BackgroundBromodomain-containing　protein　(BRD)　play　a　pivotal　role　in　the　development　and　progression　of　malignant　tumours.　This　study　aims　to　identify　prognostic　genes　linked　to　BRD-related　genes　(BRDRGs)　in　patients　with　triple-negative　breast　cancer　(TNBC)　and　to　construct　a　novel　prognostic　model.MethodsData　from　TCGA-TNBC,　GSE135565,　and　GSE161529　were　retrieved　from　public　databases.　GSE161529　was　used　to　identify　key　cell　types.　The　BRDRGs　score　in　TCGA-TNBC　was　calculated　using　single-sample　Gene　Set　Enrichment　Analysis　(ssGSEA).　Differential　expression　analysis　was　performed　to　identify　differentially　expressed　genes　(DEGs):　DEGs1　in　key　cells,　DEGs2　between　tumours　and　controls　and　DEGs3　in　high　and　low　BRDRGs　score　subgroups　in　TCGA-TNBC.　Differentially　expressed　BRDRGs　(DE-BRDRGs)　were　determined　by　overlapping　DEGs1,　DEGs2　and　DEGs3.　Gene　Ontology　(GO),　Kyoto　Encyclopedia　of　Genes　and　Genomes　(KEGG)　pathway　analysis,　and　protein-protein　interaction　(PPI)　network　analysis　were　conducted　to　investigate　active　pathways　and　molecular　interactions.　Prognostic　genes　were　selected　through　univariate　Cox　regression　and　least　absolute　shrinkage　and　selection　operator　(LASSO)　regression　analyses　to　construct　a　risk　model　and　calculate　risk　scores.　TNBC　samples　from　TCGA-TNBC　were　classified　into　high　and　low-risk　groups　based　on　the　median　risk　score.　Additionally,　correlations　with　clinical　characteristics,　Gene　Set　Enrichment　Analysis　(GSEA),　immune　analysis,　and　pseudotime　analysis　were　performed.ResultsA　total　of　120　DE-BRDRGs　were　identified　by　overlapping　605　DEGs1　from　four　key　cell　types,　10,776　DEGs2,　and　4,497　DEGs3.　GO　analysis　revealed　enriched　terms　such　as　＇apoptotic　process,＇　＇immune　response,＇　and　＇regulation　of　the　cell　cycle,＇　while　56　KEGG　pathways,　including　the　＇MAPK　signaling　pathway,＇　were　associated　with　DE-BRDRGs.　A　risk　model　comprising　six　prognostic　genes　(KRT6A,　PGF,　ABCA1,　EDNRB,　CTSD　and　GJA4)　was　constructed.　A　nomogram　based　on　independent　prognostic　factors　was　also　developed.　Immune　cell　abundance　was　significantly　higher　in　high-risk　group.　In　both　risk　groups,　TP53　exhibited　the　highest　mutation　frequency.　The　expression　of　KRT6A,　ABCA1,　EDNRB,　and　CTSD　went　decreased　progressively　in　pseudotime.ConclusionA　novel　prognostic　model　for　TNBC　associated　with　BRDRGs　was　developed　and　validated,　providing　fresh　insights　into　the　relationship　between　BRD　and　TNBC.