber (AC).
- Previous research indicated potential therapeutic avenues for ocular tumors, but effective localized treatments with minimal systemic impact were sought.
Purpose of the Study:
- To evaluate the efficacy of methotrexate (MTX) in regressing transplantable Brown-Pearce carcinoma in the rabbit anterior chamber.
- To investigate the effects of MTX chemotherapy on cyclic nucleotide metabolism (phosphodiesterase activity and cAMP/cGMP ratio) within tumor cells.
- To examine ultrastructural changes in tumor cells induced by MTX treatment using light and electron microscopy.
Main Methods:
- Successful adaptation of Brown-Pearce carcinoma in the rabbit anterior chamber.
- Treatment involved tri-weekly perfusion of the anterior chamber with 10 micromolar methotrexate.
- Analysis of tumor cyclic nucleotide phosphodiesterase (PDE) activity, protein activator levels, and PDE cAMP/cGMP ratio.
- Light and electron microscopy were used to assess intracellular organelle alterations and tumor cell death.
Main Results:
- Methotrexate perfusion led to the regression of Brown-Pearce carcinoma growth in the rabbit anterior chamber.
- Chemotherapy with MTX significantly depressed tumor cyclic nucleotide phosphodiesterase activity and protein activator levels.
- The PDE cAMP/cGMP ratio was altered during MTX treatment, and specific intracellular organelle changes were observed, correlating with tumor cell death.
Conclusions:
- Intraocular perfusion of methotrexate is an effective method for regressing Brown-Pearce carcinoma in a rabbit eye model.
- Alterations in cyclic nucleotide metabolic pathways are important in mediating the effects of chemotherapy on neoplastic cells.
- This localized perfusion method avoids systemic toxicity and preserves the animal's immunocompetence, offering a promising approach for ocular tumor treatment.