Hypoxia and differentiation in squamous cell carcinomas of the uterine cervix: pimonidazole and involucrin.
OBJECTIVE
Pimonidazole binding (hypoxia) and involucrin expression (differentiation) overlap extensively in squamous cell carcinomas. This study asks whether involucrin might serve as an endogenous marker for tumor hypoxia. A second question is whether differentiation affects hypoxia-inducible metallothionein (MT) expression in normal human epithelia and squamous cell carcinomas as it does in rodent epithelia.


METHODS
Thirty-four patients with squamous cell carcinoma of the uterine cervix were infused with pimonidazole hydrochloride solution. The next day, multiple biopsies were formalin-fixed, paraffin-embedded and sectioned at 4 micro m. Qualitative and quantitative analyses for involucrin expression, pimonidazole binding, and human MT-IIa mRNA expression were performed.


RESULTS
No overall correlation between the extent of involucrin expression and pimonidazole binding was observed. The lack of correlation was because of heterogeneous patterns of immunostaining for involucrin generally related to tumor grade. Colocalized immunostaining for involucrin and pimonidazole binding was observed in intermediate grade tumors but not in well-differentiated or poorly differentiated tumors. Human MT-IIa mRNA and MT protein were expressed in basal lamina of normal human epithelia and in the proliferative rims of tumor nests.


CONCLUSIONS
Colocalization of immunostaining for involucrin and pimonidazole binding is consistent with oxygen regulation, but the lack of involucrin expression in hypoxic regions of poorly differentiated tumors indicates that its transcriptional status with respect to hypoxia induction is altered by cell differentiation. The localization of MT message and protein in the outer rims of most tumor nests indicates that the transcriptional status of metallothionein is also altered by differentiation.
Department of Radiation Oncology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
Yoshihiro
Y
Azuma
Shu-Chuan
SC
Chou
Ruth A
RA
Lininger
Brian J
BJ
Murphy
Mahesh A
MA
Varia
James A
JA
Raleigh
D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D000860:Hypoxia; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008668:Metallothionein / Q000096:biosynthesis; D009593:Nitroimidazoles / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D011379:Prognosis; D011498:Protein Precursors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D014158:Transcription, Genetic; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis* / Q000473:pathology*
C491053:MT2A protein, human; D009593:Nitroimidazoles; D011498:Protein Precursors; D012333:RNA, Messenger; D011838:Radiation-Sensitizing Agents; C033815:pimonidazole; C032253:involucrin; D008668:Metallothionein; D010100:Oxygen