Selective Eradication of Colon Cancer Cells Harboring PI3K and/or MAPK Pathway Mutations in 3D Culture by Combined PI3K/AKT/mTOR Pathway and MEK Inhibition

by Selleckchem | Mar 27 2023

Colorectal cancer (CRC) is the second deadliest cancer in the world. Besides APC and p53 alterations, the PI3K/AKT/MTOR and MAPK pathway are most commonly mutated in CRC. So far, no treatment options targeting these pathways are available in routine clinics for CRC patients. We systematically analyzed the response of CRC cells to the combination of small molecular inhibitors targeting the PI3K and MAPK pathways. We used CRC cells in 2D, 3D spheroid, collagen gel cultures and freshly isolated organoids for drug response studies. Readout for drug response was spheroid or organoid growth, spheroid outgrowth, metabolic activity, Western blotting and immunofluorescence. We found profound tumor cell destruction under treatment with a combination of Torin 1 (inhibiting mTOR), MK2206 (targeting AKT) and selumetinib (inhibiting MEK) in 3D but not in 2D. Induction of cell death was due to apoptosis. Western blot analysis revealed efficient drug action. Gedatolisib, a dual PI3K/mTOR inhibitor, could replace Torin1/MK2206 with similar efficiency. The presence of PI3K and/or RAS-RAF-MAPK pathway mutations accounted for treatment responsiveness. Here, we identified a novel, efficient therapy, which induced proliferation stop and tumor cell destruction in vitro based on the genetic background. These preclinical findings show promise to further test this combi-treatment in vivo in mice and to potentially develop a mutation specific targeted therapy for CRC patients.

Comments：

This study systematically analyzed the response of colorectal cancer (CRC) cells to a combination of small molecular inhibitors targeting the PI3K/AKT/MTOR and MAPK pathways. These pathways are commonly mutated in CRC, but no treatment options targeting them are available in routine clinics for CRC patients. The study used CRC cells in 2D, 3D spheroid, collagen gel cultures, and freshly isolated organoids for drug response studies, with readouts including spheroid or organoid growth, spheroid outgrowth, metabolic activity, Western blotting, and immunofluorescence.

The results showed that a combination of Torin 1 (inhibiting mTOR), MK2206 (targeting AKT), and selumetinib (inhibiting MEK) led to profound tumor cell destruction in 3D cultures but not in 2D cultures. The induction of cell death was due to apoptosis, and Western blot analysis revealed efficient drug action. Gedatolisib, a dual PI3K/mTOR inhibitor, could replace Torin1/MK2206 with similar efficiency. The presence of PI3K and/or RAS-RAF-MAPK pathway mutations accounted for treatment responsiveness.

Overall, this study identified a novel and efficient therapy that induced proliferation stop and tumor cell destruction in vitro based on the genetic background of CRC. These preclinical findings show promise for further testing this combi-treatment in vivo in mice and potentially developing a mutation-specific targeted therapy for CRC patients.