Abstract
Rhein, an anthraquinone extracted from rhubarb, is used in traditional Chinese medicine
for diuresis, diarrhoea, inflammation, and immune regulation. Atezolizumab, a programmed
cell death ligand 1 monoclonal antibody, is mainly used to treat bladder cancer and
non-small cell lung cancer unresponsive to chemotherapy. We explored the effects of
rhein and atezolizumab in combination on breast cancer. Mice with established 4T1
breast cancer xenografts were administered rhein (10 mg/kg) and atezolizumab (10 mg/kg),
alone and in combination, and the effects on tumour growth were evaluated. The proportion
of CD8+ T cells in the spleen and tumour tissue, the levels of TNF-α, and interleukin-6 in serum as well as the mRNA levels of apoptotic factors (caspase-3,
caspase-8, caspase-9, and Bax/Bcl-2) were also evaluated. All of the treatment groups
had inhibitory effects on the xenograft tumour growth, with results that were significantly
different from those in the control group. In addition, the proportion of CD8+ T cells
in the spleen and tumour was significantly increased in the combination therapy group
and was significantly different from the other treatment groups. The serum levels
of TNF-α and IL-6 were significantly increased in the rhein and combination therapy groups.
Finally, the levels of various apoptotic factors in tumour tissues were significantly
higher in the combination treatment group than those in the other groups. Administration
of rhein, atezolizumab, or their combination all had therapeutic effects on 4T1 breast
cancer xenografts in mice, with the combination treatment having stronger effects.
Key words
rhein - atezolizumab - combined therapy - 4T1 - apoptosis factors
