16 research outputs found
Expression of retinoblastoma gene product in respiratory epithelium and sinonasal neoplasms: relationship with p16 and cyclin D1 expression
Transition from G1 to S phase of the cell
cycle is mediated by interactions between the
Retinoblastoma gene product (pRb), p16, and cyclin D1.
To determine the expression of these proteins in the
sinonasal mucosa immunohistochemistry was carried out
on archived tissue sections from 46 patients (37 men, 9
women, age range 17 to 82 years, median 55 years).
Nuclear immunostaining for these proteins was assessed
and the expression rates (percentages of immunoreactive
nuclei) in normal respiratory epithelium, inverted
sinonasal papillomas, cylindrical (oncocytic) sinonasal
papillomas, and squamous cell carcinomas were
compared.
Normal respiratory epithelium showed significantly
higher pRb expression in surface cells compared to basal
cells (p<0.05). In contrast, abundant pRb expression in
surface and basal cells was detected in columnar
differentiation in sinonasal papillomas and adjacent
mucosa. Cuboidal and squamous metaplasia in inverted
papillomas showed significantly reduced pRb expression
in surface cells compared to columnar epithelium in
inverted papillomas (p<0.05, respectively). Expression
of p16 was detected in all epithelial cell layers of normal
respiratory epithelium, sinonasal papillomas, and
adjacent mucosa. Cuboidal and squamous metaplasia in
inverted papillomas showed increased p16 expression in
surface cells compared to columnar epithelium in
inverted papillomas (p<0.05 between squamous metaplasia and columnar epithelium). Sinonasal
squamous cell carcinomas showed the coexpression of
pRb and p16. Expression rates of cyclin D1 higher than
10% were detected only in invasive carcinomas but not
in carcinoma in situ, sinonasal papillomas or respiratory
epithelium. Conclusively, pRb expression accompanies
terminal differentiation in columnar surface cells.
Expression of pRb in proliferating basal cells is present in sinonasal papillomas and adjacent mucosa but not in
normal respiratory epithelium. Cuboidal and squamous
metaplasia in inverted papillomas involves
downregulation of pRb expression along with increased
p16 expression in surface cells. Sinonasal squamous cell
carcinomas coexpress pRb and p16. Overexpression of
cyclin D1 in sinonasal lesions is confined to invasive
squamous cell carcinomas