Osteocalcin (OCN) is a bone-derived hormone involved in the regulation of glucose metabolism. In serum, OCN exists in carboxylated and uncarboxylated forms (ucOCN), and studies in rodents suggest that ucOCN is the bioactive form of this hormone. Whether this is also the case in humans is unclear, because a reliable assay to measure ucOCN is not available. Here, we established and validated a new immunoassay (ELISA) measuring human ucOCN and used it to determine the level of bioactive OCN in two cohorts of overweight or obese subjects, with or without type 2 diabetes (T2D). The ELISA could specifically detect ucOCN concentrations ranging from 0.037 to 1.8 ng/mL. In a first cohort of overweight or obese postmenopausal women without diabetes ( n = 132), ucOCN correlated negatively with fasting glucose (r = −0.18, P = 0.042) and insulin resistance assessed by the homeostatic model assessment of insulin resistance (r = −0.18, P = 0.038) and positively with insulin sensitivity assessed by a hyperinsulinemic-euglycemic clamp (r = 0.18, P = 0.043) or insulin sensitivity index derived from an oral glucose tolerance test (r = 0.26, P = 0.003). In a second cohort of subjects with severe obesity ( n = 16), ucOCN was found to be lower in subjects with T2D compared with those without T2D (2.76 ± 0.38 versus 4.52 ± 0.06 ng/mL, P = 0.009) and to negatively correlate with fasting glucose (r = −0.50, P = 0.046) and glycated hemoglobin (r = −0.57, P = 0.021). Moreover, the subjects with ucOCN levels below 3 ng/mL had a reduced insulin secretion rate during a hyperglycemic clamp ( P = 0.03). In conclusion, ucOCN measured with this novel and specific assay is inversely associated with insulin resistance and β-cell dysfunction in humans.

Anti-CD47 antibodies have been shown to inhibit the progression of several types of cancer by blocking the “don’t eat me” signals to macrophage through CD47/SIRPα interaction, causing phagocytosis of tumor cell. However, mechanistic details in the response of the cancer cells still remain to be explored. In this study, we investigated different cytokine levels in 4T1 mammary carcinoma induced mouse breast cancer model with or without anti-mouse CD47 monoclonal antibody treatment. The data showed that this cancer model presented significantly higher percentages of CD11b+, CD43+, CD80+, CD86+ and CD371+ cells after 1 week of 4T1 cells injection, CD11b+ cells percentage has been reached to 40% and 90% in spleen and bone marrow respectively at 2 weeks after 4T1 cells injection. After 4 doses of anti-mouse CD47 antibody treatment (i.p. injection per 2 days started from one week after 4T1 challenge), anti-CD47 antibody reduced significantly not only tumor size but also the levels of IL-1α in spleen (P=0.026) and of MCP-1/CCL2 in tumors (P=0.029). Interestingly, fresh isolated 4T1 induced breast cancer mouse spleen and bone marrow cells appeared 5%-10% CD11b+/Sca-1+ populations whereas in vitro culture of 4T1 cells had 5% of cells of Sca-1+/CD326+. When the freshly isolated 4T1 induced breast cancer mouse spleen and bone marrow cells were continuously cultured for 2–3 weeks, CD326+ cells became dominant and about 10% – 30% of population showed Sca-1+/CD11b+ positive. This study provided inside thoroughly investigated the response of cytokines and 4T1 cells induced mouse mammary carcinoma. Our data may further discover the mechanism for tumor growth and metastasis.