Study On Silica Induced DNA Damage In Cells And Its Influensce Factors

BaCkgroopd and ObjcctivesThe morbdfy of Silicosis is the higheSt amon PneUmOCOoSis Whichis the moSt Serious oeetwonal disease in our coUnny SilicoSs is aforc and unreversed lung disease, whch is caused by inhaltw ofSiliwt M, and lung Nis is a Prominot histOlogical haur.The mebosm causing fibros in silicosis hasn't been foUn ou yet.M haS declared tha Silica pAncles are caIcingen fOr huInan beings(GrOU D in Octl996. The reledOnShi among silica. Silicosis and lungcancer W, is still a hOtpe for ocCUPaonal health. COInet asscy is araPd, sHe, visual and tw tecboque for measwi DNA singleStran breakag in W mammallan cells. And it has been widelyused in genec toticOlogy ndobiology and biological mWring inrecent years' We wan to deteC DNA Stha breakags in Chinse HamstLun fibrolast (Cap and normal nd luns tw I ePthelial eells (Cct-64) exPosed to low doses of silica pwhcles (7.5l20ptw ) by comet asSayand tO W its dOse-effee reati~s. We also study the inllUenCe ofWYl radicals derived from Fenton reacion and calcium ion incytOsolic influxing thrOugh plasma IneInbran Ca2+ channel dndngdamaging process by using deferoxfore and veraPdril. --MateriaIs and McthodsWe rneasurd DNA damage of CHL and CCL-64 cell lines eXposed tosilica suSPension (the final concentalons of Silica in medium wer at rangrof 0, 7.5, l5, 30, 60 and l20 pg/nil) and then inCUated for l or 2 h at 37"Cdri 5% CO2, resPectivdy CHIJ cells wer also eXPosed tO both 90pg/nilsilica and a series of concentraions of dehaXtw (0 InM, 0.5 InM, l .0InM, 2.0InM) and veraPed (0upe, 2.5llg/ml, 5.0ug/nil, 10.0Pg/IIil,20.0pfor for 2h to detCct if they hav Protethe effeCts. At the end of thecultUI period, the cells wer bested by 025% twsin sofution and itsdenSty were adjUSted to l0'-l(ha. The viability of the cells werW by tryPapbine exclusion. de slide PreParation alkW lySs,W H' eleCtrophDsis and stain wh eAndiUm brdride op,the tail lengths of comet tw end of heads to end of ndls) must beIneaSed Unde a fluOrescence ndcroscope using a calforn scale and areused to eValuat the degree of M H' We use SPSS softwar tOmake statiincal analySis and nOnPMc hatistics are eInPloyed.RechThe tail lengths were sighficantiy lonpe in eXPosed cells, includinCffe and CCL64 cells, comared to maW contrOls (P<0.0l), and wereW in a dose-bo manner for 7.5~l20llpe silica. We USecurvilinear regression assay and find tha the effectcurvs is moSt suitableto cubic eqUation. Generaily the tall length Of cOmetS in tWo-hour grOUwer longer than onefor grouP. When eXposed to 90pg/ml silica particles,0.5n.0mM for and 2.5n0.0ptw veraPamil can attenuasilicaindueed W W effeforly Their Protective effects werincreased in a concentalondePenden manner 2.0InM deferoxamine canreduee 2/3 length of comet, and 20.0pg/nd Veradril can descend tO1/5length of POfor cOntrl.ConcIusionsSilicon diokide pAncles haVe wtcty It can indUCe DNA strandbreakag in vitro in CHL and CCL64 cell lines. Caldri ion and reactiveoXygen lers, esPeCally hydrxy radical, wer aCtiv in this Process.The Fento for was one of soures Of hydroxy edcals and theeleVallon of caldri ion in cytosolic was dUe mainl to inflUX throughplasma meInbran Ca2+ for. Calchnn for blocke can attenUa the effCCt of silica. It may be uSeful in aptw caldri boblocker and antiokidan to g and treatin PneUmOCOSis.