Role of nontoxigenic Clostridium novyi in solid tumor therapy

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.

Anti-tumor Effects of Cisplatin Synergist in Combined Treatment with Clostridium novyi-NT Spores Against Hypoxic Microenvironments in a Mouse Model of Cervical Cancer Caused by TC-1 Cell Line

Purpose

Despite the development of anti-human papillomavirus (HPV) vaccines, cervical cancer is still a common disease in women, especially in developing countries. The presence of a hypoxic microenvironment causes traditional treatments to fail. In this study, we presented a combined treatment method based on the chemotherapeutic agent cisplatin and Clostridium novyi-NT spores to treat normoxic and hypoxic areas of the tumor.

Methods

TC-1 Cell line capable of expressing HPV-16 E6/7 oncoproteins was subcutaneously transplanted into female 6-8 week old C57/BL6 mice. The tumor-bearing mice were randomly divided into four groups and treated with different methods after selecting a control group. Group 1: Control without treatment (0.1 mL sterile PBS intratumorally), Group: C. novyi-NT (107 C. novyi-NT). Group 3: Receives cisplatin intraperitoneally (10 mg/kg). Fourth group: Intratumoral administration of C. novyi-NT spores + intraperitoneal cisplatin. Western blot analysis was used to examine the effects of anti-hypoxia treatment and expression of hypoxia-inducible factor 1 (HIF-1) and vascular endothelial growth factor (VEGF) proteins.

Results

The results clearly showed that combined treatment based on C. novyi-NT and cisplatin significantly reduced the expression of HIF-1 alpha and VEGF proteins compared to cisplatin alone. At the same time, the amount of necrosis of tumor cells in the combined treatment increased significantly compared to the single treatment and the control. At the same time, the mitotic count decreased significantly.

Conclusion

Our research showed that developing a combined treatment method based on C. novyi-NT and cisplatin against HPV-positive cervical cancer could overcome the treatment limitations caused by the existence of hypoxic areas of the tumor.

Current advances in microbial-based cancer therapies

Microbes have an immense metabolic capability and can adapt to a wide variety of environments; as a result, they share complicated relationships with cancer. The goal of microbial-based cancer therapy is to treat patients with cancers that are not easily treatable, by using tumor-specific infectious microorganisms. Nevertheless, a number of difficulties have been encountered as a result of the harmful effects of chemotherapy, radiotherapy, and alternative cancer therapies, such as the toxicity to non-cancerous cells, the inability of medicines to penetrate deep tumor tissue, and the ongoing problem of rising drug resistance in tumor cells. Due to these difficulties, there is now a larger need for designing alternative strategies that are more effective and selective when targeting tumor cells. The fight against cancer has advanced significantly owing to cancer immunotherapy. The researchers have greatly benefited from their understanding of tumor-invading immune cells as well as the immune responses that are specifically targeted against cancer. Application of bacterial and viral cancer therapeutics offers promising potential to be employed as cancer treatments among immunotherapies. As a novel therapeutic strategy, microbial targeting of tumors has been created to address the persisting hurdles of cancer treatment. This review outlines the mechanisms by which both bacteria and viruses target and inhibit the proliferation of tumor cells. Their ongoing clinical trials and possible modifications that can be made in the future have also been addressed in the following sections. These microbial-based cancer medicines have the ability to suppress cancer that builds up and multiplies in the tumor microenvironment and triggers antitumor immune responses, in contrast to other cancer medications.

Recent advances in bacteria-mediated cancer therapy

Cancer is among the leading cause of deaths worldwide. Although conventional therapies have been applied in the fight against the cancer, the poor oxygen, low extracellular pH, and high interstitial fluid pressure of the tumor microenvironment mean that these treatments fail to completely eradicate cancer cells. Recently, bacteria have increasingly been considered to be a promising platform for cancer therapy thanks to their many unique properties, such as specific tumor-targeting ability, high motility, immunogenicity, and their use as gene or drug carriers. Several types of bacteria have already been used for solid and metastatic tumor therapies, with promising results. With the development of synthetic biology, engineered bacteria have been endowed with the controllable expression of therapeutic proteins. Meanwhile, nanomaterials have been widely used to modify bacteria for targeted drug delivery, photothermal therapy, magnetothermal therapy, and photodynamic therapy, while promoting the antitumor efficiency of synergistic cancer therapies. This review will provide a brief introduction to the foundation of bacterial biotherapy. We begin by summarizing the recent advances in the use of many different types of bacteria in multiple targeted tumor therapies. We will then discuss the future prospects of bacteria-mediated cancer therapies.

Therapeutic bacteria to combat cancer; current advances, challenges, and opportunities

Successful treatment of cancer remains a challenge, due to the unique pathophysiology of solid tumors, and the predictable emergence of resistance. Traditional methods for cancer therapy including radiotherapy, chemotherapy, and immunotherapy all have their own limitations. A novel approach is bacteriotherapy, either used alone, or in combination with conventional methods, has shown a positive effect on regression of tumors and inhibition of metastasis. Bacteria-assisted tumor-targeted therapy used as therapeutic/gene/drug delivery vehicles has great promise in the treatment of tumors. The use of bacteria only, or in combination with conventional methods was found to be effective in some experimental models of cancer (tumor regression and increased survival rate). In this article, we reviewed the major advantages, challenges, and prospective directions for combinations of bacteria with conventional methods for tumor therapy.