Uterine fibroids may be the most familiar enemy most people have never heard of. These benign tumors of the muscular wall of the uterus develop in the vast majority of women at some point during their reproductive years, driving abnormal bleeding, debilitating pelvic pain, and infertility, and sending enormous numbers of patients into operating rooms for hysterectomies. Yet for all their ubiquity, fibroids have guarded their deepest molecular secrets, and medicine still has no drug that can cure them. That picture may now be changing. In a study published in the journal Molecular Genetics and Genomics, a team at the University of São Paulo’s Faculty of Medicine has untangled an intricate web of genetic signals, epigenetic silencing, and regulatory microRNAs that appears to sit at the heart of how fibroids form, grow, and persist — and, in doing so, has surfaced a concrete list of molecular candidates that future therapies could one day attack.
The clinical stakes are difficult to overstate. Uterine leiomyomas, the medical term for fibroids, are the most common benign gynecological tumors affecting women of reproductive age, and their signature symptoms include abnormal uterine bleeding, dysmenorrhea, and chronic pelvic pain. The condition is closely associated with recurrent abortion and infertility, and it measurably reduces patients’ quality of life while generating significant psychosocial stress. Treatment today remains stubbornly surgical. Hysterectomy is still the most frequently performed procedure, with laparoscopic and robot-assisted variants offering fewer complications and shorter recoveries but the same definitive, fertility-ending outcome. In Brazil, where the new study’s tissue samples were collected, fibroids rank as the second leading indication for gynecological surgery, imposing a substantial economic burden on the public healthcare system. Researchers have chased the tumors’ molecular roots for years, implicating mutations in genes such as MED12 and HMGA2, the growth-promoting actions of estrogen and progesterone, and a cast of growth factors that includes VEGF, EGF, PDGF, IGF, and members of the TGF family. Two biological hallmarks define the disease: runaway smooth muscle proliferation and excessive deposition of extracellular matrix. Even so, the authors emphasize, no curative or specifically effective clinical treatment exists.
To pry open that black box, the São Paulo team assembled one of the most comprehensive molecular portraits of fibroid tissue to date. The researchers collected 100 samples — 80 uterine leiomyomas and 20 specimens of normal myometrium, the healthy muscular tissue of the uterine wall — from patients undergoing hysterectomy or myomectomy at the university’s gynecology department between March and October 2012. Each tissue specimen was divided into matched segments, one frozen in liquid nitrogen for RNA work and the other fixed in formalin and paraffin-embedded for archival analysis. Using TaqMan real-time PCR on an OpenArray platform, the team measured the expression of 106 genes related directly or indirectly to the Sonic Hedgehog and Wnt signaling pathways, master regulatory cascades previously implicated in uterine mesenchymal tumors. In parallel, the researchers profiled 84 microRNAs with quantitative PCR arrays and used methylation-specific restriction-enzyme assays to quantify chemical modifications at the promoter regions of nine pivotal genes: SHH, PTCH1, SMO, SUFU, GLI1, GLI3, BMP4, GREM1, and WNT1. Statistical tools, including stepwise linear regression and correlation tests anchored in the miRTarBase database, then stitched the layers together into a single regulatory map.
The choice of the SHH pathway as the investigation’s centerpiece reflects years of accumulating evidence. Sonic Hedgehog signaling is one of biology’s most ancient control systems, orchestrating tissue differentiation and maintenance during embryonic development and, in adult tissue, governing cell proliferation, apoptosis, cell-cycle control, angiogenesis, and adhesion. In its canonical form the pathway operates as a lock-and-key mechanism: SHH ligand proteins bind to a receptor called PTCH1 on the cell surface, releasing the brake that PTCH1 imposes on a second protein, SMO. Activated SMO then permits GLI transcription factors — the pathway’s molecular messengers — to translocate into the nucleus and switch on target genes. The pathway can also be hijacked through non-canonical routes, in which SMO or GLI proteins become activated independently of any ligand, and it can be silenced when the guardian protein SUFU, or phosphorylation of GLI proteins by the enzyme GSK3B, traps the messengers in the cytoplasm and blocks transcriptional activation. The team’s own earlier work had already found SMO and GLI1 proteins overproduced in fibroid tissue compared with normal myometrium, while the Hedgehog ligand itself showed no significant difference — an early hint that fibroids might be running this program without their usual trigger.
The new data confirmed and sharpened that suspicion. Differential expression analysis identified 23 significantly dysregulated genes in fibroids relative to normal tissue, with 13 ramped up and 10 dialed down. The upregulated set reads like a proliferation toolkit: SMO, the engine of the Hedgehog cascade; CCND1, which encodes cyclin D1, a protein that drives cells through the cell cycle; BMP7; three Frizzled receptors, FZD2, FZD3, and FZD5; PTCHD1; SFRP4; the glucose transporter gene SLC2A1; the Wnt effector TCF7; the Wnt modulators WIF1 and WNT16; and the prolactin gene PRL. Multivariate regression analysis of the interactions among SHH pathway genes then delivered the study’s most provocative conclusion: activation of the pathway in fibroids appears to occur independently of SHH–PTCH1 binding, the canonical trigger. Instead, the statistical architecture of the data pointed toward a ligand-independent circuit involving GLI1, CCND1, and BCL-2 — a combination that pairs the pathway’s transcriptional engine with a cell-cycle driver and a notoriously anti-apoptotic protein that keeps abnormal cells alive. Fibroids, in other words, may be switching on their Hedgehog program from the inside, without the external signal that developmental biology normally requires, a configuration with clear implications for where drugs should aim.
Layered on top of this transcriptional activity, the researchers found evidence that the tumor’s DNA was being chemically rewritten. DNA methylation — the attachment of methyl groups to specific positions in gene promoter regions — is a classic epigenetic mechanism capable of modulating gene expression without altering the underlying DNA sequence. Using Methyl-Profiler assays, in which methylation-sensitive and methylation-dependent restriction enzymes digest unmethylated and methylated DNA respectively before the surviving fraction is quantified by real-time PCR, the team compared methylation levels in 21 fibroid and 21 matched normal samples. The analysis revealed significant methylation alterations in six genes: PTCH1, SMO, GLI1, GLI3, GREM1, and WNT1. The pattern is mechanistically suggestive. Because PTCH1 acts as the pathway’s natural brake, methylation-driven changes at its promoter could help release that brake; parallel changes at SMO and GLI1 could amplify the downstream signal; GLI3, which often antagonizes its activating sibling GLI1, adds another potential layer of sabotage; and alterations at WNT1 and GREM1 tie the epigenetic story directly to Wnt signaling and to BMP-antagonizing GREM1. Aberrant methylation patterns have been implicated before in fibroid biology, affecting cell proliferation, differentiation, and extracellular matrix remodeling, but mapping them across the Hedgehog machinery at this resolution is new.
The third regulatory layer came from the microRNAs. These short RNA fragments, roughly 22 nucleotides long, do not encode proteins; instead they bind to messenger RNAs and either mark them for degradation or block their translation, acting as a vast post-transcriptional volume-control system. Profiling 84 cancer-associated microRNAs in 25 fibroid and 12 normal myometrium samples with quantitative PCR arrays, the researchers found 16 microRNAs that were differentially expressed between tumor and healthy tissue. Critically, eight of those 16 showed statistically significant correlations with predicted target genes identified through the miRTarBase database, meaning their abundance rose or fell in mirror image with the activity of genes they are believed to regulate. That correlation pattern suggests microRNAs are not passive bystanders in fibroid development but active participants, potentially clamping down on tumor suppressors or easing restraints on growth genes. Together with the methylation data, the findings sketch a tumor that is being regulated at every level simultaneously: its signaling genes are transcriptionally dysregulated, their promoters are epigenetically modified, and their messenger RNAs are patrolled by an altered microRNA contingent — a triple-lock configuration that may help explain why fibroids are so persistent and so difficult to treat pharmacologically.
Equally striking was how deeply the Wnt pathway was entangled in the picture. The Wnt/β-catenin cascade, a parallel signaling system with its own storied reputation in developmental biology and cancer, has previously been documented to be overexpressed in leiomyoma cells and associated with their formation and proliferation. In the new dataset, multiple Frizzled receptors — the cell-surface antennae that receive Wnt signals — were among the upregulated genes, alongside the Wnt-family ligand gene WNT16 and the effector TCF7. Intriguingly, the Wnt antagonists WIF1 and SFRP4 were also elevated, a seemingly paradoxical pattern that the researchers interpret as evidence of the pathway’s complex, self-correcting feedback loops rather than simple overactivation. Cross-talk between Hedgehog and Wnt signaling is well documented in developmental contexts, but seeing both cascades, their inhibitors, and their epigenetic and microRNA regulators light up together in fibroid tissue gives that cross-talk its most concrete footing yet in this disease. It also dovetails neatly with the tumor’s defining features: the uncontrolled proliferation of uterine smooth muscle cells and the excessive accumulation of extracellular matrix that stiffens and enlarges the fibroid mass, and with the known influence of estrogen and progesterone, which promote fibroid growth by deregulating precisely the pathways governing proliferation, apoptosis, and differentiation.
For patients, the practical promise lies in the target list the study delivers. Drugs that inhibit SMO already exist and are approved for certain cancers, but the new evidence that fibroids activate Hedgehog signaling without needing the SHH ligand suggests that ligand-blocking strategies may miss the mark, and that downstream nodes such as GLI1 — or the pathway’s partners CCND1 and BCL-2 — could prove more rational points of attack. The methylated promoters and the eight correlated microRNAs offer a second kind of quarry: candidate biomarkers that could eventually allow clinicians to distinguish aggressive fibroids from indolent ones, predict how tumors will respond to treatment, or identify molecular fingerprints before surgery becomes necessary. The authors are careful to frame these as leads for future functional studies rather than ready-made therapies; correlations, however intricate, must still be confirmed by experiment. But after decades in which fibroids were treated largely as a hormonal problem with a surgical solution, the São Paulo team has mapped a regulatory network of signaling cross-talk, epigenetic marks, and RNA guardians rich enough to redraw the field’s search image. The most common tumor most people have never heard of is finally giving up its secrets.
Subject of Research: Uterine leiomyomas (uterine fibroids) — SHH and Wnt signaling pathway dysregulation, DNA methylation, and microRNA-mediated regulation
Subject of Research: Biology
Article Title: Molecular insights into uterine fibroids: crosstalk between SHH and Wnt pathways, DNA methylation, and miRNAs regulation
Article References: Purcino, G. M. D., Ferreira, K. P., Bozzini, N., Baracat, E. C., & Carvalho, K. C. (2026). Molecular insights into uterine fibroids: crosstalk between SHH and Wnt pathways, DNA methylation, and miRNAs regulation. Molecular Genetics and Genomics, 301(1), Article 180. https://doi.org/10.1007/s00438-026-02491-3
Image Credits: AI Generated
DOI: 10.1007/s00438-026-02491-3
Keywords: uterine fibroids, uterine leiomyoma, Sonic Hedgehog (SHH) pathway, Wnt signaling, DNA methylation, microRNA, epigenetics, GLI1, biomarkers
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Juliet Wilcox. (August 30, 2026). How SHH-Wnt crosstalk, DNA methylation, and miRNAs drive uterine fibroids. Scienmag. https://scienmag.com/how-shh-wnt-crosstalk-dna-methylation-and-mirnas-drive-uterine-fibroids/
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