Objective To investigate the relationships of the mRNA expression levels of mitochondrial ribosomal large subunit protein 13 (MRPL13), BCL2-associated protein A1 (BCL2A1) and TP53 apoptosis-inducing protein 1 (TP53AIP1) in the serum of breast cancer patients with their chemotherapy efficacy as well as immune function.

Methods A total of 148 triple-negative breast cancer patients undergoing chemotherapy were selected as the study subjects. Based on chemotherapy efficacy, they were divided into responsive group (97 cases) and non-responsive group (51 cases). Sixty healthy individuals undergoing physical examinations during the same period were selected as the control group. The mRNA expression levels of MRPL13, BCL2A1 and TP53AIP1 in the serum of patients were detected. The concentrations of immunoglobulin M (IgM), immunoglobulin G (IgG) and immunoglobulin A (IgA) in the serum of patients were measured, and the proportions of CD4⁺ and CD8⁺ cells in whole blood were determined. The mRNA expression levels of MRPL13, BCL2A1 and TP53AIP1 were compared between the breast cancer group and the control group. The mRNA expression levels of MRPL13, BCL2A1 and TP53AIP1 were compared between the responsive and non-responsive groups. The differences in immune function indicators before and after chemotherapy between the responsive and non-responsive groups, were compared. The correlations of the mRNA expression levels of MRPL13, BCL2A1 and TP53AIP1 with immune indicators were analyzed. Factors influencing chemotherapy efficacy were screened.

Results The mRNA expression levels of MRPL13 and BCL2A1 in the breast cancer group were higher than those in the control group, while the mRNA expression level of TP53AIP1 was lower, with statistically significant differences (P < 0.05). In the responsive group, the mRNA expression levels of MRPL13 and BCL2A1 were lower than those in the non-responsive group, while the mRNA expression level of TP53AIP1 was higher, with statistically significant differences (P < 0.05). After chemotherapy, the IgM concentration in the responsive group was higher than that in the non-responsive group, with a statistically significant difference (P < 0.05). The proportion of CD8⁺ cells in the responsive group was lower than that in the non-responsive group, with a statistically significant difference (P < 0.05). The mRNA expression level of MRPL13 was positively correlated with IgM, IgG and CD8⁺ (r=0.672, 0.716, 0.824, P < 0.05). The mRNA expression level of BCL2A1 was positively correlated with IgA and CD4⁺ (r=0.654, 0.862, P < 0.05). The mRNA expression level of TP53AIP1 was negatively correlated with CD4⁺ and CD8⁺ (r=-0.846, -0.792, P < 0.05). High expressions of MRPL13 and BCL2A1 were independent risk factors for chemotherapy efficacy in breast cancer patients (P < 0.05), while high expression of TP53AIP1 was protective factor (P < 0.05).

Conclusion The mRNA expression levels of MRPL13, BCL2A1 and TP53AIP1 in the serum of triple-negative breast cancer patients undergoing chemotherapy are correlated with the levels of IgM, IgG and IgA, the proportions of CD4⁺ and CD8⁺ T cells, and chemotherapy efficacy. High expression of MRPL13 and BCL2A1 are independent risk factors for poor chemotherapy efficacy, while high expression of TP53AIP1 is a protective factor.