F2RL1 as a Radioligand Therapy Target
F2RL1, F2R like trypsin receptor 1, is a cell-surface protein (GPCR). In Human Protein Atlas immunohistochemistry, F2RL1 staining is highest in colorectal cancer (100% of samples positive), ovarian cancer (100% of samples positive) and gastric cancer (100% of samples positive). Published literature reports that F2RL1 internalizes after ligand binding, which helps retain a radionuclide inside tumor cells. Clinical status: Discovery-stage (no clinical drug program).
Is F2RL1 a good radioligand therapy target?
Scored against the six criteria that decide whether a protein can become a radioligand therapy:
- ✅ Cell-surface accessibility: Localized to the cell surface, so a radioligand can reach it from circulation.
- ✅ Tumor expression: High IHC staining in colorectal cancer, 100% of samples positive.
- ✅ Internalization: Reported to internalize, which favors radionuclide retention.
- ⚠️ Clinical precedent: Discovery-stage (no clinical drug program)
- ❔ Shedding: Not yet assessed.
- ❔ Normal-tissue dosimetry: Check kidney, liver, bone marrow and salivary expression in the Human Protein Atlas tissue atlas.
F2RL1 expression in cancer
Protein expression of F2RL1 across 20 cancer types from Human Protein Atlas immunohistochemistry. The score is a weighted staining intensity from 0 to 1; "% positive" is the share of patient samples with detectable staining.
| Cancer type | IHC score | Level | % positive |
|---|---|---|---|
| Colorectal Cancer | 0.67 | High | 100% |
| Ovarian Cancer | 0.67 | High | 100% |
| Gastric Cancer | 0.67 | High | 100% |
| Testicular Cancer | 0.67 | High | 100% |
| Liver Cancer | 0.67 | High | 100% |
| Pancreatic Cancer | 0.64 | High | 100% |
| Lung Cancer | 0.61 | High | 100% |
| Endometrial Cancer | 0.61 | High | 100% |
| Thyroid Cancer | 0.58 | High | 100% |
| Neuroendocrine Tumors | 0.56 | High | 100% |
| Prostate Cancer | 0.56 | High | 100% |
| Glioma | 0.56 | High | 92% |
| Melanoma | 0.53 | High | 92% |
| Bladder Cancer | 0.52 | High | 91% |
| Head and Neck Cancer | 0.50 | Medium | 100% |
| Breast Cancer | 0.50 | Medium | 83% |
| Lymphoma | 0.47 | Medium | 83% |
| Kidney Cancer | 0.39 | Medium | 92% |
| Cervical Cancer | 0.36 | Medium | 67% |
| Skin Cancer | 0.22 | Medium | 58% |
Is F2RL1 internalized?
Yes. PAR2 agonists stimulated endocytosis of PAR2 and recruitment of Gαq, Gαi, and β-arrestin to early endosomes of T84 colon carcinoma cells.
Sources: PMID 35110404. AI-extracted from abstracts, so verify before citing.
F2RL1 clinical trials
Discovery-stage (no clinical drug program). Nuclens hasn't indexed trials for F2RL1 yet. Search ClinicalTrials.gov for F2RL1 trials.
F2RL1 normal tissue expression
Normal-tissue expression in dose-limiting organs (kidney, liver, bone marrow, salivary glands) drives radioligand dosimetry risk. Nuclens is re-validating its normal-tissue values, so they are not shown here yet. See F2RL1 in the Human Protein Atlas tissue atlas, and read how normal-tissue expression predicts radioligand dosimetry risk.
F2RL1 gene essentiality (DepMap)
CRISPR knockout effect across 1258 cancer cell lines: 0.06 (not essential). Radioligands kill by radiation, not by blocking the target, so essentiality matters less than for inhibitors. A non-essential target can still be an excellent radioligand target.
Related colorectal cancer radioligand targets
c-MET (MET) · HER3 (ERBB3) · FAP · EGFR · CEA (CEACAM5) · EPCAM · SSTR2 · STEAP2
See all radioligand therapy targets in colorectal cancer.
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Subcellular localization: UniProt via Open Targets (CC BY 4.0 / CC0). Tumor immunohistochemistry: Human Protein Atlas (CC BY-SA 4.0). Clinical trials: ClinicalTrials.gov (public domain). Gene essentiality: DepMap (CC BY 4.0). Internalization and shedding: AI-extracted from PubMed abstracts, so verify against the cited papers before relying on them. Nuclens is a first-pass triage layer, not a substitute for wet-lab validation or clinical dosimetry. Derived expression data on this page is shared under CC BY-SA 4.0.