In vitro antitumour activity, safety testing and subcellular distribution of two poly [oxyethylene(aminophosphonate-co-H-phosphonate)]s in Ehrlich ascites carcinoma and BALB/c 3T3 cell culture systems

Abstract

Two polyphosphoesters containing anthracene-derived aminophosphonate and hydrophilic H-phosphonate repeating units, poly[oxyethylene(aminophosphonate-co-H-phosphonate)]s (1 and 2), were tested for the in vitro antitumour activity on cell cultures derived from ascitic form of Ehrlich mammary adenocarcinoma by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-dye reduction assay. The in vitro safety testing of the copolymers was performed by BALB/c 3T3 neutral red uptake assay. A study on their uptake and subcellular distribution in non- tumourigenic and tumour cells was performed by means of fluorescence microscopy. Both copolymers showed significant antitumour activity towards Ehrlich ascites carcinoma (EAC) cells. However, the in vitro safety testing revealed significant toxicity of polymer 2 to BALB/c 3T3 mouse embryo cells. In contrast, polymer 1 showed complete absence of cytotoxicity to BALB/c 3T3 cells. The fluorescent studies showed that the substances were diffusely distributed in the cytoplasm in both cell culture systems. As opposed to BALB/c 3T3 cells, in EAC cells, intense fluorescent signal was observed in the nuclei and in the perinuclear region. The tested polyphosphoesters are expected to act under physiological conditions as prodrugs of aminophosphonates.