Aging increases ovarian cancer growth, metastasis, and immunosuppression that can be alleviated by inhibiting hedgehog signaling

Background

Despite significant improvements in treatment, ovarian cancer remains one of the most challenging gynaecological malignancies, with overall survival less than 50% in most clinical settings.^1,2. Postmenopausal women have exhibited poorer overall survival across studies.³. It remains unclear whether this is reflective of hormonal decline alone or broader age-associated changes in the tumour microenvironment.

The hedgehog (HH) signalling pathway is best known for its role in embryonic development as well as cancer progression. Aberrant activation of the pathway is linked to prolonged cellular proliferation, immune suppression, and epithelial-to-mesenchymal transition (EMT)⁴. Whether it plays a role in age-associated tumour progression in ovarian cancer is still uncertain.

The authors of this preprint⁵ hence ask a seemingly simple but pertinent question: what is the role of physiological ageing in supporting the tumour microenvironment of ovarian cancer, and does HH signalling contribute to the process or not?

Key findings

To address this question, the authors compared ovarian tumours of different cell origins (epithelial origin and fallopian tube derived) in young and aged mice. Spatial transcriptomics, histological analyses, and immune-cell profiling were performed to characterise the age-associated changes.

Physiological ageing, rather than a menopause-like state, accelerates ovarian cancer progression.

The authors asked whether the tumour burden in older mice was reflective of menopause or broader age-associated changes. First, they compared tumour growth in young and aged mice. They then chemically induced ovarian follicle depletion, creating a menopause-like state without physiological ageing. Tumours growing in aged mice exhibited significantly greater growth, ascites formation and metastatic spread, as opposed to young mice. However, follicle-depleted young mice did not display such an aggressive phenotype. This suggests that ovarian failure attributed to menopause is insufficient to describe the age-associated progression of the cancer. Physiological ageing, on the other hand, appears to establish a tumour-promoting microenvironment.

Ageing promotes an immunosuppressive state.

To understand why aged mice developed more aggressive tumours, spatial transcriptomic, immune profiling via Flow Cytometry and gene set enrichment analysis (GSEA) were conducted. Compared with younger mice, aged ones had increased levels of HH signalling, with the levels of Indian hedgehog (IHH) highly upregulated in CD45+ cells. Aged mice were also enriched for immunosuppressive cell populations, including M2-macrophages (CD206+), tumour-associated macrophages (CD68+) and T regulatory cells (Tregs – CD25+ and FoxP3+) (Figure 1; preprint Figure 3A-H). These findings indicate a cellular and molecular basis for the changed immune landscape favouring tumour growth in aged mice.

Figure 1 Immunofluorescence and immunohistochemistry analysis of immune cells in ovarian cancer tissue from two different lineages – epithelial (ID8Trp^–/^–) and fallopian tube-derived (PPNM). Preprint figure 3A-H, made available under a CC-BY 4.0 International License.

Hedgehog signalling suppresses tumour growth and metastasis.

The authors next evaluated whether inhibiting the HH signalling pathway could reverse the observed age-associated changes. They administered Vismodegib (a HH pathway inhibitor that blocks Smoothened – Smo) in 65-week-old mice. Treated mice exhibited delayed disease progression and reduced metastatic burden overall. Tumour proliferation was also reduced, as indicated by fewer PCNA+ cells. Importantly, the inhibition of HH signalling markedly reduced the abundance of immunosuppressive cells (M2-macrophages and Tregs), while preserving the CD8+ cytotoxic T cells.

Finally, analyses of bulk and single-cell RNA-sequencing datasets from ovarian cancer patients reflected positive correlations between HH pathway activity and an immunosuppressive tumour-microenvironment, suggesting that these findings may be relevant in humans as well.

Conclusions and future directions

Together, this work implies the role of developmental signalling pathways in disease biology, long after embryogenesis. Rather than acting within tumour cells only, HH signalling appears to orchestrate interactions between immune cells and collectively shape the tumour-microenvironment in ageing tumours (Figure 2).

Figure 2 Schematic overview of the proposed mechanism underlying age-associated ovarian cancer progression. Created by the author using Inkscape. Icon (ovary) adapted from Flaticon. Schematic based on findings reported in the referenced bioRxiv preprint⁵.

Although Vismodegib had a substantial impact in aged mice, several questions remain. Since HH signalling impacts tumour cells, stromal fibroblasts and immune cells simultaneously, future studies dissecting the contribution and role of each compartment would be beneficial and add to our understanding of its therapeutic impact.

Finally, it remains to be determined whether the role of HH signalling in an age-dependent context is unique to ovarian cancer or represents a broader feature of solid tumours. Investigating this possibility in patient cohorts with respect to age, gene expression and cancer type could help identify the prognostic biomarkers in elderly patients.

Why I liked this preprint

Having primarily worked on Hedgehog signalling in haematological malignancies such as chronic myeloid and acute lymphoblastic leukaemia, I found it particularly interesting to see the pathway implicated in an entirely different context. Rather than acting within tumour cells alone, this study highlights how HH signalling coordinates immune interactions within the ageing tumour microenvironment. I also appreciated how the authors experimentally separated hormonal decline and physiological ageing.

Questions for the authors

1. As these preclinical observations with Vismodegib in mice are in contrast with the phase II trial⁶ where Vismodegib failed to improve progression-free survival, what do you think is the molecular reason behind the different observed effects?
2. Would combining HH inhibitors with immunotherapy further improve the therapeutic response in aged ovarian cancer models?
3. What do you think is the primary age-associated trigger for HH signalling to promote an immunosuppressive environment, if not follicle depletion?

References

1. Tavares V, Marques IS, Melo IG de, Assis J, Pereira D, Medeiros R. Paradigm Shift: A Comprehensive Review of Ovarian Cancer Management in an Era of Advancements. Int J Mol Sci 2024, Vol 25, Page 1845 [Internet]. 2024 Feb 3 [cited 2026 Jul 13];25(3):1845. Available from: https://www.mdpi.com/1422-0067/25/3/1845/htm

2. Nag S, Aggarwal S, Rauthan A, Warrier N. Maintenance therapy for newly diagnosed epithelial ovarian cancer- a review. J Ovarian Res [Internet]. 2022 Dec 1 [cited 2026 Jul 13];15(1). Available from: https://pubmed.ncbi.nlm.nih.gov/35902911/

3. Trifanescu OG, Gales LN, Trifanescu RA, Anghel RM. CLINICAL PROGNOSTIC FACTORS IN PRE- AND POST-MENOPAUSAL WOMEN WITH OVARIAN CARCINOMA. Acta Endocrinol [Internet]. 2018 Jul 1 [cited 2026 Jul 13];14(3):353. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6525767/

4. Berrino C, Omar A. Unravelling the Mysteries of the Sonic Hedgehog Pathway in Cancer Stem Cells: Activity, Crosstalk and Regulation. Curr Issues Mol Biol [Internet]. 2024 Jun 1 [cited 2026 Jul 13];46(6):5397. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11202538/

5. Kumari A, Elbahoty MH, Rajkarnikar R, Sureja K, Nayyar MV, Monavarian M, et al. Aging increases ovarian cancer growth, metastasis, and immunosuppression that can be alleviated by inhibiting hedgehog signaling. bioRxiv [Internet]. 2026 Jul 1 [cited 2026 Jul 14];2025.12.23.695206. Available from: https://www.biorxiv.org/content/10.64898/2025.12.23.695206v2

6. Kaye SB, Fehrenbacher L, Holloway R, Amit A, Karlan B, Slomovitz B, et al. A phase II, randomized, placebo-controlled study of vismodegib as maintenance therapy in patients with ovarian cancer in second or third complete remission. Clin Cancer Res [Internet]. 2012 Dec 1 [cited 2026 Jul 14];18(23):6509–18. Available from: https://pubmed.ncbi.nlm.nih.gov/23032746/

 

 

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