Microarray expression analysis has become one of the most widely used functional genomics tools. Efficient application of this technique requires the development of robust and reproducible protocols. We have optimized all aspects of the process, including PCR amplification of target cDNA clones, microarray printing, probe labeling and hybridization, and have developed strategies for data normalization and analysis.

The central problem in cancer chemotherapy is the severe toxic side effects of anticancer drugs on healthy tissues. Invariably the side effects impose dose reduction, treatment delay, or discontinuance of therapy. To limit the adverse side effects of cancer chemotherapy on healthy organs, we proposed a drug delivery system (DDS) with specific targeting ligands for cancer cells. The proposed DDS minimizes the uptake of the drug by normal cells and enhances the influx and retention of the drug in cancer cells. This delivery system includes three main components: (i) an apoptosis-inducing agent (anticancer drug), (ii) a targeting moiety-penetration enhancer, and (iii) a carrier. We describe one of the variants of such a system, which utilizes camptothecin as an apoptosis-inducing agent and poly(ethylene glycol) as a carrier. Luteinizing hormone-releasing hormone ( adverse side effects ͉ apoptosis ͉ cancer ͉ targeted drug delivery T he efficacy of cancer chemotherapy is limited by severe adverse side effects induced by anticancer drugs (1-4). The cytotoxic effect on healthy organs can be significantly diminished by employing special drug delivery systems (DDS) targeted specifically to cancer cells (5, 6). Targeting is especially important in circumstances where a localized tumor is removed surgically, and chemotherapy is prescribed as a follow-up preventive against potential metastases.Cancer targeting is usually achieved by adding to the DDS a ligand moiety specifically directed to certain types of binding sites on cancer cells. Several different targeting moieties were examined, including sugars (7-11), lectins (12-14), receptor ligands (5, 15-18), and antibodies (19-23) and their fragments (24). Recently, we found that the receptors for luteinizing hormone-releasing hormone (LHRH) are overexpressed in breast, ovarian, and prostate cancer cells (5,15,25). LHRH receptors (LHRHRs) are not expressed detectably in most visceral organs. We have taken advantage of this differential receptor expression and used a modified LHRH peptide as a targeting moiety on DDS to enhance drug uptake by the mentioned cancer cells and reduce the relative availability of the toxic drug to normal cells. We constructed and evaluated in vitro targeted DDS, which included (i) poly(ethylene glycol) (PEG) polymer as a carrier; (ii) camptothecin (CPT) as an anticancer drug; and (iii) modified LHRH peptide as a targeting moiety (5,15). In vitro evaluations confirmed the high anticancer activity of such conjugates against human ovarian, breast, and prostate cancer cells (15). Further, it was demonstrated that the cytotoxicity of the LHRH-targeted conjugates in human cancer cells was competitively inhibited by free LHRH peptide (25). The present investigations were aimed at evaluating the antitumor activity and apoptosis-induction capacity of the conjugates in experiments on mice bearing xenografts of human ovarian carcinoma. Tumor and organ distribution profiles of the targeted and nontargeted conjugates were also determined in these mice for cau...

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This review presents molecular targeting approaches in anticancer drug delivery systems (DDS) and identifies new developments in these systems. Targeting approaches include passive targeting (enhanced permeability and retention effect), targeting specific tumor conditions, topical delivery and active targeting, namely, targeting organs, cells, intracellular organelles and molecules, sandwich targeting, promoter targeting, indirect targeting and targeting by external stimuli. A novel advanced proapoptotic anticancer DDS that utilizes several molecular targets will be considered. Experimental data suggest that this DDS can simultaneously: (1) induce cell death, (2) prevent adverse effects on healthy tissues; (3) suppress and prevent multidrug resistance; and (4) inhibit cellular antiapoptotic defense.

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Chemotherapeutic agents are known to induce programmed cell death or apoptosis. The activation of cellular antiapoptotic defense that prevents the translation of drug-induced damage into cell death is the key factor in cellular antiapoptotic resistance that decreases the chemotherapeutic effectiveness of a broad spectrum of anticancer drugs. A novel proapoptotic anticancer drug delivery system (DDS) was designed to simultaneously induce apoptosis and suppress antiapoptotic cellular defense. The system includes three main components: 1) anticancer drug camptothecin (CPT) as an apoptosis inducer, 2) synthetic BCL2 homology 3 domain (BH3) peptide as a suppressor of cellular antiapoptotic defense, and 3) poly(ethylene glycol) (PEG) polymer as a carrier. The above DDS was studied in vitro using A2780 human ovarian carcinoma cells and in vivo on nude mice bearing xenografts of human ovarian tumor. The results obtained in both series of experiments corroborate each other. They show that the designed DDS provided intracellular delivery of active components and suppressed cellular antiapoptotic defense, leading to the more pronounced induction of caspase-dependent signaling pathway of apoptosis compared with CPT alone and simple CPT-PEG conjugate. Including BH3 peptide in complex DDS decreased apoptotic cellular defense, substantially increased toxicity of the whole complex, and provided high antitumor activity. Therefore, the proposed novel multicomponent proapoptotic anticancer drug delivery system has high potential to enhance the efficacy of chemotherapy.

The proposed anticancer proapoptotic LHRH-BH3 peptide simultaneously affects two molecular targets: 1) extracellular cancer-specific LHRH receptors and 2) the intracellular controlling mechanisms of apoptosis. The results of this work may be used to design novel approaches for the treatment of various cancers.

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