Objective　Renal　cell　carcinoma　is　a　malignant　tumor　originating　from　the　renal　tubular　epithelial　system.In　the　fieldof　miRNA　biomarkers　for　renal　cancer,many　previous　researches　had　ignored　the　large　gap　in　the　amounts　of　samples　betweendifferent　subtypes　of　renal　cancer,this　may　lead　to　differences　in　the　diagnostic　ability　of　selected　miRNA　biomarkers　amongpatients　with　different　subtypes　of　renal　cancer,and　may　cause　missed　diagnosis　and　misdiagnosis.Therefore,we　considered　twosubtypes　of　kidney　cancer　common　markers　for　the　study.MethodsStatistics　and　two　machine　learning　methods　were　performedto　screen　the　expression　profile　data　of　clear　renal　cell　carcinoma(ccRCC,KIRC)and　papillary　renal　cell　carcinoma(pRCC,KIRP)respectively　and　the　results　were　intersected　to　obtain　common　miRNA　markers　for　both　types　of　kidney　cancer.Then,ROC　curvewas　used　to　verify　the　diagnostic　ability　of　these　biomarkers,machine　learning　methods　using　external　data　set(KICH)were　alsoconformed　to　these　biomarkers,the　two　methods　further　proved　that　these　miRNA　biomarkers＇diagnostic　ability　and　avoided　over-fitting.The　rationality　of　these　biomarkers　was　also　verified　by　existing　experimental　literature.The　molecular　mechanisms　ofmiRNA　markers　were　investigated　using　bioinformatics　methods.ResultsA　total　of6common　miRNA　markers　for　both　types　ofkidney　cancer　were　obtained(miR-21,mir-210,mir-185,mir-188,mir-362,mir-199a-2),4of　them　have　been　reported　to　beassociated　with　renal　cancer.Mir-188and　mir-199a-2have　not　been　reported　to　be　associated　with　renal　cancer,and　maybe　novelmiRNA　biomarkers　of　renal　cancer.Then,we　performed　bioinformatic　analysis　on　these6miRNA　biomarkers,the　results　showedthat　the　newly　discovered　biomarkers(mir-188and　mir-199a-2),were　involved　in　the　regulation　of　two　renal　cancer　related　pathway,MAPK　signaling　pathway　and　TGF-beta　signaling　pathway.The　differential　expression　of　miRNA　and　its　target　genes　in　the　pathwaywas　verified,which　further　proved　the　reliability　of　miRNA　as　a　marker　and　its　regulatory　effect　on　target　genes.Also　a　possiblemechanism　of　how9target　genes　of　mir-185(all　belonging　to　the　UGT1A　gene　family)participate　in　renal　cancer　was　found,andthere　was　no　related　literature.ConclusionThe　present　study　identifies　possible　new　common　miRNA　markers　for　both　types　ofkidney　cancer　and　discovers　a　mechanism　of　kidney　carcinogenesis　that　has　not　been　seen　in　kidney　cancer-related　fields.