Blocking the functional domain of cancer cell surface TIP1 upregulates Midkine via the β-catenin/Wnt signaling pathway.

Drug resistance exhibited by cancer cells remains one of the primary reasons for the failure of therapeutic approaches to increase the survival of cancer patients. Marginal improvement in therapeutic efficacy with current treatment approaches for non-small cell lung cancer (NSCLC) mandates new treatment strategies. Tax interacting Protein-1 (TIP1) is a radiation-inducible molecular target involved in various cancer pathways. TIP1 expression correlates with poor survival in NSCLC patients. Antibody blocking the functional domain of TIP1 reduced cell proliferation and sensitized cancer cells to radiation. A ten-fold increase in Midkine (MDK) was observed in the proteomic analysis of cells treated with anti-TIP1 antibody. Wnt signaling activation led to MDK upregulation at the mRNA and protein levels following TIP1 blockade. Genetic silencing of β-catenin abrogated the induction of MDK following anti-TIP1 antibody treatment. Inhibiting TIP1 along with MDK showed a reduction in the colony-forming capability of the cells, indicating that MDK upregulation might be a strategy employed by cancer cells to combat the anti-proliferative capabilities of the anti-TIP1 antibody. Co-targeting cell surface TIP1 and MDK may be an effective therapeutic strategy for NSCLC patients.