Parathyroid hormone inhibits the apoptosis of osteoblast MC-3T3E1 cells through a non-PLC-dependent protein kinase C pathway / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of the non-PLC-dependent protein kinase C (PKC) pathway of parathyroid hormone (PTH) on the apoptosis and proliferation of osteoblast MC-3T3E1 cells.</p><p><b>METHODS</b>MC-3T3E1 cells were seeded in 96-well plates at the density of 1.5×10(4) cells/mL and incubated for 3 day. The cells were then exposed to 100 nmol/L of [Gly(1), Arg(19)]hPTH(1-28), 100 nmol/L of [Gly(1), Arg(19)]hPTH(1-34), 100 nmol/L of [Gly(1), Arg(19)]hPTH(1-34)+1 µmol/L Go6983, 1 µmol/L Go6983, or deionized water (control) for 1, 24 or 48 h. After the treatments, cell counting kit-8 (CCK-8) and Caspase-Glo® 3/7 Assay (Caspase-3) were used to examine the proliferation and apoptosis of MC3T3-E1 cells.</p><p><b>RESULTS</b>CCK-8 results showed that hPTH(1-34) increased the number of MC3T3-E1 cells compared with hPTH(1-34)+Go6983 at 1 h and 24 h, but this difference was not statistically different. At 48 h, treatment with hPTH(1-34), as compared with hPTH(1-28), significantly increased the number of MC3T3-E1 cells (P<0.05), and this effect was blocked by the PKC inhibitor Go6983 (P<0.05). hPTH(1-34) did not result in significant inhibition of MC3T3-E1 cell apoptosis at 1 h and 24 h as compared with hPTH(1-34)+Go6983, but significantly inhibited the cell apoptosis as compared with hPTH(1-28) (P<0.05); this inhibitory effect was blocked by Go6983 (P<0.05).</p><p><b>CONCLUSION</b>s A relatively long time (for 48 h) of exposure to PTH can inhibit apoptosis and promote the proliferation of MC3T3-E1cells through a non-PLC-dependent PKC pathway.</p>

Teriparatide for conservative treatment of osteoporotic vertebral fracture: analysis of 12 cases / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the efficacy of conservative treatment with teriparatide for promoting bone fracture healing in patients with osteoporotic vertebral fracture.</p><p><b>METHODS</b>Twelve postmenopausal patients (aged 73±4.8 years) with osteoporotic spinal fracture confirmed by MRI or CT scanning received conservative treatment with teriparatidesc injection supplemented with calcium and analgesics for 6 months. At the beginning and at the end of the therapy, VAS score, Oswestry Disability Index (ODI), bone mass densitometry, and X-ray of the thoracic and lumbar spine, and serum P1NP and beta-CTX levels were measured. Six of the patients received a second MRI scan after the therapy to evaluate the bone healing.</p><p><b>RESULTS</b>All the 12 patients completed the treatment, during which no new fractures or adverse events occurred. At the end of the first month of treatment, analgesic was withdrawn for all the patients. The average VAS score decreased from 8±2 to 1±2 at 1 month during the therapy, and ODI was reduced from (76±12)% to (20±5)% at 1 month and further to (5±4)% at 6 month. After the 6-month therapy, the height of the fractured vertebrae (presented as the anterior to posterior wall height ratio) was insignificantly decreased from (75±20)% to (61±20)%, the BMD was increased by (20±5)%, P1NP increased significantly from 20.9±11.4 ng/mL to 80.0±41.2 ng/mL, and beta-CTX increased from 0.30±0.17 ng/mL to 0.51±0.3 ng/mL. The 6 patients re-examined with MRI demonstrated complete bone healing after the therapy.</p><p><b>CONCLUSION</b>Teriparatide is effective for conservative treatment of osteoporotic spinal fracture and can promote bone fracture healing, improve the quality of life, and prevents vertebral collapse, and can be therefore an alternative treatment to PVP or BV.</p>

Activation of phospholipase C-independent protein kinase C signaling pathway of parathyroid hormone enhances CITED1 expression in mouse osteoblasts / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the functions of phospholipase C (PLC)-independent protein kinase C signaling pathway (PTH/nonPLC/PKC) of parathyroid hormone (PTH) and its role in bone metabolism.</p><p><b>METHODS</b>Osteoblasts isolated from the calvaria of 2- or 3-day-old C57BL mice, identified by alkaline phosphatase staining and Alizarin red staining, were treated for 4 h with 100 nmol/L [Gly(1), Arg(19)]hPTH(1-28) plus 10 nmol/L RP-cAMP, 10 nmol/L [Gly(1), Arg(19)]hPTH(1-34) plus 10 nmol/L RP-cAMP , 10 nmol/L PTH(1-34), or and 0.1% trifluoroacetic acid (TFA). The total RNA was then isolated for screening differentially expressed genes related to PTH/nonPLC/PKC pathway using Affymetrix mouse 12x135K gene expression profile microarray, and the identified genes were confirmed by real-time quantitative PCR. MC3T3-E1 cells treated with [Gly(1), Arg(19)]hPTH(1-28)+RP-cAMP, [Gly(1), Arg(19)]hPTH(1-34)+RP-cAMP, [Gly(1), Arg(19)]hPTH(1-34)+ RP-cAMP +100 nmol/L Go6983, or 0.1% TFA were also examined for GR(1-28)- or GR(1-34)-mediated gene expression changes using real-time quantitative PCR.</p><p><b>RESULTS</b>Alizarin red staining visualized red mineralized nodules in the osteoblasts at 28 days of culture. According to the genechip results, we selected 56 target genes related to PTH/nonPLC/PKC pathway, among which CITED1 showed higher expressions in [Gly(1), Arg(19)]hPTH(1-34)+ RP-cAMP group than in both the control group and [Gly(1), Arg(19)]hPTH(1-28)+RP-cAMP group (P<0.05), and its expression was the highest in PTH(1-34) group (P<0.05). RT-PCR of MC3T3-E1 cells yielded consist results with those in the primary osteoblasts, and the cells treated with Go6983 (a PKC inhibitor) did not show GR(1-28)- or GR(1-34)-mediated differential expression of CITED1.</p><p><b>CONCLUSION</b>The activation of PLC-independent protein kinase C signaling pathway of PTH enhances the expression of CITED1 in mouse osteoblasts to mediate the effect of PTH on bone metabolism, and this pathway is not dependent on the activation of PLC or PKA signaling.</p>