Identification of Novel Protein Expression Changes Following Cisplatin Treatment and Application to Combination Therapy

Unexpected therapeutic effects of cisplatin

Cisplatin is a widely used chemotherapeutic agent that is clinically approved to fight both carcinomas and sarcomas. It has relatively high efficiency in treating ovarian cancers and metastatic testicular cancers. It is generally accepted that the major mechanism of cisplatin anti-cancer action is DNA damage. However, cisplatin is also effective in metastatic cancers and should, therefore, affect slow-cycling cancer stem cells in some way. In this review, we focused on the alternative effects of cisplatin that can support a good therapeutic response. First, attention was paid to the effects of cisplatin at the cellular level such as changes in intracellular pH and cellular mechanical properties. Alternative cellular targets of cisplatin, and the effects of cisplatin on cancer cell metabolism and ER stress were also discussed. Furthermore, the impacts of cisplatin on the tumor microenvironment and in the whole organism context were reviewed. In this review, we try to reveal possible causes of the unexpected effectiveness of this anti-cancer drug.

Enabling Methods to Elucidate the Effects of Metal-based Anticancer Agents

Next-generation metal-based pharmaceuticals are considered promising therapeutic agents, which may follow novel modes of action and engage with different targets compared to classical platinum(ii) anticancer agents. However, appropriate methods and assays are required to provide evidence of such unprecedented drug effects. Mass spectrometry (MS) has proved useful in probing the reactivity and selectivity of metal-based anticancer agents on a molecular level and recently also in the cellular context, especially with regard to the proteome. This chapter will discuss the design and use of competitive experiments to investigate activation pathways and binding preferences of metal-based anticancer agents by identifying reaction products via different MS setups. Moreover, cell-based approaches are described to obtain insights into novel potential targets and modes of action. Thus, mass spectrometry emerges as an enabling technology that connects molecules to mechanisms, highlighting the broad applicability of this analytical technique to the discovery and understanding of metal-based anticancer agents.

Key Players of Cisplatin Resistance: Towards a Systems Pharmacology Approach

The major obstacle in the clinical use of the antitumor drug cisplatin is inherent and acquired resistance. Typically, cisplatin resistance is not restricted to a single mechanism demanding for a systems pharmacology approach to understand a whole cell's reaction to the drug. In this study, the cellular transcriptome of untreated and cisplatin-treated A549 non-small cell lung cancer cells and their cisplatin-resistant sub-line A549^rCDDP²⁰⁰⁰ was screened with a whole genome array for relevant gene candidates. By combining statistical methods with available gene annotations and without a previously defined hypothesis HRas, MAPK14 (p38), CCL2, DOK1 and PTK2B were identified as genes possibly relevant for cisplatin resistance. These and related genes were further validated on transcriptome (qRT-PCR) and proteome (Western blot) level to select candidates contributing to resistance. HRas, p38, CCL2, DOK1, PTK2B and JNK3 were integrated into a model of resistance-associated signalling alterations describing differential gene and protein expression between cisplatin-sensitive and -resistant cells in reaction to cisplatin exposure.