The bioactivity of the extracts was tested on the redox activity of PDIA3 disulfide isomerase, an enzyme involved in the regulation of several cellular functions and associated with different diseases such as cancer, prion disorders, Alzheimer's and Parkinson's diseases.
GSEA of the Cancer Genome Atlas dataset showed that Kyoto Encyclopedia of Genes and Genomes oxidative phosphorylation and amino sugar and nucleotide sugar metabolism pathways could be correlated with PDIA3 expression; this was further confirmed in AML cells by Western blotting.
In HCT116 colon carcinoma cells, lentiviral depletion of ERp57 resulted in oxidation of PDI and activation of PERK, whereas depletion or chemical inhibition of PDI reduced PERK signaling and sensitized the cancer cells to hypoxia and ER stress.
Unspecifically downregulated proteins include cancer markers involved in apoptotic resistance and endoplasmatic reticulum (ER) stress such as the 78 kDa glucose regulated protein (GRP 78), protein disulfide isomerase A3 (PDIA3, GRP 58), calumenin, and galectin-1, as well as the glycolytic enzymes triose phosphate isomerase, glyceraldehyde phosphodehydrogenase, and phosphoglycerate mutase.
Moreover, ERp57(low) cancer cells (which failed to expose CRT) treated with anthracyclines were unable to elicit an anti-tumor response in conditions in which control cells were highly immunogenic.