Prostate Cancer Cell Extracellular Vesicles Increase Mineralisation of Bone Osteoblast Precursor Cells in an In Vitro Model

Skeletal metastases are the most common form of secondary tumour associated with prostate cancer (PCa). The aberrant function of bone cells neighbouring these tumours leads to the devel-opment of osteoblastic lesions. Communication between PCa cells and bone cells in bone envi-ronments governs both the formation/development of the associated lesion, and growth of the secondary tumour. Using osteoblasts as a model system, we observed that PCa cells and their conditioned medium could stimulate and increase mineralisation and osteoblasts’ differentiation. Secreted factors within PCa-conditioned medium responsible for osteoblastic changes included small extracellular vesicles (sEVs), which were sufficient to drive osteoblastogenesis. Using MiR-seq, we profiled the miRNA content of PCa sEVs, showing that miR-16-5p was highly ex-pressed. MiR-16 was subsequently higher in EV-treated 7F2 cells and a miR-16 mimic could also stimulate mineralisation. Next, using RNA-seq of extracellular vesicle (EV)-treated 7F2 cells, we observed a large degree of gene downregulation and an increased mineralisation. Ingenuity® Pathway Analysis (IPA®) revealed that miR-16-5p (and other miRs) was a likely upstream effec-tor. MiR-16-5p targets in 7F2 cells, possibly involved in osteoblastogenesis, were included for val-idation, namely AXIN2, PLSCR4, ADRB2 and DLL1. We then confirmed the targeting and dow-regulation of these genes by sEV miR-16-5p using luciferase UTR (untranslated region) reporters. Conversely, the overexpression of PLSCR4, ADRB2 and DLL1 lead to decreased osteoblastogene-sis. These results indicate that miR-16 is an inducer of osteoblastogenesis and is transmitted through prostate cancer-derived sEVs. The mechanism is a likely contributor towards the for-mation of osteoblastic lesions in metastatic PCa.

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.

An Ancient Skeleton with Multiple Osteoblastic Bone Lesions Containing a Scapular Sunburst Appearance from a 5th–6th Century Grave Excavated in Oita, Japan

A human skeleton of a middle-aged adult male was found in a 5th–6th century Kinoue-Kodo stone coffin excavated from the southwest marginal region of the Oita plains, northeast Kyushu, Japan. The skeleton was buried respectfully in the ancient tomb, and red pigment was applied to his face after death. We report herein findings from computed tomography imaging of the skeleton and discuss the multiple osteoblastic lesions identified in the humerus, scapula, clavicle, vertebra, pelvic bones, and skull of this individual. These lesions comprised cortical bone thickening with periosteal reaction localized to the surface and osteosclerotic changes mainly observed in the trabecular structure of cancellous bone. In particular, a typical sunburst pattern was also noted on the left scapula as another characteristic lesion found in this case. By differential diagnosis, the disease suffered by this individual was most likely to be metastatic bone tumors, especially of prostate cancer. This person may have survived until many bone metastases had developed throughout his whole body.

Different Levels of Alkaline Phospatase (ALP) in Multiple Myeloma (MM) and SOLID Tumors with BONE Lesions

Background: alkaline phosphatase (ALP) is an enzyme localized in different tissues and its levels may increase in diseases with skeletal involvement. Aim: To compare ALP levels in patients with Multiple Myeloma and osteolytic lesions, and in patients with solid tumors (breast, prostate, lung, stomach, kidney and colon) and osteolytic, osteoblastic and mixed (osteolytic and osteoblastic) bone metastatic lesions. Patients and Methods: From 1991 we collected 400 patients with MM and 308 patients with solid cancer with bone involvement. We grouped patients according to the metastases type (osteolytic, osteoblastic mixed), number of metastasis (1, 2-3, more than 3), ISS and D&S Stage. Among patients with solid tumors 45% had lytic lesions, while 31,5% had osteoblastic lesions and 23,5% had mixed lesions. Comparing MM vs. bone metastasis from solid cancer respectively 64.5% vs. 59% had normal ALP values, while 29% vs. 28% had <2xUNL, and 6.5% vs. 13% had >2UNL values of ALP. Patients with MM had significantly lower ALP values when compared to patients with osteoblastic bone lesions (P<0.05). In particular, comparing ALP levels of MM patients with the levels observed in cancer patients with >3 osteoblastic lesions difference is even more significant (P<0.01). Moreover, patients with Breast and Prostate cancer had ALP values significantly higher than MM pts (P<0.05 and P<0.05 respectively).In the group of patients with solid tumors, ALP levels were significantly higher in those with >3 osteoblastic lesions than in those with only osteolytic lesions (P<0.05). Conclusion: These preliminary results indicate that ALP should be part of the initial work up in pts with bone lesions. This simple and cheap test, if normal or reduced in presence of osteolytic bone lesions, suggests an initial complete protein study including serum and urine protein electrophoresis associated to Bone Marrow aspirate, in case of the presence of a paraprotein. Disclosures Petrucci: Celgene, Janssen-Cilag, Amgen, Mundipharma, BMS: Honoraria.

Traumatic Fracture in a Patient with Osteopoikilosis

We report a case of traumatic humeral neck fracture occurring in a patient with osteopoikilosis after a motorcycle accident. The radiograph revealed the fracture but also multiple bone lesions. A few years before, the patient had been operated for a maldiagnosed chondrosarcoma of the humeral head. Osteopoikilosis is a rare benign hereditary bone disease, whose mode of inheritance is autosomal dominant. It is usually asymptomatic and discovered incidentally on radiograph that shows the presence of multiple osteoblastic lesions. It can mimic other bone pathologies, in particular osteoblastic metastases. Osteopoikilosis is a diagnosis that should be kept in mind to avoid misdiagnosis, particularly with regard to cancer metastasis. This disorder does not require any treatment and complications are rare. However, there may be associated anomalies that require follow-up.