The effect of bisphosphonates on gene expression: GAPDH as a housekeeping or a new target gene?
BACKGROUND
RT-PCR has been widely used for the analysis of gene expression in many systems, including tumor samples. GAPDH (Glyceraldehyde-3-phosphate dehydrogenase) has been frequently considered as a constitutive housekeeping gene and used to normalize changes in specific gene expression. However, GAPDH has been shown to be up-regulated in many cancers and down-regulated by chemotherapic drugs. Bisphosphonates, potent inhibitors of bone resorption, have recently shown a direct and indirect antitumor effect in vitro and in animal models. They exert their effects mainly by inhibiting the mevalonate pathway but also by modulating the expression of many genes not only in osteoclasts but also in cancer cells.


METHODS
We evaluated GAPDH gene expression by real time RT PCR in breast (MCF-7 and T47D) and prostate (PC3 and DU-145) cancer cell lines treated with amino and non-amino bisphosphonates.


RESULTS
Our results showed that amino-bisphosphonates significantly decrease in a dose-dependent manner the expression of GAPDH gene.


CONCLUSIONS
Therefore, GAPDH is inaccurate to normalize mRNA levels in studies investigating the effect of bisphosphonates on gene expression and it should be avoided. On the other hand, this gene could be considered a potential target to observe the effects of bisphosphonates on cancer cells.
Valenti
Maria Teresa
MT
Department of Biomedical and Surgical Sciences, University of Verona, Italy. valenti.lab.oncnoale@inwind.it
Bertoldo
Francesco
F
Dalle Carbonare
Luca
L
Azzarello
Giuseppe
G
Zenari
Sonia
S
Zanatta
Mirko
M
Balducci
Elena
E
Vinante
Orazio
O
Lo Cascio
Vincenzo
V
D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D004164:Diphosphonates / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D020869:Gene Expression Profiling; D005819:Genetic Markers; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+) / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D012333:RNA, Messenger / Q000032:analysis; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D004164:Diphosphonates; D005819:Genetic Markers; D012333:RNA, Messenger; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+)