SMOC1 as a Radioligand Therapy Target
SMOC1, SPARC related modular calcium binding 1, is a cell-surface protein (GPCR). In Human Protein Atlas immunohistochemistry, SMOC1 staining is highest in head and neck cancer (25% of samples positive), neuroendocrine tumors (25% of samples positive) and bladder cancer (18% of samples positive). Published literature reports that SMOC1 internalizes after ligand binding, which helps retain a radionuclide inside tumor cells. Clinical status: Discovery-stage (no clinical drug program).
Is SMOC1 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: Low IHC staining in head and neck cancer, 25% 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.
SMOC1 expression in cancer
Protein expression of SMOC1 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 |
|---|---|---|---|
| Head and Neck Cancer | 0.17 | Low | 25% |
| Neuroendocrine Tumors | 0.17 | Low | 25% |
| Bladder Cancer | 0.06 | Low | 18% |
| Cervical Cancer | 0.06 | Low | 18% |
| Melanoma | 0.06 | Low | 9% |
| Lung Cancer | 0.06 | Low | 17% |
| Skin Cancer | 0.03 | Low | 9% |
| Pancreatic Cancer | 0.03 | Low | 9% |
| Ovarian Cancer | 0.03 | Low | 8% |
| Gastric Cancer | 0.03 | Low | 8% |
| Glioma | 0.03 | Low | 8% |
Not detected by IHC in: colorectal cancer, lymphoma, breast cancer, kidney cancer, thyroid cancer, prostate cancer, testicular cancer, endometrial cancer, liver cancer.
Is SMOC1 internalized?
Yes. In high-calcium-treated AVICs, SMOC1 lost its ability to bind to BMPR-II, but not to caveolin-1, promoting p-p38 and cell apoptosis due to increased expression of BMPR-II and enhanced endocytosis.
Sources: PMID 33757126. AI-extracted from abstracts, so verify before citing.
SMOC1 clinical trials
Discovery-stage (no clinical drug program). Nuclens hasn't indexed trials for SMOC1 yet. Search ClinicalTrials.gov for SMOC1 trials.
SMOC1 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 SMOC1 in the Human Protein Atlas tissue atlas, and read how normal-tissue expression predicts radioligand dosimetry risk.
SMOC1 gene essentiality (DepMap)
CRISPR knockout effect across 1252 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 head and neck cancer radioligand targets
EGFR · c-MET (MET) · HER3 (ERBB3) · ITGAV · SSTR2 · B7-H3 (CD276) · STEAP2 · Mesothelin (MSLN)
See all radioligand therapy targets in head and neck cancer.
See how SMOC1 ranks against 15,000 targets for your indication.
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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.