Related Experiment Video
Updated: May 14, 2026
A Practical Guide for the Production and PET/CT Imaging of 68Ga-DOTATATE for Neuroendocrine Tumors in Daily Clinical Practice
Published on: April 17, 2019
Impact of Neuroendocrine Neoplasm-Specific Systemic Treatments on Somatostatin Receptors Expression and Function in
Christof Däubler1, Clara Böttcher1, Laura-Sophie Landwehr2
1Department of Internal Medicine II, Gastroenterology, University Hospital Würzburg, 97080 Würzburg, Germany.
Abstract:
Background: Somatostatin receptors (SSTRs) are pivotal diagnostic and therapeutic targets in well-differentiated neuroendocrine neoplasms (NENs). SSTR-directed treatment strategies rely on sufficient SSTR2 expression. Thus, receptor loss during dedifferentiation limits therapeutic efficacy. Preclinical data suggest pharmacologic modulation of SSTRs' expression. However, there are no robust data on the effect of NEN-specific systemic treatments on SSTRs' expression and function. Methods: We systematically evaluated the effects of six systemic agents commonly used in NEN therapy-isplatin, etoposide, 5-fluorouracil (5-FU), streptozotocin (STZ), temozolomide (TMZ), and everolimus-on SSTR2 and SSTR5 expression, as well as on uptake of 68Ga-DOTATOC, in BON-1 and QGP-1 cells, as well as the MS-18 cell line. Analyses included qRT-PCR, Western blotting, immunohistochemistry, and radiopeptide uptake assays. Results: Systemic agents modulated SSTR expression and radioligand uptake in a drug- and cell line-dependent manner. Etoposide consistently upregulated SSTR2 expression and significantly increased radioligand uptake across all three cell lines. TMZ enhanced SSTR2 expression and uptake in BON-1 cells, but reduced uptake in QGP-1 and MS-18 cells. In contrast, 5-FU, STZ, cisplatin, and everolimus showed heterogeneous, compound- and cell line-specific effects on SSTR2 expression and 68Ga-DOTATOC uptake, including both up- and downregulation depending on the model. Conclusions: All agents under investigation affect SSTR expression in vitro, while etoposide is identified as the most consistent enhancer of SSTR2's expression and function across cellular NEN models. Our findings highlight both the potential and the risks of systemic therapy-induced receptor modulation and therefore support further investigation of treatment sequencing strategies to optimize SSTR-targeted approaches. However, further studies are required to translate these observations to a clinical setting.
Insights
Systemic treatments for neuroendocrine neoplasms (NENs) can alter somatostatin receptors (SSTRs). Etoposide consistently enhances SSTR2 expression and function, suggesting potential for optimizing SSTR-targeted therapies.
Area of Science:
- Oncology
- Molecular Biology
- Radiopharmacology
Background:
- Somatostatin receptors (SSTRs), particularly SSTR2, are crucial targets for diagnosing and treating neuroendocrine neoplasms (NENs).
- Loss of SSTR expression during tumor dedifferentiation can limit the effectiveness of SSTR-targeted therapies.
- The impact of NEN-specific systemic treatments on SSTR expression and function remains largely uncharacterized.
Purpose of the Study:
- To systematically evaluate the in vitro effects of six common NEN systemic agents on SSTR2 and SSTR5 expression and function.
- To assess the impact of these agents on the uptake of the radioligand 68Ga-DOTATOC in NEN cell lines.
Main Methods:
- Six systemic agents (cisplatin, etoposide, 5-FU, STZ, TMZ, everolimus) were tested on BON-1, QGP-1, and MS-18 NEN cell lines.
- SSTR2 and SSTR5 expression was analyzed using qRT-PCR, Western blotting, and immunohistochemistry.
- Radioligand uptake assays were performed to measure 68Ga-DOTATOC binding.
Main Results:
- All tested systemic agents modulated SSTR expression and radioligand uptake in a drug- and cell line-dependent manner.
- Etoposide consistently upregulated SSTR2 expression and significantly increased 68Ga-DOTATOC uptake across all tested cell lines.
- Other agents like TMZ, 5-FU, STZ, cisplatin, and everolimus demonstrated heterogeneous effects, with both up- and downregulation observed.
Conclusions:
- Systemic NEN therapies can significantly alter SSTR expression and function in vitro.
- Etoposide emerges as a consistent enhancer of SSTR2 expression and function in NEN cellular models.
- Findings underscore the need for careful consideration of treatment sequencing to optimize SSTR-targeted strategies and warrant further clinical investigation.