:" : ".~!: :,.~.. i l" ELSEVIER Biochimica et Biophysica Acta 1201 (1994) 173-178 BB Biochi~i et Biophysica fl~ta Enhancing effect of ATP on intracellular adriamycin penetration in human ovarian cancer cell lines Ron Maymon a,*, Batia Bar-Shira Maymon b,1, Malca Cohen-Armon c, Michael Holtzinger Judith Leibovici b a Department of Obstetrics and Gynecology, AssafHarofe Medical Center, Tzrifin, Israel b Department of Pathology, Sackler Faculty of Medicine at TelAviv University, RamatAviv, Israel c Neufeld Cardiac Research Institute, Sackler Faculty of Medicine at TelAviv University, RamatAviv, Israel d Department of Obstetrics and Gynecology, Sapir Medical Center, Kfar Saba, Israel Received 1 February 1994 d Abstract Ovarian cancer has the highest mortality rate of all gynecological malignancies probably due to the evolution of clones resistant to cytotoxic drugs. Exploring possibilities to overcome such resistance constitutes a challenge in this study. We present the effect of adenosine triphosphate (ATP), serving as a chemosensitizer, in combination with adriamycin on three human ovarian cancer cell lines of epithelial origin, OC-109, OC-238 and OC-7-NU, obtained from malignant ascites of different patients, and were proven to be tumorigenic in nude mice. The three lines differ in their sensitivity to the ATP-induced increase in adriamycin accumulation. FACS analysis showed a pronounced increase in intracellular adriamycin accumulation after treatment with various concentrations of ATP. In the OC-238 line, a 50.1% increase was observed at a low ATP concentration (200/xM), whereas higher concentrations (400/.~M and 500 /zM) were needed to obtain an increase in ADR accumulation of 30% with the other two lines. Our study demonstrates that ATP improves the penetration of adriamycin at the neoplastic cellular level. Furthermore, our results may indicate that intratumoral ATP may serve as an alternative chemosensitizer which lacks the deleterious side effects of other chemosensitizing options. Keywords: Adenosine triphosphate; Adriamycin; Chemosensitizing effect; Flow cytometry; (Ovarian carcinoma) 1. Introduction Epithelial ovarian tumors represent 25% of the female reproductive organ malignancies, accounting for a higher mortality rate than the combination of cervical and uterine cancers [1,2], and the number of cases is ever increasing [2,3]. Among the explanations for this phenomenon is the clinical observation that early ovarian cancer is asymp- tomatic, resulting in more than 60% of the patients present- ing in the late stages of the disease when the 5-year survival rate is estimated at 20-30% [4]. Effective treat- ment revolves around ablative surgery and chemotherapy. However, a serious drawback of chemotherapy is the evolution of drug resistant clones during tumor progression * Corresponding author. Fax: + 972 3 6409043. 1 In partial fulfillment towards a Postdoctoral Fellowship, supported by the Wolf Foundation to Promote Science and Art for the Benefit of Mankind. 0304-4165/94//$07.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0304-4165(94)00068-9 which may evolve towards single or multiple drugs [5,6]. This is possibly one of the major reasons for its response failure, which may be due to a decrease in intracellular drug accumulation, due either to a decrease in cell perme- ability [7-9] or to an increased efflux of the drug [10-12]. Thus, the use of cytotoxic drugs in conjunction with permeabilization agents may have the potential for coun- teracting this resistance and increasing cell permeability to the drugs. When using several tumor progression murine models, previous studies have disclosed increased cytotoxic agent activity with hyperthermia [13,14], or other chemosensitiz- ers, such as verapamil [15] and Tween 80 [16]. Adriamycin (ADR) was used as a cytotoxic agent, because its fluores- cence permits a follow-up of its intracellular accumulation by various methods, including fluorescence microscopy, FACS analysis and spectrofluorometry. The degree of combined treatment effect on the tumorigenicity of the treated cells was in correlation with the intracellular accu-