The Role of TGFβ in Bone-Muscle Crosstalk

Purpose of Review The role of bone-derived factors in regulation of skeletal muscle function is an important emerging aspect of research into bone-muscle crosstalk. Implications for this area of research are far reaching and include understanding skeletal muscle weakness in cancer, osteoporosis, cachexia, rare diseases of bone, and aging. Recent Findings Recent research shows that bone-derived factors can lead to changes in the skeletal muscle. These changes can either be anabolic or catabolic, and we focus this review on the role of TGFβ in driving oxidative stress and skeletal muscle weakness in the setting of osteolytic cancer in the bone. Summary The bone is a preferred site for breast cancer metastasis and leads to pathological bone loss. Osteolytic cancer in the bone leads to release of TGFβ from the bone via osteoclast-mediated bone destruction. Our appreciation of crosstalk between the muscle and bone has recently expanded beyond mechanical force-driven events to encompass a variety of signaling factors originating in one tissue and communicating to the other. This review summarizes some previously known mediators of bone-to-muscle signaling and also recent work identifying a new role for bone-derived TGFβ as a cause of skeletal muscle weakness in the setting of osteolytic cancer in the bone. Multiple points of potential therapeutic intervention are discussed

Role of Interleukin-18 in Thyroid tumorigenesis

Purpose: Although the significance of Interleukin-18 (IL-18) has been studied in pathogenesis of different cancers including, ovarian, gastric, breast, lung carcinoma and melanoma, its role in thyroid cancer- the most common endocrine malignancy has not yet been looked at extensively. Hence, this study intended to examine the role of IL-18 in thyroid tumorigenesis.Methods: Sixty seven patients with benign thyroid diseases and 106 thyroid cancer patients (including 83 papillary, 6 follicular, 9 medullary and 8 anaplastic thyroid carcinoma patients) were enrolled in the study. To accomplish the aim, the circulating levels of IL-18 were estimated by enzyme linked immunosorbent assay (ELISA) from all patients and compared with controls. Further, protein expression of IL-18 was determined from the primary tumors of the patients using immunohistochemistry.Results: It was observed that the circulating levels of IL-18 were significantly higher in all patients: benign thyroid diseases (p = 0.006), papillary (p < 0.001), follicular (p = 0.023), medullary (p = 0.002) and anaplastic thyroid cancer (p < 0.001) than the controls. In addition to this, IL-18 could well discriminate papillary (AUC = 0.627, p =0.008) and anaplastic thyroid carcinoma patients (AUC = 0.777, p = 0.011) from patients with benign thyroid diseases. However, the difference between tumoral protein expression of IL-18 in patients with benign thyroid diseases and thyroid carcinoma was not significant. The Kaplan - Meier survival analysis revealed that neither the circulating nor the tumoral protein expression of IL-18 was the significant predictor of disease free survival (DFS) or overall survival (OS) in papillary thyroid cancer patients.Conclusion: Though not a significant prognosticator, circulating IL-18 may be useful as a differentiating factor in thyroid tumorigenesis and the increase in serum IL-18 levels may be provoked in response to the tumor. Thus, including IL-18 along with the current treatment practice may have a significant role in better management of the disease. However, further exploration of this interleukin is required in a larger series of patients with longer follow up period

Myeloid Sarcoma: A Mediastinal Masquerader

Mediastinal Myeloid Sarcoma is a rare entity. Here we present a case of a 28-year-old gentleman, who first presented with a mediastinal mass and was clinically considered lymphoblastic lymphoma. He was diagnosed initially as having T lymphoblastic lymphoma on a mediastinal trucut biopsy. After one month patient was diagnosed with Acute myeloid leukemia on peripheral smear and bone marrow examination and was confirmed with the help of flow cytometry. The biopsy slides from the mediastinal mass were reviewed and based on the smear findings additional immunohistochemical markers were added and diagnosed as Myeloid Sarcoma. Keywords: Myeloid sarcoma, Mediastinum, Acute myeloid leukemi

The vitamin D receptor is involved in the regulation of human breast cancer cell growth via a ligand-independent function in cytoplasm

Vitamin D has pleiotropic effects on multiple tissues, including malignant tumors. Vitamin D inhibits breast cancer growth through activation of the vitamin D receptor (VDR) and via classical nuclear signaling pathways. Here, we demonstrate that the VDR can also function in the absence of its ligand to control behaviour of human breast cancer cells both outside and within the bone microenvironment. Stable shRNA expression was used to knock down VDR expression in MCF-7 cells, generating two VDR knockdown clonal lines. In ligand-free culture, knockdown of VDR in MCF-7 cells significantly reduced proliferation and increased apoptosis, suggesting that the VDR plays a ligand-independent role in cancer cell growth. Implantation of these VDR knockdown cells into the mammary fat pad of nude mice resulted in reduced tumor growth in vivo compared with controls. In the intra-tibial xenograft model, VDR knockdown greatly reduced the ability of the cells to form tumors in the bone microenvironment. The in vitro growth of VDR knockdown cells was rescued by the expression of a mutant form of VDR which is unable to translocate to the nucleus and hence accumulates in the cytoplasm. Thus, our data indicate that in the absence of ligand, the VDR promotes breast cancer growth both in vitro and in vivo and that cytoplasmic accumulation of VDR is sufficient to produce this effect in vitro. This new mechanism of VDR action in breast cancer cells contrasts the known anti-proliferative nuclear actions of the VDR-vitamin D ligand complex

Excess TGF-β mediates muscle weakness associated with bone metastases in mice

Cancer-associated muscle weakness is a poorly understood phenomenon, and there is no effective treatment. Here we find that seven different mouse models of human osteolytic bone metastases-representing breast, lung and prostate cancers, as well as multiple myeloma-exhibited impaired muscle function, implicating a role for the tumor-bone microenvironment in cancer-associated muscle weakness. We found that transforming growth factor (TGF)-β, released from the bone surface as a result of metastasis-induced bone destruction, upregulated NADPH oxidase 4 (Nox4), resulting in elevated oxidization of skeletal muscle proteins, including the ryanodine receptor and calcium (Ca(2+)) release channel (RyR1). The oxidized RyR1 channels leaked Ca(2+), resulting in lower intracellular signaling, which is required for proper muscle contraction. We found that inhibiting RyR1 leakage, TGF-β signaling, TGF-β release from bone or Nox4 activity improved muscle function in mice with MDA-MB-231 bone metastases. Humans with breast- or lung cancer-associated bone metastases also had oxidized skeletal muscle RyR1 that is not seen in normal muscle. Similarly, skeletal muscle weakness, increased Nox4 binding to RyR1 and oxidation of RyR1 were present in a mouse model of Camurati-Engelmann disease, a nonmalignant metabolic bone disorder associated with increased TGF-β activity. Thus, pathological TGF-β release from bone contributes to muscle weakness by decreasing Ca(2+)-induced muscle force production

Aging-associated skeletal muscle defects in HER2/Neu transgenic mammary tumor model

Background: Loss of skeletal muscle volume and resulting in functional limitations are poor prognostic markers in breast cancer patients. Several molecular defects in skeletal muscle including reduced MyoD levels and increased protein turn over due to enhanced proteosomal activity have been suggested as causes of skeletal muscle loss in cancer patients. However, it is unknown whether molecular defects in skeletal muscle are dependent on tumor etiology. Methods: We characterized functional and molecular defects of skeletal muscle in MMTV-Neu (Neu+) mice (n= 6-12), an animal model that represents HER2+ human breast cancer, and compared the results with well-characterized luminal B breast cancer model MMTV-PyMT (PyMT+). Functional studies such as grip strength, rotarod performance, and ex vivo muscle contraction were performed to measure the effects of cancer on skeletal muscle. Expression of muscle-enriched genes and microRNAs as well as circulating cytokines/chemokines were measured. Since NF-κB pathway plays a significant role in skeletal muscle defects, the ability of NF-κB inhibitor dimethylaminoparthenolide (DMAPT) to reverse skeletal muscle defects was examined. Results: Neu+ mice showed skeletal muscle defects similar to accelerated aging. Compared to age and sex-matched wild type mice, Neu+ tumor-bearing mice had lower grip strength (202±6.9 vs. 179±6.8 g grip force, p=0.0069) and impaired rotarod performance (108±12.1 vs. 30±3.9 seconds, P<0.0001), which was consistent with reduced muscle contractibility (p<0.0001). Skeletal muscle of Neu+ mice (n=6) contained lower levels of CD82+ (16.2±2.9 vs 9.0±1.6) and CD54+ (3.8±0.5 vs 2.4±0.4) muscle stem and progenitor cells (p<0.05), suggesting impaired capacity of muscle regeneration, which was accompanied by decreased MyoD, p53 and miR-486 expression in muscles (p<0.05). Unlike PyMT+ mice, which showed skeletal muscle mitochondrial defects including reduced mitochondria levels and Pgc1β, Neu+ mice displayed accelerated aging-associated changes including muscle fiber shrinkage and increased extracellular matrix deposition. Circulating "aging factor" and cachexia and fibromyalgia-associated chemokine Ccl11 was elevated in Neu+ mice (1439.56±514 vs. 1950±345 pg/ml, p<0.05). Treatment of Neu+ mice with DMAPT significantly restored grip strength (205±6 g force), rotarod performance (74±8.5 seconds), reversed molecular alterations associated with skeletal muscle aging, reduced circulating Ccl11 (1083.26 ±478 pg/ml), and improved animal survival. Conclusions: These results suggest that breast cancer subtype has a specific impact on the type of molecular and structure changes in skeletal muscle, which needs to be taken into consideration while designing therapies to reduce breast cancer-induced skeletal muscle loss and functional limitations

Identification of a Novel Ligand Independent Function of the Cytoplasmic Vitamin D Receptor in Breast Cancer

This thesis aims to define the role of the vitamin D receptor (VDR) in breast cancer (BC), hypothesising that in contrast to the anti-proliferative effects of its ligand, 1.25-dihydroxy vitamin D3, VDR knockdown would enhance BC cell growth. Using stable shRNA expression, VDR expression was knocked down (VDR-KD) in two human BC cell lines, namely MDA-Tx-SA and MCF-7 cells. Parental (PA) and non-target (shNT) cells served as controls. In ligand-free culture, VDR-KD significantly reduced BC cell growth and induced cell apoptosis. In vivo, VDR-KD suppressed BC cell growth in both the mammary fat pad and the bone environment. However, VDR-KD cells exhibited increased invasive potential, likely via changes in beta-catenin and E-cadherin signaling. These findings suggest a ligand-independent effect of the VDR on BC cell behaviour. Transfection of VDR-KD BC cells with a mutant VDR construct unable to translocate to the nucleus restored normal growth of VDR-KD BC cells. I conclude that in contrast to the known anti-proliferative actions of the liganded VDR, the cytoplasmic VDR promotes BC cell growth. This discovery adds to our understanding of VDR signaling in BC and may help to resolve discrepancies regarding the association between vitamin D status and BC prognosis

Translational Strategies to Target Metastatic Bone Disease

Metastatic bone disease is a common and devastating complication to cancer, confounding treatments and recovery efforts and presenting a significant barrier to de-escalating the adverse outcomes associated with disease progression. Despite significant advances in the field, bone metastases remain presently incurable and contribute heavily to cancer-associated morbidity and mortality. Mechanisms associated with metastatic bone disease perpetuation and paralleled disruption of bone remodeling are highlighted to convey how they provide the foundation for therapeutic targets to stem disease escalation. The focus of this review aims to describe the preclinical modeling and diagnostic evaluation of metastatic bone disease as well as discuss the range of therapeutic modalities used clinically and how they may impact skeletal tissue

Translational Strategies to Target Metastatic Bone Disease

Metastatic bone disease is a common and devastating complication to cancer, confounding treatments and recovery efforts and presenting a significant barrier to de-escalating the adverse outcomes associated with disease progression. Despite significant advances in the field, bone metastases remain presently incurable and contribute heavily to cancer-associated morbidity and mortality. Mechanisms associated with metastatic bone disease perpetuation and paralleled disruption of bone remodeling are highlighted to convey how they provide the foundation for therapeutic targets to stem disease escalation. The focus of this review aims to describe the preclinical modeling and diagnostic evaluation of metastatic bone disease as well as discuss the range of therapeutic modalities used clinically and how they may impact skeletal tissue

IL-2 and IL-12 in thyroid cancer: Clinical implication

Purpose: The roles of IL-2 and IL-12, in different malignancies have been looked for since years. But very few studies have elucidated their role in thyroid tumorigenesis. Hence, present study sought to explore their utility in thyroid cancer, mainly the papillary thyroid cancer (PTC).Methods: A total of 67 patients with benign thyroid diseases, 106 with thyroid cancer and 67 healthy individuals were included in the study. Circulating levels of IL-2 and IL-12 were estimated by ELISA from all patients and controls. Protein expression of both interleukins was determined using immunohistochemistry. The results were statistically analysed using SPSS software.Results: Serum IL-12 exhibited good discriminatory efficacy between patients with benign thyroid diseases and healthy individuals. IL-2 and IL-12 levels could efficiently differentiate PTC and anaplastic thyroid cancer (ATC) patients from healthy individuals. Additionally, IL-12 showed good discriminating efficacy between PTC and benign thyroid disease patients and IL-2 well discriminated ATC patients from benign thyroid diseases. IL-2 was significantly higher in patients having unilateral tumors (P=0.006) while, IL-12 was significantly higher in patients with smaller tumor size (P=0.036) and early stage disease (P=0.008). The cytokine protein expressions in benign thyroid tissues and carcinoma did not differ significantly. IL-12 expression was significantly higher in male patients (P=0.042) and unilateral tumors (P=0.031).Kaplan-Meier survival analysis revealed that nuclear IL-2 expression was able to predict disease free survival and overall survival (OS) in subgroup of PTC patients having multifocal tumors and only OS in patients having bilateral tumors. Moreover, higher IL-12 immunoreactivity was a significant predictor of shorter OS in PTC patients treated with surgery alone.Conclusion: Serologic determination of IL-2 and IL-12 may help in validating indeterminate FNAC results and disclose diagnostic difference between benign and malignant thyroid diseases. However, a large cohort study is mandatory to establish a defined cut off for such discrimination