Determining the effect of chemotherapeutic treatment on changes in
protein expression can provide important targets for overcoming resistance. Due to challenges in simultaneously measuring large numbers of
proteins, a paucity of data exists on global changes. To overcome these challenges, we utilized microwestern arrays that allowed us to measure the abundance and modification state of hundreds of cell signaling and
transcription factor proteins in cells following drug exposure. HapMap lymphoblastoid cell lines (LCLs) were exposed to
cisplatin, a chemotherapeutic agent commonly used to treat testicular, head and neck, non-small cell lung, and gynecological
cancers. We evaluated the expression of 259
proteins following 2, 6, and 12 h of
cisplatin treatment in two LCLs with discordant sensitivity to
cisplatin. Of these 259
proteins, 66 displayed significantly different
protein expression changes (p < 0.05). Fifteen of these
proteins were evaluated in a second pair of LCLs with discordant sensitivities to
cisplatin; six demonstrated significant differences in expression. We then evaluated a subset of 63
proteins in a second set of LCLs with discordant sensitivity, and 40% of those that were significant in the first pair were also significant in the second part with concordant directionality (p < 0.05). We functionally validated one of the top
proteins identified, PDK1, and demonstrated a synergistic relationship between
cisplatin and a PDK1 inhibitor in multiple
lung cancer lines. This study highlights the potential for identifying novel targets through an understanding of cellular changes in
protein expression and modification following drug treatments.