Scientists Engineer Shear-Resistant Prostate Cancer Cells and Uncover a Survival Gene

When cancer cells leave a tumor and enter the bloodstream, they face one of the most hostile environments the body can offer. Blood surging through arteries and around heart valves generates fluid shear stress that can tear cells apart, and fewer than one in ten thousand circulating tumor cells survives the journey. Yet those that do survive are the seeds of metastasis, the process that drives most prostate cancer deaths. A new study published in Advanced Science has now done something no previous research team has managed: it created stable lines of prostate cancer cells that have been repeatedly hammered by blood-vessel-level forces over months of continuous culture, and used them to identify a gene that helps tumor cells endure these brutal mechanical conditions.

The research team, working at Rice University with collaborators at Vanderbilt University Medical Center, exposed two well-known prostate cancer cell lines to repeated pulses of high-intensity fluid shear stress reaching 3950 dyn/cm2, a level far beyond anything previously tested in sustained experiments. For context, venous blood flow typically imposes forces of roughly 0.5 to 4 dyn/cm2, arterial flow ranges from 4 to 30 dyn/cm2, and turbulent regions near arterial bifurcations or inside the heart can briefly generate pulses on the order of 1000 dyn/cm2. The researchers used a syringe pump to perfuse cells through a fine 30-gauge needle at high speed, producing a brief pulse lasting just over a millisecond, with each pulse delivered two minutes apart. Over four to five months, the cells endured approximately sixty of these treatments, with the number of pulses per session gradually increased.

The two cell lines told strikingly different stories. LNCaP cells, originally derived from a lymph node metastasis, showed limited innate resistance and could only tolerate up to ten shear pulses per treatment. PC3 cells, which came from a bone metastasis and therefore plausibly experienced circulatory forces in the patient from whom they were isolated, proved innately tough, maintaining viability above eighty percent even after twenty pulses. By repeatedly selecting the survivors, the team generated what they call mechanoresistant, or MR, populations. After ten pulses, the mechanoresistant LNCaP cells retained nearly seventy percent viability, while unmodified parental cells dropped to under thirty-eight percent. The PC3 cells, already robust, showed that innate resistance alone does not capture the full picture of how metastatic cells adapt.

Under the microscope, the mechanoresistant PC3 cells revealed a fascinating physical transformation. They became significantly smaller, less granular, and less spread out when attached to a surface, adopting features consistent with an amoeboid morphology, a rounded, highly deformable state that has been linked to enhanced metastatic capacity in several cancer types. Analysis of epithelial and mesenchymal markers showed that these cells occupied a hybrid state, expressing both E-cadherin and vimentin, rather than committing fully to either program. This plasticity may be exactly what allows circulating tumor cells to survive the mechanical gauntlet of the bloodstream and then squeeze back out of vessels to seed new tumors, a process during which many cells are known to undergo partial transitions between epithelial and mesenchymal states.

The cell cycle findings were equally unexpected. Previous studies had generally shown that fluid shear stress drives tumor cells into cell cycle arrest and promotes stress-induced death. Here, the mechanoresistant cells did the opposite. Twenty-four hours after shear exposure, the PC3 mechanoresistant cells showed a significantly elevated fraction of cells in S phase, the DNA replication stage, and a corresponding reduction in the G1 phase, indicating accelerated progression through the cycle rather than arrest. Both mechanoresistant lines also displayed elevated expression of Piezo1, a calcium-permeable mechanosensitive ion channel that has previously been implicated in prostate cancer progression, migration, and proliferation. The researchers found that Piezo1 levels correlated positively with proliferative activity, suggesting a mechanistic link between mechanical sensing and the growth behavior of these adapted cells.

Bulk RNA sequencing, performed after roughly sixty shear treatments, confirmed that the mechanoresistant cells had acquired genuinely distinct molecular identities, clustering separately from both parental cells and higher-passage controls designed to rule out artifacts of long-term culture. Among the significantly upregulated genes in the PC3 mechanoresistant cells, one stood out: CALB2, which encodes the calcium-binding protein calretinin. Calretinin buffers intracellular calcium levels, placing it in a prime position to modulate signaling downstream of mechanosensitive channels like Piezo1. Quantitative PCR and Western blotting confirmed the elevated mRNA and protein expression, and the finding carried particular weight because calretinin had never before been examined in the context of fluid shear stress in any cancer.

To probe calretinin’s role in human disease, the team measured the protein in prostate tissue microarrays. Calretinin expression was highest in adenocarcinoma and metastatic samples compared with normal adjacent tissue and samples from patients with hyperplasia or prostatitis, and in paired comparisons, four of six patients showed elevated calretinin in tumor tissue relative to their healthy neighbors. Mining large clinical datasets, including the TCGA prostate adenocarcinoma cohort, revealed that high CALB2 expression correlated with reduced overall survival, although the association did not reach statistical significance in that particular analysis. Intriguingly, CALB2-high outlier tumors appeared across all Gleason grades, suggesting that calretinin elevation may reflect a patient-specific transcriptional state rather than a simple marker of tumor aggressiveness. The team also found that CALB2 expression correlated with DGK1, a lipid signaling gene, and with EPB41L3, a tumor suppressor, hinting at a broader co-expression network tied to membrane and cytoskeletal biology.

The decisive experiment came with genetic deletion. Using lentiviral CRISPR constructs, the researchers knocked out CALB2 in their PC3 lines and re-exposed the cells to twenty shear pulses. The result was dramatic and highly specific: while parental and mechanonaive knockout cells barely noticed the treatment, the mechanoresistant cells lost their hard-won protection, with viability plummeting to roughly thirty-six percent after twenty pulses. The knockout cells also showed reduced proliferative activity, with a larger fraction displaying low Ki67 expression. Because parental cells never depended on CALB2 for shear survival, the gene appears to be a genuine acquired mechanoresistance factor, a molecular prop that the adapted cells came to rely upon. This makes CALB2 the first gene to be functionally validated as a mediator of resistance to high-intensity fluid shear stress through repeated exposure experiments.

In vivo work reinforced the picture. In a pilot subcutaneous study, mechanoresistant cells produced higher tumor burden than parental controls, showing that their adapted traits persisted outside the dish. The team then performed an orthotopic model, surgically implanting luciferase-labeled PC3 cells into the prostate of immunodeficient mice and tracking tumor growth by bioluminescence for twelve weeks. Mechanoresistant tumors grew slightly faster during the first nine weeks, and calretinin levels in the resected tumors were highest in the mechanoresistant group, mirroring the in vitro findings, though the magnitude of the difference was more modest, likely reflecting the complexity of the tumor microenvironment. Few metastases were detected in any group, a limitation the authors attribute to the Matrigel used for engraftment and the severe immunodeficiency of the mouse strain.

The implications reach beyond prostate cancer. Circulating tumor cell survival remains the least studied stage of metastasis, partly because these cells spend an estimated twenty-five to thirty minutes in the bloodstream and are extraordinarily difficult to capture and study. By building the first stable mechanoresistant cancer cell lines, the researchers have created a durable experimental platform for dissecting how tumor cells withstand hemodynamic forces, a question that touches on cytoskeletal remodeling, membrane repair, calcium signaling, and ion channel biology all at once. Calretinin itself lacks well-defined drug-binding pockets, so direct pharmacological targeting may be difficult, and compensatory calcium buffers such as calmodulin could blunt any single-gene strategy. But the discovery that a calcium-buffering protein underpins mechanical survival opens a concrete therapeutic avenue: combining mechanosensitive channel inhibitors, such as the Piezo1 blocker GsMTx4, with existing apoptosis-triggering agents like TRAIL could exploit the very adaptations that make metastatic cells lethal. For the roughly seventy percent drop in five-year survival that accompanies distant prostate cancer metastasis, understanding and disrupting this mechanical armor may prove to be a critical step forward.

Subject of Research: Mechanoresistance and the role of CALB2 in metastatic prostate cancer cell survival under fluid shear stress

Article Title: CALB2 is a Mechanoresistance Gene in Metastatic Prostate Cancer

Article References: Fabiano, A. R., Luo, A. C., Taufalele, P., Dombroski, J. A., Aalaei, E., Rowland, S. J., Cantú, M. S., Carter, A. T., Knoblauch, S. V., Reinhart‐King, C. A., & King, M. R. (2026). CALB2 is a Mechanoresistance Gene in Metastatic Prostate Cancer. Advanced Science, 13(55), Article e76535. https://doi.org/10.1002/advs.76535

Image Credits: AI Generated

DOI: 10.1002/advs.76535

Keywords: prostate cancer, metastasis, circulating tumor cells, fluid shear stress, CALB2, calretinin, mechanotransduction, Piezo1, CRISPR knockout, RNA sequencing, orthotopic mouse model, Advanced Science