Polychlorinated　biphenyls　(PCBs)　are　still　prevalent　in　the　environment　despite　the　fact　that　they　have　been　banned　in　many　countries　for　several　decades.　Recent　epidemiologic　studies　have　demonstrated　a　link　between　PCBs　exposure　and　pathological　alterations　of　bone　tissues.　The　aim　of　this　study　was　to　investigate　the　toxic　effects　of　the　PCBs　mixture　Aroclor　1254　on　MC3T3-E1　preosteoblasts　and　explore　the　underlying　molecular　mechanism.　Different　doses　of　Aroclor　1254　were　used　to　treat　MC3T3-E1　and　the　cell　viability,　apoptosis.　ALP　activity,　intracellular　calcium　(Ca2+)　level　and　oxidative　stress　response　were　measured.　The　expression　level　of　related　proteins　TRPV6,　Apaf-1　and　Bax　was　evaluated　with　Western　blot　assay.　The　subcellular　distribution　of　TRPV6　protein　was　detected　with　immunofluorescence　assay.　The　results　indicated　that　the　higher　dose　of　Aroclor　1254　(＞10　mg/L)　could　inhibit　the　cell　proliferation　and　induce　apoptosis　in　MC3T3-E1.　The　ROS　level　following　Aroclor　1254　exposure　was　elevated　with　the　concentration,　while　the　ALP　activity　and　intracellular　calcium　(Ca2+)　level　decreased.　After　Aroclor　1254　exposure,　the　expression　level　of　calcium　transport　related　protein　TRPV6　was　down-regulated,　while　the　expression　level　of　apoptosis　related　proteins　Apaf-1　and　Bax　up-regulated　in　a　dose　dependant　manner.　The　immunofluorescence　assay　results　showed　that　the　expression　of　TRPV6　in　the　cytoplasm　was　greatly　suppressed　after　Aroclor　1254　exposure.　In　conclusion,　Aroclor　1254　exposure　could　induce　toxic　effects　in　MC3T3-E1　as　evidenced　by　inhibition　of　proliferation,　induction　of　apoptosis　and　suppression　of　ALP　activity.　The　ROS　production　and　alteration　of　intracellular　Ca2+　level　induced　by　down-regulation　of　TRPV6　might　involve　the　toxic　effects,　and　cell　apoptosis　induced　by　Aroclor　1254　exposure　is　associated　with　the　pro-apoptotic　Apaf-1　pathway　as　well　as　alteration　of　Bcl-2/Bax　ratio.　(C)　2012　Elsevier　Ireland　Ltd.　All　rights　reserved.