Animal Posters.

A-1008Cadmium Affects Expression of Several microRNAs That Regulate the Wnt-beta Catenin Pathway in the hFOB 1.19 Osteoblast Cell Line. MICHAEL J. FAY, Elisha Pendleton, and Nalini Chandar. Midwestern University, Downers Grove, IL 60515. Email: mfayxx@midwestern.eduCadmium, an environmental pollutant, is known to cause bone damage and osteoporosis in individuals exposed to it. While several different mechanisms have been reported for their effects on bone, we and others have focused on the Wnt-beta catenin pathway as it plays an important role in osteoblast differentiation. As several microRNAs (miRNAs) can influence this pathway, we first conducted a study to determine the effect of cadmium using a human microRNA array containing 2632 unique probes. We found over 100 different miRNAs to be significantly altered by exposure of osteoblasts to 0.2 μM cadmium chloride for 24 hours. Roughly half of these miRNAs showed a significant increase or decrease in expression after cadmium treatment. We validated the changes seen in the microarray with a subset of these miRNAs using Realtime PCR. To determine how cadmium affects osteoblast differentiation, we chose a set of miRNAs that are known to either positively or negatively affect osteoblast differentiation via the Wnt/beta catenin pathway. The expression of these miRNAs was analyzed after exposure of cells to an osteoblast differentiation promoting media for 1, 3 and 7 days. As expected in osteoblasts miRNAs 119a, 15b, 21a, 24, 146a and 335 were increased robustly with differentiation. Cadmium treatment either resulted in no significant response or a stunted response. In the case of miRNAs that are known to negatively impact osteoblast differentiation, we found miR23b to be reduced during differentiation while cadmium treatment increased it. In the case of miRNAs 30b and 30d the levels remained reduced in both treatment types. Overall, these results show that treatment with cadmium can also affect miRNAs and cause an inhibition to osteoblast differentiation by altering the Wnt/beta catenin pathway.