Background: Family with sequence similarity 234 member B (FAM234B ), a protein-coding gene, is mainly expressed in brain tissues. Its clinical significance and biological function in tumors, especially in breast cancer (BC), have not been elucidated.
Methods: We firstly investigated the expression pattern of FAM234B  at the mRNA and protein levels using Oncomine, TCGA portal, GEPIA, TIMER, HPA, and UALCAN databases, then applied bc-GenExMiner to assess the associations between expression level of FAM234B  and clinicopathological features of BC. Besides, we also verified the expression of FAM234B  expression in clinical BC samples using qRT-PCR. Subsequently, GEPIA, bc-GenExMiner, and TIMER databases were used to analyze the prognostic significance of FAM234B  in all BC and different molecular subtypes. Finally, we conducted co-expression analysis and gene set enrichment analysis (GSEA). Additionally, we explored the regulatory mechanism of FAM234B  in BC.
Results: Both bioinformatics analysis and experimental verification confirmed that the FAM234B  expression was significantly higher at the mRNA and protein levels in luminal BC tissues than in adjacent normal tissues. High FAM234B  expression was significantly correlated with older age, estrogen receptor-positive, progesterone receptor-positive, human epidermal growth factor receptor 2-negative, wild-type p53, low Nottingham prognostic index, low Scarff-Bloom-Richardson grade, lymph node metastasis positivity, and high tumor stage. Moreover, survival analysis indicated that high FAM234B  expression was significantly related to a worse prognosis in patients with luminal BC. GSEA indicated that FAM234B  was positively related to membrane transport process and negatively associated with immune response function. Besides, mechanism exploration indicated that pseudogene HTR7P1  might act as endogenous RNA to compete with has-miR-1271-5p  or has-miR-381-3p  for binding to FAM234B , thereby upregulating the expression of FAM234B  in luminal BC.
Conclusion: Our results suggest that FAM234B  may be a candidate therapeutic target or prognostic marker for luminal breast cancer.
Keywords: FAM234B , luminal breast cancer, HTR7P1 , prognosis