Figure 7. NF-kB inhibitor suppresses proliferation of ARID1A/PIK3CA mutant cells and synergizes with carboplatin.

(A) NF-kB inhibitor synergizes with carboplatin in suppressing T80 (AM) cell proliferation. 3x10⁵ of indicated cells were plated on 6-well plates. One day after seeding, cells were treated with the indicated drugs and counted every two days (n=3). Error bars, S.E.M.

(B) Synergistic effect of IKK-IIV and carboplatin in suppressing TOV-21G, but not ES-2, cell proliferation. Cells were assayed as in (A) (n=3). Error bars, S.E.M.

(C) Combined treatment of IKK-IIV and carboplatin inhibits TOV-21G tumor growth in a mouse xenograft model. 3x10⁶ TOV-21G cells were subcutaneously transplanted to 6-weeks old female nude mice and housed until tumors reached palpable size of about 100mm³. Mice were randomized into four groups for the indicated treatment and tumor sizes were measured at the indicated days (n=5 per group). Statistical analysis comparing combined treatment and single treatments is performed (either carboplatin only or IKK-IIV only, which resulted in the same range of p-values). Error bars, S.E.M.

(D) Image of dissected tumors at the time of mouse sacrifice shown in (C). Scale bar, 5cm.

(E) Working model of how ARID1A/PIK3CA mutation induces cytokine expression. (a) In wild-type cells, cytokine genes are repressed by the Sin3A-HDAC complex recruited by ARID1A. At the same time, RelA is sequestered by IkB. (b) In ARID1A mutant cells, the recruitment of Sin3-HDAC complex is abolished leading to histone acetylation. However, RelA is still sequestered by IkB. Thus, cytokine induction is limited. (c) In PIK3CA active cells, the AKT-IKK2 pathway releases RelA from IkB. However, the presence of Sin3A-HDAC complex limits cytokine induction. (d) In presence of both mutations, cytokine genes are robustly induced, which contributes to cell proliferation and drug resistance.

**, p-value < 0.01; ***, p-value < 0.001. See also Figure S7.