Abstract
Neuroblastoma (NB) is the most common solid extracranial cancer of childhood. Amplification and over-expression of the MYCN oncogene characterize the most aggressive forms and are believed to severely downregulate MHC class I molecules by transcriptional inhibition of the p50 NF-κB subunit. In this study, we found that in human NB cell lines, high MYCN expression is not responsible for low MHC class I expression because neither transfection-mediated overexpression nor small interfering RNA suppression of MYCN affects MHC class I and p50 levels. Furthermore, we identified NF-κB as the immediate upstream regulator of MHC class I because the p65 NF-κB subunit binds MHC class I promoter in chromatin immunoprecipitation experiments, and MHC class I expression is enhanced by p65 transfection and reduced by (a) the chemical NF-κB inhibitor sulfasalazine, (b) a dominant-negative IKBα gene, and (c) p65 silencing. Moreover, we showed that the endoplasmic reticulum aminopeptidases ERAP1 and ERAP2, which generate MHC class I binding peptides, are regulated by NF-κB, contain functional NF-κB-binding elements in their promoters, and mimic MHC class I molecules in the expression pattern. Consistent with these findings, nuclear p65 was detected in NB cells that express MHC class I molecules in human NB specimens. Thus, the coordinated downregulation of MHC class I, ERAP1, and ERAP2 in aggressive NB cells is attributable to a low transcriptional availability of NF-κB, possibly due to an unknown suppressor other than MYCN.
| Original language | English |
|---|---|
| Pages (from-to) | 916-924 |
| Number of pages | 9 |
| Journal | Cancer Research |
| Volume | 70 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Feb 1 2010 |
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ASJC Scopus subject areas
- Cancer Research
- Oncology
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NF-κB, and not MYCN, regulates MHC class I and endoplasmic reticulum aminopeptidases in human neuroblastoma cells. / Forloni, Matteo; Albini, Sonia; Limongi, Maria Zaira; Cifaldi, Loredana; Boldrini, Renata; Nicotra, Maria Rita; Giannini, Giuseppe; Natali, Pier Giorgio; Giacomini, Patrizio; Fruci, Doriana.
In: Cancer Research, Vol. 70, No. 3, 01.02.2010, p. 916-924.Research output: Contribution to journal › Article
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TY - JOUR
T1 - NF-κB, and not MYCN, regulates MHC class I and endoplasmic reticulum aminopeptidases in human neuroblastoma cells
AU - Forloni, Matteo
AU - Albini, Sonia
AU - Limongi, Maria Zaira
AU - Cifaldi, Loredana
AU - Boldrini, Renata
AU - Nicotra, Maria Rita
AU - Giannini, Giuseppe
AU - Natali, Pier Giorgio
AU - Giacomini, Patrizio
AU - Fruci, Doriana
PY - 2010/2/1
Y1 - 2010/2/1
N2 - Neuroblastoma (NB) is the most common solid extracranial cancer of childhood. Amplification and over-expression of the MYCN oncogene characterize the most aggressive forms and are believed to severely downregulate MHC class I molecules by transcriptional inhibition of the p50 NF-κB subunit. In this study, we found that in human NB cell lines, high MYCN expression is not responsible for low MHC class I expression because neither transfection-mediated overexpression nor small interfering RNA suppression of MYCN affects MHC class I and p50 levels. Furthermore, we identified NF-κB as the immediate upstream regulator of MHC class I because the p65 NF-κB subunit binds MHC class I promoter in chromatin immunoprecipitation experiments, and MHC class I expression is enhanced by p65 transfection and reduced by (a) the chemical NF-κB inhibitor sulfasalazine, (b) a dominant-negative IKBα gene, and (c) p65 silencing. Moreover, we showed that the endoplasmic reticulum aminopeptidases ERAP1 and ERAP2, which generate MHC class I binding peptides, are regulated by NF-κB, contain functional NF-κB-binding elements in their promoters, and mimic MHC class I molecules in the expression pattern. Consistent with these findings, nuclear p65 was detected in NB cells that express MHC class I molecules in human NB specimens. Thus, the coordinated downregulation of MHC class I, ERAP1, and ERAP2 in aggressive NB cells is attributable to a low transcriptional availability of NF-κB, possibly due to an unknown suppressor other than MYCN.
AB - Neuroblastoma (NB) is the most common solid extracranial cancer of childhood. Amplification and over-expression of the MYCN oncogene characterize the most aggressive forms and are believed to severely downregulate MHC class I molecules by transcriptional inhibition of the p50 NF-κB subunit. In this study, we found that in human NB cell lines, high MYCN expression is not responsible for low MHC class I expression because neither transfection-mediated overexpression nor small interfering RNA suppression of MYCN affects MHC class I and p50 levels. Furthermore, we identified NF-κB as the immediate upstream regulator of MHC class I because the p65 NF-κB subunit binds MHC class I promoter in chromatin immunoprecipitation experiments, and MHC class I expression is enhanced by p65 transfection and reduced by (a) the chemical NF-κB inhibitor sulfasalazine, (b) a dominant-negative IKBα gene, and (c) p65 silencing. Moreover, we showed that the endoplasmic reticulum aminopeptidases ERAP1 and ERAP2, which generate MHC class I binding peptides, are regulated by NF-κB, contain functional NF-κB-binding elements in their promoters, and mimic MHC class I molecules in the expression pattern. Consistent with these findings, nuclear p65 was detected in NB cells that express MHC class I molecules in human NB specimens. Thus, the coordinated downregulation of MHC class I, ERAP1, and ERAP2 in aggressive NB cells is attributable to a low transcriptional availability of NF-κB, possibly due to an unknown suppressor other than MYCN.
UR - http://www.scopus.com/inward/record.url?scp=76249104776&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=76249104776&partnerID=8YFLogxK
U2 - 10.1158/0008-5472.CAN-09-2582
DO - 10.1158/0008-5472.CAN-09-2582
M3 - Article
C2 - 20103633
AN - SCOPUS:76249104776
VL - 70
SP - 916
EP - 924
JO - Journal of Cancer Research
JF - Journal of Cancer Research
SN - 0008-5472
IS - 3
ER -