Rationales for cancer chemotherapy with PDMP, a specific inhibitor of glucosylceramide synthase
Related Experiment Videos
1Nephrology Division, University of Michigan Medical Center, Ann Arbor 48109-0676.
Abstract:
A proposed weak point in cancer cells is their need to synthesize novel or rare glucosphingolipids. It is further proposed that cancer patients be treated with a drug that slows the synthesis of glucosylceramide, the precursor of a large family of glucosphingolipids. Experimental data are furnished for chemotherapeutic and biochemical effects of PDMP, an analog of glucosylceramide and its precursor, ceramide. Promising results were obtained in the treatment of mice carrying Ehrlich ascites carcinoma cells and rats carrying C6 glioma cells. PDMP was found to be oxidized by cytochrome P-450, but this process could be blocked in vivo with piperonyl butoxide or cimetidine. A high level of blood glucose was found to elevate the size of rat kidneys and their content of UDP-glucose and its product, glucosylceramide. The excessive growth could be blocked by PDMP, which competes with UDP-glc for binding to glucosylceramide synthase. It is suggested that cancer patients be maintained at a low glucose level in order to slow the synthesis of glucosylceramide by tumor cells. Metabolic changes produced by PDMP in cultured cells, besides a rapid deletion of glucosphingolipids, were accumulation of the precursors (ceramide and sphingosine), loss of protein kinase C, and accumulation of diacylglycerol. It is suggested that many of the cellular changes produced by PDMP, such as loss of cell binding, are owing to existence of glucosylceramide-based "islands" floating in the outer cell surface; the islands may contain growth factor receptors and adhesion factors. An inhibitor that blocks sphingolipid synthesis, such as cycloserine, may prove to be a useful adjuvant for therapy with PDMP.
Insights
This study explores targeting cancer cell glucosphingolipid synthesis with PDMP, a glucosylceramide analog. Promising results in animal models suggest potential for novel cancer therapies by inhibiting tumor growth and altering cell surface structures.
Area of Science:
- Biochemistry
- Cancer Biology
- Pharmacology
Background:
- Cancer cells rely on synthesizing unique glucosphingolipids.
- Glucosylceramide is a precursor to many essential glucosphingolipids.
- Targeting this pathway presents a potential therapeutic strategy.
Purpose of the Study:
- To investigate the chemotherapeutic and biochemical effects of PDMP, a glucosylceramide analog.
- To evaluate PDMP's efficacy in preclinical cancer models.
- To understand the metabolic impact of PDMP on cancer cells.
Main Methods:
- Administered PDMP to mice with Ehrlich ascites carcinoma and rats with C6 glioma.
- Analyzed biochemical changes in cultured cells treated with PDMP.
- Investigated the role of blood glucose levels and cytochrome P-450 interactions.
Main Results:
- PDMP demonstrated promising therapeutic effects in rodent cancer models.
- High blood glucose levels increased kidney size and glucosylceramide synthesis, which PDMP counteracted.
- PDMP induced metabolic changes including sphingolipid depletion and precursor accumulation in cultured cells.
Conclusions:
- PDMP shows potential as a cancer therapeutic by inhibiting glucosylceramide synthesis.
- Maintaining low blood glucose may enhance cancer therapy efficacy.
- PDMP's mechanism involves disrupting glucosphingolipid-based cell surface structures and may benefit from adjuvant sphingolipid synthesis inhibitors.