title: Bitter melon protects against ER stress in LS174T colonic epithelial cells.
abstract: BACKGROUND
  Bitter Melon (BM) has been used as a functional food in traditional Chinese and Indian medicine for many generations and has gained a great deal of attention due to its apparent benefits in moderating some of the pathogenic processes in a variety of inflammatory conditions. BM extract (BME) has been shown to possess strong anti-oxidant properties. In addition, it can ameliorate oxidative stress and potentially ER stress. There is increasing evidence that oxidative and ER stress are major contributors for intestinal secretory cell dysfunction which leads to local inflammation and disease pathogenesis that are hallmarks of inflammatory bowel diseases (IBD). Hence, the search for potential therapeutics against ER stress and oxidative stress in intestinal epithelial secretory cells may provide valuable resources for the management of IBD. The aim of the present study was to investigate the effects of BME in ameliorating ER stress in colonic epithelial cells.
  
  
  METHODS
  Human colonic adenocarcinoma LS174T cells were used for the assessment of BME effects on colonic epithelial cells in vitro. Cell viability was assessed using trypan blue exclusion and the effect of BME in ameliorating tunicamycin (TM)-induced ER stress was determined by analysing the mRNA expression of the common ER stress markers; ATF6, XBP1, GRP78, CHOP and PERK by quantitative RT-PCR and GRP78 and CHOP by western blot.
  
  
  RESULTS
  In the absence of ER stress, BME exhibited no cell toxicity up to 2.0% w/v and no significant effect on the basal mRNA expression of ER stress markers in LS174T cells. In contrast, pre-treatment of LS174T cells with BME followed by induction of ER stress resulted in a significant decrease in mRNA expression of ATF6, XBP1, GRP78, CHOP and PERK and protein expression of GRP78 and CHOP. Co-treatment during induction of ER stress and post- treatment following induction of ER Stress in LS174T cells resulted in a lower but still significant reduction in mRNA expression levels of most ER stress markers.
  
  
  CONCLUSIONS
  This is one of the first studies demonstrating the efficacy of BME in reducing expression of ER stress markers in colonic epithelial cells suggesting the potential of BME as a dietary intervention in ameliorating ER stress and oxidation in IBD. Interestingly, while the most significant effect was seen with pre-treatment of cells with BME there was a reduced but still significant effect when co-treated or even post-treated. This suggests that BME may even be effective in modulating ER stress in the face of an existing cell stress environment.
authors.affiliation: School of Health Sciences, University of Tasmania, Launceston, 7250, TAS, Australia.
authors.forename: Dale A
authors.initials: DA
authors.lastname: Kunde
authors.affiliation: School of Health Sciences, University of Tasmania, Launceston, 7250, TAS, Australia.
authors.forename: Wai Chin
authors.initials: WC
authors.lastname: Chong
authors.affiliation: Department of Molecular Biosciences & Bioengineering, University of Hawaii, Honolulu, HI, USA.
authors.forename: Prathiba V
authors.initials: PV
authors.lastname: Nerurkar
authors.affiliation: School of Health Sciences, University of Tasmania, Launceston, 7250, TAS, Australia.
authors.forename: Kiran D K
authors.initials: KD
authors.lastname: Ahuja
authors.affiliation: School of Physical Sciences, University of Tasmania, Hobart, 7000, TAS, Australia.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Just
authors.affiliation: School of Physical Sciences, University of Tasmania, Hobart, 7000, TAS, Australia.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Smith
authors.affiliation: School of Medicine, University of Tasmania, Hobart, 7000, TAS, Australia.
authors.forename: Nuri
authors.initials: N
authors.lastname: Guven
authors.affiliation: School of Health Sciences, University of Tasmania, Launceston, 7250, TAS, Australia. rderi@utas.edu.au.|School of Health Sciences, University of Tasmania, Locked Bag 1322, Launceston, TAS, 7250, Australia. rderi@utas.edu.au.
authors.forename: Rajaraman D
authors.initials: RD
authors.lastname: Eri
mesh_terms: D045744:Cell Line, Tumor; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D029777:Momordica charantia / Q000737:chemistry*; D018384:Oxidative Stress / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D020011:Protective Agents / Q000737:chemistry / Q000494:pharmacology*; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism; D014415:Tunicamycin / Q000032:analysis / Q000494:pharmacology; D000071717:X-Box Binding Protein 1 / Q000235:genetics / Q000378:metabolism
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D010936:Plant Extracts; D020011:Protective Agents; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; D014415:Tunicamycin; D051742:Transcription Factor CHOP
keywords: Bitter melon; Endoplasmic reticulum stress; Inflammatory bowel disease; Intestinal secretory cells; Oxidative stress; Unfolded protein responses