Growth inhibition of human salivary gland tumor cells by introduction of progesterone (Pg) receptor and Pg treatment

Cancerofthesalivaryglandisoneofthecommoncancersintheheadandtheneckregions.Thistype ofcancerdevelopsintheminorandthemajorsalivaryglands,anditsometimesmetastasizestoother organs,particularlythelung.Morphologicmimicryandsimilarityintheexpressionofsteroidhormone receptorsbetweensalivaryglandtumors(SGTs)and breasttumorsarewell-knownphenomenaand are occasionally debated in the field of surgical pathology. Progesterone (Pg), one of the female sex steroid hormone, is intimately involved in the development of the mammary gland. Further, it is believedthatPgplaysaroleinbreastcancerprogression.However,littleisknownregardingitsrolein SGTs.Inthisstudy,weusedACCM,ahumanadenoidcysticcarcinomacelllineestablishedfromthe salivarygland,inordertoclarifytheroleofthePgreceptor(PR)oncellproliferation.NoeffectofPgon cellproliferationwasobservedinthePR-deficientaggressiveACCMcells.However,afterintroducing PR into the ACCM cells, Pg markedly inhibited the proliferative activity of the cells. This inhibitory effectoncellproliferationwasaccompaniedbyp21upregulation,andId1andc-mycdownregulation. Moreover, Pg-treated PR transfectants showed significant morphological change; they appeared more flattened and spread out when compared with the ethanol-treated control cells. Our results providedsignificantinsightsintothemechanismofsuppressionoftheproliferativepropertyofthecells via the function of PR, and suggested that PR reintroduction therapy might be a viable method of inhibiting human SGT progression.