Characterization of FOLR2 Expression on Tumor-Associated Macrophages (TAMs) Across Breast Cancer Molecular Subtypes in Bandung
DOI:
https://doi.org/10.29313/bcsms.v5i3.21657Keywords:
FOLR2, breast cancer, tumor microenvironment, tumor-associated macrophages (TAMs), molecular subtypesAbstract
Abstract. Breast cancer is a heterogeneous disease and a leading cause of death in women worldwide. The tumor microenvironment (TME), which includes tumor-associated macrophages (TAMs), plays a key role in its progression. Folate Receptor 2 (FOLR2) is a marker of M2 macrophages and is associated with pro-tumor activity. Previous studies have shown increased FOLR2 expression on TAMs in various cancers, including breast cancer, which has been linked to poor clinical outcomes. This study aimed to characterize FOLR2 expression on TAMs in breast cancer subtypes and evaluate its potential as a diagnostic and prognostic marker. Immunohistochemistry (IHC) results of FOLR2⁺ TAMs, which are expressed as the immunoreactive score (IRS), were analyzed across three molecular subtypes of breast cancer (TNBC, Luminal, and HER2-enriched). Kruskal–Wallis analysis demonstrated significant differences in FOLR2 expression among the subtypes. The mean ± SD IRS values were TNBC = 3.81 ± 1.16, HER2-enriched = 2.42 ± 1.73, and Luminal = 2.18 ± 1.54. Post hoc Dunn’s test revealed that the difference was statistically significant between TNBC and Luminal subtypes (p < 0.05), whereas no significant difference was observed between TNBC and HER2-enriched, or between Luminal and HER2-enriched subtypes. Fisher’s exact test revealed a statistically significant association between molecular subtype and FOLR2 expression in breast cancer (p-value < 0.05). Spatial analysis further showed that FOLR2 was predominantly expressed in peritumoral areas, particularly around blood vessels and adipose tissue, while its expression in the intratumoral stroma was relatively lower. These findings suggest that FOLR2 expression on TAMs varies among breast cancer molecular subtypes, with TNBC showing the highest levels, and that its spatial distribution within the TME may contribute to tumor progression, therefore highlights the potential of FOLR2 as a diagnostic and prognostic biomarker in breast cancer.
References
1. Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA A Cancer J Clinicians. 2021 May;71(3):209–49.
2. Andinata B, Bachtiar A, Oktamianti P, Partahi JR, Dini MSA. A Comparison of Cancer Incidences Between Dharmais Cancer Hospital and GLOBOCAN 2020: A Descriptive Study of Top 10 Cancer Incidences. Indonesian Journal of Cancer. 2023 Jun 21;17(2):119.
3. Carvalho E, Canberk S, Schmitt F, Vale N. Molecular Subtypes and Mechanisms of Breast Cancer: Precision Medicine Approaches for Targeted Therapies. Cancers. 2025 Mar 25;17(7):1102.
4. Sharma JD, Khanna S, Ramchandani S, Kakoti LM, Baruah A, Mamidala V. Prevalence of Molecular Subtypes of Breast Carcinoma and Its Comparison between Two Different Age Groups: A Retrospective Study from a Tertiary Care Center of Northeast India. South Asian J Cancer. 2021 Dec;10(04):220–4.
5. Anderson NM, Simon MC. The tumor microenvironment. Current Biology. 2020 Aug;30(16):R921–5.
6. Noy R, Pollard JW. Tumor-Associated Macrophages: From Mechanisms to Therapy. Immunity. 2014 Jul;41(1):49–61.
7. Currenti J, Mishra A, Wallace M, George J, Sharma A. Immunosuppressive mechanisms of oncofetal reprogramming in the tumor microenvironment: implications in immunotherapy response. Biochemical Society Transactions. 2023;
8. Qiu SQ, Waaijer SJH, Zwager MC, De Vries EGE, Van Der Vegt B, Schröder CP. Tumor-associated macrophages in breast cancer: Innocent bystander or important player? Cancer Treatment Reviews. 2018 Nov;70:178–89.
9. Miao S, Bian C, Fang J, Wang S, You H, Zhou Y, et al. Integrated analysis reveals prognostic correlation and immune characteristics of a tumor-associated macrophage-based risk signature in triple-negative breast cancer. Transl Cancer Res. 2024 Oct;13(10):5214–32.
10. Jiang D, Xiao R, Bai J, Wang X, Fang Y, Liu J, et al. FOLR2+ macrophages in cancer: allies or enemies. Cell Commun Signal [Internet]. 2025 Jun 2 [cited 2025 Jul 21];23(1). Available from: https://biosignaling.biomedcentral.com/articles/10.1186/s12964-025-02257-1
11. Vyas D, Patel M, Wairkar S. Strategies for active tumor targeting-an update. European Journal of Pharmacology. 2022 Jan;915:174512.
12. Samaniego R, Domínguez-Soto Á, Ratnam M, Matsuyama T, Sánchez-Mateos P, Corbí ÁL, et al. Folate Receptor β (FRβ) Expression in Tissue-Resident and Tumor-Associated Macrophages Associates with and Depends on the Expression of PU.1. Cells. 2020 Jun 10;9(6):1445.
13. Rodriguez Garcia AB, Ramirez Lopez LJ. Aprender haciendo – investigar reflexionando: caso de estudio paralelo en Colombia y Chile. Academia y Virtualidad. 2014 Dec 1;7(2):53.
14. Zhu J, Yong S, Wan L, Qiao J, Yajie Z, Wang Q. A novel 12-gene prognostic signature in breast cancer based on the tumor microenvironment. Annals of Translational Medicine. 2022;10(3):143.
15. Kurahara H, Takao S, Kuwahata T, Nagai T, Ding Q, Maeda K, et al. Clinical Significance of Folate Receptor β–expressing Tumor-associated Macrophages in Pancreatic Cancer. Ann Surg Oncol. 2012 Jul;19(7):2264–71.
16. Xu X, Jiang J, Yao L, Ji B. Silencing the FOLR2 Gene Inhibits Cell Proliferation and Increases Apoptosis in the NCI-H1650 Non-Small Cell Lung Cancer Cell Line via Inhibition of AKT/Mammalian Target of Rapamycin (mTOR)/Ribosomal Protein S6 Kinase 1 (S6K1) Signaling. Med Sci Monit. 2018 Nov 11;24:8064–73.
17. Remmele W, Stegner HE. [Recommendation for uniform definition of an immunoreactive score (IRS) for immunohistochemical estrogen receptor detection (ER-ICA) in breast cancer tissue]. Pathologe. 1987 May;8(3):138–40.
18. Gajaria P, Kadu V, Patil A, Desai S, Shet T. Triple Negative Breast Cancer: Expression of Folate Receptor Alpha in Indian population. Annals of Diagnostic Pathology. 2020 Dec;49:151598.
19. Bottai G, Raschioni C, Székely B, Di Tommaso L, Szász AM, Losurdo A, et al. AXL-associated tumor inflammation as a poor prognostic signature in chemotherapy-treated triple-negative breast cancer patients. npj Breast Cancer. 2016 Nov 2;2(1):16033.
20. Nalio Ramos R, Missolo-Koussou Y, Gerber-Ferder Y, Bromley CP, Bugatti M, Núñez NG, et al. Tissue-resident FOLR2+ macrophages associate with CD8+ T cell infiltration in human breast cancer. Cell. 2022 Mar;185(7):1189-1207.e25.
21. Zhang F, Al-Amin MY, Utturkar S, Jiang R, Cresswell G, Alfar R, et al. Folate receptor β performs an immune checkpoint function in activated macrophages. Front Immunol. 2025 Sep 29;16:1638907.
22. Swain SM, Shastry M, Hamilton E. Targeting HER2-positive breast cancer: advances and future directions. Nat Rev Drug Discov. 2023 Feb;22(2):101–26.
23. Jääskeläinen MM, Tumelius R, Hämäläinen K, Rilla K, Oikari S, Rönkä A, et al. High Numbers of CD163+ Tumor-Associated Macrophages Predict Poor Prognosis in HER2+ Breast Cancer. Cancers. 2024 Feb 1;16(3):634.
24. Zhan C, Jin Y, Xu X, Shao J, Jin C. Antitumor therapy for breast cancer: Focus on tumor‐associated macrophages and nanosized drug delivery systems. Cancer Medicine. 2023 May;12(10):11049–72.
25. Kim J, Suh H, Kim S, Kim K, Ahn C, Yim J. Identification and characteristics of the structural gene for the Drosophila eye colour mutant sepia , encoding PDA synthase, a member of the Omega class glutathione S-transferases. Biochemical Journal. 2006 Sep 15;398(3):451–60.
26. Puig-Kröger A, Sierra-Filardi E, Domínguez-Soto A, Samaniego R, Corcuera MT, Gómez-Aguado F, et al. Folate Receptor β Is Expressed by Tumor-Associated Macrophages and Constitutes a Marker for M2 Anti-inflammatory/Regulatory Macrophages. Cancer Research. 2009 Dec 15;69(24):9395–403.
27. Hanamura T, Kitano S, Kagamu H, Yamashita M, Terao M, Okamura T, et al. Expression of hormone receptors is associated with specific immunological profiles of the breast cancer microenvironment. Breast Cancer Res. 2023 Jan 31;25(1):13.
28. Bao X, Li Q, Chen D, Dai X, Liu C, Tian W, et al. A multiomics analysis-assisted deep learning model identifies a macrophage-oriented module as a potential therapeutic target in colorectal cancer. Cell Reports Medicine. 2024 Feb;5(2):101399.
29. Laviron M, Petit M, Weber-Delacroix E, Combes AJ, Arkal AR, Barthélémy S, et al. Tumor-associated macrophage heterogeneity is driven by tissue territories in breast cancer. Cell Reports. 2022 May;39(8):110865.
30. Nowosad A, Marine JC, Karras P. Perivascular niches: critical hubs in cancer evolution. Trends in Cancer. 2023 Nov;9(11):897–910.
31. Petit M, Weber-Delacroix E, Lanthiez F, Barthélémy S, Guillou N, Firpion M, et al. Visualizing the spatial organization of monocytes, interstitial macrophages, and tissue-specific macrophages in situ. Cell Reports. 2024 Oct;43(10):114847.
32. Liu SQ, Chen DY, Li B, Gao ZJ, Feng HF, Yu X, et al. Single-cell analysis of white adipose tissue reveals the tumor-promoting adipocyte subtypes. J Transl Med. 2023 Jul 15;21(1):470.
33. Mukherjee A, Bilecz AJ, Lengyel E. The adipocyte microenvironment and cancer. Cancer Metastasis Rev. 2022 Sep;41(3):575–87.
34. Wu Q, Li B, Li Z, Li J, Sun S, Sun S. Cancer-associated adipocytes: key players in breast cancer progression. J Hematol Oncol. 2019 Dec;12(1):95.
35. Nieman KM, Romero IL, Van Houten B, Lengyel E. Adipose tissue and adipocytes support tumorigenesis and metastasis. Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. 2013 Oct;1831(10):1533–41.
36. Corrêa LH, Corrêa R, Farinasso CM, De Sant’Ana Dourado LP, Magalhães KG. Adipocytes and Macrophages Interplay in the Orchestration of Tumor Microenvironment: New Implications in Cancer Progression. Front Immunol. 2017 Sep 19;8:1129.
37. Rodriguez-Garcia A, Lynn RC, Poussin M, Eiva MA, Shaw LC, O’Connor RS, et al. CAR-T cell-mediated depletion of immunosuppressive tumor-associated macrophages promotes endogenous antitumor immunity and augments adoptive immunotherapy. Nat Commun [Internet]. 2021 Feb 9 [cited 2025 Jul 21];12(1). Available from: https://www.nature.com/articles/s41467-021-20893-2
38. Goksen S, Varan G, Bilensoy E, Esendagli G. Folate Receptor β (FRβ) Expression on Myeloid Cells and the Impact of Reticuloendothelial System on Folate-Functionalized Nanoparticles’ Biodistribution in Cancer. Mol Pharmaceutics. 2024 Sep 2;21(9):4688–99.
39. Zhang F, Huang B, Utturkar SM, Luo W, Cresswell G, Herr SA, et al. Tumor-specific activation of folate receptor beta enables reprogramming of immune cells in the tumor microenvironment. Front Immunol. 2024 Feb 7;15:1354735.
2. Andinata B, Bachtiar A, Oktamianti P, Partahi JR, Dini MSA. A Comparison of Cancer Incidences Between Dharmais Cancer Hospital and GLOBOCAN 2020: A Descriptive Study of Top 10 Cancer Incidences. Indonesian Journal of Cancer. 2023 Jun 21;17(2):119.
3. Carvalho E, Canberk S, Schmitt F, Vale N. Molecular Subtypes and Mechanisms of Breast Cancer: Precision Medicine Approaches for Targeted Therapies. Cancers. 2025 Mar 25;17(7):1102.
4. Sharma JD, Khanna S, Ramchandani S, Kakoti LM, Baruah A, Mamidala V. Prevalence of Molecular Subtypes of Breast Carcinoma and Its Comparison between Two Different Age Groups: A Retrospective Study from a Tertiary Care Center of Northeast India. South Asian J Cancer. 2021 Dec;10(04):220–4.
5. Anderson NM, Simon MC. The tumor microenvironment. Current Biology. 2020 Aug;30(16):R921–5.
6. Noy R, Pollard JW. Tumor-Associated Macrophages: From Mechanisms to Therapy. Immunity. 2014 Jul;41(1):49–61.
7. Currenti J, Mishra A, Wallace M, George J, Sharma A. Immunosuppressive mechanisms of oncofetal reprogramming in the tumor microenvironment: implications in immunotherapy response. Biochemical Society Transactions. 2023;
8. Qiu SQ, Waaijer SJH, Zwager MC, De Vries EGE, Van Der Vegt B, Schröder CP. Tumor-associated macrophages in breast cancer: Innocent bystander or important player? Cancer Treatment Reviews. 2018 Nov;70:178–89.
9. Miao S, Bian C, Fang J, Wang S, You H, Zhou Y, et al. Integrated analysis reveals prognostic correlation and immune characteristics of a tumor-associated macrophage-based risk signature in triple-negative breast cancer. Transl Cancer Res. 2024 Oct;13(10):5214–32.
10. Jiang D, Xiao R, Bai J, Wang X, Fang Y, Liu J, et al. FOLR2+ macrophages in cancer: allies or enemies. Cell Commun Signal [Internet]. 2025 Jun 2 [cited 2025 Jul 21];23(1). Available from: https://biosignaling.biomedcentral.com/articles/10.1186/s12964-025-02257-1
11. Vyas D, Patel M, Wairkar S. Strategies for active tumor targeting-an update. European Journal of Pharmacology. 2022 Jan;915:174512.
12. Samaniego R, Domínguez-Soto Á, Ratnam M, Matsuyama T, Sánchez-Mateos P, Corbí ÁL, et al. Folate Receptor β (FRβ) Expression in Tissue-Resident and Tumor-Associated Macrophages Associates with and Depends on the Expression of PU.1. Cells. 2020 Jun 10;9(6):1445.
13. Rodriguez Garcia AB, Ramirez Lopez LJ. Aprender haciendo – investigar reflexionando: caso de estudio paralelo en Colombia y Chile. Academia y Virtualidad. 2014 Dec 1;7(2):53.
14. Zhu J, Yong S, Wan L, Qiao J, Yajie Z, Wang Q. A novel 12-gene prognostic signature in breast cancer based on the tumor microenvironment. Annals of Translational Medicine. 2022;10(3):143.
15. Kurahara H, Takao S, Kuwahata T, Nagai T, Ding Q, Maeda K, et al. Clinical Significance of Folate Receptor β–expressing Tumor-associated Macrophages in Pancreatic Cancer. Ann Surg Oncol. 2012 Jul;19(7):2264–71.
16. Xu X, Jiang J, Yao L, Ji B. Silencing the FOLR2 Gene Inhibits Cell Proliferation and Increases Apoptosis in the NCI-H1650 Non-Small Cell Lung Cancer Cell Line via Inhibition of AKT/Mammalian Target of Rapamycin (mTOR)/Ribosomal Protein S6 Kinase 1 (S6K1) Signaling. Med Sci Monit. 2018 Nov 11;24:8064–73.
17. Remmele W, Stegner HE. [Recommendation for uniform definition of an immunoreactive score (IRS) for immunohistochemical estrogen receptor detection (ER-ICA) in breast cancer tissue]. Pathologe. 1987 May;8(3):138–40.
18. Gajaria P, Kadu V, Patil A, Desai S, Shet T. Triple Negative Breast Cancer: Expression of Folate Receptor Alpha in Indian population. Annals of Diagnostic Pathology. 2020 Dec;49:151598.
19. Bottai G, Raschioni C, Székely B, Di Tommaso L, Szász AM, Losurdo A, et al. AXL-associated tumor inflammation as a poor prognostic signature in chemotherapy-treated triple-negative breast cancer patients. npj Breast Cancer. 2016 Nov 2;2(1):16033.
20. Nalio Ramos R, Missolo-Koussou Y, Gerber-Ferder Y, Bromley CP, Bugatti M, Núñez NG, et al. Tissue-resident FOLR2+ macrophages associate with CD8+ T cell infiltration in human breast cancer. Cell. 2022 Mar;185(7):1189-1207.e25.
21. Zhang F, Al-Amin MY, Utturkar S, Jiang R, Cresswell G, Alfar R, et al. Folate receptor β performs an immune checkpoint function in activated macrophages. Front Immunol. 2025 Sep 29;16:1638907.
22. Swain SM, Shastry M, Hamilton E. Targeting HER2-positive breast cancer: advances and future directions. Nat Rev Drug Discov. 2023 Feb;22(2):101–26.
23. Jääskeläinen MM, Tumelius R, Hämäläinen K, Rilla K, Oikari S, Rönkä A, et al. High Numbers of CD163+ Tumor-Associated Macrophages Predict Poor Prognosis in HER2+ Breast Cancer. Cancers. 2024 Feb 1;16(3):634.
24. Zhan C, Jin Y, Xu X, Shao J, Jin C. Antitumor therapy for breast cancer: Focus on tumor‐associated macrophages and nanosized drug delivery systems. Cancer Medicine. 2023 May;12(10):11049–72.
25. Kim J, Suh H, Kim S, Kim K, Ahn C, Yim J. Identification and characteristics of the structural gene for the Drosophila eye colour mutant sepia , encoding PDA synthase, a member of the Omega class glutathione S-transferases. Biochemical Journal. 2006 Sep 15;398(3):451–60.
26. Puig-Kröger A, Sierra-Filardi E, Domínguez-Soto A, Samaniego R, Corcuera MT, Gómez-Aguado F, et al. Folate Receptor β Is Expressed by Tumor-Associated Macrophages and Constitutes a Marker for M2 Anti-inflammatory/Regulatory Macrophages. Cancer Research. 2009 Dec 15;69(24):9395–403.
27. Hanamura T, Kitano S, Kagamu H, Yamashita M, Terao M, Okamura T, et al. Expression of hormone receptors is associated with specific immunological profiles of the breast cancer microenvironment. Breast Cancer Res. 2023 Jan 31;25(1):13.
28. Bao X, Li Q, Chen D, Dai X, Liu C, Tian W, et al. A multiomics analysis-assisted deep learning model identifies a macrophage-oriented module as a potential therapeutic target in colorectal cancer. Cell Reports Medicine. 2024 Feb;5(2):101399.
29. Laviron M, Petit M, Weber-Delacroix E, Combes AJ, Arkal AR, Barthélémy S, et al. Tumor-associated macrophage heterogeneity is driven by tissue territories in breast cancer. Cell Reports. 2022 May;39(8):110865.
30. Nowosad A, Marine JC, Karras P. Perivascular niches: critical hubs in cancer evolution. Trends in Cancer. 2023 Nov;9(11):897–910.
31. Petit M, Weber-Delacroix E, Lanthiez F, Barthélémy S, Guillou N, Firpion M, et al. Visualizing the spatial organization of monocytes, interstitial macrophages, and tissue-specific macrophages in situ. Cell Reports. 2024 Oct;43(10):114847.
32. Liu SQ, Chen DY, Li B, Gao ZJ, Feng HF, Yu X, et al. Single-cell analysis of white adipose tissue reveals the tumor-promoting adipocyte subtypes. J Transl Med. 2023 Jul 15;21(1):470.
33. Mukherjee A, Bilecz AJ, Lengyel E. The adipocyte microenvironment and cancer. Cancer Metastasis Rev. 2022 Sep;41(3):575–87.
34. Wu Q, Li B, Li Z, Li J, Sun S, Sun S. Cancer-associated adipocytes: key players in breast cancer progression. J Hematol Oncol. 2019 Dec;12(1):95.
35. Nieman KM, Romero IL, Van Houten B, Lengyel E. Adipose tissue and adipocytes support tumorigenesis and metastasis. Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. 2013 Oct;1831(10):1533–41.
36. Corrêa LH, Corrêa R, Farinasso CM, De Sant’Ana Dourado LP, Magalhães KG. Adipocytes and Macrophages Interplay in the Orchestration of Tumor Microenvironment: New Implications in Cancer Progression. Front Immunol. 2017 Sep 19;8:1129.
37. Rodriguez-Garcia A, Lynn RC, Poussin M, Eiva MA, Shaw LC, O’Connor RS, et al. CAR-T cell-mediated depletion of immunosuppressive tumor-associated macrophages promotes endogenous antitumor immunity and augments adoptive immunotherapy. Nat Commun [Internet]. 2021 Feb 9 [cited 2025 Jul 21];12(1). Available from: https://www.nature.com/articles/s41467-021-20893-2
38. Goksen S, Varan G, Bilensoy E, Esendagli G. Folate Receptor β (FRβ) Expression on Myeloid Cells and the Impact of Reticuloendothelial System on Folate-Functionalized Nanoparticles’ Biodistribution in Cancer. Mol Pharmaceutics. 2024 Sep 2;21(9):4688–99.
39. Zhang F, Huang B, Utturkar SM, Luo W, Cresswell G, Herr SA, et al. Tumor-specific activation of folate receptor beta enables reprogramming of immune cells in the tumor microenvironment. Front Immunol. 2024 Feb 7;15:1354735.
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2025-12-03
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