| Popis: |
Clinically nonfunctional pituitary adenomas cause hypopituitarism or compression of regional structures. Unlike functional tumors, there is no available medical treatment or specific imaging technique for these tumors. We have recently discovered that both folate receptor (FR)α mRNA and protein are uniquely overexpressed in nonfunctional pituitary tumors, but not in functional adenomas. We hypothesized that FRα may hold significant promise for medical treatment by enabling novel molecular imaging and targeted therapy. Here, we used murine pituitary tumor cell line αT3‐1 as a model to investigate the biological significance of FRα and its mutant FR67. We demonstrate that overexpression of FR facilitated tumor cell growth and anchorage‐independent growth in soft agar. More colonies were observed in FR overexpressing cells than in mutant FR67 clones in soft agar. Cell proliferation rate was increased, the percentage of cells in S‐phase was increased, and high PCNA staining was detected in cells overexpressing the receptor. In αT3‐1 cells transfected with mutant FR67, cell proliferation rate was reduced, the percentage of cells residing in S‐phase was slightly decreased, and low PCNA staining was observed. By real‐time quantitative PCR, the genes involved in NOTCH3 pathway including NOTCH3, HES‐1, and TLE2 were altered; the mRNA expression of FGFR1 was upregulated, and ERβ mRNA was downregulated in FR overexpressing cells. Our findings suggest that FRα plays a role in pituitary tumor formation, and this effect may in part be due to its regulation of the NOTCH3 pathway. |
