乳腺癌是全球女性中最致命的癌症类型。许多针对乳腺癌的化学治疗药物具有可怕的副作用。控制肿瘤细胞增长的一种方法是靶向凋亡。本研究旨在通过抑制Caspases 8和9，以从人类乳汁中的Lactobacillus reuteri分离物纯化L-天冬氨酸酶来诱导乳腺癌细胞凋亡。从人类乳汁中鉴定出产生酶活性最高的L. reuteri分离物，用于L-天冬氨酸酶纯化。使用MTT细胞存活率试验来测量酶的毒性。使用基质细胞系研究酶对Caspase 8和Caspase 9基因表达的影响。MTT细胞存活率试验显示，当使用3.125、6.25、12.5、25、50和100 μg/ml的酶时，细胞死亡的抑制率在30%至80%之间，IC50为4.305 μg/ml。将乳腺细胞系以IC50浓度的酶进行处理。在L-天冬氨酸酶处理的乳腺癌细胞系中，以IC50浓度为单位，Cas8和Cas9基因表达上调（基因表达倍数分别为2.071和1.197）。乳汁中的L. reuteri L-天冬氨酸酶通过Cas8和Cas9上调诱导乳腺癌细胞系凋亡。L. reuteri L-天冬氨酸酶治疗可能是管理乳腺癌的有希望的方法。此外，结果可能还突显出人类乳汁中存在L-天冬氨酸酶产生的L. reuteri分离物能够帮助改善或甚至预防乳腺癌的事实。

Breast cancer is the most fatal type of cancer in women worldwide. Many chemotherapeutics targeted breast cancer however, they have frightening side effects. One method of controlling cancer cell growth is targeting apoptosis.This study aimed to induce apoptosis in breast cancer cells by purifying L-asparaginase from human breast milk Lactobacillus reuteri isolates via inhibition of Caspases 8 and 9.The best L. reuteri isolates producing L-asparagine with the highest enzyme activity were identified from human breast milk and chosen for L-asparaginase purification. The MTT cell viability assay used for measure the toxicity of the enzyme. Breast cancer cell line was used to study the effect of the enzyme on the caspase 8 and caspase 9 gene expression.The MTT cell viability assay showed the inhibition rates ranged between 30% and 80%, of cell death, occurred when 3.125, 6.25, 12.5, 25, 50, and 100 μg/ml of the enzyme used and IC50 was 4.305 μg/ml. The breast cell lines were treated with the enzyme at a concentration of IC50 value. The Cas8 and Cas9 genes expression in L-asparagine treated breast cancer cell line at a concentration of IC50 value were upregulated (the fold of gene expression are 2.071 and 1.197 respectively).Breast milk L. reuteri L-asparaginase induces apoptosis via Cas8 and Cas9 upregulation in the breast cancer cell line. L. reuteri L-asparaginase treatment may be the hopeful approach for the management of breast cancer. Furthermore, the results may highlight the fact that the presence of L-asparaginase-producing L. reuteri isolates in human breast milk may aid in breast cancer improvement or even prevention.