Expression of the p73 protein in rectal cancers with or without preoperative radiotherapy.
OBJECTIVE
To investigate p73 expression in normal mucosa, primary tumor, and metastasis in relation to radiotherapy (RT) response and clinicopathologic/biologic variables in rectal cancers.


METHODS
p73 was immunohistochemically examined on biopsies (unirradiated, n=102), distant (from the large bowel, n=82), and adjacent (adjacent to primary tumor, n=89) normal mucosa samples, primary tumors (n=131), and lymph node metastasis (n=32) from rectal cancer patients participating in a clinical trial of preoperative RT. Seventy-four patients received surgery alone and 57 received additional RT.


RESULTS
Cytoplasmic p73 was increased in the primary tumor compared with the distant or adjacent mucosa (p<or=0.0001). Nuclear (p=0.02) and cytoplasmic (p=0.003) p73 was higher in irradiated distant mucosa samples than in unirradiated ones, and nuclear p73 tended to be increased in irradiated primary tumors compared with unirradiated ones (p=0.06). p73 was positively related to cyclooxygenase-2 expression in irradiated tumors (p=0.03). p73-negative tumors tended to have a lower local recurrence after RT compared with unirradiated cases (p=0.06).


CONCLUSIONS
Normal epithelial cells seem more sensitive to RT than tumor cells regarding p73 expression. Patients with p73-negative rectal tumors may have a lower risk of local recurrence after RT.
Pfeifer
Daniella
D
Department of Oncology, Institute of Biomedicine and Surgery, Linköping University, Linköping, Sweden.
Gao
Jingfang
J
Adell
Gunnar
G
Sun
Xiao-Feng
XF
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D051546:Cyclooxygenase 2 / Q000032:analysis; D004268:DNA-Binding Proteins / Q000032:analysis*; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D007413:Intestinal Mucosa / Q000737:chemistry; D008207:Lymphatic Metastasis; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D008875:Middle Aged; D009687:Nuclear Proteins / Q000032:analysis*; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000737:chemistry* / Q000473:pathology / Q000532:radiotherapy*; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins
D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human