Lubiprostone (a prostone) slows the in vitro growth of colon adenosarcoma cells with low [NAD+] 15‐OH PGDH (LB856)

Abstract

Objective. Lubiprostone is a bicyclic fatty acid (prostone) which is used widely for treatment of chronic idiopathic constipation (CIC), opioid‐induced constipation (OIC) and constipation‐associated irritable bowel syndrome (IBS‐C). [NAD+]‐15‐OH PGDH (PGDH), which synthesizes endogenous prostones from prostaglandins, is a suppressor of human gastrointestinal cancers and genetic therapy with PGDH slowed the growth of colon tumor xenographs. The present study was to determine whether lubiprostone, acting as a prostone, would slow growth of colon cancer cells which express low PGDH and whether transfection of low PGDH colon cancer cells with PGDH would ablate the effects of lubiprostone on the cancer cells.Methods. LS174T (colon adenosarcoma) cells that contain low PGDH were grown in Eagle’s MEM/10% FBS, transfected with human PGDH cDNA in pCMV6‐Entry vector or vector alone using Lipofectamine and selected using G418 (200 µg/ml). PGDH:GAPDH levels were determined by densitometry of western blots. LS174T cells, non‐transfected and transfected with hPGDH or vector alone (mock) were grown in 35mm petri dishes (0.5x104 cells/ dish) to 40% confluence and then treated with either 0.1% EtOH‐0.01% DMSO (vehicle) or 100 nM lubiprostone. Every 24 h media were changed and fresh vehicle or lubiprostone added. DMSO and lubiprostone were from Sucampo. Cell growth was monitored by directly counting the cells in a randomly chosen field using a cell cytometer at 0, 24, 48, 72 and 96 h. Similar studies were carried out with HT‐29 colon cancer cells.Results. LS174 T cell growth was slowed or stopped by 100 nM lubiprostone. Transfection of LS174T cells with PGDH, but not mock transfection, prevented lubiprostone inhibition of cell growth. Similar results were found with H‐T29 colon cancer cells.Conclusions. These results demonstrate that lubiprostone will slow or prevent the growth of colon cancer cells which contain low 15‐OH PGDH. These results provide a rationale for further study in clinical trials.