Screening-based approach to discover effective platinum-based chemotherapies for cancers with poor prognosis

Drug combinations are extensively used to treat cancer and are often selected according to complementary mechanisms. Here, we describe a cell-based high-throughput screening assay for identification of synergistic combinations between broadly applied platinum-based chemotherapeutics and drugs from a library composed of 1280 chemically and pharmacologically diverse (mostly FDA approved) compounds. The assay was performed on chemoresistant cell lines derived from lung (A549) and pancreatic (PANC-1) carcinoma, where platinum-based combination regimens are currently applied though with limited success. The synergistic combinations identified during the screening were validated by synergy quantification using the combination index method and via high content fluorescent microscopy analysis. New promising synergistic combinations discovered using this approach include compounds currently not used as anticancer drugs, such as cisplatin or carboplatin with hycanthone and cisplatin with spironolactone in pancreatic carcinoma, and carboplatin and deferoxamine in non-small cell lung cancer. Strong synergy between cisplatin or carboplatin and topotecan in PANC-1 cells, compared to A549 cells, suggests that this combination, currently used in lung cancer treatment regimens, could be applied to pancreatic carcinoma as well. Several drugs used to treat diseases other than cancer, including pyrvinium pamoate, auranofin, terfenadine and haloprogin, showed strong cytotoxicity on their own and synergistic interactions with platinum drugs. This study demonstrates that non-obvious drug combinations that would not be selected based on complementary mechanisms can be identified via high-throughput screening.

Repositioning approved drugs for the treatment of problematic cancers using a screening approach

Damiano Banfi, Paul Joseph Dyson, Fabien Kuttler, Gerardo Turcatti, Hristo Plamenov Varbanov

Advances in treatment strategies together with an earlier diagnosis have considerably increased the average survival of cancer patients over the last four decades. Nevertheless, despite the growing number of new antineoplastic agents introduced each year, there is still no adequate therapy for problematic malignancies such as pancreatic, lung and stomach cancers. Consequently, it is important to ensure that existing drugs used to treat other types of cancers, and potentially other diseases, are not overlooked when searching for new chemotherapy regimens for these problematic cancer types. We describe a screening approach that identifies chemotherapeutics for the treatment of lung and pancreatic cancers, based on drugs already approved for other applications. Initially, the 1280 chemically and pharmacologically diverse compounds from the Prestwick Chemical Library (R) (PCL) were screened against A549 (lung cancer) and PANC-1 (pancreatic carcinoma) cells using the PrestoBlue fluorescent-based cell viability assay. More than 100 compounds from the PCL were identified as hits in one or both cell lines (80 of them, being drugs used to treat diseases other than cancer). Selected PCL hits were further evaluated in a dose-response manner. Promising candidates for repositioning emanating from this study include antiparasitics, cardiac glycosides, as well as the anticancer drugs vorinostat and topotecan.

2017

Recent Considerations in the Application of RAPTA-C for Cancer Treatment and Perspectives for Its Combination with Immunotherapies

Paul Joseph Dyson, Patrycja Nowak-Sliwinska, Magdalena Rausch

The organometallic ruthenium(II) [Ru(arene)Cl2PTA] PTA - 1,3,5-triaza-7-phosphaadamantane compound, RAPTA-C, represents an innovative anti-cancer therapeutic and a better-tolerated alternative to platinum (Pt)-based chemotherapeutic drugs in the treatment of cancer. RAPTA-C exhibits anti-metastatic, anti-angiogenic, and anti-tumoral activities through protein and histone-deoxyribonucleic acid alterations. In comparison to other ruthenium-based drugs, which have been recently evaluated in clinical trials, RAPTA-C is strikingly competitive, especially when administered in combination with other targeted drugs. In this review, the uniqueness of RAPTA-C as an anti-cancer chemotherapeutic compared to metal-based drugs under clinical evaluation and those approved by the Food and Drug Administration is emphasized; specifically, comparing the application of RAPTA-C to platinum-based drugs, for example, cisplatin and oxaliplatin, as well as to prominent ruthenium-based compounds, such as NAMI-A imidazolium-trans-tetrachloro(dimethylsulfoxide) imidazoleruthenium(III) and trans-[tetrachlorobis (1Hindazole) ruthenate(III)] (KP1019)/(N)KP1339 (N)KP1339 - sodium. Additionally, the possible correlation between RAPTA-C and immune response modulation, as well as potential applications of RAPTA-C in combination with immune therapeutic regimens, is highlighted.

WILEY2019

A Competitive Co-cultivation Assay for Cancer Drug Specificity Evaluation

Christoph Merten

The identification of compounds that specifically inhibit or kill cancer cells without affecting cells from healthy tissues is very challenging but very important for reducing the side effects of current cancer therapies. Hence, there is an urgent need for improved assays allowing the selectivity of a given compound to be monitored directly. The authors present an assay system based on the competitive co-cultivation of an excess of cancer cells with a small fraction of noncancer human indicator cells generating a fluorescence signal. In the absence of a specific anticancer compound, the cancer cells outgrow the indicator cells and abolish the fluorescence signal. In contrast, the presence of specific anticancer drugs (such as Tyrphostin-AG1478 or PLX4720) results in the selective growth of the indicator cells, giving rise to a strong fluorescence signal. Furthermore, the authors show that the nonspecific cytotoxic compound sodium azide kills both cancer and noncancer cells, and no fluorescence signal is obtained. Hence, this assay system favors the selection of compounds that specifically target cancer cells and decreases the probability of selecting nonspecific cytotoxic molecules. Z factors of up to 0.85 were obtained, indicating an excellent assay that can be used for high-throughput screening.

2011