Table 1 Typical examples of conventional drugs as anti-tumor agents

Sulfasalazine

Rheumatic arthritis, ulcerative colitis

Specific inhibition of xCT cystine transporter

Disruption of reduced glutathione (GSH) synthesis and to make cancer cells suscptible to oxidative stress

Gastric tumor and NSCLC progression, breast cancer metastasis

Itraconazole

Fungal infections such as Aspergillus

Inhibition of Smoothened (Smo), active Shh receptor

To inhibit proliferation of secondary mutated Shh signal (e.g. Gli2 amplification)

Difficult-to-cure medulloblastoma

Terfenadine

Auto-immune disorders such as allergic dermatitis

Histamine receptor H1 antagonist

To prevent secretion of VEGF from mast cells localized in hypoxic lesion, and to induce ROS-mediated apoptosis and autophagy of melanoma cells

Malignant melanoma

Simvastatin

Hyperlipidemia

Specific inhibition of HMG-CoA reductase

To prevent mutant p53 from activating mevalonate pathway for cholesterol synthesis

Breast tumor, ovarian cancer