Therapeutic effect of chemoimmunotherapy on breast cancer sensitized by polymerized human cord hemoglobin in mice: a preliminary study

Abstract

Objective To investigate the effect of polymerized human cord hemoglobin (PolyCHb) in chemoimmunotherapy for breast cancer in mice. Methods A 4T1 breast cancer in situ tumor model was established, and 15 mice were randomly divided into 3 groups: blank group: no intervention; Control group: doxorubicin + PD-1 inhibitor was given intraperitoneal injection of doxorubicin 5 mg·kg-1 once a week and PD-1 inhibitor 12.5 mg·kg-1 once a week; Experimental group: DOX+ a-PD-1+ PolyCHb, the usage of DOX and a-PD-1 was the same as above, PolyCHb: PolyCHb 600 mg·kg-1 was injected into the tail vein, three times a week; The administration period was 4 weeks. During the administration, the tumor volume was recorded 3 times per week, the tumor growth curve of each group was drawn and the tumor inhibition rate was calculated. The mice were killed on the 29th day, and the tumor was removed and weighed to calculate the tumor inhibition rate. Immunofluorescence, HE staining, TUNEL method and immunohistochemistry was used to detect the expression of HIF-1α, observe the pathological changes of tumor tissue, detect the apoptosis of tumor cells, and detect the expression of tumor proliferation index Ki67. Results Compared with the blank group and the control group, the tumor volume in the experimental group decreased significantly (P<0.05) and the tumor inhibition rate (%) increased significantly (P<0.05). The content of HIF-1α in tumor tissue in experimental group decreased (P<0.05). In the experimental group, the growth area of tumor tissue decreased, accompanied by the increase of necrosis area; The positive rates (%) of apoptosis in tumor tissues of blank group, control group and experimental group were 18.79±0.62, 20.68±1.19 and 41.65±2.99 respectively (F=135.2, P<0.001). In addition, the results of tumor proliferation index Ki67 showed that there was a statistical difference between the control group and the experimental group (P<0.05). Conclusion PolyCHb increases the sensitivity of chemoimmunotherapy in breast cancer mouse model, and the mechanism may be related to the decrease of HIF-1α expression, the promotion of apoptosis and the inhibition of cell proliferation.

Keywords

• polymerized human cord hemoglobin
• breast cancer
• in situ tumor model
• chemimmunotherapy
• animal experiments