BC is the predominant malignant tumor that endangers female physical and mental health. BC incidence has been rising year by year, and the tendency for rejuvenation is obvious, presenting an urgent need for an accurate tool to predict BC prognosis for improvements in clinical diagnosis and treatment. Necroptosis occurs under the mediation of death receptors and their ligands when the apoptotic pathways are inhibited17. In cancer, necroptosis plays complex roles, especially in cancer development and progression18. As of today, no previous reports have attempted to predict BC prognosis by constructing predictive signatures based on necroptosis-related lncRNAs.
In this study, a co-expression network of necroptosis-related genes and lncRNA was implemented to screen the necroptosis-related lncRNAs. Furthermore, Cox and Lasso regression analyses were implemented to reveal 10 prognostic necroptosis-related lncRNAs, namely AL606834.2, SEMA3B-AS1, AL731571.1, BAIAP2-DT, EGOT, AL136531.1, LINC01871, AL122010.1, OTUD6B-AS1, and Z68871.1. These lncRNAs may serve as the potential therapeutic targets and prognostic molecular markers for BC patients. Besides, several mRNAs (e.g. BCL2, BIRC3, CFLAR, CHMP2A, CHMP4A, CHMP4C, JMJD7a, and TRPM7) were also found to significantly co-express with these lncRNAs.
Three necroptosis-related lncRNAs (SEMA3B-AS1, EGOT, OTUD6B-AS1) were revealed to be cancer-associated. Specifically, an upregulation of SEMA3B-AS1 was found in hepatocellular carcinoma (HCC) and the overexpression of the lncRNA may promote PTEN expression, which could in turn inhibit the proliferation of hepatocellular carcinoma cells. Besides, SEMA3B-AS1 is also a prognostic marker for HCC19. Firstly, previous research has shown that SEMA3B, miR-6872-5p, and SEMA3B-AS1 may impose tumor-suppressive effects in the tumorigenesis of gastric cardia adenocarcinoma. Moreover, these molecules may also be used as potential markers in predicting the survival and prognosis of gastric cardia adenocarcinoma patients20. Secondly, EGOT upregulation is marked in gastric cancer (GC), and such upregulation is related to the TNM stages and lymphatic metastasis. In addition, siRNA-mediated EGOT knockdown could provide a marked inhibition on GC cell proliferation and arrest cell cycles in the G1 phase. As an oncogene in GC, EGOT could be adopted as a convincing biomarker for GC diagnosis and prognosis21. Thirdly, OTUD6B-AS1 was found to be downregulated in thyroid carcinoma (TC) tissues, and its expression is correlated with size of the tumor size, clinical stages, and the lymphatic metastasis of TC. Besides, OTUD6B-AS1 overexpression demonstrated a significant and negative correlation with the viability as well as the migration and invasion capabilities of TC cells22.
The three necroptosis-related lncRNAs (BAIAP2-DT, LINC01871, Z68871.1) can be used as markers for the prognosis of BC, but the pathogenesis of BC has not yet been studied in depth23. As for the other 4 lncRNAs (AL606834.2, AL731571.1, AL136531.1, AL122010.1), no previous studies have been published about their prognostic roles in cancer.
In this study, 10 necroptosis-related lncRNAs were used to construct a signature model that can predict BC prognosis with satisfactory prediction performance. Specifically, compared to the predicted high-risk group, the predicted low-risk group exhibited longer OS, which had been revealed in previous studies. The AUC values corresponding to 1, 3, and 5-year survival were 0.71, 0.729 and 0.707, respectively, indicating some potential in the constructed risk score signature to predict survival. Besides, according to the results of univariate and multivariate Cox analyses, the constructed signature is an independent prognostic indicator. C-index results, ROC curves, and calibration curves suggested that the model proposed in this study exhibited good precision and accuracy, demonstrating the model’s potential as a predictive tool for BC patients.
Functional enrichment analysis found that the identified necroptosis-related prognostic lncRNAs were enriched in signal transduction, metabolism, immune-related regulations as well as the formation of malignant tumors. Furthermore, the gene sets were revealed to be correlated to tumorigenesis and cancer progression, which has provided more information about the mechanisms of the effects of necroptosis-related lncRNAs. Previous studies have suggested that necroptosis signaling may involve in the proliferation and migration of BC cells. Specifically, the key components of necroptosis signaling were identified to correlate significantly with the pathological and clinical parameters of BC, and such correlations were present regardless of TNM stages and pathological subtypes; therefore, necroptosis activation could be a common phenomenon along with BC development. In addition, necroptosis activation was well correlated with TNFα expression, and TNFα is a key pro-inflammatory factor that recruits immune cells to tumors. In a word, necroptosis signaling pathways are endogenous protective pathways in human systems, and these pathways are activated to counter tumor malignancy, representing a potential target for BC therapy24.
Subsequent GSEA results showed that the high-risk group exhibited higher macrophage scores. Previous studies have revealed that tumor-associated macrophages (TAMs) can promote tumorigenesis in the BC microenvironment. In BC models, preclinical TAMs were found to possibly stimulate the tumor cell growth,, invasion, and metastasis of BC while inducing resistance against multiple treatments25.
Besides, this study also showed that high-risk patients as identified by the proposed model are possibly more sensitive to anti-CD80, TNF SF4, or CD276 immunotherapies and conventional chemotherapy drugs (including AKT inhibitor VIII, Saracatinib, Bicalutamide, Imatinib, Lapatinib, Linsitinib, and Pazopanib) while being more resistant to methotrexate, suggesting that these BC patients can benefit from the individualized and precise combination of immunotherapies and chemotherapies.
However, this research still exhibit certain limitations. First, data from other databases are needed to perform external validation on our predictive signature for its applicability. Second, the action mechanisms of the necroptosis-related lncRNAs in BC still need more investigations.