ANTITUMOR EFFECT OF POSITIVELY CHARGED RESIN IN THE HAMSTER-CHEEK POUCH MODEL

Following the signal observation that contact with positively charged dextran resin (PCDR) inhibited the growth of cultured mammary (Hs578T and MDA-MB-231), pancreatic (H2T), and myeloma (RR-658) tumor cell lin es, studies were developed in the hamster cheek pouch model using hams ter H2T pancreatic tumor cells to determine if the antiproliferative e ffect of PCDR could inhibit tumorigenesis. In these studies, the contr ol population represented groups injected with H2T cells alone or in c ombination with either neutral or negatively charged resin. When cells (5 x 10(2) to 1 x 10(5)) and PCDR were administered simultaneously, t he tumor incidence (percent engraftment) and growth of tumors that alr eady had been established were significantly reduced. When PCDR was in jected into already established 1-35-mm(2) H2T tumors (engraftment for 21 days = 96%), the resin suppressed the growth of the smallest tumor s (<10 mm(2)). In none of these trials was the somatic growth of the h ost hamsters affected. PCDR contact with H2T cells in vitro for 4 days or used to treat growing solid tumors for 72 days significantly reduc ed cellular ornithine decarboxylase activity. While the mechanism of P CDR action has not been established, the observations have implication s for in vivo tumor therapeutic models. (C) 1997 John Wiley & Sons, In c.