Abstract 3873: Single cell cisplatin measurements by ICP-MS

Abstract

Cisplatin, carboplatin, and oxaliplatin are the most widely used class of cancer chemotherapy drugs in the Western world. Many cancers are initially sensitive to platinum treatment but drug resistance frequently occurs. Cellular uptake of cisplatin is related to tumor burden, thus lower intracellular cisplatin levels are associated with a decreased tumor response. Traditional methods to assess cisplatin uptake in cells involves digesting a cell population and measuring the total platinum content. This approach does not reflect the distribution and individual cellular variation of cisplatin uptake. Here, we present a new method, single cell inductively coupled plasma-mass spectrometry (SC-ICP-MS) to quantitate the platinum concentration within individual cells. Experiments were performed using the A2780 cisplatin-sensitive and the corresponding cisplatin-resistant A2780-CP70 ovarian cancer cell lines. Time course experiments were performed to measure the change of cisplatin uptake over time. Serum starvation experiments were also performed to examine if differences in cisplatin uptake were dependent on the cell cycle. SC-ICP-MS was performed by injecting cell suspensions and analyzing the platinum 195 isotope. Individual cellular cisplatin levels were collected and a histogram representing the cell population was generated using the instrument software (Syngistix Nano Application). Other metals, such as zinc, iron, and copper, were analyzed to measure the variation between cell lines after treatment. We observed a heterogeneous distribution of cisplatin concentrations within the sample reflecting that cisplatin uptake differs from cell to cell. Serum starvation affected the uptake of cisplatin within cells, changing the cisplatin distribution curve. SC-ICP-MS was also effective in measuring other metals within individual cells and differences were observed between the A2780 and A2780-CP70 cell lines. In conclusion, single cell ICP-MS analysis allows for the quantitation of cisplatin within individual cells. The heterogeneous distribution of cisplatin uptake more closely reflects what occurs within tumor cells. SC-ICP-MS allows for the development of strategies to increase cisplatin uptake, translating to better clinical responses. Citation Format: Lauren Amable, Stan Smith, Chady Stephan. Single cell cisplatin measurements by ICP-MS. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3873.

Sequenced Combinations of Cisplatin and Selected Phytochemicals towards Overcoming Drug Resistance in Ovarian Tumour Models

“…Another study using ICP-MS to measure platinum levels has also shown that that A2780 cells accumulate more than twofold of platinum than wild-type p53 A2780/CP70 (cisplatin-resistant) cells [ 19 ]. Moreover, measuring platinum at the level of a single cell using Single Cell ICP-MS method in ovarian cancer cell lines A2780 and A2780/CP70 shows that the cisplatin uptake is lower in the cisplatin resistant A2780/CP70 cell line [ 20 ].…”

Quantitative Evaluation of Cisplatin Uptake in Sensitive and Resistant Individual Cells by Single-Cell ICP-MS (SC-ICP-MS)

“…As alternative to PBS washing, the cells were three times washed with 0.9% solution of NaCl. Finally, Cellstripper was tested as gentle, nonenzymatic reagent to dissociate adherent cells in cell cultures …”

“…Finally, Cellstripper was tested as gentle, nonenzymatic reagent to dissociate adherent cells in cell cultures. 29 For single cell analysis, the collected cells were diluted with 10% methanol to the required concentration. As recommended by the manufacturer, the addition of small amounts of an organic modifier is necessary for the undisturbed operation of the EnyaMist nebulizer.…”

In Vitro Evaluation of No-Carrier-Added Radiolabeled Cisplatin ([189, 191Pt]cisplatin) Emitting Auger Electrons

“…radio-cisplatin, and the estimated number of Pt per cell, few Pt atoms bound to DNA in each cell ( Table 1 ). This number was obtained by assuming equal uptake in individual cells, as a previous single-cell ICP-MS of non-radioactive cisplatin observed almost identical uptake of the standard dose of cisplatin, i.e., the uptake does not depend on the cell cycle [ 43 , 44 , 45 ]. Almost all radio-Pt decays without binding to DNA ( Table 1 ), and consequently exerts minimal cell damage and induces a low rate of cell death ( Table 2 and Table 3 ).…”