Traditional chemotherapy remains the main treatment option for cancer. However, drugs discovered through conventional targets are often accompanied by side effects and drug resistance, so more effective treatment options are urgently needed. Discovery of antitumor drugs targeting G-quadruplexes is an effective pathway. Here, a novel series of pyrazolo[4,3-c]quinolines as potential stabilizing ligands for c-MYC Pu27 and KRAS G-quadruplexes was synthesized. Compound PQ32 was observed to stabilize these G-quadruplexes with high ΔTm values. Biological investigations indicated that PQ32 inhibited tumor cell proliferation with an IC50 of ∼ 1.00 μM, arrested the cell cycle in the G2 phase, and caused cell apoptosis. Further studies revealed that PQ32 could inhibit the expression of c-MYC and KRAS genes. Xenograft animal model assay suggested that PQ32 effectively inhibited the tumor growth in mice