Targeting the BMP Pathway in Prostate Cancer Induced Bone Disease

Bridging the Gap in Understanding Bone Metastasis: A Multifaceted Perspective

The treatment of patients with advanced cancer poses clinical problems due to the complications that arise as the disease progresses. Bone metastases are a common problem that cancer patients may face, and currently, there are no effective drugs to treat these individuals. Prostate, breast, and lung cancers often spread to the bone, causing significant and disabling health conditions. The bone is a highly active and dynamic tissue and is considered a favorable environment for the growth of cancer. The role of osteoblasts and osteoclasts in the process of bone remodeling and the way in which their interactions change during the progression of metastasis is critical to understanding the pathophysiology of this disease. These interactions create a self-perpetuating loop that stimulates the growth of metastatic cells in the bone. The metabolic reprogramming of both cancer cells and cells in the bone microenvironment has serious implications for the development and progression of metastasis. Insight into the process of bone remodeling and the systemic elements that regulate this process, as well as the cellular changes that occur during the progression of bone metastases, is critical to the discovery of a cure for this disease. It is crucial to explore different therapeutic options that focus specifically on malignancy in the bone microenvironment in order to effectively treat this disease. This review will focus on the bone remodeling process and the effects of metabolic disorders as well as systemic factors like hormones and cytokines on the development of bone metastases. We will also examine the various therapeutic alternatives available today and the upcoming advances in novel treatments.

Increased Bone Formation and Accelerated Bone Mass Accrual in a Man Presenting with Diffuse Osteosclerosis/High Bone Mass Phenotype and Adenocarcinoma of Unknown Primary

A 71-year-old man was referred for evaluation of incidental generalized osteosclerosis. He was found to have a high bone mass (HBM) with an elevated lumbar spine bone mineral density (BMD) Z-score of +5.3. Over an 18-month period, his lumbar spine BMD measured by dual energy X-ray absorptiometry (DXA) had increased by +64% from 1.09 to 1.79 g/cm2 and femoral neck by +21% from 0.83 to 1.01 g/cm2. Biochemical markers of bone turnover were markedly increased (serum propeptide of type 1 collagen and urine telopeptides greater than 10-times normal). The high bone formation and increased skeletal calcium acquisition resulted in profound hypocalcemia (low serum calcium 1.88 mmol/L) and hypocalciuria (low urinary calcium <0.2 mmol/day). Positron emission tomography (PET) with 2-deoxy-2-[fluorine-18] fluoro-D-glucose (FDG) confirmed diffuse osteosclerosis without focal areas of abnormal FDG uptake in the skeleton or elsewhere to suggest either an underlying primary malignancy or metastatic disease. Bone biopsy showed markedly sclerotic woven and lamellar bone. The marrow space was devoid of typical bone cells and adipocytes and instead was filled by fibromyxoid stroma, infiltrated by small clusters of tumor cells. Bone histomorphometry and micro-computed tomography demonstrated an elevated trabecular bone volume and trabecular plate thickness. The bone disorder in this case is unique and raises the possibility of a new yet undefined novel anabolic paracrine factor (or factors) secreted by an adenocarcinoma of unknown primary that resulted in dramatic increases in BMD, HBM, and radiological osteosclerosis. The differential diagnosis and potential mechanisms responsible for the HBM are discussed. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Bone morphogenetic protein pathway responses and alterations of osteogenesis in metastatic prostate cancers

BACKGROUND

Prostate cancer is a common cancer in men that annually results in more than 33 000 US deaths. Mortality from prostate cancer is largely from metastatic disease, reflecting on the great strides in the last century of treatments in care for the localized disease. Metastatic castrate resistant prostate cancer (mCRPC) will commonly travel to the bone, creating unique bone pathology that requires nuanced treatments in those sites with surgical, radio and chemotherapeutic interventions. The bone morphogenetic protein (BMP) pathway has been historically studied in the capacity to regulate the osteogenic nature of new bone. New mineralized bone generation is a frequent and common observation in mCRPC and referred to as blastic bone lesions. Less common are bone destructive lesions that are termed lytic.

METHODS

We queried the cancer genome atlas (TCGA) prostate cancer databases for the expression of the BMP pathway and found that distinct gene expression of the ligands, soluble antagonists, receptors, and intracellular mediators were altered in localized versus metastatic disease. Human prostate cancer cell lines have an innate ability to promote blastic- or lytic-like bone lesions and we hypothesized that inhibiting BMP signaling in these cell lines would result in a distinct change in osteogenesis gene expression with BMP inhibition.

RESULTS

We found unique and common changes by comparing these cell lines response and unique BMP pathway alterations. We treated human PCa cell lines with distinct bone pathologic phenotypes with the BMP inhibitor DMH1 and found distinct osteogenesis responses. We analyzed distinct sites of metastatic PCa in the TCGA and found that BMP signaling was selectively altered in commons sites such as lymph node, bone and liver compared to primary tumors.

CONCLUSIONS

Overall we conclude that BMPs in metastatic prostate cancer are important signals and functional mediators of diverse processes that have potential for individualized precision oncology in mCRPC.

Muscle and Bone Defects in Metastatic Disease

PURPOSE OF REVIEW

The present review addresses most recently identified mechanisms implicated in metastasis-induced bone resorption and muscle-wasting syndrome, known as cachexia.

RECENT FINDINGS

Metastatic disease in bone and soft tissues is often associated with skeletal muscle defects. Recent studies have identified a number of secreted molecules and extracellular vesicles that contribute to cancer cell growth and metastasis leading to bone destruction and muscle atrophy. In addition, alterations in muscle microenvironment including dysfunctions in hepatic and mitochondrial metabolism have been implicated in cancer-induced regeneration defect and muscle loss. Moreover, we review novel in vitro and animal models including promising new drug candidates for bone metastases and cancer cachexia. Preservation of bone health could be highly beneficial for maintaining muscle mass and function. Therefore, a better understanding of molecular pathways implicated in bone and muscle crosstalk in metastatic disease may provide new insights and identify new strategies to improve current anticancer therapeutics.

Biological and Clinical Aspects of Metastatic Spinal Tumors

Simple Summary

Spine metastases are a common life-threatening complication of advanced-stage malignancies and often result in poor prognosis. Symptomatic spine metastases develop in the course of about 10% of malignant neoplasms. Therefore, it is essential for contemporary medicine to understand metastatic processes in order to find appropriate, targeted therapeutic options. Our literature review aimed to describe the up-to-date knowledge about the molecular pathways and biomarkers engaged in the spine’s metastatic processes. Moreover, we described current data regarding bone-targeted treatment, the emerging targeted therapies, radiotherapy, and immunotherapy used for the treatment of spine metastases. We hope that knowledge comprehensively presented in our review will contribute to the development of novel drugs targeting specific biomarkers and pathways. The more we learn about the molecular aspects of cancer metastasis, the easier it will be to look for treatment methods that will allow us to precisely kill tumor cells.

Abstract

Spine metastases are a common life-threatening complication of advanced-stage malignancies and often result in poor prognosis. Symptomatic spine metastases develop in the course of about 10% of malignant neoplasms. Therefore, it is essential for contemporary medicine to understand metastatic processes in order to find appropriate, targeted therapeutic options. Thanks to continuous research, there appears more and more detailed knowledge about cancer and metastasis, but these transformations are extremely complicated, e.g., due to the complexity of reactions, the variety of places where they occur, or the participation of both tumor cells and host cells in these transitions. The right target points in tumor metastasis mechanisms are still being researched; that will help us in the proper diagnosis as well as in finding the right treatment. In this literature review, we described the current knowledge about the molecular pathways and biomarkers engaged in metastatic processes involving the spine. We also presented a current bone-targeted treatment for spine metastases and the emerging therapies targeting the discussed molecular mechanisms.

Isoquercitrin Attenuates Osteogenic Injury in MC3T3 Osteoblastic Cells and the Zebrafish Model via the Keap1-Nrf2-ARE Pathway

Isoquercitrin (IQ) widely exists in natural products, with a variety of pharmacological activities. In this study, the anti-apoptotic and antioxidative activities of IQ were evaluated. IQ showed protective activity against 2, 2′-azobis [2-methylpropionamidine] dihydrochloride (AAPH)-induced cell damage, as well as a marked reduction in reactive oxygen species (ROS). The evidence of IQ regulating Keap1-Nrf2-ARE and the mitochondrial-mediated Caspase 3 pathway were found in the MC3T3 osteoblastic cell line. Furthermore, IQ significantly decreased ROS production, apoptosis, and lipid peroxidation in AAPH-treated 72 h post-fertilization (hpf) zebrafish, as observed via DCFH-DA, acridine orange (AO), and a 1,3-bis(diphenylphosphino) propane (DPPP) probe, respectively. In AAPH-treated 9 day post-fertilization (dpf) zebrafish, IQ strongly promoted osteogenic development, with increased concentrations by calcein staining, compared with the untreated group. In a molecular docking assay, among all signal proteins, Keap1 showed the strongest affinity with IQ at −8.6 kcal/mol, which might be the reason why IQ regulated the Keap1-Nrf2-ARE pathway in vitro and in vivo. These results indicated that IQ promotes bone development and repairs bone injury, which is valuable for the prevention and treatment of bone diseases.