Blocking a Calcium Sensor Could Weaken Liver Cancer Cells

Liver cancer remains one of the most formidable challenges in modern oncology, and a new study now points to an unexpected molecular player that could be exploited to fight it. Researchers have found that blocking the calcium-sensing receptor, a protein better known for regulating calcium levels in the body, substantially weakens the malignant behaviour of human hepatocellular carcinoma cells. The work, published in the Journal of Cellular and Molecular Medicine, combines detailed cell culture experiments with animal models to build a case that this receptor may represent a promising therapeutic target in a disease where treatment options remain stubbornly limited.

The calcium-sensing receptor, or CaSR, was first cloned from bovine parathyroid glands and has long been recognised as a central guardian of calcium homeostasis. It sits in the cell membrane and detects even small fluctuations in extracellular calcium, triggering intracellular signalling cascades that keep blood calcium within a narrow, life-sustaining range. Although the liver is not a calciotropic organ, calcium signalling within hepatocytes influences glucose and lipid metabolism, bile secretion, mitochondrial activity, and fundamental cellular processes such as growth, differentiation, movement and programmed cell death. Disturbances in intracellular calcium have even been implicated in the progression of non-alcoholic fatty liver disease towards liver cancer, and CaSR has been linked to cholestasis, ischemia-reperfusion injury, insulin resistance and genetic susceptibility to hepatocellular carcinoma.

What makes CaSR particularly intriguing in cancer biology is its dual personality. In some tumours, including parathyroid and gastrointestinal cancers, the receptor appears to restrain growth and act as a tumour suppressor. In others, such as intrahepatic cholangiocarcinoma, breast cancer, osteosarcoma and Leydig cell tumours, CaSR activation instead promotes proliferation and metastatic behaviour. Genetic polymorphisms in the CaSR gene, particularly at the rs17251221 locus, have been shown to influence susceptibility to hepatocellular carcinoma and treatment outcomes. Yet the precise mechanisms by which the receptor operates in the most common form of primary liver cancer had remained poorly characterised, leaving an important gap in understanding that the new study set out to fill.

The stakes are considerable. Hepatocellular carcinoma accounts for roughly ninety percent of primary liver cancers, and liver cancer overall ranks as the sixth most commonly diagnosed malignancy and the third leading cause of cancer-related death worldwide. Patients diagnosed at an early stage can benefit from surgical resection, but those presenting with intermediate or advanced disease typically rely on chemotherapy or immunotherapy regimens whose clinical benefits remain constrained. Long-term survival is limited for a substantial proportion of patients, and the restricted array of validated therapeutic targets has made the search for new strategies an urgent medical priority.

In the new research, the team first confirmed that CaSR is present in two widely used human hepatocellular carcinoma cell lines, HepG2 and SMMC-7721, using immunofluorescence microscopy, quantitative reverse transcription PCR and Western blotting. Notably, SMMC-7721 cells expressed significantly higher levels of the receptor protein than HepG2 cells. The researchers then pharmacologically inhibited the receptor with NPS-2143, a well-characterised negative allosteric modulator of CaSR, and measured the consequences across a battery of functional assays. The results were striking: NPS-2143 reduced the proliferation of both cell lines in a concentration-dependent manner, with effects becoming particularly pronounced at 48 and 72 hours after treatment. The drug also lowered expression of PCNA, a proliferation marker, alongside reducing CaSR mRNA and protein levels.

Beyond proliferation, the researchers examined whether CaSR blockade could blunt the metastatic machinery of liver cancer cells, a critical question given that metastasis drives recurrence and poor outcomes in hepatocellular carcinoma. Using Transwell migration and invasion assays, they showed that treated cells migrated and invaded far less efficiently than untreated controls. At the molecular level, the expression of MMP-2 and MMP-9, matrix metalloproteinases that remodel the extracellular matrix and enable cells to breach tissue barriers, dropped significantly after NPS-2143 exposure. These findings suggest that CaSR supports the invasive potential of hepatocellular carcinoma cells at least partly by sustaining the production of these matrix-degrading enzymes.

The study also uncovered a pro-death effect. Flow cytometric analysis using Annexin V and propidium iodide staining revealed a marked increase in apoptotic cells after 24 hours of NPS-2143 treatment. Western blotting illuminated the underlying mechanism: the anti-apoptotic protein Bcl-2 was downregulated, while the pro-apoptotic protein Bax and cleaved caspase-3, the executioner enzyme of programmed cell death, were upregulated. This coordinated shift in the balance of apoptotic regulators indicates that blocking CaSR actively pushes liver cancer cells towards self-destruction rather than merely slowing their division.

To trace the signalling pathways responsible, the researchers turned their attention to the mitogen-activated protein kinases, or MAPKs, which govern proliferation, apoptosis, migration and survival in cancer. NPS-2143 treatment increased the phosphorylation of p38 MAPK, a pathway often associated with apoptotic signalling and tumour growth suppression, while simultaneously reducing the phosphorylation of ERK1/2, a cascade frequently hijacked by cancers to drive proliferation and invasion. Total levels of both proteins were unaffected, pointing to a specific change in pathway activation rather than protein abundance. The team then confirmed these results genetically: silencing CaSR with siRNA reproduced every pharmacological effect, curbing growth, migration and invasion while raising apoptotic rates and producing the same p38 and ERK1/2 phosphorylation changes.

Crucially, the anti-tumour effects extended into living animals. In female BALB/c nude mice bearing HepG2 xenografts, intraperitoneal injection of NPS-2143 at 10 micromoles per kilogram every 48 hours for 12 days significantly reduced tumour size and weight compared with vehicle controls, without any measurable loss of body weight. Immunohistochemistry of excised tumours showed reduced CaSR immunoreactivity and a sharp decline in Ki67 staining, indicating diminished cell division. Western blotting of tumour tissue mirrored the in vitro findings, with increased p-p38 and Bax and decreased p-ERK, MMP-9 and Bcl-2. Because NPS-2143 is primarily a functional antagonist rather than a transcriptional inhibitor, the authors interpret the reduced CaSR expression after treatment as a secondary feedback change rather than direct repression of the gene. To address the influence of sex, since hepatocellular carcinoma occurs more frequently in males, an independent experiment using Huh7 cells in male nude mice reproduced the tumour-shrinking effect, strengthening confidence in the result across cell lines and sexes.

The authors are careful to acknowledge the limitations of their work. Two cell lines cannot capture the full molecular diversity of hepatocellular carcinoma, the animal cohorts were modest in size, and immunodeficient mice cannot recapitulate the complex immune microenvironment of human liver cancer. Potential off-target interactions of NPS-2143 also cannot be entirely dismissed, and CRISPR-based knockout experiments would provide firmer genetic validation. Nevertheless, the convergence of pharmacological and genetic evidence, in vitro and in vivo, paints a coherent picture: CaSR supports the proliferation, motility and survival of hepatocellular carcinoma cells through ERK1/2 and p38 MAPK signalling, and its blockade reverses these malignant behaviours. If future studies in immunocompetent models and patient-derived systems confirm these findings, drugs that silence this calcium sensor could open a genuinely new front against one of the world’s deadliest cancers.

Subject of Research: The role of the calcium-sensing receptor in hepatocellular carcinoma progression and its inhibition as a potential therapy

Article Title: Inhibition of Calcium‐Sensing Receptor Suppresses Malignant Behaviours of Human Hepatocellular Carcinoma

Article References: Liu, T., Xu, W., Gao, Q., Ngwa Adeline, N., Yang, Q., He, D., Tao, Y., Sun, J., Gu, J., Shi, H., Aschner, M., Ye, Y., Chen, J., & Lu, R. (2026). Inhibition of Calcium‐Sensing Receptor Suppresses Malignant Behaviours of Human Hepatocellular Carcinoma. Journal of Cellular and Molecular Medicine, 30(19), Article e71389. https://doi.org/10.1111/jcmm.71389

Image Credits: AI Generated

DOI: 10.1111/jcmm.71389

Keywords: calcium-sensing receptor, hepatocellular carcinoma, liver cancer, NPS-2143, MAPK signalling, p38 MAPK, ERK1/2, apoptosis, cell migration, xenograft model, MMP-9, therapeutic target