Quantitation of somatostatin receptor type 2 gene expression in neuroblastoma cell lines and primary tumors using competitive reverse transcription-polymerase chain reaction.
We previously reported the presence of somatostatin (SS-14)-binding sites in a wide panel of human neuroblastoma (NB) tumor cell lines. Given that the adrenal gland and its relative embryonal and adult tumors express an abundance of mRNA for somatostatin receptor type 2 (sst2) mRNA, we studied the quantitative expression of sst2 in 6 NB cell lines and 15 primary tumors using competitive reverse transcription (RT)-PCR. This method uses an insertion mutant of the target gene as a competitor for the RT-PCR reaction, thus allowing exact quantitation of sst2 mRNA abundance. We found expression of specific transcripts for sst2 in all of the NB cell lines and tumors investigated (range, 9 x 10(5)-4 x 10(9) molecules/microg RNA). In NB cells, the expression of sst2 was highly correlated with SS-14-binding sites (R = 0.93). In primary tumors, sst2 was positively related to the expression of the neuroendocrine marker secretogranin II (P < 0.05) and negatively related to N-myc amplification (a poor prognostic factor, P < 0.005) and metastatic dissemination (P < 0.05). In addition, Kaplan-Meier curves indicate that sst2 expression is positively related to survival (P = 0.01). In a patient with stage IVs disease (a spontaneously regressing form), we found the highest sst2 expression (4 x 10(9) molecules/microgram RNA), a value relatively similar to that of normal adrenal. In conclusion, these data indicate that quantitation of sst2, as assessed with competitive RT-PCR, could represent a new prognostic tool in the neuroendocrine tumor NB. Since sst2 recognizes octreotide with high affinity, these findings could also have both diagnostic and therapeutic value.
Sestini
R
R
Clinical Biochemistry, Endocrinology, and Andrology Units, Department of Clinical Physiopathology, University of Florence viale Pieraccini 6, 50139 Florence, Italy.
Orlando
C
C
Peri
A
A
Tricarico
C
C
Pazzagli
M
M
Serio
M
M
Pagani
A
A
Bussolati
G
G
Granchi
S
S
Maggi
M
M
D000328:Adult; D001665:Binding Sites; D015152:Blotting, Northern; D002675:Child, Preschool; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009447:Neuroblastoma / Q000235:genetics* / Q000473:pathology; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D012334:RNA, Neoplasm / Q000032:analysis / Q000235:genetics; D011869:Radioligand Assay; D017481:Receptors, Somatostatin / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013004:Somatostatin / Q000378:metabolism; D016019:Survival Analysis; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D016271:Proto-Oncogene Proteins c-myc; D012334:RNA, Neoplasm; D017481:Receptors, Somatostatin; D013004:Somatostatin; C093733:somatostatin receptor 2