Substance P and its receptor NK-1R were found overexpressed in all 43 human craniopharyngioma samples compared to normal pituitary tissue, suggesting NK-1R antagonist drugs could be a new treatment approach for these tumors.
100% of tumors overexpressed SPSubstance P was overexpressed in all 43 craniopharyngioma samples compared to healthy pituitary tissue, the first time this has been demonstrated in this rare brain tumor.
What the researchers found
Substance P and NK-1R were overexpressed in all 43 human adamantinomatous craniopharyngioma (ACP) samples compared to healthy pituitary gland tissue. This is reported for the first time in this tumor type.
Substance P expression was widespread throughout the tumor and preferentially localized in the nucleus rather than the cytoplasm of tumor cells. Areas of glial reaction and endothelial cells also expressed SP, primarily in cell nuclei.
NK-1R was expressed mainly in the glial reaction zone, particularly in the nuclei and membranes of inflammatory cells, and in endothelial cells and fibroblasts of tumor blood vessels. Notably, tumor cells themselves did not show significant NK-1R expression, suggesting the peptide-receptor signaling operates primarily through the tumor microenvironment rather than directly on tumor cells.
Why it matters
Craniopharyngiomas are difficult to treat — surgery and radiation near the optic nerves and hypothalamus frequently cause devastating side effects including vision loss and hormonal dysfunction. NK-1R antagonist drugs already exist and have been tested in preclinical cancer trials. Finding that SP/NK-1R are overexpressed in these tumors opens the possibility of a less invasive, drug-based treatment approach that could spare patients from the severe sequelae of current therapies.
How the study worked
The researchers used immunohistochemistry to examine the expression and distribution of Substance P and NK-1R in 43 human adamantinomatous craniopharyngioma tissue samples, comparing them to healthy pituitary gland samples. They analyzed the cellular localization (nucleus, cytoplasm, membrane) across different cell types within the tumor microenvironment.
What this study cannot tell us
This is an observational immunohistochemistry study showing expression patterns, not a functional study demonstrating that blocking SP/NK-1R would actually slow tumor growth. The sample size of 43 tumors is reasonable for a rare tumor but still limited. The study does not include quantitative expression data or survival correlations. The healthy pituitary comparison may not perfectly match the developmental origin of craniopharyngiomas. No NK-1R antagonist treatment was tested.
How to read the evidence
This is an observational tissue study using immunohistochemistry on human tumor samples. While it provides novel descriptive evidence about SP/NK-1R expression in a rare tumor type, it does not demonstrate functional significance or therapeutic efficacy.
When this study was published
Published in late 2024, this is the first study to characterize SP/NK-1R expression in craniopharyngiomas, opening a new line of investigation.
The bigger picture
The Substance P/NK-1R system has been implicated in multiple cancer types, and NK-1R antagonists like aprepitant (originally developed as an anti-nausea drug) have shown anticancer potential in preclinical studies. This discovery extends that research to craniopharyngiomas, a rare tumor with few treatment options. The finding that NK-1R is expressed mainly in the tumor microenvironment rather than tumor cells themselves provides important mechanistic insight for designing targeted therapies.
Questions still open
- Would NK-1R antagonist drugs like aprepitant show antitumor activity against craniopharyngiomas in preclinical models?
- Why is NK-1R expressed mainly in the tumor microenvironment rather than tumor cells, and what does this mean for drug targeting?
- Could SP/NK-1R expression levels serve as biomarkers for tumor aggressiveness or treatment response in craniopharyngiomas?
Common questions
What is Substance P and why is it important in cancer?
What is a craniopharyngioma and why is it hard to treat?
Read the original research
Substance P and Neurokinin-1 receptor are overexpressed in adamantinomatous craniopharyngioma than in the pituitary gland.
Pituitary, 28(1), 5
Citation
Alcaide, Carlos; Perez, Francisco; Esteban, Francisco; Muñoz, Miguel. (2024). Substance P and Neurokinin-1 receptor are overexpressed in adamantinomatous craniopharyngioma than in the pituitary gland.. Pituitary, 28(1), 5. https://doi.org/10.1007/s11102-024-01490-0