Synergistic tumor suppression by a Perilla frutescens-derived methoxyflavanone and anti-cancer tyrosine kinase inhibitors in A549 human lung adenocarcinoma.

Anti-cancer tyrosine kinase inhibitors (TKIs) are effective in many types of cancers including non-small cell lung cancer, while appearance of TKI-resistant tumors suggests a need for the development of their potentiation strategies. We have previously shown that a methoxyflavanone derivative from the Asian medicinal herb Perilla frutescens (Perilla-derived methoxyflavanone; PDMF) shows a prominent anti-tumor activity against A549 human lung adenocarcinoma. Here we show that PDMF and anti-cancer TKIs (nilotinib, bosutinib, dasatinib, and ponatinib) synergistically suppress proliferation of A549 cells. Flow cytometric analysis indicated that co-stimulation with nilotinib (4 μM) and PDMF induced G2/M cell cycle arrest in low PDMF doses (10-50 μM), whereas this combination triggered de novo G1 arrest in higher PDMF dosages (50-125 μM). We also found that co-administration with nilotinib and PDMF significantly suppressed in vivo tumorigenicity of A549 cells in athymic nude mice.