Brachytherapy for targeting the immune system in cervical cancer patients

The Effects of Gynecological Tumor Irradiation on the Immune System

Radiobiology has evolved from a mechanistic model based on DNA damage and response factors into a more complex model that includes effects on the immune system and the tumor microenvironment (TME). Irradiation has an immunomodulatory effect that can manifest as increased anti-tumor immunity or immunosuppression. Irradiation promotes an inflammatory microenvironment through the release of pro-inflammatory cytokines and endothelial damage, which recruit immune system cells to the irradiated area. Radiation-induced immunogenic cell death (ICD), characterized by the release of damage-associated molecular patterns (DAMPs) and tumor antigens, triggers an anti-tumor immune response of both innate and adaptive immunity. Anti-tumor immunity can manifest at a distance from the irradiated area, a phenomenon known as the abscopal effect (AE), which involves dendritic cells and CD8+ T cells. Irradiation also produces an immunosuppressive effect mediated by tumor-associated macrophages (TAMs) and regulatory T lymphocytes (Tregs), which counterbalances the immunostimulatory effect. In this work, we review the mechanisms involved in the radiation-induced immune response, which support the combined treatment of RT and immunotherapy, focusing, where possible, on gynecologic cancer.

Dose Rate Effects from the 1950s through to the Era of FLASH

Numerous dose rate effects have been described over the past 6-7 decades in the radiation biology and radiation oncology literature depending on the dose rate range being discussed. This review focuses on the impact and understanding of altering dose rates in the context of radiation therapy, but does not discuss dose rate effects as relevant to radiation protection. The review starts with a short historic review of early studies on dose rate effects, considers mechanisms thought to underlie dose rate dependencies, then discusses some current issues in clinical findings with altered dose rates, the importance of dose rate in brachytherapy, and the current timely topic of the use of very high dose rates, so-called FLASH radiotherapy. The discussion includes dose rate effects in vitro in cultured cells, in in vivo experimental systems and in the clinic, including both tumors and normal tissues. Gaps in understanding dose rate effects are identified, as are opportunities for improving clinical use of dose rate modulation.

The Effects of Radiation Dose Heterogeneity on the Tumor Microenvironment and Anti-Tumor Immunity

Radiotherapy elicits dose- and lineage-dependent effects on immune cell survival, migration, activation, and proliferation in targeted tumor microenvironments. Radiation also stimulates phenotypic changes that modulate the immune susceptibility of tumor cells. This has raised interest in using radiotherapy to promote greater response to immunotherapies. To clarify the potential of such combinations, it is critical to understand how best to administer radiation therapy to achieve activation of desired immunologic mechanisms. In considering the multifaceted process of priming and propagating anti-tumor immune response, radiation dose heterogeneity emerges as a potential means for simultaneously engaging diverse dose-dependent effects in a single tumor environment. Recent work in spatially fractionated external beam radiation therapy demonstrates the expansive immune responses achievable when a range of high to low dose radiation is delivered in a tumor. Brachytherapy and radiopharmaceutical therapies deliver inherently heterogeneous distributions of radiation that may contribute to immunogenicity. This review evaluates the interplay of radiation dose and anti-tumor immune response and explores emerging methodological approaches for investigating the effects of heterogeneous dose distribution on immune responses.

Listeria-vectored cervical cancer vaccine candidate strains reduce MDSCs via the JAK-STAT signaling pathway

BACKGROUND

Immunosuppressive status is prevalent in cancer patients and increases the complexity of tumor immunotherapy. It has been found that Listeria-vectored tumor vaccines had the potential ability of two-side regulatory effect on the immune response during immunotherapy.

RESULTS

The results show that the combined immunotherapy with the LM∆E6E7 and LI∆E6E7, the two cervical cancer vaccine candidate strains constructed by our lab, improves the antitumor immune response and inhibits the suppressive immune response in tumor-bearing mice in vivo, confirming the two-sided regulatory ability of the immune response caused by Listeria-vectored tumor vaccines. The immunotherapy reduces the expression level of myeloid-derived suppressor cells (MDSCs)-inducing factors and then inhibits the phosphorylation level of STAT3 protein, the regulatory factor of MDSCs differentiation, to reduce the MDSCs formation ability. Moreover, vaccines reduce the expression of functional molecules associated with MDSCs may by inhibiting the phosphorylation level of the JAK1-STAT1 and JAK2-STAT3 pathways in tumor tissues to attenuate the immunosuppressive function of MDSCs.

CONCLUSIONS

Immunotherapy with Listeria-vectored cervical cancer vaccines significantly reduces the level and function of MDSCs in vivo, which is the key point to the destruction of immunosuppression. The study for the first to elucidate the mechanism of breaking the immunosuppression.

Exploring a novel seven-gene marker and mitochondrial gene TMEM38A for predicting cervical cancer radiotherapy sensitivity using machine learning algorithms

Background

Radiotherapy plays a crucial role in the management of Cervical cancer (CC), as the development of resistance by cancer cells to radiotherapeutic interventions is a significant factor contributing to treatment failure in patients. However, the specific mechanisms that contribute to this resistance remain unclear. Currently, molecular targeted therapy, including mitochondrial genes, has emerged as a new approach in treating different types of cancers, gaining significant attention as an area of research in addressing the challenge of radiotherapy resistance in cancer.

Methods

The present study employed a rigorous screening methodology within the TCGA database to identify a cohort of patients diagnosed with CC who had received radiotherapy treatment. The control group consisted of individuals who demonstrated disease stability or progression after undergoing radiotherapy. In contrast, the treatment group consisted of patients who experienced complete or partial remission following radiotherapy. Following this, we identified and examined the differentially expressed genes (DEGs) in the two cohorts. Subsequently, we conducted additional analyses to refine the set of excluded DEGs by employing the least absolute shrinkage and selection operator regression and random forest techniques. Additionally, a comprehensive analysis was conducted in order to evaluate the potential correlation between the expression of core genes and the extent of immune cell infiltration in patients diagnosed with CC. The mitochondrial-associated genes were obtained from the MITOCARTA 3.0. Finally, the verification of increased expression of the mitochondrial gene TMEM38A in individuals with CC exhibiting sensitivity to radiotherapy was conducted using reverse transcription quantitative polymerase chain reaction and immunohistochemistry assays.

Results

This process ultimately led to the identification of 7 crucial genes, viz., GJA3, TMEM38A, ID4, CDHR1, SLC10A4, KCNG1, and HMGCS2, which were strongly associated with radiotherapy sensitivity. The enrichment analysis has unveiled a significant association between these 7 crucial genes and prominent signaling pathways, such as the p53 signaling pathway, KRAS signaling pathway, and PI3K/AKT/MTOR pathway. By utilizing these 7 core genes, an unsupervised clustering analysis was conducted on patients with CC, resulting in the categorization of patients into three distinct molecular subtypes. In addition, a predictive model for the sensitivity of CC radiotherapy was developed using a neural network approach, utilizing the expression levels of these 7 core genes. Moreover, the CellMiner database was utilized to predict drugs that are closely linked to these 7 core genes, which could potentially act as crucial agents in overcoming radiotherapy resistance in CC.

Conclusion

To summarize, the genes GJA3, TMEM38A, ID4, CDHR1, SLC10A4, KCNG1, and HMGCS2 were found to be closely correlated with the sensitivity of CC to radiotherapy. Notably, TMEM38A, a mitochondrial gene, exhibited the highest degree of correlation, indicating its potential as a crucial biomarker for the modulation of radiotherapy sensitivity in CC.