Quantitation of somatostatin receptor type 2 gene expression in neuroblastoma cell lines and primary tumors using competitive reverse transcription-polymerase chain reaction
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1Clinical Biochemistry, Endocrinology, and Andrology Units, Department of Clinical Physiopathology, University of Florence viale Pieraccini 6, 50139 Florence, Italy.
Abstract:
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.
Insights
Quantifying somatostatin receptor type 2 (sst2) mRNA in neuroblastoma (NB) cells and tumors revealed its strong correlation with patient survival. This suggests sst2 expression is a valuable prognostic marker for NB, potentially aiding diagnosis and therapy.
Area of Science:
- Oncology
- Molecular Biology
- Neuroscience
Background:
- Somatostatin (SS-14)-binding sites are present in human neuroblastoma (NB) cell lines.
- The adrenal gland and related tumors show high expression of somatostatin receptor type 2 (sst2) mRNA.
Purpose of the Study:
- To quantitatively assess the expression of sst2 mRNA in neuroblastoma cell lines and primary tumors.
- To investigate the correlation between sst2 expression and neuroblastoma characteristics, including prognosis.
Main Methods:
- Utilized competitive reverse transcription (RT)-PCR with an insertion mutant competitor for precise sst2 mRNA quantitation.
- Analyzed sst2 expression in 6 NB cell lines and 15 primary NB tumors.
- Correlated sst2 levels with SS-14 binding, neuroendocrine markers, N-myc amplification, metastasis, and patient survival.
Main Results:
- All investigated NB cell lines and tumors expressed sst2 mRNA (range: 9 x 10^5 - 4 x 10^9 molecules/µg RNA).
- NB cell sst2 expression strongly correlated with SS-14 binding (R = 0.93).
- In primary tumors, sst2 expression positively correlated with secretogranin II, and negatively with N-myc amplification and metastasis.
- Higher sst2 expression was significantly associated with improved patient survival (P = 0.01).
- The highest sst2 expression was observed in a stage IVs disease patient, similar to normal adrenal levels.
Conclusions:
- Quantitative assessment of sst2 mRNA using competitive RT-PCR is a potential new prognostic tool for neuroblastoma.
- sst2 expression levels may serve as a valuable indicator for patient survival in neuroblastoma.
- Given sst2's high affinity for octreotide, these findings suggest potential diagnostic and therapeutic applications for neuroblastoma.
