Combinational silencing of components involved in JAK/STAT signaling pathway.

Combinatorial silencing of more than one protein via small interfering RNA (siRNA) is a new strategy that can enhance the effect of RNA interference on cell function. To explore this strategy, we selected JAK/STAT axis as a major signaling pathway that contributes to several mechanisms involved in cancer cell proliferation and survival. We focused on four proteins involved in this pathway to explore the possibility of identifying a combinatorial targeting strategy (as the proof of concept) with enhanced efficiency: gp 130 (a co-receptor for IL6 cytokines), JAK2, STAT3, and importin α3 (the nuclear transporter reportedly involved in translocation of activated STAT3 to nucleus). Selected proteins were targeted by siRNA in two selected Triple Negative Breast Cancer cell lines (MDA-MB-231 and MDA-MB-468). The effect of individual and selected combinations of siRNAs on selected downstream antiapoptotic proteins, pro-apoptosis proteins, and cell-cycle regulating proteins was explored. Combinatorial silencing of JAK2/gp 130 enhanced the effect of RNA interference on downstream proteins significantly, and demonstrated enhanced effect in reducing cell viability, cell migration, and the level of activation of STAT3. In conclusion, the promising results of simultaneous targeting of JAK2 and gp 130 might be an example for potential combinatorial silencing strategies in cancer treatment.