Apoptin can specifically kill cancer cells but has no toxicity to normal cells. Human telomerase reverse transcriptase (hTERT) can act as a tumour‐specific promoter by triggering the expression of certain genes in tumour cells. This study aims to investigate the inhibitory effects and to explore the inhibitory pathway of a dual cancer‐specific recombinant adenovirus (Ad‐apoptin‐hTERTp‐E1a, Ad‐VT) on breast cancer stem cells. Breast cancer cell spheres were obtained from MCF‐7 cells through serum‐free suspension culture. The cell spheres were detected by flow cytometry for CD44⁺ CD24⁻ cell subsets. The stemness of MCF‐7‐CSC cells was confirmed by in vivo tumorigenesis experiments. The inhibitory effect of the recombinant adenoviruses on MCF‐7‐CSC cells was evaluated by CCK‐8 assay. In addition, the stemness of adenovirus‐infected MCF‐7‐CSC cells was analysed by testing the presence of CD44⁺ CD24⁻ cell subsets. The ability of the recombinant adenovirus to induce MCF‐7‐CSC cell apoptosis was detected by staining JC‐1, TMRM and Annexin V. Our results showed that a significantly higher proportion of the CD44⁺ CD24⁻ cell subsets was present in MCF‐7‐CSC cells with a significantly increased expression of stem cell marker proteins. The MCF‐7‐CSC cells, whlist exhibited a strong tumorigenic ability with a certain degree of stemness in mice, were shown to be strongly inhibited by recombinant adenovirus Ad‐VT through cell apoptosis. In addition, Ad‐VT was shown to exert a killing effect on BCSCs. These results provide a new theoretical basis for the future treatment of breast cancer.

中文翻译：

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双重癌症特异性溶瘤腺病毒对乳腺癌干细胞的抗肿瘤作用

凋亡素可以特异性杀死癌细胞，但对正常细胞没有毒性。人类端粒酶逆转录酶 (hTERT) 可以通过触发肿瘤细胞中某些基因的表达来充当肿瘤特异性启动子。本研究旨在探讨双重癌症特异性重组腺病毒（Ad-apoptin-hTERTp-E1a，Ad-VT）对乳腺癌干细胞的抑制作用和抑制途径。通过无血清悬浮培养从 MCF-7 细胞中获得乳腺癌细胞球。通过流式细胞仪检测细胞球的 CD44 ⁺ CD24 ^-细胞亚群。体内肿瘤发生实验证实了 MCF-7-CSC 细胞的干性。通过CCK-8法评价重组腺病毒对MCF-7-CSC细胞的抑制作用。此外，通过检测 CD44 ⁺ CD24 ^-细胞亚群的存在来分析腺病毒感染的 MCF-7-CSC 细胞的干性。通过染色 JC-1、TMRM 和 Annexin V 检测重组腺病毒诱导 MCF-7-CSC 细胞凋亡的能力。我们的结果表明，CD44 ⁺ CD24 ^{-的比例明显更高。}细胞亚群存在于 MC​​F-7-CSC 细胞中，干细胞标记蛋白的表达显着增加。MCF-7-CSC 细胞在小鼠体内表现出很强的致瘤能力和一定程度的干性，通过细胞凋亡被重组腺病毒 Ad-VT 强烈抑制。此外，Ad-VT 被证明对 BCSCs 具有杀伤作用。这些结果为今后乳腺癌的治疗提供了新的理论依据。