4-HPR Is an Endoplasmic Reticulum Stress Aggravator and Sensitizes Breast Cancer Cells Resistant to TRAIL/Apo2L

Anticancer Res. 2018 Aug;38(8):4403-4416. doi: 10.21873/anticanres.12742.

Abstract

Background/aim: N-(4-hydroxyphenyl)retinamide (4-HPR) is a synthetic retinoid, less toxic than the parent all-trans retinoic acid (RA). Unlike RA, 4-HPR induces apoptosis in tumor cells. Because 4-HPR can hydrolyze to liberate RA, a potent human teratogen, the unhydrolyzable ketone analog of 4-HPR, 4-hydroxybenzylretinone (4-HBR) has been prepared and has been found to cause apoptosis in tumor cells and shrink carcinogen-induced rat mammary tumors as 4-HPR does. Herein, we examined the mechanism whereby 4-HPR and 4-HBR induce apoptosis and death in breast cancer cells.

Materials and methods: Gene expression profiling was conducted in MCF-7 cells over a 1.5- to 6-h time course and changes were validated by quantitative polymerase chain reaction (qPCR). Growth arrest and DNA damage-inducible protein 153 (GADD153 or C/EBP homologous protein, CHOP) was knocked down and the effect on 4-HPR-induced cell death and gene expression was assessed. 4-HPR synergy with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL or Apo2 ligand) was also examined.

Results: Drug treatment induced increased expression of endoplasmic reticulum (ER) stress-related and pro-apoptotic genes. Gene expression changes were verified by qPCR in three invasive ductal breast carcinoma cell lines (MCF-7, T-47D, MDA-MB-231). GADD153 showed the largest increase in the microarray experiment; however, knockdown of GADD153 did not abrogate apoptosis and death. Genes related to the extrinsic pathway of apoptosis including a receptor for TRAIL, death receptor 5 (DR5), were up-regulated by drug treatment. A dose of 4-HPR that alone is ineffective in killing TRAIL-resistant MCF-7 cells, synergized with recombinant TRAIL to induce breast cancer cell death.

Conclusion: 4-HPR and analogs might be useful in sensitizing tumor cells to death receptor agonists.

Keywords: Breast cancer; DR5; TRAIL; endoplasmic reticulum stress; fenretinide; retinoid analog.

MeSH terms

  • Apoptosis / drug effects
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / metabolism
  • Cell Death / drug effects
  • Cell Division / drug effects
  • Cell Line, Tumor
  • Endoplasmic Reticulum Stress / drug effects*
  • Female
  • Fenretinide / pharmacology*
  • Humans
  • MCF-7 Cells
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / metabolism
  • TNF-Related Apoptosis-Inducing Ligand / metabolism*
  • Transcription Factor CHOP / metabolism
  • Tretinoin / metabolism
  • Up-Regulation / drug effects

Substances

  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFSF10 protein, human
  • Transcription Factor CHOP
  • Fenretinide
  • Tretinoin