Περίληψη:
Dentin sialophosphoprotein (DSPP) is upregulated in various human cancers, including head and neck squamous cell carcinoma. Cancer cells are commonly found under constant endoplasmic reticulum (ER) stress and exhibit increased levels of misfolded proteins, due to gene mutations and a stressful microenvironment. The present study examined the effects of DSPP silencing on the regulation of ER stress and the unfolded protein response (UPR) in oral cancer cells. A recently established stable DSPP short hairpin (sh)RNA-silenced OSC2 oral cancer cell line was used. The mRNA expression levels of ER stress-associated proteins, including 78 kDa glucose-regulated protein (GRP78), sarcoplasmic/endoplasmic reticulum calcium ATPase 2b (SERCA2b), inositol 1,4,5-trisphosphate receptor (IP3r), protein kinase R-like endoplasmic reticulum kinase (PERK), serine/threonine-protein kinase/endoribonuclease IRE1 (IRE1), activating transcription factor 6 (ATF6) and matrix metalloproteinase 20 (MMP20), were assessed by reverse transcription-quantitative polymerase chain reaction. The expression levels of apoptosis-related [B-cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax) and cytochrome c] and cell proliferation-related [proliferating cell nuclear antigen (PCNA)] proteins were analyzed by western blotting. Cell viability, apoptosis and migration were monitored by MTT assay, Annexin V-fluorescein isothiocyanate flow cytometry and wound-healing assay, respectively. In transiently trans-fected puromycin-free OSC2 cells, DSPP silencing markedly downregulated the mRNA expression levels of major ER stress regulators, including GRP78, SERCA2b, PERK, IRE1 and ATF6, as well as MMP20. DSPP silencing also resulted in decreased cell viability and migration, and enhanced apoptosis. Furthermore, PCNA and Bcl2 levels were decreased, whereas Bax and cytochrome c protein levels were increased in DSPP-silenced OSC2 cells. Sustained puromycin treatment partially counteracted the effects of DSPP silencing on the mRNA expression levels of ER stress-related proteins and MMP20, and on the migratory capacity of OSC2 cells. However, following puromycin treatment of DSPP-silenced cells, cell viability was further reduced and apoptosis was enhanced. In conclusion, these data provide evidence to suggest that DSPP may be involved in ER stress mechanisms in oral squamous cell carcinoma, since its downregulation in OSC2 cells led to significant alterations in the levels of major ER stress-associated proteins, and subsequent collapse of the UPR system. © 2018 Spandidos Publications. All rights reserved.
Συγγραφείς:
Gkouveris, I.
Nikitakis, N.G.
Aseervatham, J.
Ogbureke, K.U.E.
Λέξεις-κλειδιά:
activating transcription factor 6; cycline; cytochrome c; dentin sialophosphoprotein; fluorescein isothiocyanate; glucose regulated protein 78; inositol 1,4,5 trisphosphate receptor; lipocortin 5; matrix metalloproteinase 20; messenger RNA; oncoprotein; protein Bax; protein bcl 2; protein IRE1; sarcoplasmic reticulum calcium transporting adenosine triphosphatase; SERCA2b protein; short hairpin RNA; unclassified drug; dentin sialophosphoprotein; messenger RNA; phosphoprotein; scleroprotein; sialoglycoprotein; small interfering RNA, apoptosis; Article; cell migration; cell proliferation; cell viability; controlled study; down regulation; endoplasmic reticulum stress; flow cytometry; molecular pathology; mouth cancer; MTT assay; oral cancer cell line; priority journal; protein determination; protein expression; protein function; protein stability; reverse transcription polymerase chain reaction; unfolded protein response; Western blotting; wound healing assay; animal; carcinogenesis; endoplasmic reticulum; endoplasmic reticulum stress; gene expression regulation; genetics; human; metabolism; mouth tumor; pathology; signal transduction; tumor cell line; unfolded protein response; upregulation, Animals; Carcinogenesis; Cell Line, Tumor; Down-Regulation; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Extracellular Matrix Proteins; Gene Expression Regulation, Neoplastic; Humans; Mouth Neoplasms; Phosphoproteins; RNA, Messenger; RNA, Small Interfering; Sialoglycoproteins; Signal Transduction; Squamous Cell Carcinoma of Head and Neck; Unfolded Protein Response; Up-Regulation
