746 Preclinical report Antineoplastic and cytogenetic effects of chlorpromazine on human lymphocytes in vitro and on Ehrlich ascites tumor cells in vivo Theodore S. Lialiaris a , Fotini Papachristou a , Constantine Mourelatos a and Maria Simopoulou b The inhibitory effect of phenothiazines in tumor growth and cancer cell proliferation in vitro and in vivo has been established. These reports motivated us to investigate the genotoxic, cytotoxic, and cytostatic potential of chlorpromazine, alone or in combination with mitomycin C, in vitro and in vivo. Sister chromatid exchange levels were assessed providing a quantitative index of genotoxicity. In-vitro studies were performed on human lymphocyte cultures and in-vivo studies involved Ehrilch ascites tumor (EAT) cells. An antitumour study was also conducted on the survival time and the ascitic volume in EAT-bearing Balb/C mice. The combination of chlorpromazine plus caffeine and mitomycin C exerted cytostatic and cytotoxic actions in human lymphocytes. The combination of chlorpromazine plus mitomycin C exerted cytostatic and cytotoxic actions in EAT cells, significantly increased the survival span of the mice inoculated with EAT cells, and suppressed the expected tumor growth increase. The findings of this basic study illustrate that high chlorpromazine concentrations increase chemotherapeutic effectiveness of mitomycin C. Chlorpromazine concentrations within the observed human plasma concentration range need to be tested along with antineoplastic agents in vitro for its synergistic action so as to evaluate a potential clinical application. Further investigation including other phenothiazines, biological systems, and cancer models is required. Anti-Cancer Drugs 20:746–751  c 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins. Anti-Cancer Drugs 2009, 20:746–751 Keywords: caffeine, chlorpromazine, Ehrlich ascites tumor, mitomycin C, sister chromatid exchanges Departments of a Genetics and b Physiology, Medical School, Demokrition University of Thrace, Alexandroupolis, Greece Correspondence to Theodore S. Lialiaris, Laboratory of Genetics, Medical School, Demokritos University of Thrace, University Campus – Dragana, Alexandroupolis, Greece 681 00 Tel/fax: + 30 25510 30522; e-mail: lialiari@med.duth.gr Received 13 January 2009 Revised form accepted 11 June 2009 Introduction Chlorpromazine (CPZ) is one of the oldest representa- tives of the phenothiazine–thioxanthene group of anti- psychotic agents and is given particular attention as newer agents can be compared and contrasted with it [1]. Phenothiazines possess strong inhibitory effects on various molecules involved in carcinogenesis and tumor growth in vitro and in vivo [2–8]. It has been illustrated that they exert their antiproliferative activity in a concentration-dependent manner [9,10]. Other studies have found that they promoted programmed cell death in human neuroblastomas and rat C6 glioma cells and in primary mouse brain tissue [11]. Administration of CPZ and other phenothiazines such as thioridazine can induce cytotoxicity [12–14] and cause cell division delays [15,16]. CPZ, combined with caffeine (CAF) and antineoplastic agents, such as melphalan, bleomycin, or chlorambucil, enhanced the antitumour effect of these antineoplastic agents in human lympho- cytes and murine L1210 leukemia cells [14,17]. Lee et al. [18] reported the synergistic action of pentamidine, an antiparasitic agent, and CPZ, and their inhibitory effect on tumor cell proliferation in vivo. Hoshi et al. [19] reported the synergistic action and antitumor activity of psycho- tropic drugs, including CPZ, with cyclophosphamide, in Ehrlich ascites tumor (EAT) sarcoma in ascites form. Although phenothiazines have been extensively studied in in-vitro models, studies in in-vivo systems and cancer models are inadequate. All these prompted us to conduct the present study aiming at the following: (i) study the effect of CPZ, as a representative of the phenothia- zine group, on sister chromatid exchange (SCE) levels, mitotic index (MI), and cell kinetics in human lympho- cytes in combination with mitomycin C (MMC) (a well-known antineoplastic agent), (ii) investigate the genotoxic and cytostatic effects of CPZ on EAT cells pretreated in vivo with MMC, and (iii) examine the antitumor activity of CPZ in combination with MMC in mice inoculated with EAT cells, by observing and recording survival time and suppression of ascitic volume. 0959-4973  c 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI: 10.1097/CAD.0b013e32832f567b Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.