Bone Abstracts

Osteoporosis is a metabolic disorder of the bones that shows increased incidence in post-menopausal women where estrogen deficiency plays a significant role in its development. Estrogen also decreases endoplasmic reticulum stress by decreasing the expression of ER stress markers.

Using a combination of subtractive cDNA libraries and microarray analysis, a panel of estrogen dependent mRNAs/proteins was identified, including transcription factor, XBP1/1S; protein disulphide isomerase, AGR2 and heat shock protein HSP90/GP96. Not only are these proteins, either under estrogen regulation (AGR2, XBP1) or as an estrogen receptor chaperone (HSP90/GP96), but they are also associated with the ER-stress-UPR signalling pathway.

The aim of this project is to understand the interplay between reduced levels of estrogen, reduced ER stress response and the development of osteoporosis by investigating the effect of steroid hormones on mRNAs/proteins of the ER stress-UPR pathways and on their microRNAs regulators in osteosarcoma (osteoblast-like) cell lines. Identified proteins/mRNAs/miRNAs will be validated as potential biomarkers using clinical specimens from normal and osteoporosis patients.

1 nM of Estradiol in 48 hours showed a variable effect on the proliferation of osteosarcoma cell lines after stripping down 3 days using 1% in-house hormone stripped. RNAs were isolated from cultured cells and RNA libraries were constructed for sequencing, showing different genes have significantly different expression between the treated cells and non-treated controls. Commercially available qPCR arrays containing mRNAs that are associated with ER stress-UPR signalling pathways will also be used as an alternative strategy. Once identified, potential biomarkers will be validated using clinical specimens by qRT-PCR. This research will advance our knowledge and help us to understand mechanisms underlying osteoporosis. It will also generate a potential strategy to develop innovative diagnostic and therapeutic applications in the future to improve patients’ healthcare.