Spatio-temporal localization of HIF-1alpha and COX-2 during irradiation-induced oral mucositis in a rat model system.
OBJECTIVE
Oral mucositis is a common side effect of radiotherapy for head and neck cancer. The purpose of this study was to examine the significance of and the relationship between hypoxia inducible factor-1alpha (HIF-1alpha) and cyclooxygenase-2 (COX-2) gene expression and the corresponding protein levels in irradiated rat mucosa.


METHODS
A Sprague-Dawley rat model of irradiation-induced oral mucositis was generated. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate the HIF-1alpha and COX-2 mRNA level in rat buccal mucosa exposed to a fractionated irradiation regime. The Streptavidin-Biotin-Complex method was applied to delineate the in situ localization, intensity, and distribution of both proteins. The right buccal mucosa was not irradiated and used as control tissue.


RESULTS
The RT-PCR analyses demonstrated that, upon irradiation, HIF-1alpha and COX-2 expression was significantly induced in the left buccal mucosa in contrast to control buccal mucosa. Based on immunohistochemical analyses, the HIF-1alpha and COX-2 level, in situ localization, and the type of cells exhibiting the highest HIF-1alpha and COX-2 amounts appear to correlate.


CONCLUSIONS
The expression and protein levels of HIF-1alpha and COX-2 are substantially enhanced in irradiated rat mucosa and correlate with each other and with the severity of irradiation-induced oral mucositis.
Feng
Chong-Jin
CJ
Department of Stomatology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, PR China. drfcj@yahoo.com.cn
Guo
Jun-Bing
JB
Jiang
Hong-Wei
HW
Zhu
Shuang-Xi
SX
Li
Chun-Yang
CY
Cheng
Bin
B
Chen
Yong
Y
Wang
Han-Yu
HY
D000818:Animals; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D009061:Mouth Mucosa / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D012333:RNA, Messenger / Q000378:metabolism; D011833:Radiation Injuries, Experimental / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013280:Stomatitis / Q000209:etiology / Q000378:metabolism* / Q000473:pathology
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat