ULK1 Suppresses Osteoclast Differentiation and Bone Resorption via Inhibiting Syk-JNK through DOK3

Bone resorption diseases, including osteoporosis, are usually caused by excessive osteoclastogenesis. Unc-51-like autophagy activating kinase 1 (ULK1), a mammalian serine/threonine kinase, may participate in the regulation of bone homeostasis and osteolytic metastasis. In this study, ULK1 expression during osteoclastogenesis was detected with RT-PCR. We knocked down or overexpressed ULK1 through siRNA or lentiviral transduction in bone marrow macrophage (BMM). TRAP and phalloidin staining were performed to detect the osteoclastogenesis activity. Ovariectomized (OVX) mouse model of osteoporosis and a mouse of model osteoclast-induced bone resorption were applied to explore the role of ULK1 in bone resorption in vivo. The results showed that ULK1 expression was downregulated during osteoclast differentiation and was clinically associated with osteoporosis. ULK1 inhibited osteoclast differentiation in vitro. Knockdown of ULK1 expression activated phosphorylation of c-Jun N-terminal kinase (JNK) and spleen tyrosine kinase (Syk). Docking protein 3 (DOK3) was coexpressed with ULK1 during osteoclastogenesis. Downregulation of DOK3 offsets the effect of ULK1 on osteoclastogenesis and induced phosphorylation of JNK and Syk. Activation of ULK1 impeded bone loss in OVX mice with osteoporosis. Additionally, upregulation of ULK1 inhibited osteoclast-induced bone resorption in vivo. Therefore, our study reveals a novel ULK1/DOK3/Syk axis that regulates osteoclast differentiation and bone resorption, and targeting ULK1 is a potential therapeutic strategy for osteoporosis.

Melatonin Inhibits Osteoclastogenesis and Osteolytic Bone Metastasis: Implications for Osteoporosis

Osteoblasts and osteoclasts are major cellular components in the bone microenvironment and they play a key role in the bone turnover cycle. Many risk factors interfere with this cycle and contribute to bone-wasting diseases that progressively destroy bone and markedly reduce quality of life. Melatonin (N-acetyl-5-methoxy-tryptamine) has demonstrated intriguing therapeutic potential in the bone microenvironment, with reported effects that include the regulation of bone metabolism, acceleration of osteoblastogenesis, inhibition of osteoclastogenesis and the induction of apoptosis in mature osteoclasts, as well as the suppression of osteolytic bone metastasis. This review aims to shed light on molecular and clinical evidence that points to possibilities of melatonin for the treatment of both osteoporosis and osteolytic bone metastasis. It appears that the therapeutic qualities of melatonin supplementation may enable existing antiresorptive osteoporotic drugs to treat osteolytic metastasis.

MON-LB66 Altered Mental Status and Hypercalcemia: A Rare Presentation of Pure Osteolytic Metastatic Prostate Cancer

Background: We present a rare case of hypercalcemia with the concomitant presence of parathyroid adenoma, secondary hyperparathyroidism due to kidney disease and hypercalcemia of malignancy. Mild hypercalcemia due to primary hyperparathyroidism often precedes the acute, more severe hypercalcemia of malignancy. Prostate cancers are usually known to cause osteoblastic lesions. We present a rare case of prostate cancer with pure osteolytic metastasis. Case: 73 year old male with past history of ESRD on hemodialysis was brought to the ER with change in mental status. Labs showed elevated serum calcium 13.3 mg/dl (8.6-10.2 mg/dl) and creatinine 7.0 mg/dl (0.60-1.30mg/dl). Patient underwent emergent hemodialysis. Additional lab work revealed, elevated phosphorus level of 5.8mg/dl (2.5-5 mg/dl), low vitamin D 25-hydroxy of 22 ng/ml (30-100 ng/ml) and vitamin 1-25 dihydroxy level of 7 ng/ml (20-79 ng/ml). Both PTH 172.6 pg/ml (12-88 pg/ml) and PTHrP 64 pg/ml (14-27 pg/dl) levels were elevated. Parathyroid scan showed increased uptake in left inferior parathyroid gland indicating the presence of a parathyroid adenoma. Serum calcium levels remained persistently elevated despite being continued on dialysis with a low calcium bath and receiving calcium lowering therapy with calcium binding agent- cinacalcet, calcitonin, bisphosphonate. Further work up for refractory hypercalcemia revealed an elevated prostate-specific antigen (PSA) level of 1420 ng/ml (0-3.999 ng/ml). Bone scan showed no evidence of osseous metastasis. CT abdomen & pelvis showed extensive lytic bony metastases, with metastasis to lung and lymph nodes in mesenteric root and in the pelvis. Prostate gland showed asymmetric contour along the left posterolateral zone suspicious for malignancy with extracapsular spread.Biopsy from the left iliac lytic bone lesion was done that showed poorly differentiated metastatic adenocarcinoma, consistent with a prostatic primary. The patient was started on treatment with anti-androgen medication- Bicalutamide and prednisone and was planned to be started on Leuprolide as outpatient. Discussion: Hypercalcemia is uncommon in advanced prostate cancer compared to other malignancies where osteolytic metastasis is more common than osteoblastic metastasis. Incidence of malignancy in patients with primary hyperparathyroidism and vice-versa is high, hence serum PTH and PTHrP should be measured in hypercalcemic patients with malignancy. If PTHrP and PTH are both elevated, it indicates co-existent primary hyperparathyroidism. Prostate cancers are usually known to cause osteoblastic lesions and pure osteolytic metastasis from prostate carcinoma is extremely rare. Radio-nucleotide bone scan preferentially detects osteoblastic metastasis. CT or MRI is indicated to look for osteolytic lesions if suspicion for bone metastasis is high.

Percutaneous Vertebroplasty

Percutaneous Vertebroplasty is a minimally invasive procedure initially developed to treat aggressive hemangiomas, which was then further extended to vertebral tumors - especially aggressive osteolytic metastasis and myeloma - and is currently largely applied in osteoporotic compression fractures that are refractory to medical therapy. In this article we formulate and answer questions reviewing the current technique, its indications and potential complications. This paper summarizes the experience of the Department of Neurosurgery at Hospital Santa Cruz in Curitiba (PR) and aims at providing a source of reference to neurosurgeons interested in this procedure.

Ultrasound-guided biopsy of osteolytic metastasis – could be less than three cores enough?

Aims: The purpose of this study was to analyze the diagnostic yield and accuracy of the ultrasound (US) guided core biopsy in a population of patients with osteolytic metastasis. Materials and methods: We performed a retrospective analysis of 16 consecutive cases of US-guided core biopsies of osteolytic lesions performed in our Ultrasound Unit, from January 2006 to May 2017. We used 18G or 16G Tru-cut needles coupled with automated biopsy guns. We procured a maximum number of two tissue specimens per patient.Results: We obtained a diagnostic yield and accuracy of 93.75% (15 of 16 patients) for US-guided core biopsy of osteolytic metastasis. Most of our cases were metastasis of adenocarcinomas (8 patients), squamous cell carcinomas (3 patients) followed by multiple myelomas (2 patients). Other pathologic lesions recorded were undifferentiated carcinoma (1 patient) and mesenchimal undifferentiated tumor (1 patient). The pathologic result was inconclusive in one patient.Conclusions: Our study supports the important diagnostic role of US-guided core biopsy for osteolytic bone metastasis. Two US-guided passages may be sufficient to procure a diagnostic tissue samples from osteolytic bone metastasis, if theirlength is at least 10 mm.

Knockdown of Bone Morphogenetic Proteins Type 1a Receptor (BMPR1a) in Breast Cancer Cells Protects Bone from Breast Cancer-Induced Osteolysis by Suppressing RANKL Expression

Background/Aims: Bone morphogenetic proteins (BMPs) and BMP receptors widely participate in osteolytic metastasis of breast cancer, while their role in tumor-stromal interaction is largely unknown. In this study, we investigated whether BMP receptor type 1a (BMPR1a) can alter the interaction between metastatic cancer cells and osteoclast precursors. Methods: Adenovirus-mediated RNA interference was used to interrupt target genes of human breast cancer cell lines and nude mice were injected intratibially with the cancer cells. Tumor-bearing mice were examined by bioluminescence imaging and microCT. Sections of metastatic legs were measured by a series of staining methods. Murine bone marrow mononuclear cells or RAW264.7 cells were cultured with conditioned media of breast cancer cells. RT-PCR, Western blotting and ELISA were used to test mRNA and protein expressions of target molecules. Results: Expression of BMPR1a of MDA-MB-231-luc cells at tumor-bone interface was apparently stronger than that of cancer cells distant from the interface. Mice injected with BMPR1a-knockdown MDA-MB-231-luc cells showed reduced tumor growth and bone destruction compared with control groups. Knockdown (KD) of BMPR1a of MDA-MB-231-luc cells or MCF-7 cells decreased the level of receptor activator for NF-κB ligand (RANKL). Level of RANKL in MDA-MB-231-luc cells or MCF-7 cells was reduced by p38 inhibitor. Compared with control group, knockdown of p38 of breast cancer cells decreased cancer-induced osteoclastogenesis. Conclusion: Knockdown of BMPR1a of breast cancer cells suppresses their production of RANKL via p38 pathway and inhibits cancer-induced osteoclastogenesis, which indicates that BMPR1a might be a possible target in breast cancer-induced osteolytic metastasis.

Hypercalcemia of Malignancy in Thymic Carcinoma: Evolving Mechanisms of Hypercalcemia and Targeted Therapies

Here we describe, to our knowledge, the first case where an evolution of mechanisms responsible for hypercalcemia occurred in undifferentiated thymic carcinoma and discuss specific management strategies for hypercalcemia of malignancy (HCM). Case Description. We report a 26-year-old male with newly diagnosed undifferentiated thymic carcinoma associated with HCM. Osteolytic metastasis-related hypercalcemia was presumed to be the etiology of hypercalcemia that responded to intravenous hydration and bisphosphonate therapy. Subsequently, refractory hypercalcemia persisted despite the administration of bisphosphonates and denosumab indicative of refractory hypercalcemia. Elevated 1,25-dihydroxyvitamin D was noted from the second admission with hypercalcemia responding to glucocorticoid administration. A subsequent PTHrP was also elevated, further supporting multiple mechanistic evolution of HCM. The different mechanisms of HCM are summarized with the role of tailoring therapies based on the particular mechanism underlying hypercalcemia discussed. Conclusion. Our case illustrates the importance of a comprehensive initial evaluation and reevaluation of all identifiable mechanisms of HCM, especially in the setting of recurrent and refractory hypercalcemia. Knowledge of the known and possible evolution of the underlying mechanisms for HCM is important for application of specific therapies that target those mechanisms. Specific targeting therapies to the underlying mechanisms for HCM could positively affect patient outcomes.