Bioinformatic analysis of the role of solute carrier-glutamine transporters in breast cancer

Background: Breast cancer (BC) is a highly heterogeneous disease. Solute carriers (SLCs) have been involved in the tumor progression of various cancer types. This study aimed to evaluate the role of these SLC-related glutamine transporters in the prognosis of BC patients by bioinformatics analysis. Methods: This study examined the transcription and prognostic data for glutamine-related transporters in BC from Oncomine Database, which is currently the largest oncogene microarray database platform in the world. As well as Gene Expression Profiling Interactive Analysis (GEPIA), Kaplan-Meier (K-M), and cBioPortal online resources. The Tumor Immune Estimation Resource (TIMER) and GEPIA were also used to examine the relationship between SLCs and immune cell infiltration. Results: The expression levels of SLC1A5, SLC3A2, SLC7A5, SLC7A8, and SLC38A1 were higher in BC tissues than normal breast tissues, but the expression level of SLC6A14 was lower. The expression levels of SLC7A5, SLC7A8, SLC6A14, and SLC38A2 were related to a later clinical tumor stage. In the K-M analyses, The K-M curves revealed that patients with high SLCIA5 expression had a poor prognosis (OS HR =1.28, 95% CI: 1.06-1.54; P=0.01). The high expression of SLC3A2 was significantly correlated with a poor prognosis (DMFS HR =1.19, 95% CI: 1.02-1.39; P=0.027). Increased SLC7A5 mRNA levels and decreased SLC7A8 mIt.NA levels were significantly associated with a poor prognosis in terms of OS, RFS, DMFS and PPS. The high expression of SLC6A14 was significantly correlated with a poor prognosis (PPS HR =1.35, 95% CI: 1.07-1.7; P=0.011). The high expression of SI.C38A1 was correlated with a better prognosis than low expression of SLC38A1 (RFS HR =0.84, 95% CI: 0.76-0.93; P=0.00077; DMFS HR =0.78, 95% CI: 0.67-0.91; P=0.0013). The infiltration of immune cells and their marker genes were associated with SLC1A5, SLC3A2, SLC7A5, SLC7A8, SLC6A14, SLC38A1, and SLC38A2 expression. SLC7A5, SLC7A8, SLC38A1, and SIE38A2 have the potential to regulate polarization in tumor-associated macrophages. Conclusions: SLC7A5, SLC7A8, SLC38A1, and SLC38A2 may regulate the polarization of tumorassociated macrophages (TAMs). SLCIA5, SLC3A2, SLC7A5, and SLC6A14 may be promising biomarkers for the BC diagnosis and may represent potential therapeutic targets for these patients.

Automated summary

This study using bioinformatics analysis found that increased expression levels of SLC-related glutamine transporters were associated with poor prognosis in breast cancer patients, while decreased expression levels of SLC6A14 and SLC38A1 were also associated with poor prognosis. Additionally, these SLC-related proteins may regulate the polarization of tumor-associated macrophages.