The role of granulocyte macrophage colony stimulating factor (GM-CSF) in radiation-induced tumor cell migration

CD301b+ monocyte-derived dendritic cells mediate resistance to radiotherapy

Monocytes infiltrating tumors acquire various states that distinctly impact cancer treatment. Here, we show that resistance of tumors to radiotherapy (RT) is controlled by the accumulation of monocyte-derived dendritic cells (moDCs). These moDCs are characterized by the expression of CD301b and have a superior capacity to generate regulatory T cells (Tregs). Accordingly, moDC depletion limits Treg generation and improves the therapeutic outcome of RT. Mechanistically, we demonstrate that granulocyte-macrophage colony-stimulating factor (GM-CSF) derived from radioresistant tumor cells following RT is necessary for the accumulation of moDCs. Our results unravel the immunosuppressive function of moDCs and identify GM-CSF as an immunotherapeutic target during RT.

Adipose tissue from oesophageal adenocarcinoma patients is differentially affected by chemotherapy and chemoradiotherapy regimens altering immune cell phenotype and cancer cell metabolism

Oesophageal adenocarcinoma (OAC) is a poor prognosis cancer with limited responses to standard of care treatments including chemotherapy and chemoradiotherapy. OAC has one of the strongest associations with obesity, its anatomical location surrounded by visceral adipose tissue has been postulated to intensify this association. Adipose tissue is a regulatory organ with many unknown downstream functions, including its direct response to chemotherapy and radiotherapy. To elucidate the role of visceral adipose tissue in this disease state, metabolic and secreted pro-inflammatory cytokines analysis was conducted on human ex-vivo adipose tissue explants following exposure to FLOT-chemotherapy and CROSS-chemoradiotherapy. To assess how these complex treated microenvironments impact cancer cell metabolism, dendritic cell, and macrophage phenotype, mitochondrial bioenergetics and surface markers expression were examined using seahorse technology and flow cytometry respectively. This study observed that chemotherapy and chemoradiotherapy differentially alter adipose tissue metabolism and secretome, with chemoradiotherapy increasing pro-inflammatory associated mediators (p<0.05). The chemoradiotherapy-treated adipose secretome increased cancer cell spare respiratory capacity and dendritic cell adhesion markers (p<0.05). In contrast, the chemotherapy-treated adipose microenvironment enhanced mitochondrial dysfunction in cancer cells, increasing their reliance on glycolysis and enhancing pro-inflammatory marker expression on LPS-primed macrophages (p<0.05). This study for the first time demonstrates how adipose tissue, and its microenvironment can be significantly impacted by chemotherapy and chemoradiotherapy. These alterations in the adipose secretome in response to therapeutic regimens elicited distinct effects on immune cell phenotype and cancer cells metabolism, raising the question, does the wider tumour microenvironment including the adipose milieu mitigate the efficacy of current treatments.

Granulocyte-Macrophage Colony-Stimulating Factor in Combination With Chemoradiation for Recurrent or Metastatic Cervical Cancer

Recurrent or metastatic cervical cancer carries a bleak prognosis and presents a formidable challenge in terms of treatment. Granulocyte-macrophage colony-stimulating factor (GM-CSF) increases the body's immune response by enhancing antigen presentation, which has been rarely reported in recurrent or metastatic cervical cancer. A 44-year-old woman presented to the hospital with vaginal bleeding four years after radical hysterectomy for stage IB2 squamous cell carcinoma (SCC) of the cervix (grade II-III). Gynecological examination and imaging revealed a vaginal mass, and the biopsy confirmed the recurrence of grade III SCC. The patient was treated with chemoradiation (CRT) combined with immunoadjuvant GM-CSF and achieved complete remission and a progression-free survival of two years.

Scutellarin suppresses the metastasis of triple-negative breast cancer via targeting TNFα/TNFR2-RUNX1-triggered G-CSF expression in endothelial cells

Triple-negative breast cancer (TNBC) is heterogeneous and aggressive, with high vascularity and frequent metastasis. We have already found natural flavonoid scutellarin (SC) suppressed spontaneous TNBC metastasis via normalizing tumor vasculature in vivo. In this study, supernatant from tumor necrosis factorα (TNFα)-treated human mammary microvascular endothelial cell (HMMEC) promoted cell migration and pseudopod formation in TNBC cells, but these phenomena were disappeared in SC-co-treated HMMEC. TNFα enhanced the expression of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in both HMMEC and human umbilical vein endothelial cell (HUVEC). G-CSF promoted TNBC migration and invasion in vitro, while G-CSF neutralization antibody and SC both inhibited TNBC metastasis in Balb/c mice. SC had no inhibition on the G-CSF-induced TNBC cell migration, but reduced G-CSF content in TNBC tumor tissues and TNFα-stimulated endothelial cells (ECs). SC restricted the nuclear translocation of runt-related transcription factor 1 (RUNX1) in TNBC tumor vessels and TNFα-treated ECs. RUNX1 was found to directly bind to the promoter of G-CSF in TNBC tumor vessels and regulated G-CSF expression. TNF receptor 2 (TNFR2) was crucial for regulating the TNFα-induced RUNX1 activation and G-CSF expression. Notably, SC hindered the interaction between TNFα and TNFR2 via binding to TNFR2. This work demonstrated that SC reduced TNBC metastasis by targeting TNFα/TNFR2-initiated RUNX1 activation and subsequent G-CSF production in TNBC-associated ECs.

Curcumin, but not its degradation products, in combination with silibinin is primarily responsible for the inhibition of colon cancer cell proliferation

Colorectal cancer (CRC) is the third leading cause of cancer death globally and the most-commonly diagnosed cancer in men and women in the United States. We have previously shown that the phytochemicals curcumin, derived from turmeric, and silibinin from milk thistle exhibit synergistically enhanced anticancer activity against colorectal cancer cells. In the present study, the combination of curcumin, a major component of turmeric, and its degraded products trans-ferulic acid, ferulic aldehyde, and vanillin in combination with silibinin were assessed for their action against cancer cell proliferation. Our results indicate that only curcumin plus silibinin has significant antiproliferative effects on colon cancer cells.

GM-CSF-miRNA-Jak2/Stat3 Signaling Mediates Chemotherapy-Induced Cancer Cell Stemness in Gastric Cancer

Chemotherapy serves as the first choice in clinic to treat advanced gastric cancer. However, emerging evidence indicated the induction of drug resistance and cancer stem cells occasionally by chemotherapy, which seriously limit the therapeutic effects, but the regulatory mechanism remains unclear. Here we treated two human gastric cancer cell lines SGC7901 and BGC823 with 5-Fluorouracil (5-Fu) or Cisplatin (DDP) in vitro. The survived cells showed significant increase of drug resistance, cell stemness and cytokine GM-CSF expression and secretion. As such, GM-CSF was applied to stimulate gastric cancer cells, followed by the subpopulation of CD133⁺ CSC analysis, sphere formation assay and stemness genes expression analysis. As a result, CSCs showed induction by GM-CSF treatment. A gastric cancer animal model further indicated that the gastric cancer cells significantly promoted tumor growth after GM-CSF treatment in vivo. High-throughput miRNA and mRNA sequencing analyses identified a subset of miRNAs and mRNAs under regulation of both 5-Fu and GM-CSF in gastric cancer cells, including upregulation of miR-877-3p and downregulation of SOCS2. Targeted overexpression or knockdown of miR-877-3p in gastric cancer cells revealed the oncogenic function of miR-877-3p in regulating gastric cancer by suppressing target gene SOCS2. Jak2/Stat3 signaling pathway, as a downstream target of SOCS2, showed activation in vitro and in vivo after treatment with miR-877-3p or GM-CSF. Our findings not only revealed a novel mechanism through which chemotherapy induced CSCs in gastric cancer via GM-CSF-miRNA-Jak2/Stat3 signaling, but also provided an experimental evidence for appropriate dose reduction of adjuvant chemotherapy in treatment of cancer patients.

A Combination of Cabozantinib and Radiation Does Not Lead to an Improved Growth Control of Tumors in a Preclinical 4T1 Breast Cancer Model

The tyrosine kinase inhibitor Cabozantinib has been applied in clinical studies in combination with radiotherapy. We investigated the effect of such combination on triple-negative 4T1 cells as a metastatic breast cancer model in vitro and in vivo upon inoculation in BALB/c mice. In vitro assays indicated a potential for improved effects using the combination. Both Cabozantinib (2.5 µM) and 10 Gy of 250 kV x-rays were able to cease the growth of 4T1 cells as revealed by growth curves. In a clonogenic survival assay, the effect of Cabozantinib added on the effects of irradiation and the effectiveness of inhibiting the clonogenic survival was found to be 2 (RBE₁₀). Additionally, cell death measurements of apoptosis plus necrosis revealed a synergistic effect when combining irradiation with Cabozantinib. Surprisingly, however, in vivo tumor growth kinetics showed no additional effect in growth control when irradiation was used together with Cabozantinib. Since both ionizing radiation and Cabozantinib are acknowledged to feature immunogenic effects, we additionally investigated the effect of the treatments on lung metastases. No difference to the control groups was found here, neither for irradiation nor Cabozantinib alone nor in combination. Yet, upon analysis of the mice’ livers, CD11b-positive cells, indicating immune suppressive myeloid derived suppressor cells were found diminished following treatment with Cabozantinib. In conclusion, despite promising in vitro controls of the combination of Cabozantinib and irradiation, tumor growth control was not increased by the combination, which was true also for the occurrence of lung metastases.

Synergistic effect of immunotherapy and radiotherapy in non-small cell lung cancer: current clinical trials and prospective challenges

Lately, the success of ICIs has drastically changed the landscape of cancer treatment, and several immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration (FDA) for advanced non-small cell lung cancer (NSCLC). However, numerous patients are resistant to ICIs and require additional procedures for better efficacy results. Thus, combination therapy is urgently needed to strengthen the anti-tumor immunity. A variety of preclinical and clinical studies combining ICIs with radiotherapy (RT) have demonstrated that the combination could induce synergistic effects, as RT overcomes the resistance to ICIs. However, the underlying mechanism of the synergistic effect and the optimal arrangement of the combination therapy are indecisive now. Hence, this review was conducted to provide an update on the current clinical trial results and highlighted the ongoing trials. We also discussed the optimal parameters in clinical trials, including radiation dose, radiation fractionation, radiation target field, and sequencing of combination therapy. In this review, we found that combination therapy showed stronger anti-tumor immunity with tolerable toxicities in clinical trials. However, the best combination mode and potential biomarkers for the target patients in combination therapy are still unclear.

Integrating Small Animal Irradiators withFunctional Imaging for Advanced Preclinical Radiotherapy Research

Translational research aims to provide direct support for advancing novel treatment approaches in oncology towards improving patient outcomes. Preclinical studies have a central role in this process and the ability to accurately model biological and physical aspects of the clinical scenario in radiation oncology is critical to translational success. The use of small animal irradiators with disease relevant mouse models and advanced in vivo imaging approaches offers unique possibilities to interrogate the radiotherapy response of tumors and normal tissues with high potential to translate to improvements in clinical outcomes. The present review highlights the current technology and applications of small animal irradiators, and explores how these can be combined with molecular and functional imaging in advanced preclinical radiotherapy research.

Targeting Innate Immunity to Enhance the Efficacy of Radiation Therapy

Radiation continues to play a major role in the treatment of almost every cancer type. Traditional radiation studies focused on its ability to damage DNA, but recent evidence has demonstrated that a key mechanism driving the efficacy of radiation in vivo is the immune response triggered in irradiated tissue. Innate immune cells including macrophages, dendritic cells, and natural killer cells are key mediators of the radiation-induced immune response. They regulate the sensing of radiation-mediated damage and subsequent radiation-induced inflammation. Given the importance of innate immune cells as determinants of the post-radiation anti-tumor immune response, much research has been devoted to identify ways to both enhance the innate immune response and prevent their ability to suppress ongoing immune responses. In this review, we will discuss how the innate immune system shapes anti-tumor immunity following radiation and highlight key strategies directed at the innate immune response to enhance the efficacy of radiation.

Preliminary Study of the Effect of Stereotactic Body Radiotherapy (SBRT) on the Immune System in Lung Cancer Patients Unfit for Surgery: Immunophenotyping Analysis

An immunophenotyping analysis was performed in peripheral blood samples from seven patients with lung cancer unfit for surgery treated with stereotactic body radiotherapy (SBRT). The objective was to characterize the effect of SBRT on the host immune system. Four patients received 60 Gy (7.5 Gy × 8) and three 50 Gy (12.5 Gy × 4). Analyses were performed before SBRT, 72 h after SBRT, and at one, three, and six months after the end of SBRT. Of note, there was a specific increase of the immunoactive component of the immune system, with elevation of CD56^+highCD16+ natural killer (NK) cells (0.95% at baseline to 1.38% at six months), and a decrease of the immunosuppressive component of the immune system, with decreases of CD4+CD25+Foxp3+CDA5RA- regulatory T cells (4.97% at baseline to 4.46% at six months), granulocytic myeloid-derived suppressor cells (G-MDSCs) (from 66.1% at baseline to 62.6% at six months) and monocytic (Mo-MDSCs) (8.2% at baseline to 6.2% at six months). These changes were already apparent at 72 h and persisted over six months. SBRT showed an effect on systemic immune cell populations, which is a relevant finding for supporting future combinations of SBRT with immunotherapy for treating lung cancer patients.

Editorial: Therapy-induced metastasis

The idea for this Special Issue originated from our recent review in Nature Reviews Clinical Oncology entitled "Does the mobilization of circulating tumour cells during cancer therapy cause metastasis?" Martin et al. (Nat Rev Clin Oncol 14:32-44, 2017). While preparing this review, it became evident that an overwhelming number of preclinical and clinical papers were implicating the involvement of all the major and indispensable cancer treatment modalities in causing increased numbers of tumour cells in circulation (CTCs), and potentially increased risk of distant metastasis. This led to our decision to expand the topic by addressing some of the issues associated with therapy-induced tumour progression. Here, we present papers from ten research groups who give a comprehensive coverage of the biological processes and clinical procedures that can lead to enhanced metastasis and/or tumour recurrence. Our authors provide evidence that all the common therapies, including radiotherapy, chemotherapy, fine needle biopsies, surgical procedures and anaesthesia have the potential to contribute to tumour progression.