Cancer and Bone

Bone metastases affect over 1.5 million cancer patients globally, making bones a favored metastatic site for solid tumors (1). The presence of skeletal metastases can significantly reduce the quality of life for individuals with advanced cancer, as weakened bones can cause pain, fractures, and increase the risk of mortality (2, 3).

Bones have numerous important functions which include structural support, mobility, hematopoiesis, and mineral storage (4). The health and performance of our bone tissue are overseen by a range of cell types, which include:

• Osteoblasts – cells responsible for creating new bone tissue
• Osteoclasts – cells responsible for breaking down bone tissue
• Osteocytes –  cells within the bone that monitor mechanical loading and regulate the process of bone remodeling 

 

Bone biology- cancer and bone

Cancer and Bone – bone a preferred target site for cancer metastasis

Bone is a favored destination for metastasis in specific types of cancer, whereby cancer cells detach from the primary tumor and disseminate throughout the body. Certain cancers, such as breast, prostate, kidney, lung, ovarian, and thyroid, are especially prone to spread to bone (5).

Cancer and  Bone – the RANK/RANKL/OPG system

The RANK/RANKL/OPG system (receptor activator of the nuclear factor-κB ligand/ Osteoprotegerin) was identified more than 20 years ago and remains a widely researched topic until this day. The interaction between RANK and RANKL is essential for bone metabolism and osteoclast development. OPG acts as a decoy receptor for RANKL. By binding completely to RANKL, OPG obstructs the RANKL-RANK interaction, thereby blocking bone resorption. In addition to its role in regulating bone remodeling, the RANK/RANKL/OPG system is directly implicated in tumor cell development, particularly in the progression of breast and prostate cancer as well as leukemia (6-8).

Inhibiting RANK/RANKL signaling in human cancer

A fully humanized monoclonal antibody has been developed to counteract the effects of RANKL, which has received approval for treating bone loss conditions. The antibody functions by disrupting RANK signaling, preventing osteoclast activation and inhibiting bone resorption (6-8). More recently, inhibiting RANKL has been recognized as a significant checkpoint with the potential to influence anti-tumor response. Consequently, RANKL blockade has a direct impact on bone metastasis. Ongoing clinical and experimental trials are evaluating this emerging therapeutic approach (9).

Studies analyzing serum levels of OPG and RANKL

Serum concentrations of both OPG and soluble RANKL can be accessed via an enzyme-linked immunosorbent assay (ELISA). The predictive value of RANKL/OPG serum levels and disseminated tumor cells in breast cancer patients without metastasis was investigated in 509 patients with primary, nonmetastatic breast cancer. The results demonstrated that RANKL serum levels were significantly elevated in patients who developed bone metastases (10). A different study highlighted the role of OPG as a marker of breast cancer risk in women with a BRCA1 mutation. The authors suggested that OPG levels could be associated with disease risk, potentially serving as a marker for breast cancer risk and improving existing risk prediction models by identifying women at high risk of developing the disease (11).

How are circulating serum levels of Osteoprotegerin and soluble RANKL measured?

Both markers can easily be measured with a conventional ELISA assay.

• Osteoprotegerin (OPG) ELISA (cat. no. BI-20403) – day test, 20µl sample volume/well
• Soluble free RANKL ELISA (cat. no. BI-20462) – highly sensitive and reliable

 

– Widely cited in + 450 publications (citations for OPG, and RANKL)

– Extensively validated ELISA assays following international quality guidelines

High Quality ELISA kits – Developed & Manufactured by Biomedica

Related ELISA kits:  DKK-1, Sclerostin, IL-6, VEGF, Angiopoietin-2

References

1. Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells. Florencio-Silva R, Sasso GR, Sasso-Cerri E, Simões MJ, Cerri PS. Biomed Res Int. 2015;2015:421746. doi: 10.1155/2015/421746. Epub 2015 Jul 13. PMID: 26247020; PMCID: PMC4515490.
2. Understanding the Bone in Cancer Metastasis. Fornetti J, Welm AL, Stewart SA. J Bone Miner Res. 2018 Dec;33(12):2099-2113. doi: 10.1002/jbmr.3618. Epub 2018 Nov 26. PMID: 30476357.
3. Bone as a Preferential Site for Metastasis. JBMR Plus. Sowder ME, Johnson RW. 2019 Jan 15;3(3):e10126. doi: 10.1002/jbm4.10126. PMID: 30918918; PMCID: PMC6419612.
4. Cancer to bone: a fatal attraction. Weilbaecher KN, Guise TA, McCauley LK. Nat Rev Cancer. 2011 Jun;11(6):411-25. doi: 10.1038/nrc3055. Epub 2011 May 19. PMID: 21593787; PMCID: PMC3666847.
5. Bone metastasis: mechanisms, therapies, and biomarkers. Clézardin P, Coleman R, Puppo M, Ottewell P, Bonnelye E, Paycha F, Confavreux CB, Holen I. Physiol Rev. 2021 Jul 1;101(3):797-855. doi: 10.1152/ physrev.00012.2019. Epub 2020 Dec 24. PMID: 33356915.
6. The Roadmap of RANKL/RANK Pathway in Cancer. Casimiro S, Vilhais G, Gomes I, Costa L. Cells. 2021 Aug 4;10(8):1978. doi: 10.3390/cells10081978. PMID: 34440747; PMCID: PMC8393235.
7. RANKL biology: bone metabolism, the immune system, and beyond. Ono T, Hayashi M, Sasaki F, Nakashima T. Inflamm Regen. 2020 Feb 7;40:2. doi: 10.1186/s41232-019-0111-3. PMID: 32047573; PMCID: PMC7006158.
8. RANKL and RANK in Cancer Therapy. Physiology (Bethesda). Onji M, Penninger JM. 2023 May 1;38(3):0. doi: 10.1152/physiol.00020.2022. Epub 2022 Dec 6. PMID: 36473204.
9. The Role of the RANKL/RANK Axis in the Prevention and Treatment of Breast Cancer with Immune Checkpoint Inhibitors and Anti-RANKL. Simatou A, Sarantis P, Koustas E, Papavassiliou AG, Karamouzis MV. Int J Mol Sci. 2020 Oct 14;21(20):7570. doi: 10.3390/ijms21207570. PMID: 33066388; PMCID: PMC7590202.
10. Prognostic Value of RANKL/OPG Serum Levels and Disseminated Tumor Cells in Nonmetastatic Breast Cancer. Rachner TD, Kasimir-Bauer S, Göbel A, Erdmann K, Hoffmann O, Browne A, Wimberger P, Rauner M, Hofbauer LC, Kimmig R, Bittner AK. Clin Cancer Res. 2019 Feb 15;25(4):1369-1378. doi: 10.1158/1078-0432.CCR-18-2482. Epub 2018 Nov 13. PMID: 30425091.
11. Delineating the role of osteoprotegerin as a marker of breast cancer risk among women with a BRCA1 mutation. Park SS, Uzelac A, Kotsopoulos J. Hered Cancer Clin Pract. 2022 Apr 13;20(1):14. doi: 10.1186/s13053-022-00223-3. PMID: 35418083; PMCID: PMC9008947.