The ability of clostridium novyi-NT spores to induce apoptosis via the mitochondrial pathway in mice with HPV-positive cervical cancer tumors derived from the TC-1 cell line.

Background: A precise observation is that the cervix's solid tumors possess hypoxic regions where the oxygen concentration drops below 1.5%. Hypoxia negatively impacts the host's immune system and significantly diminishes the effectiveness of several treatments, including radiotherapy and chemotherapy. Utilizing oncolytic spores of Clostridium novyi-NT to target the hypoxic regions of solid tumors has emerged as a noteworthy treatment strategy.

Methods: The transplantation procedure involved injecting TC-1 cells, capable of expressing HPV-16 E6/7 oncoproteins, into the subcutaneous layer of 6-8-week-old female C57/BL6 mice. The TC-1 cell line, was subcutaneously transplanted into 6-8-week-old female C57/BL6 mice. The tumor-bearing mice were randomly divided into 4 groups, and after selecting the control group, they were treated with different methods. Group 1- control without treatment (0.1 ml sterile PBS intratumor) Group 2- received cisplatin intraperitoneally (10 mg/kg) Group 3- received 10⁷Clostridium novyi-NT spores systemically through the tail vein Group 4-tumor mice received 10⁷Clostridium novyi-NT spores intratumorally. 20 days after the start of treatment, the mice were sacrificed and tumor tissues were isolated. In order to clarify the mechanism of the therapeutic effect with spores, the amount of ROS and ceramide was measured by ELISA technique, and the expression level of cytochrome c, cleaved caspase- 3, Bax, Bcl-2, HIF-1α, and VEGF proteins was measured by western blotting.

Results: Our results clearly showed that the injection of Clostridium novyi-NT spores (either intratumorally or intravenously) causes the regression of mouse cervical tumors. Spore germination induces internal apoptosis in cancer cells by inducing ROS production and increasing total cell ceramide, releasing cytochrome c and damaging mitochondria. Additionally, the results provided clear evidence of a significant decrease in the expression of HIF-1 alpha and VEGF proteins among the tumor groups that received spores, when compared to both the cisplatin-treated group and the control group.

Conclusions: The study's outcomes demonstrated that the introduction of Clostridium novyi-NT spores triggered apoptosis in cervical cancer cells (derived from the TC-1 cell line) via the mitochondrial pathway, subsequently resulting in tumor regression in a mouse model.