Scientists Uncover Molecular Switch That Helps Prostate Cancer Spread to Bone

When prostate cancer turns lethal, it usually does so through the skeleton. Bone metastasis is one of the leading causes of disease progression and cancer-related death in patients with advanced prostate cancer, and once tumor cells take hold in bone, treatment options shrink dramatically. Now, a team of researchers in China has mapped a previously hidden molecular circuit that appears to give prostate cancer cells the stability they need to thrive in that hostile environment. Writing in the journal Cellular and Molecular Life Sciences, the group describes how a cascade of chemical modifications, acting like a series of molecular switches, keeps a key protein alive inside metastatic cells and fuels the cancer’s aggressive behavior.

At the center of the new study is a protein called SPICE1, short for spindle and centriole associated protein 1. SPICE1 has been implicated in tumor biology before, but its role in prostate cancer metastasis and, crucially, the way its abundance is controlled inside cells remained largely unknown. The researchers began by measuring SPICE1 levels in prostate cancer tissues and in bone metastatic lesions taken from patients. The results were striking: SPICE1 was markedly upregulated in prostate cancer tissue compared with normal tissue, and it was increased even further in lesions that had spread to bone. When the team analyzed clinicopathological data, they found that high SPICE1 expression was associated with aggressive disease features and poor prognosis, marking the protein as a potential red flag for the most dangerous forms of the illness.

To determine whether SPICE1 was merely a bystander or an active driver of metastasis, the researchers turned to laboratory experiments using two prostate cancer cell lines, PC3 and C42B. When they silenced SPICE1, the cells lost much of their malignant vigor. Proliferation slowed, migration and invasion were suppressed, and the cells were less able to undergo epithelial–mesenchymal transition, or EMT, the process by which cancer cells shed their rigid epithelial identity and become mobile, invasive, and resistant to therapy. These in vitro findings suggested that SPICE1 is not just correlated with aggressive disease but functionally required for it.

The team then moved from the dish to living systems, using two complementary animal models: subcutaneous xenografts, in which tumor cells are implanted under the skin, and an intra-arterial bone metastasis model that more faithfully reproduces how prostate cancer cells travel through the bloodstream and colonize bone. In both settings, silencing SPICE1 attenuated tumor growth and reduced bone metastasis. Together with the tissue data, the experiments establish SPICE1 as a pro-metastatic effector in prostate cancer, a molecule that tumor cells appear to depend on when they are establishing themselves in the skeleton.

Having shown what SPICE1 does, the researchers next asked how cancer cells keep it from being destroyed. Proteins inside cells are constantly being tagged for degradation by ubiquitin, a small molecular marker that condemns them to the cellular waste disposal system. The team used a battery of biochemical techniques, including co-immunoprecipitation, proximity ligation assays, site-directed mutagenesis, cycloheximide chase experiments, and dedicated ubiquitination and SUMOylation assays, to trace the fate of SPICE1. What emerged was an elegant two-step protection mechanism involving two other proteins: AURKA, a well-known cancer-associated enzyme, and TRIM28, a member of a family of proteins that attach SUMO, a tag that can shield proteins from ubiquitin-mediated destruction.

The first step of the mechanism involves phosphorylation, the attachment of a phosphate group to a protein. The researchers found that AURKA directly interacts with SPICE1 and phosphorylates it at a specific location, the amino acid serine 811. This single chemical modification proved to be the key that unlocks the rest of the pathway. Once SPICE1 is phosphorylated at serine 811, it becomes competent to recruit TRIM28, which functions as a SUMO E3 ligase, an enzyme that catalyzes the attachment of SUMO tags to target proteins. TRIM28 then SUMOylates SPICE1 at a second precise location, lysine 838. The SUMO tag at that site antagonizes ubiquitination, preventing SPICE1 from being marked for degradation. In effect, phosphorylation licenses SUMOylation, and SUMOylation stabilizes SPICE1, allowing the protein to accumulate to levels that support metastatic behavior.

The precision of this mechanism is what makes it scientifically compelling. Both modifications occur at defined amino acid positions, and the researchers demonstrated that disrupting either one collapses the protective chain. Without AURKA-mediated phosphorylation, SPICE1 cannot recruit TRIM28 efficiently. Without TRIM28-dependent SUMOylation at lysine 838, ubiquitination proceeds unchecked and SPICE1 is degraded. The team also performed rescue experiments: when they restored AURKA or TRIM28 in cells where SPICE1 had been silenced, the inhibitory effects on cell proliferation, migration, and invasion were partially reversed. This confirms that the AURKA/TRIM28/SPICE1 axis is not a side observation but a central regulatory circuit that drives the malignant phenotype.

Downstream of SPICE1 stabilization, the researchers identified changes that likely explain how the protein promotes cancer progression. Stabilized SPICE1 was accompanied by increased expression of FASN, the enzyme fatty acid synthase, which allows cancer cells to manufacture their own lipids and supports rapid growth. The team also observed activation of PI3K/AKT signaling, one of the most frequently hijacked growth pathways in human cancer, known for promoting cell survival, proliferation, and metabolic reprogramming. The authors note that these downstream changes likely contribute to the malignant phenotype but are secondary to the core AURKA/TRIM28/SPICE1 regulatory axis, which sits at the top of the cascade.

The clinical implications of the work are considerable. Because each node in the pathway is a defined molecular interaction, the axis offers multiple potential points of intervention. AURKA inhibitors already exist and are being evaluated in various cancers, and the new findings suggest that blocking AURKA could destabilize SPICE1 in prostate cancer cells, undermining their ability to survive and spread in bone. Alternatively, disrupting the SPICE1–TRIM28 interaction or the SUMOylation event itself could achieve a similar effect. The strong association between high SPICE1 expression and poor prognosis also raises the possibility that SPICE1 could serve as a biomarker, helping clinicians identify patients whose disease is most likely to metastasize to bone and who might benefit from more aggressive surveillance or targeted therapy.

As with any laboratory study, the path from mechanism to medicine will require further validation, including studies in larger patient cohorts and the development of strategies that can safely target the pathway in humans. The human tissue collection and animal experiments in the study were approved by the relevant ethics committees of the First Affiliated Hospital of Nanchang University, and the work was partially funded by a grant from the National Natural Science Foundation of China. Still, by revealing how phosphorylation, SUMOylation, and ubiquitination converge to keep a single metastasis-promoting protein alive, the study adds an important piece to the puzzle of why prostate cancer so relentlessly seeks out bone, and it hands researchers a detailed molecular map of where the next generation of therapies might strike.

Subject of Research: Post-translational regulation of SPICE1 by AURKA and TRIM28 in prostate cancer bone metastasis

Article Title: AURKA phosphorylation licenses TRIM28-dependent SUMOylation to stabilize SPICE1 in prostate cancer bone metastasis

Article References: Jiang, H., Tong, W., Wang, S., Xiong, X., Yao, G., Yang, F., Xu, Y., Liu, J., Xie, X., & Liu, Z. (2026). AURKA phosphorylation licenses TRIM28-dependent SUMOylation to stabilize SPICE1 in prostate cancer bone metastasis. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06396-7

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06396-7

Keywords: prostate cancer, bone metastasis, SPICE1, AURKA, TRIM28, SUMOylation, phosphorylation, ubiquitination, PI3K/AKT signaling, FASN, EMT, biomarker