Intricate Macrophage-Colorectal Cancer Cell Communication in Response to Radiation

Strategies to reprogram anti-inflammatory macrophages towards pro-inflammatory macrophages to support cancer immunotherapies

Tumor-associated myeloid cells, including macrophages and myeloid-derived suppressor cells, can be highly prevalent in solid tumors and play a significant role in the development of the tumor. Therefore, myeloid cells are being considered potential targets for cancer immunotherapies. In this review, we focused on strategies aimed at targeting tumor-associated macrophages (TAMs). Most strategies were studied preclinically but we also included a limited number of clinical studies based on these strategies. We describe possible underlying mechanisms and discuss future challenges and prospects.

Enhancement of the Tumor Suppression Effect of High-dose Radiation by Low-dose Pre-radiation Through Inhibition of DNA Damage Repair and Increased Pyroptosis

Radiation therapy has been a critical and effective treatment for cancer. However, not all cells are destroyed by radiation due to the presence of tumor cell radioresistance. In the current study, we investigated the effect of low-dose radiation (LDR) on the tumor suppressive effect of high-dose radiation (HDR) and its mechanism from the perspective of tumor cell death mode and DNA damage repair, aiming to provide a foundation for improving the efficacy of clinical tumor radiotherapy. We found that LDR pre-irradiation strengthened the HDR-inhibited A549 cell proliferation, HDR-induced apoptosis, and G2 phase cell cycle arrest under co-culture conditions. RNA-sequencing showed that differentially expressed genes after irradiation contained pyroptosis-related genes and DNA damage repair related genes. By detecting pyroptosis-related proteins, we found that LDR could enhance HDR-induced pyroptosis. Furthermore, under co-culture conditions, LDR pre-irradiation enhances the HDR-induced DNA damage and further suppresses the DNA damage-repairing process, which eventually leads to cell death. Lastly, we established a tumor-bearing mouse model and further demonstrated that LDR local pre-irradiation could enhance the cancer suppressive effect of HDR. To summarize, our study proved that LDR pre-irradiation enhances the tumor-killing function of HDR when cancer cells and immune cells were coexisting.

Modulation of tumor-associated macrophage activity with radiation therapy: a systematic review

OBJECTIVE

Tumor-associated macrophages (TAMs) are the most represented cells of the immune system in the tumor microenvironment (TME). Besides its effects on cancer cells, radiation therapy (RT) can alter TME composition. With this systematic review, we provide a better understanding on how RT can regulate macrophage characterization, namely the M1 antitumor and the M2 protumor polarization, with the aim of describing new effective RT models and exploration of the possibility of integrating radiation with other available therapies.

METHODS

A systematic search in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was carried out in PubMed, Google Scholar, and Scopus. Articles from January 2000 to April 2020 which focus on the role of M1 and M2 macrophages in the response to RT were identified.

RESULTS

Of the 304 selected articles, 29 qualitative summary papers were included in our analysis (16 focusing on administration of RT and concomitant systemic molecules, and 13 reporting on RT alone). Based on dose intensity, irradiation was classified into low (low-dose irradiation, LDI; corresponding to less than 1 Gy), moderate (moderate-dose irradiation, MDI; between 1 and 10 Gy), and high (high-dose irradiation, HDI; greater than 10 Gy). While HDI seems to be responsible for induced angiogenesis and accelerated tumor growth through early M2-polarized TAM infiltration, MDI stimulates phagocytosis and local LDI may represent a valid treatment option for possible combination with cancer immunotherapeutic agents.

CONCLUSION

TAMs seem to have an ambivalent role on the efficacy of cancer treatment. Radiation therapy, which exerts its main antitumor activity via cell killing, can in turn interfere with TAM characterization through different modalities. The plasticity of TAMs makes them an attractive target for anticancer therapies and more research should be conducted to explore this potential therapeutic strategy.

Pro-inflammatory polarization and colorectal cancer modulate alternative and intronic polyadenylation in primary human macrophages

Introduction

Macrophages are essential cells of the immune system that alter their inflammatory profile depending on their microenvironment. Alternative polyadenylation in the 3'UTR (3'UTR-APA) and intronic polyadenylation (IPA) are mechanisms that modulate gene expression, particularly in cancer and activated immune cells. Yet, how polarization and colorectal cancer (CRC) cells affect 3'UTR-APA and IPA in primary human macrophages was unclear.

Methods

In this study, we isolated primary human monocytes from healthy donors, differentiated and polarized them into a pro-inflammatory state and performed indirect co-cultures with CRC cells. ChrRNA-Seq and 3'RNA-Seq was performed to quantify gene expression and characterize new 3'UTR-APA and IPA mRNA isoforms.

Results

Our results show that polarization of human macrophages from naïve to a pro-inflammatory state causes a marked increase of proximal polyA site selection in the 3'UTR and IPA events in genes relevant to macrophage functions. Additionally, we found a negative correlation between differential gene expression and IPA during pro-inflammatory polarization of primary human macrophages. As macrophages are abundant immune cells in the CRC microenvironment that either promote or abrogate cancer progression, we investigated how indirect exposure to CRC cells affects macrophage gene expression and 3'UTR-APA and IPA events. Co-culture with CRC cells alters the inflammatory phenotype of macrophages, increases the expression of pro-tumoral genes and induces 3'UTR-APA alterations. Notably, some of these gene expression differences were also found in tumor-associated macrophages of CRC patients, indicating that they are physiologically relevant. Upon macrophage pro-inflammatory polarization, SRSF12 is the pre-mRNA processing gene that is most upregulated. After SRSF12 knockdown in M1 macrophages there is a global downregulation of gene expression, in particular in genes involved in gene expression regulation and in immune responses.

Discussion

Our results reveal new 3'UTR-APA and IPA mRNA isoforms produced during pro-inflammatory polarization of primary human macrophages and CRC co-culture that may be used in the future as diagnostic or therapeutic tools. Furthermore, our results highlight a function for SRSF12 in pro-inflammatory macrophages, key cells in the tumor response.

Macrophage Resistance to Ionizing Radiation Exposure Is Accompanied by Decreased Cathepsin D and Increased Transferrin Receptor 1 Expression

PURPOSE

To identify a molecular signature of macrophages exposed to clinically relevant ionizing radiation (IR) doses, mirroring radiotherapy sessions.

METHODS

Human monocyte-derived macrophages were exposed to 2 Gy/ fraction/ day for 5 days, mimicking one week of cancer patient's radiotherapy. Protein expression profile by proteomics was performed.

RESULTS

A gene ontology analysis revealed that radiation-induced protein changes are associated with metabolic alterations, which were further supported by a reduction of both cellular ATP levels and glucose uptake. Most of the radiation-induced deregulated targets exhibited a decreased expression, as was the case of cathepsin D, a lysosomal protease associated with cell death, which was validated by Western blot. We also found that irradiated macrophages exhibited an increased expression of the transferrin receptor 1 (TfR1), which is responsible for the uptake of transferrin-bound iron. TfR1 upregulation was also found in tumor-associated mouse macrophages upon tumor irradiation. In vitro irradiated macrophages also presented a trend for increased divalent metal transporter 1 (DMT1), which transports iron from the endosome to the cytosol, and a significant increase in iron release.

CONCLUSIONS

Irradiated macrophages present lower ATP levels and glucose uptake, and exhibit decreased cathepsin D expression, while increasing TfR1 expression and altering iron metabolism.

Exploring Silk Sericin for Diabetic Wounds: An In Situ-Forming Hydrogel to Protect against Oxidative Stress and Improve Tissue Healing and Regeneration

Chronic wounds are one of the most frequent complications that are associated with diabetes mellitus. The overproduction of reactive oxygen species (ROS) is a key factor in the delayed healing of a chronic wound. In the present work, we develop a novel in situ-forming silk sericin-based hydrogel (SSH) that is produced by a simple methodology using horseradish peroxidase (HRP) crosslinking as an advanced dressing for wound healing. The antioxidant and angiogenic effects were assessed in vitro and in vivo after in situ application using an excisional wound-healing model in a genetically-induced diabetic db/db mice and though the chick embryo choriollantoic membrane (CAM) assay, respectively. Wounds in diabetic db/db mice that were treated with SSH closed with reduced granulation tissue, decreased wound edge distance, and wound thickness, when compared to Tegaderm, a dressing that is commonly used in the clinic. The hydrogel also promoted a deposition of collagen fibers with smaller diameter which may have had a boost effect in re-epithelialization. SSH treatment slightly induced two important endogenous antioxidant defenses, superoxide dismutase and catalase. A CAM assay made it possible to observe that SSH led to an increase in the number of newly formed vessels without inducing an inflammatory reaction. The present hydrogel may result in a multi-purpose technology with angiogenic, antioxidant, and anti-inflammatory properties, while advancing efficient and organized tissue regeneration.

KRAS as a Modulator of the Inflammatory Tumor Microenvironment: Therapeutic Implications

KRAS mutations are one of the most frequent oncogenic mutations of all human cancers, being more prevalent in pancreatic, colorectal, and lung cancers. Intensive efforts have been encouraged in order to understand the effect of KRAS mutations, not only on tumor cells but also on the dynamic network composed by the tumor microenvironment (TME). The relevance of the TME in cancer biology has been increasing due to its impact on the modulation of cancer cell activities, which can dictate the success of tumor progression. Here, we aimed to clarify the pro- and anti-inflammatory role of KRAS mutations over the TME, detailing the context and the signaling pathways involved. In this review, we expect to open new avenues for investigating the potential of KRAS mutations on inflammatory TME modulation, opening a different vision of therapeutic combined approaches to overcome KRAS-associated therapy inefficacy and resistance in cancer.

How Macrophages Become Transcriptionally Dysregulated: A Hidden Impact of Antitumor Therapy

Tumor-associated macrophages (TAMs) are the essential components of the tumor microenvironment. TAMs originate from blood monocytes and undergo pro- or anti-inflammatory polarization during their life span within the tumor. The balance between macrophage functional populations and the efficacy of their antitumor activities rely on the transcription factors such as STAT1, NF-κB, IRF, and others. These molecular tools are of primary importance, as they contribute to the tumor adaptations and resistance to radio- and chemotherapy and can become important biomarkers for theranostics. Herein, we describe the major transcriptional mechanisms specific for TAM, as well as how radio- and chemotherapy can impact gene transcription and functionality of macrophages, and what are the consequences of the TAM-tumor cooperation.

Tumor-Associated Macrophage Status in Cancer Treatment

Tumor-associated macrophages (TAMs) represent the most abundant innate immune cells in tumors. TAMs, exhibiting anti-inflammatory phenotype, are key players in cancer progression, metastasis and resistance to therapy. A high TAM infiltration is generally associated with poor prognosis, but macrophages are highly plastic cells that can adopt either proinflammatory/antitumor or anti-inflammatory/protumor features in response to tumor microenvironment stimuli. In the context of cancer therapy, many anticancer therapeutics, apart from their direct effect on tumor cells, display different effects on TAM activation status and density. In this review, we aim to evaluate the indirect effects of anticancer therapies in the modulation of TAM phenotypes and pro/antitumor activity.

Antagonist biocompatibilities of Zn-based materials functionalized with physiological active metal oxides

Zinc coated with nanostructured ZnO flowers has received increasing attention as a versatile biomaterial for medical applications. Whatsoever, the potential of these materials to meet specific medical requirements must be explored. Despite in its infancy, surface functionalization is the key strategy to achieve this goal. The functionalization, successfully achieved with cooper (Cu), iron (Fe) or manganese (Mn) oxides (Ox), was highly dependent on the presence of the flowered structures, with the deep physicochemical characterization of these new surfaces revealing specific metal oxide distributions. The functionalization with these metal oxides resulted in distinct biological and in vitro behaviours. The biological response, assessed by fibroblast viability, hemocompatibility, and chick chorioallantoic membrane (CAM), further supported by the in vitro degradation studies, evaluated by immersion and electrochemical techniques, revealed that the deleterious role of CuOx functionalization brought potential for anti-cancer applications; with an antagonist behaviour, the functionalization with MnOx, and in a less extent with FeOx, can be used to favour wound healing in traumatic processes. Despite the possible correlation between biocompatibility and hydroxyapatite precipitation, no correlation could be drawn with the corrosion activity of these surfaces. Overall, the minor addition of relevant physiological as Cu, Fe or Mn oxides resulted in antagonist in vitro responses that can be used as expedite strategies to modulate the behaviour of Zn-based materials, contributing in this way for the design of anti-cancer or wound healing therapies.

Implementation of the Chick Chorioallantoic Membrane (CAM) Model in Radiation Biology and Experimental Radiation Oncology Research

Radiotherapy (RT) is part of standard cancer treatment. Innovations in treatment planning and increased precision in dose delivery have significantly improved the therapeutic gain of radiotherapy but are reaching their limits due to biologic constraints. Thus, a better understanding of the complex local and systemic responses to RT and of the biological mechanisms causing treatment success or failure is required if we aim to define novel targets for biological therapy optimization. Moreover, optimal treatment schedules and prognostic biomarkers have to be defined for assigning patients to the best treatment option. The complexity of the tumor environment and of the radiation response requires extensive in vivo experiments for the validation of such treatments. So far in vivo investigations have mostly been performed in time- and cost-intensive murine models. Here we propose the implementation of the chick chorioallantoic membrane (CAM) model as a fast, cost-efficient model for semi high-throughput preclinical in vivo screening of the modulation of the radiation effects by molecularly targeted drugs. This review provides a comprehensive overview on the application spectrum, advantages and limitations of the CAM assay and summarizes current knowledge of its applicability for cancer research with special focus on research in radiation biology and experimental radiation oncology.

Fibroblast-Mediated Immunoregulation of Macrophage Function Is Maintained after Irradiation

The abilities of cancer-associated fibroblasts (CAFs) to regulate immune responses in the context of radiotherapy remain largely unknown. This study was undertaken to determine whether ionizing radiation alters the CAF-mediated immunoregulatory effects on macrophages. CAFs were isolated from freshly-resected non-small cell lung cancer tumors, while monocyte-derived macrophages were prepared from peripheral blood of healthy donors. Experimental settings included both (CAF-macrophage) co-cultures and incubations of M0 and M1-macrophages in the presence of CAF-conditioned medium (CAF-CM). Functional assays to study macrophage polarization/activation included the expression of cell surface markers, production of nitric oxide, secretion of inflammatory cytokines and migratory capacity. We show that CAFs promote changes in M0-macrophages that harmonize with both M1-and M2-phenotypes. Additionally, CAFs inhibit pro-inflammatory features of M1-macrophages by reducing nitric oxide production, pro-inflammatory cytokines, migration, and M1-surface markers expression. Radiation delivered as single-high dose or in fractioned regimens did not modify the immunoregulatory features exerted by CAFs over macrophages in vitro. Protein expression analyses of CAF supernatants showed that irradiated and non-irradiated CAFs produce approximately the same protein levels of immunoregulators. Thus, CAF-derived soluble factors mediate measurable changes on uncommitted macrophages and down-regulate pro-inflammatory features of M1-polarized macrophages. Notably, ionizing radiation does not curtail the CAF-mediated immunosuppressive effects.

Predicting MicroRNA Target Genes and Identifying Hub Genes in IIA Stage Colon Cancer Patients Using Bioinformatics Analysis

Background

Colon cancer is a heterogeneous disease, differing in clinical symptoms, epigenetics, and prognosis for each individual patient. Identifying the core genes is important for early diagnoses and it provides a more precise method for treating colon cancer.

Materials and Methods

In this study, we wanted to pinpoint these core genes so we obtained GSE101502 microRNA profiles from the GEO database, which resulted in 17 differential expressed microRNAs that were identified by GEO2R analysis. Then, 875 upregulated and 2920 downregulated target genes were predicted by FunRich. GO and KEGG pathway were used to do enrich analysis.

Results

GO analysis indicated that upregulated genes were significantly enriched in the regulation of cell communication and signaling and in nervous system development, while the downregulated genes were significantly enriched in nervous system development and regulation of transcription from the RNA polymerase II promoter. KEGG pathway analysis suggested that the upregulated genes were enriched in axon guidance, MAPK signaling pathway, and endocytosis, while the downregulated genes existed in pathways in cancer, focal adhesion, and PI3K-Akt signaling pathway. The top four molecules including 82 hub genes were identified from the PPI network and involved in endocytosis, spliceosome, TGF-beta signaling pathway, and lysosome. Finally, NUDT21, GNB1, CLINT1, and COL1A2 core gene were selected due to their correlation with the prognosis of IIA stage colon cancer.

Conclusion

this study suggested that NUDT21, GNB1, CLINT1, and COL1A2 might be the core genes for colon cancer that play an important role in the development and prognosis of IIA stage colon cancer.

Immune targets in the tumor microenvironment treated by radiotherapy

Radiotherapy (RT), the major anti-cancer modality for more than half of cancer patients after diagnosis, has the advantage of local tumor control with relatively less systematic side effects comparing to chemotherapy. However, the efficacy of RT is limited by acquired tumor resistance leading to the risks of relapse and metastasis. To further enhance the efficacy of RT, with the renaissances of targeted immunotherapy (TIT), increasing interests are raised on RT combined with TIT including cancer vaccines, T-cell therapy, and antibody-based immune checkpoint blockers (ICB) such as anti-CTLA-4 and anti-PD1/PD-L1. In achieving a significant synergy between RT and TIT, the dynamics of radiation-induced response in tumor cells and stromal cells, especially the cross-talk between tumor cells and immune cells in the irradiated tumor microenvironment (ITME) as highlighted in recent literature are to be elucidated. The abscopal effect refereeing the RT-induced priming function outside of ITME could be compromised by the immune-suppressive factors such as CD47 and PD-L1 on tumor cells and Treg induced or enhanced in the ITME. Cell surface receptors temporally or permanently induced and bioactive elements released from dead cells could serve antigenic source (radiation-associated antigenic proteins, RAAPs) to the host and have functions in immune regulation on the tumor. This review is attempted to summarize a cluster of factors that are inducible by radiation and targetable by antibodies, or have potential to be immune regulators to synergize tumor control with RT. Further characterization of immune regulators in ITME will deepen our understanding of the interplay among immune regulators in ITME and discover new effective targets for the combined modality with RT and TIT.

Radiation-Induced Transformation of Immunoregulatory Networks in the Tumor Stroma

The implementation of novel cancer immunotherapies in the form of immune checkpoint blockers represents a major advancement in the treatment of cancer, and has renewed enthusiasm for identifying new ways to induce antitumor immune responses in patients. Despite the proven efficacy of neutralizing antibodies that target immune checkpoints in some refractory cancers, many patients do not experience therapeutic benefit, possibly owing to a lack of antitumor immune recognition, or to the presence of dominant immunosuppressive mechanisms in the tumor microenvironment (TME). Recent developments in this field have revealed that local radiotherapy (RT) can transform tumors into in situ vaccines, and may help to overcome some of the barriers to tumor-specific immune rejection. RT has the potential to ignite tumor immune recognition by generating immunogenic signals and releasing neoantigens, but the multiple immunosuppressive forces in the TME continue to represent important barriers to successful tumor rejection. In this article, we review the radiation-induced changes in the stromal compartments of tumors that could have an impact on tumor immune attack. Since different RT regimens are known to mediate strikingly different effects on the multifarious elements of the tumor stroma, special emphasis is given to different RT schedules, and the time after treatment at which the effects are measured. A better understanding of TME remodeling following specific RT regimens and the window of opportunity offered by RT will enable optimization of the design of novel treatment combinations.

INSL5 activates multiple signalling pathways and regulates GLP-1 secretion in NCI-H716 cells

Insulin-like peptide 5 (INSL5) is a newly discovered gut hormone expressed in colonic enteroendocrine L-cells but little is known about its biological function. Here, we show using RT-qPCR and in situ hybridisation that Insl5 mRNA is highly expressed in the mouse colonic mucosa, colocalised with proglucagon immunoreactivity. In comparison, mRNA for RXFP4 (the cognate receptor for INSL5) is expressed in various mouse tissues, including the intestinal tract. We show that the human enteroendocrine L-cell model NCI-H716 cell line, and goblet-like colorectal cell lines SW1463 and LS513 endogenously express RXFP4. Stimulation of NCI-H716 cells with INSL5 produced phosphorylation of ERK1/2 (Thr²⁰²/Tyr²⁰⁴), AKT (Thr³⁰⁸ and Ser⁴⁷³) and S6RP (Ser^235/236) and inhibited cAMP production but did not stimulate Ca²⁺ release. Acute INSL5 treatment had no effect on GLP-1 secretion mediated by carbachol or insulin, but modestly inhibited forskolin-stimulated GLP-1 secretion in NCI-H716 cells. However, chronic INSL5 pre-treatment (18 h) increased basal GLP-1 secretion and prevented the inhibitory effect of acute INSL5 administration. LS513 cells were found to be unresponsive to INSL5 despite expressing RXFP4 Another enteroendocrine L-cell model, mouse GLUTag cells did not express detectable levels of Rxfp4 and were unresponsive to INSL5. This study provides novel insights into possible autocrine/paracrine roles of INSL5 in the intestinal tract.

CCL18 - Beyond chemotaxis

The chemokine CCL18 is constitutively expressed in human lung and serum, and is further elevated during pathologic conditions such as allergy, fibrosis and cancer, suggesting that it may participate in both homeostatic and inflammatory processes. Under steady state conditions, CCL18 has chemotactic activity, albeit modest, toward naïve T cells and as such, may be involved in the initiation of the adaptive response. Its chemotactic effect on inflammatory cells is ambiguous as it attracts both regulatory and inflammatory immune cells. CCL18 can also modulate tissue inflammation by inhibiting cell recruitment through binding to glycosaminoglycans with high affinity, thereby displacing other chemokines bound to the endothelial surface. CCL18 induces regulatory phenotype and function of immune cells through direct activation and plays a major role in fibrotic processes, particularly in the lung. Finally, CCL18 is involved in cancer cell activation and migration and also participates in immune tolerance toward cancer. Its high constitutive expression levels and its further up-regulation in many diseases, together with its moderate chemoattractant properties support the fact that this chemokine has activities beyond cell recruitment.

Reprogramming of Tumor-Associated Macrophages with Anticancer Therapies: Radiotherapy versus Chemo- and Immunotherapies

Tumor-associated macrophages (TAMs) play a central role in tumor progression, metastasis, and recurrence after treatment. Macrophage plasticity and diversity allow their classification along a M1–M2 polarization axis. Tumor-associated macrophages usually display a M2-like phenotype, associated with pro-tumoral features whereas M1 macrophages exert antitumor functions. Targeting the reprogramming of TAMs toward M1-like macrophages would thus be an efficient way to promote tumor regression. This can be achieved through therapies including chemotherapy, immunotherapy, and radiotherapy (RT). In this review, we first describe how chemo- and immunotherapies can target TAMs and, second, we detail how RT modifies macrophage phenotype and present the molecular pathways that may be involved. The identification of irradiation dose inducing macrophage reprogramming and of the underlying mechanisms could lead to the design of novel therapeutic strategies and improve synergy in combined treatments.