Oops, you're using an old version of your browser so some of the features on this page may not be displaying properly.

MINIMAL Requirements: Google Chrome 24+Mozilla Firefox 20+Internet Explorer 11Opera 15–18Apple Safari 7SeaMonkey 2.15-2.23


46P - Enhanced 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT) Efficacy by hormones in uterine sarcoma cells via upregulation of proporphyrinogen oxidase


06 Oct 2021




Ellie Chu


Annals of Oncology (2021) 32 (suppl_6): S1345-S1371. 10.1016/annonc/annonc740


E.S.M. Chu1, H. Lau2, Z. Huang3

Author affiliations

  • 1 TWC-Tung Wah College:King's Park Campus, Kowloon/HK
  • 2 TWC-Tung Wah College:King's Park Campus, 852 - Kowloon/HK
  • 3 Fujian Normal University, 86 - Fuzhou/CN

Abstract 46P


Photodynamic therapy (PDT) is an FDA approved cancer treatment modality for various cancers. In principle, PDT induces a photochemical reaction with exogenous photosensitizer (PS) in cancer cells upon light irradiation with oxygen, which generates reactive oxygen species leading to cancer cell death. Studies showed that hormones enhanced accumulation of photosensitive protoporphyrin IX (PpIX) generated by ALA PS in human endometrial cells, implying the increased PpIX potentially boost up ALA-based PDT effect in hormonal dependent cancers. Yet the underlying mechanism remains unexplored.


Uterine sarcoma cells were cultured with fluctuated 17β-estradiol (E2) and progesterone (P) levels as human menstrual cycle, then treated with exogenous Hexyl-ALA compared with normal cultured cells. PpIX localization and accumulation in the cells were determined by confocal microscopy and flow cytometry respectively. Hexyl-ALA-PDT effect was evaluated by MTT assay with sulfentrazone (Sul) inhibitor of proporphyrinogen oxidase (PPOX) - a limiting factor of PpIX in the heme pathway. The PPOX expression in cells was quantified by flow cytometry.


PpIX localized in mitochondria. PpIX accumulation increased 30% with E2 and P in a time-dependent manner compared with hexyl-ALA (30 μM) only. At 4hr, the phototoxicity increased from 20% to 60% at hexyl-ALA (30 μM, 2J/cm2) compared with hormones respectively. Addition of Sul further enhanced the phototoxicity to 70%. PPOX level also enhanced by hormones; implying the hormonal microenvironment boost up Hexyl-ALA-PDT effect in the cells via up-regulation of PPOX.


This study showed that hormones played a vital role in enhancing hexyl-ALA PDT effect via up-regulation of PPOX. The simulated hormonal microenvironment culture model is suitable to study hexyl-ALA-PDT effect in hormonal dependent cancers.

Legal entity responsible for the study

The authors.


Hexyl-ALA was provided by Photocure ASA. This study was fully supported by a grant from Research Grants Council (RGC) of the Hong Kong Special Administrative Region, China (project no.: UGC/FDS17/M06/19).


All authors have declared no conflicts of interest.

This site uses cookies. Some of these cookies are essential, while others help us improve your experience by providing insights into how the site is being used.

For more detailed information on the cookies we use, please check our Privacy Policy.

Customise settings
  • Necessary cookies enable core functionality. The website cannot function properly without these cookies, and you can only disable them by changing your browser preferences.