ARS | Publication request: SCREENING POTATO GERMPLASM FOR CARBOXYPEPTIDASE INHIBITOR AND ITS POTENTIAL ANTICANCER PROPERTIES

Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2006
Publication Date: February 1, 2007
Citation: Vega, S.E., Aziz, M., Bamberg, J.B., Verma, A., Palta, J.P. 2007. Screening potato germplasm for carboxypeptidase inhibitor and its potential anticancer properties [abstract]. American Journal of Potato Research. 84:118.

Technical Abstract: POTATO Carboxypeptidase Inhibitor (PCI) is among the smallest proteinase inhibitors present in the potato tuber (4.3 kDa, 39 amino acids). PCI is heat resistant and stable at low-pH. Recent studies have shown that PCI has anti-tumor properties as evidenced by its ability to inhibit the growth of human cancer cells in both in vivo and nude mice. PCI has also been shown to be antagonistic to human epidermal growth factor, a key signaling component linked to tumor cell growth and metastasis. The level of PCI activity in the tuber juice varied among potato clones. The present study screened four cultivars and a wide range of wild potato germplasm (encompassing seven Solanum species) for PCI. To accomplish this study, PCI from crude tuber extracts was partially purified by ammonium sulfate precipitation and dialysis. The PCI activity was assayed for the inhibition of carboxypeptidase enzyme activity. Depending on the species/cultivar, a wide range of enzyme inhibition was observed (30 to 100 %). The wild species S. bulbocastanum and the cultivar Atlantic showed the highest inhibition among all the germplasm tested. These tuber extracts are also being tested for potential anti-tumor activity using both in-vitro and in-vivo human cancer models. Our results will open the door for increased levels of this highly desirable nutritional attribute of potato tubers through classical and molecular breeding approaches. Even without breeding improvements, quantifying the value of PCI as an anticancer agent would validate the importance of potatoes in our diet.