Revisiting multi-pathway modulation with theophylline derivatives: Targeting STAT3, NF-κB, and apoptotic signaling in breast cancer.

Among female cancers, breast cancer is the most prevalent type with a high tendency for metastasis, which makes it compelling to develop new therapeutic modalities in the battle against this disease. For this purpose, a new series of theophylline-based derivatives was designed as dual STAT3/NF-B signaling pathway inhibitors. The most active three compounds (12a, 12b and 17b) exhibited potent inhibition of both STAT3 and NF-κB activation in 4 T1 cells with IC50 values of 4.22-8.21 μM. They also exerted considerable anticancer activity with IC50 values of 1.53 to 7.68 μM in 4 T1, MDA-MB-231, MDA-MB-468 and MCF-7 breast cancer cell lines. These compounds demonstrated their ability to inhibit breast cancer cell migration, and invasion in scratch and transwell assays, respectively. As a consequence of STAT3 inhibition, compound 12a was able to induce apoptosis via its effects on key apoptotic regulators; caspases-3,9, Bax and Bcl-2. Besides, western blotting of 12a-treated MDA-MB-231 cells confirmed decreased expression of STAT3, p-STAT3, Bcl-xl, c-Myc and NF-κB. Moreover, compound 12a reduced tumor volume in a comparable manner to 5FU in an Ehrlich solid carcinoma model. Docking of these compounds into the active sites of STAT3 and NF-κB revealed adequate binding patterns, providing further support for their effectiveness. Hence, these compounds proved to possess structural determinants that could be further tuned into more potent anticancer agents for breast cancer.