Chemokines and chemokine receptors required for optimal responses to anticancer chemotherapy

The paradoxical role of cytokines and chemokines at the tumor microenvironment: a comprehensive review

Tumor progression and eradication have long piqued the scientific community's interest. Recent discoveries about the role of chemokines and cytokines in these processes have fueled renewed interest in related research. These roles are frequently viewed as contentious due to their ability to both suppress and promote cancer progression. As a result, this review critically appraised existing literature to discuss the unique roles of cytokines and chemokines in the tumor microenvironment, as well as the existing challenges and future opportunities for exploiting these roles to develop novel and targeted treatments. While these modulatory molecules play an important role in tumor suppression via enhanced cancer-cell identification by cytotoxic effector cells and directly recruiting immunological effector cells and stromal cells in the TME, we observed that they also promote tumor proliferation. Many cytokines, including GM-CSF, IL-7, IL-12, IL-15, IL-18, and IL-21, have entered clinical trials for people with advanced cancer, while the FDA has approved interferon-alpha and IL-2. Nonetheless, low efficacy and dose-limiting toxicity limit these agents' full potential. Conversely, Chemokines have tremendous potential for increasing cancer immune-cell penetration of the tumor microenvironment and promoting beneficial immunological interactions. When chemokines are combined with cytokines, they activate lymphocytes, producing IL-2, CD80, and IL-12, all of which have a strong anticancer effect. This phenomenon opens the door to the development of effective anticancer combination therapies, such as therapies that can reverse cancer escape, and chemotaxis of immunosuppressive cells like Tregs, MDSCs, and TAMs.

Immunogenic cell death (ICD)-inducers in non-small-cell lung carcinoma (NSCLC): current knowledge and future perspective

The prevalence of non-small-cell lung cancer (NSCLC) is rising every year all around the world. The interaction between cancer cells and the tumor microenvironment (TME) is a crucial factor in determining the development of human neoplasms. Organellar and cellular stress are induced during immunogenic cell death (ICD), a particularly functional response pattern. ICD is a separate but poorly characterized entity caused by various cancer treatments. The induction of ICD has the potential to change TME and the recruitment of tumor-infiltrating lymphocytes (TILs), and the coupling of ICD-inducers and other therapeutic approaches can have a synergistic role in boosting anticancer impacts. The purpose of this study is to review the studies in the field of NSCLC using ICD-inducers as a treatment strategy or as a combination therapy. This review provide for researches a better view of what has been done so far and the challenges they face in the future.

Ccl3 enhances docetaxel chemosensitivity in breast cancer by triggering proinflammatory macrophage polarization

Background

Although the antitumor efficacy of docetaxel (DTX) has long been attributed to the antimitotic activities, its impact on the tumor microenvironment (TME) has recently gained more attention. Macrophages are a major component of the TME and play a critical role in DTX efficacy; however, the underlying action mechanisms remain unclear.

Methods

DTX chemotherapeutic efficacy was demonstrated via both macrophage depletion and C–C motif chemokine ligand 3 (Ccl3)-knockout transgenic allograft mouse model. Ccl3-knockdown and Ccl3-overexpressing breast cancer cell allografts were used for the in vivo study. Combination therapy was used to evaluate the effect of Ccl3 induction on DTX chemosensitivity. Vital regulatory molecules and pathways were identified using RNA sequencing. Macrophage phagocytosis of cancer cells and its influence on cancer cell proliferation under DTX treatment were assessed using an in vitro coculture assay. Serum and tumor samples from patients with breast cancer were used to demonstrate the clinical relevance of our study.

Results

Our study revealed that Ccl3 induced by DTX in macrophages and cancer cells was indispensable for the chemotherapeutic efficacy of DTX. DTX-induced Ccl3 promoted proinflammatory macrophage polarization and subsequently facilitated phagocytosis of breast cancer cells and cancer stem cells. Ccl3 overexpression in cancer cells promoted proinflammatory macrophage polarization to suppress tumor progression and increase DTX chemosensitivity. Mechanistically, DTX induced Ccl3 by relieving the inhibition of cAMP-response element binding protein on Ccl3 via reactive oxygen species accumulation, and Ccl3 then promoted proinflammatory macrophage polarization via activation of the Ccl3–C-C motif chemokine receptor 5–p38/interferon regulatory factor 5 pathway. High CCL3 expression predicted better prognosis, and high CCL3 induction revealed better DTX chemosensitivity in patients with breast cancer. Furthermore, both the Creb inhibitor and recombinant mouse Ccl3 significantly enhanced DTX chemosensitivity.

Conclusions

Our results indicate that Ccl3 induced by DTX triggers proinflammatory macrophage polarization and subsequently facilitates phagocytosis of cancer cells. Ccl3 induction in combination with DTX may provide a promising therapeutic rationale for increasing DTX chemosensitivity in breast cancer.

Chemokine-Directed Tumor Microenvironment Modulation in Cancer Immunotherapy

Chemokines are a large family of small chemotactic cytokines that coordinates immune cell trafficking. In cancer, they have a pivotal role in the migration pattern of immune cells into the tumor, thereby shaping the tumor microenvironment immune profile, often towards a pro-tumorigenic state. Furthermore, chemokines can directly target non-immune cells in the tumor microenvironment, including cancer, stromal and vascular endothelial cells. As such, chemokines participate in several cancer development processes such as angiogenesis, metastasis, cancer cell proliferation, stemness and invasiveness, and are therefore key determinants of disease progression, with a strong influence in patient prognosis and response to therapy. Due to their multifaceted role in the tumor immune response and tumor biology, the chemokine network has emerged as a potential immunotherapy target. Under the present review, we provide a general overview of chemokine effects on several tumoral processes, as well as a description of the currently available chemokine-directed therapies, highlighting their potential both as monotherapy or in combination with standard chemotherapy or other immunotherapies. Finally, we discuss the most critical challenges and prospects of developing targeted chemokines as therapeutic options.

SLC1A1, SLC16A9, and CNTN3 Are Potential Biomarkers for the Occurrence of Colorectal Cancer

Background

This study is aimed at identifying unknown clinically relevant genes involved in colorectal cancer using bioinformatics analysis.

Methods

Original microarray datasets GSE107499 (ulcerative colitis), GSE8671 (colorectal adenoma), and GSE32323 (colorectal cancer) were downloaded from the Gene Expression Omnibus. Common differentially expressed genes were filtered from the three datasets above. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed, followed by construction of a protein-protein interaction network to identify hub genes. Kaplan-Meier survival analysis and TIMER database analysis were used to screen the genes related to the prognosis and tumour-infiltrating immune cells of colorectal cancer. Receiver operating characteristic curves were used to assess whether the genes could be used as markers for the diagnosis of ulcerative colitis, colorectal adenoma, and colorectal cancer.

Results

A total of 237 differentially expressed genes common to the three datasets were identified, of which 60 were upregulated, 125 were downregulated, and 52 genes that were inconsistently up- and downregulated. Common differentially expressed genes were mainly enriched in the cellular component of extracellular exosome and integral component of membrane categories. Eight hub genes, i.e., CXCL3, CXCL8, CEACAM7, CNTN3, SLC1A1, SLC16A9, SLC4A4, and TIMP1, were related to the prognosis and tumour-infiltrating immune cells of colorectal cancer, and these genes have diagnostic value for ulcerative colitis, colorectal adenoma, and colorectal cancer.

Conclusion

Three novel genes, CNTN3, SLC1A1, and SLC16A9 were shown to have diagnostic value with respect to the occurrence of colorectal cancer and should be verified in future studies.

A S100A14-CCL2/CXCL5 signaling axis drives breast cancer metastasis

Rationale: Chemokines contribute to cancer metastasis and have long been regarded as attractive therapeutic targets for cancer. However, controversy exists about whether neutralizing chemokines by antibodies promotes or inhibits tumor metastasis, suggesting that the approach to directly target chemokines needs to be scrutinized. Methods: Transwell assay, mouse metastasis experiments and survival analysis were performed to determine the functional role of S100A14 in breast cancer. RNA-Seq, secreted proteomics, ChIP, Western blot, ELISA, transwell assay and neutralizing antibody experiments were employed to investigate the underlying mechanism of S100A14 in breast cancer metastasis. Immunohistochemistry and ELISA were performed to examine the expression and serum levels of S100A14, CCL2 and CXCL5, respectively. Results: Overexpression of S100A14 significantly enhanced migration, invasion and metastasis of breast cancer cells. In contrast, knockout of S100A14 exhibited the opposite effects. Mechanistic studies demonstrated that S100A14 promotes breast cancer metastasis by upregulating the expression and secretion of CCL2 and CXCL5 via NF-κB mediated transcription. The clinical sample analyses showed that S100A14 expression is strongly associated with CCL2/CXCL5 expression and high expression of these three proteins is correlated with worse clinical outcomes. Notably, the serum levels of S100A14, CCL2/CXCL5 have significant diagnostic value for discerning breast cancer patients from healthy individuals. Conclusions: S100A14 is significantly upregulated in breast cancer, it can promote breast cancer metastasis by increasing the expression and secretion of CCL2/CXCL5 via RAGE-NF-κB pathway. And S100A14 has the potential to serve as a serological marker for diagnosis of breast cancer. Collectively, we identify S100A14 as an upstream regulator of CCL2/CXCL5 signaling and a metastatic driver of breast cancer.

Significance of CXCL12/CXCR4 Ligand/Receptor Axis in Various Aspects of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is defined as an aggressive disorder which is described by accumulation of immature malignant cells into the bone marrow. Chemokine-receptor axes are defined as factors involved in AML pathogenesis and prognosis. The chemokine receptor CXCR4 along with its ligand, CXCL12 fit in important players that are actively involved in the cross-talk between leukemia cells and bone marrow microenvironment. Therefore, according to the above introductory comments, in this review article, we have focused on delineating some parts played by CXCL12/CXCR4 axis in various aspects of AML malignancy. Targeting both leukemic and stromal cell interaction is nowadays accepted as a wide and attractive strategy for improving the outcome of treatment in AML in a non-cell autonomous manner. This strategy might be employed in a wide variety of AML patients regardless of their causative mutations. In addition to several potential targets involved in the disruption of malignant leukemic cells from their specific protective niches, compounds which interfere with CXCL12/CXCR4 axis have also been explored in multiple early-phase established clinical trials. Moreover, extensive research programs are exploring novel leading mechanisms for leukemia-stromal interactions that appear to find out novel therapeutic targets within the near future.

Transcriptional Profiling Reveals the Regulatory Role of CXCL8 in Promoting Colorectal Cancer

C-X-C motif chemokine ligand 8 (CXCL8) is involved in tumor proliferation, migration, and invasion. However, the function of CXCL8 in colorectal cancer (CRC) is controversial. Here, we analyzed RNA-sequencing (RNA-seq) data to identify differentially expressed genes and pathways according to gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with CRC. The levels of the mRNA encoding CXCL8 were significantly increased in early and advanced stages of CRC, as well as in metastases and nonmetastasis cases using RNA-seq analysis (n = 91). These findings were consistent with immunohistochemical analysis of CXCL8 expression (n = 87). Protein-protein interaction (PPI) prediction combined with transcriptional profiling data revealed that CXCL8 levels positively correlated with cAMP responsive element binding protein 1 (CREB1)/ribosomal protein S6 kinase B1 (RPS6KB1) expression, which promotes cell proliferation and differentiation in high expression, while inversely correlated with the expression of Bcl2 associated agonist of cell death (BAD) protein to inhibit apoptosis during the progression of CRC. These findings provide compelling clinical and molecular evidence to support the conclusion that CXCL8 contributes to the genesis and progression of CRC.

An Inflammation-Immunity Classifier of 11 Chemokines for Prediction of Overall Survival in Head and Neck Squamous Cell Carcinoma

BACKGROUND Chemokines are important in inflammation, immunity, tumor progression, and metastasis. The purpose of this research was to find an integrated-RNA signature of chemokine family genes to predict the survival prognosis in head and neck squamous carcinoma (HNSC) patients. MATERIAL AND METHODS Relevant data of 504 HNSC patients were extracted from The Cancer Genome Atlas (TCGA) database. Through analyzing RNA sequencing data, the univariate Cox model was used to identify chemokine family genes associated with survival and then to develop a multiple-RNA signature in the training set. The prediction value of this multiple-RNA signature was further verified in the validation and entire sets. The receiver operating characteristic curves were used to assess the predictive value of this multiple-RNA signature. RESULTS Eleven chemokines were included in this prognostic signature. Based on this 11-chemokine signature, we further categorized patients as high or low risk. Compared with low-risk patients, high-risk patients had shorter overall survival (OS) time in the training set [hazard ratio (HR)=3.497, 95% confidence interval (CI)=2.142-5.711, p<0.001], validation set (HR=3.575, 95% CI=1.988-6.390, p<0.001), and entire set (HR=3.416, 95% CI=2.363-4.939, p<0.001). This 11-chemokine signature was an independent prognostic factor for OS in these datasets (p<0.05). The AUC values for predicting overall survival within 48 months in the training, validation, and entire sets were 0.71, 0.69, and 0.69, respectively. CONCLUSIONS This 11-chemokine signature could serve as a reliable prognostic tool for HNSC patients and might be useful to guide individualized treatment or even gene target therapy for high-risk patients.

Chemokine Receptor CXCR3 Correlates with Decreased M2 Macrophage Infiltration and Favorable Prognosis in Gastric Cancer

Aim

The aim of this study was to explore the correlation of chemokine receptor CXCR3 with M2 macrophage infiltration, various clinicopathological features, and prognosis in patients diagnosed with gastric cancer (GC).

Methods

Expression of CXCR3 protein and M2 macrophage was evaluated in 156 GC patients and corresponding paracancerous tissues by immunohistochemical (IHC) analysis.

Results

In our study, 59 (37.82%) showed high expression of CXCR3 protein in 156 GC tissues. Expression of CXCR3 protein was significantly increased in tumor tissues compared with corresponding paracancerous tissues (P < 0.001). Overexpression of CXCR3 protein correlated with decreased M2 macrophage infiltration (P = 0.001). By analyzing the association between expression of CXCR3 protein and clinicopathological factors of GC patients, we found that high level of CXCR3 protein was significantly correlated with better differentiation (P =0.017), I/II TNM stage (P = 0.02), and smaller invasion depth (P = 0.003). Moreover, we found through Kaplan-Meier analysis and log-rank test that GC patients with high expression of CXCR3 protein and low M2 macrophage infiltration had better overall survival (OS) and low mortality rate (P < 0.001 and P = 0.024, respectively). The multivariate survival analysis showed that high expression of CXCR3 protein could serve as a favorable independent biomarker for prognosis in GC patients [hazard ratio (HR): 0.342 (0.204-0.571); P < 0.001].

Conclusion

Our study indicates that overexpression of CXCR3 protein in GC is associated with decreased M2 macrophage infiltration and improved OS and thus can be further exploited as a biomarker in GC.

Combination of chemotherapy and physical plasma elicits melanoma cell death via upregulation of SLC22A16

Malignant melanoma is an aggressive cancer that develops drug resistance leading to poor prognosis. Efficient delivery of chemotherapeutic drugs to the tumor tissue remains a major challenge in treatment regimens. Using murine (B16) and human (SK-MEL-28) melanoma cells, we investigated traditional cytotoxic agents in combination with cold physical plasma-derived oxidants. We report synergistic cytotoxicity of doxorubicin and epirubicin, and additive toxicity of oxaliplatin with plasma exposure in coefficient of drug interaction analysis. The combination treatment led to an increased DNA damage response (increased phosphorylation of ATM, γ-H2AX foci, and micronuclei formation). There was also an enhanced secretion of immunogenic cell death markers ATP and CXCL10 in cell culture supernatants following combination treatment. The observed synergistic effects in tumor cells was due to enhanced intracellular doxorubicin accumulation via upregulation of the organic cationic transporter SLC22A16 by plasma treatment. The doxorubicin uptake was reversed by pretreating cells with antioxidants or calcium influx inhibitor BTP2. Endoribonuclease-prepared siRNAs (esiRNA)-mediated knockdown of SLC22A16 inhibited the additive cytotoxic effect in tumor cells. SK-MEL 28 and THP-1 monocytes co-culture led to greater THP-1 cell migration and SK-MEL-28 cytotoxicity when compared with controls. Taken together, we propose pro-oxidant treatment modalities to sensitize chemoresistant melanoma cells towards subsequent chemotherapy, which may serve as therapeutic strategy in combination treatment in oncology.

Multiple anti-tumor effects of Reparixin on thyroid cancer

Background

Expression of IL-8 and its receptors CXCR1 and CXCR2 is a common occurrence in human epithelial thyroid cancer (TC). In human TC samples, IL-8 expression is associated with tumor progression. IL-8 enhances proliferation, survival, motility, and leads to the maintenance of stemness features and tumor-initiating ability of TC cells. Here, we studied the effects of Reparixin (formerly Repertaxin), a small molecular weight CXCR1 and CXCR2 inhibitor, on the malignant phenotype of various TC cell lines.

Results

Reparixin impaired the viability of epithelial thyroid cancerous cells, but not that of the non-malignant counterpart. Reparixin treatment significantly decreased TC cell survival, proliferation, Epithelial-to-Mesenchymal Transition (EMT) and stemness. CXCR1 and CXCR2 silencing abolished these effects. Reparixin sensitized TC cells to Docetaxel and Doxorubicin in culture. Used as single agent, Reparixin significantly inhibited TC cell tumorigenicity in immunodeficient mice. Finally, Reparixin potentiated the effects of Docetaxel on TC cell xenotransplants in mice.

Materials and Methods

We assessed the effects of Reparixin on TC cell viability (by growth curves, BrdU incorporation, TUNEL assay), EMT (by RT-PCR, Flow Cytometry, Migration assays), stemness (by RT-PCR, Flow Cytometry, sphere-formation and self-renewal), and tumorigenicity (by xenotransplantation in nude mice).

Conclusions

The present study suggests that Reparixin, both alone and in combination with classic chemotherapics, represents a novel potential therapeutic strategy for aggressive forms of TC.

Epidermal growth factor receptor inhibitors trigger a type I interferon response in human skin

The Epidermal Growth Factor Receptor (EGFR) is centrally involved in the regulation of key processes of the epithelia, including cell proliferation, survival, differentiation, and also tumorigenesis. Humanized antibodies and small-molecule inhibitors targeting EGFR were developed to disrupt these functions in cancer cells and are currently used in the treatment of diverse metastatic epithelial cancers. By contrast, these drugs possess significant skin-specific toxic effects, comprising the establishment of a persistent inflammatory milieu. So far, the molecular mechanisms underlying these epiphenomena have been investigated rather poorly. Here we showed that keratinocytes respond to anti-EGFR drugs with the development of a type I interferon molecular signature. Upregulation of the transcription factor IRF1 is early implicated in the enhanced expression of interferon-kappa, leading to persistent activation of STAT1 and further amplification of downstream interferon-induced genes, including anti-viral effectors and chemokines. When anti-EGFR drugs are associated to TNF-α, whose expression is enhanced by the drugs themselves, all these molecular events undergo a dramatic enhancement by synergy mechanisms. Finally, high levels of interferon-kappa can be observed in epidermal keratinocytes and also in leukocytes infiltrating the upper dermis of cetuximab-driven skin lesions. Our data suggest that dysregulated activation of type I interferon innate immunity is implicated in the molecular processes triggered by anti-EGFR drugs and leading to persistent skin inflammation.

The MEK Inhibitors Trametinib and Cobimetinib Induce a Type I Interferon Response in Human Keratinocytes

Mitogen-activated protein kinase kinases (MEK) 1 and 2 have crucial roles in tumorigenesis, cell proliferation, and protection from apoptosis, and their inhibition is therefore an attractive therapeutic strategy in cancer. Orally available and highly selective MEK inhibitors have been developed and assessed in numerous clinical trials, either alone or in combination with cytotoxic chemotherapy and/or other targeted agents. Of note, a complex picture of class-specific adverse effects associates with these drugs, frequently including inflammatory skin rash. Here, we investigated the response of normal human keratinocytes to the MEK inhibitors trametinib and cobimetinib, alone and in combination with the v-Raf murine sarcoma viral oncogene homolog B (BRAF) inhibitors dabrafenib and vemurafenib, in terms of signal transduction and de novo gene expression. MEK inhibitors triggered enhanced expression of interferon regulatory factor 1 (IRF1) and phosphorylation of signal transducer and activator of transcription 1 (STAT1), and up-regulated the keratinocyte-specific type I interferon κ (IFN-κ), the anti-viral effectors interferon-induced tetratricopeptide repeats (IFIT) 1 and 2, and the pro-inflammatory chemokine (C-C motif) ligand 2 (CCL2) and the C-X-C motif chemokine 10 (CXCL10), both at the mRNA and protein level. Impairment of IRF1 expression, or abrogation of STAT1 phosphorylation due to IFN-κ gene silencing, suppressed anti-viral and pro-inflammatory gene expression. These data suggest that, similar to what we observed for epidermal growth factor receptor (EGFR) blockade, MEK inhibition activates a type I interferon response, which is now recognized as an effective anti-cancer response, in human epidermal keratinocytes.

A gene expression inflammatory signature specifically predicts multiple myeloma evolution and patients survival

Multiple myeloma (MM) is closely dependent on cross-talk between malignant plasma cells and cellular components of the inflammatory/immunosuppressive bone marrow milieu, which promotes disease progression, drug resistance, neo-angiogenesis, bone destruction and immune-impairment. We investigated the relevance of inflammatory genes in predicting disease evolution and patient survival. A bioinformatics study by Ingenuity Pathway Analysis on gene expression profiling dataset of monoclonal gammopathy of undetermined significance, smoldering and symptomatic-MM, identified inflammatory and cytokine/chemokine pathways as the most progressively affected during disease evolution. We then selected 20 candidate genes involved in B-cell inflammation and we investigated their role in predicting clinical outcome, through univariate and multivariate analyses (log-rank test, logistic regression and Cox-regression model). We defined an 8-genes signature (IL8, IL10, IL17A, CCL3, CCL5, VEGFA, EBI3 and NOS2) identifying each condition (MGUS/smoldering/symptomatic-MM) with 84% accuracy. Moreover, six genes (IFNG, IL2, LTA, CCL2, VEGFA, CCL3) were found independently correlated with patients' survival. Patients whose MM cells expressed high levels of Th1 cytokines (IFNG/LTA/IL2/CCL2) and low levels of CCL3 and VEGFA, experienced the longest survival. On these six genes, we built a prognostic risk score that was validated in three additional independent datasets. In this study, we provide proof-of-concept that inflammation has a critical role in MM patient progression and survival. The inflammatory-gene prognostic signature validated in different datasets clearly indicates novel opportunities for personalized anti-MM treatment.

Chemokine Receptor Signaling and the Hallmarks of Cancer

The chemokines are a family of chemotactic cytokines that mediate their activity by acting on seven-transmembrane-spanning G protein-coupled receptors. Both the ability of the chemokines and their receptors to form homo- and heterodimers and the promiscuity of the chemokine-chemokine receptor interaction endow this protein family with enormous signaling plasticity and complexity that are not fully understood at present. Chemokines were initially identified as essential regulators of homeostatic and inflammatory trafficking of innate and adaptive leucocytes from lymphoid organs to tissues. Chemokines also mediate the host response to cancer. Nevertheless, chemokine function in this response is not limited to regulating leucocyte infiltration into the tumor microenvironment. It is now known that chemokines and their receptors influence most-if not all-hallmark processes of cancer; they act on both neoplastic and untransformed cells in the tumor microenvironment, including fibroblasts, endothelial cells (blood and lymphatic), bone marrow-derived stem cells, and, obviously, infiltrating leucocytes. This review begins with an overview of chemokine and chemokine receptor structure, to better define how chemokines affect the proliferation, survival, stemness, and metastatic potential of neoplastic cells. We also examine the main mechanisms by which chemokines regulate tumor angiogenesis and immune cell infiltration, emphasizing the pro- and antitumorigenic activity of this protein superfamily in these interrelated processes.

The oncolytic peptide LTX-315 triggers necrotic cell death

The oncolytic peptide LTX-315 has been designed for killing human cancer cells and turned out to stimulate anti-cancer immune responses when locally injected into tumors established in immunocompetent mice. Here, we investigated the question whether LTX-315 induces apoptosis or necrosis. Transmission electron microscopy or morphometric analysis of chromatin-stained tumor cells revealed that LTX-315 failed to induce apoptotic nuclear condensation and rather induced a necrotic phenotype. Accordingly, LTX-315 failed to stimulate the activation of caspase-3, and inhibition of caspases by means of Z-VAD-fmk was unable to reduce cell killing by LTX-315. In addition, 2 prominent inhibitors of regulated necrosis (necroptosis), namely, necrostatin-1 and cycosporin A, failed to reduce LTX-315-induced cell death. In conclusion, it appears that LTX-315 triggers unregulated necrosis, which may contribute to its pro-inflammatory and pro-immune effects.

Immunotherapy for neuro-oncology: the critical rationale for combinatorial therapy

A successful therapeutic paradigm established historically in oncology involves combining agents with potentially complementary mechanisms of antitumor activity into rationally designed regimens. For example, cocktails of cytotoxic agents, which were carefully designed based on mechanisms of action, dose, and scheduling considerations, have led to dramatic improvements in survival including cures for childhood leukemia, Hodgkin's lymphoma, and several other complex cancers. Outcome for glioblastoma, the most common primary malignant CNS cancer, has been more modest, but nonetheless our current standard of care derives from confirmation that combination therapy surpasses single modality therapy. Immunotherapy has recently come of age for medical oncology with exciting therapeutic benefits achieved by several types of agents including vaccines, adoptive T cells, and immune checkpoint inhibitors against several types of cancers. Nonetheless, most benefits are relatively short, while others are durable but are limited to a minority of treated patients. Critical factors limiting efficacy of immunotherapeutics include insufficient immunogenicity and/or inadequate ability to overcome immunosuppressive factors exploited by tumors. The paradigm of rationally designed combinatorial regimens, originally established by cytotoxic therapy for oncology, may also prove relevant for immunotherapy. Realization of the true therapeutic potential of immunotherapy for medical oncology and neuro-oncology patients may require development of combinatorial regimens that optimize immunogenicity and target tumor adaptive immunosuppressive factors.

Conserved genes and pathways in primary human fibroblast strains undergoing replicative and radiation induced senescence

Background

Cellular senescence is induced either internally, for example by replication exhaustion and cell division, or externally, for example by irradiation. In both cases, cellular damages accumulate which, if not successfully repaired, can result in senescence induction. Recently, we determined the transcriptional changes combined with the transition into replicative senescence in primary human fibroblast strains. Here, by γ-irradiation we induced premature cellular senescence in the fibroblast cell strains (HFF and MRC-5) and determined the corresponding transcriptional changes by high-throughput RNA sequencing.

Results

Comparing the transcriptomes, we found a high degree of similarity in differential gene expression in replicative as well as in irradiation induced senescence for both cell strains suggesting, in each cell strain, a common cellular response to error accumulation. On the functional pathway level, “Cell cycle” was the only pathway commonly down-regulated in replicative and irradiation-induced senescence in both fibroblast strains, confirming the tight link between DNA repair and cell cycle regulation. However, “DNA repair” and “replication” pathways were down-regulated more strongly in fibroblasts undergoing replicative exhaustion. We also retrieved genes and pathways in each of the cell strains specific for irradiation induced senescence.

Conclusion

We found the pathways associated with “DNA repair” and “replication” less stringently regulated in irradiation induced compared to replicative senescence. The strong regulation of these pathways in replicative senescence highlights the importance of replication errors for its induction.

Electronic supplementary material

The online version of this article (doi:10.1186/s40659-016-0095-2) contains supplementary material, which is available to authorized users.

Trial Watch-Small molecules targeting the immunological tumor microenvironment for cancer therapy

Progressing malignancies establish robust immunosuppressive networks that operate both systemically and locally. In particular, as tumors escape immunosurveillance, they recruit increasing amounts of myeloid and lymphoid cells that exert pronounced immunosuppressive effects. These cells not only prevent the natural recognition of growing neoplasms by the immune system, but also inhibit anticancer immune responses elicited by chemo-, radio- and immuno therapeutic interventions. Throughout the past decade, multiple strategies have been devised to counteract the accumulation or activation of tumor-infiltrating immunosuppressive cells for therapeutic purposes. Here, we review recent preclinical and clinical advances on the use of small molecules that target the immunological tumor microenvironment for cancer therapy. These agents include inhibitors of indoleamine 2,3-dioxigenase 1 (IDO1), prostaglandin E2, and specific cytokine receptors, as well as modulators of intratumoral purinergic signaling and arginine metabolism.

Inhibition of formyl peptide receptor 1 reduces the efficacy of anticancer chemotherapy against carcinogen-induced breast cancer

The loss-of-function mutation of formyl peptide receptor 1 (FPR1) has a negative impact on the progression-free and overall survival of breast cancer patients treated with anthracycline-based adjuvant chemotherapy. This effect may be attributed to the fact that chemotherapy-induced antitumor immunity requires FPR1 and that such anticancer immune responses are responsible for the long-term effects of chemotherapy. Here, we investigated the possible contribution of FPR1 to the efficacy of a combination of mitoxantrone (MTX) and cyclophosphamide (CTX) for the treatment of hormone-induced breast cancer. Breast cancer induced by a combination of medroxyprogesterone acetate (MPA) and 7,12-Dimethylbenz[a]anthracene (DMBA) could be successfully treated with MTX plus CTX in thus far that tumor growth was retarded and overall survival was extended (as compared to vehicle-only treated controls). However, the therapeutic efficacy of the combination therapy was completely abolished when FPR1 receptors were blocked by means of cyclosporin H (CsH). Future genetic studies on neoadjuvant chemotherapy-treated breast cancers are warranted to validate these findings at the clinical level.

N-methyl-N-nitro-N'-nitrosoguanidine induces the expression of CCR2 in human gastric epithelial cells promoting CCL2-mediated migration

Chronic inflammation has a decisive role in tumorigenesis, particularly in gastric carcinogenesis. The CC chemokine ligand 2 (CCL2), an important inflammatory cytokine, is involved in the initiation, development and progression of various types of cancer. However, the role of CCL2 in gastric cancer remains to be elucidated. The present study demonstrated that recombinant CCL2 stimulation caused no effect on the morphology, proliferation and migration of human GES-1 gastric mucosa epithelial cells, in which the protein expression of CC-chemokine receptor 2 (CCR2) was markedly low. However, the expression of CCR2 was significantly upregulated in the GES-1 cells following pretreatment with the chemical carcinogen, N-methyl-N-nitro-N′-nitrosoguanidine (MNNG), for 12 h or transformed with MNNG (MC cells). The present study used CCL2 to stimulate MNNG pretreated GES-1 cells and MC cells, and demonstrated that CCL2 clearly promoted their migration and the epithelial-mesenchymal transition (EMT). However, no effect was observed on the proliferative ability of the cells. Taken together, these findings suggested that the CCL2/CCR2 chemokine signaling may regulate the EMT in gastric epithelial cells and resulted in gastric carcinogenesis in response to the intake of the carcinogen, MNNG.

A multi-targeted approach to suppress tumor-promoting inflammation

Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes.

Impact of chemokine receptor CXCR3 on tumor-infiltrating lymphocyte recruitment associated with favorable prognosis in advanced gastric cancer

Chemokine receptor CXCR3 has been proved to play an important role in tumorigenesis and tumor progression in many malignancies, but its precise efficacy on gastric cancer (GC) has not been evaluated yet. The present study was aimed to explore the correlation of chemokine receptor CXCR3 with tumor-infiltrating lymphocytes (TILs) and prognosis in advanced gastric cancer (GC). Expression of CXCR3 and CD4+, CD8+ TILs was conducted in 192 advanced GC specimens and 48 corresponding paracancerous tissues by immunohistochemical (IHC) analysis. CXCR3 expression in GC tissues was significantly higher than that in paracancerous tissues (P<0.001) and CD8+, CD4+ TILs infiltration increased with high CXCR3 expression (P=0.032 and P<0.001, respectively). Our study showed significantly lower CXCR3 expression in patients with greater tumor invasion depth and lymph node metastasis compared with patients with lesser tumor invasion depth and without lymph node metastasis (P=0.002 and P=0.001, respectively). Univariate analysis indicated that patients with high CXCR3 expression and high CD8+ TILs infiltration had longer overall survival (OS) (log-rank test, P<0.001 and P=0.002, respectively). Univariate and multivariate analyses indicated that CXCR3 expression was an independent prognostic factor for OS (P=0.002). The present study suggested that CXCR3 expression was upregulated in advanced GC and was associated with increased CD4+, CD8+ TILs infiltration and improved OS. Therefore, CXCR3 overexpression is implicated as a favorable prognostic biomarker in human advanced GC.

Overexpression of the chemokine receptor CXCR3 and its correlation with favorable prognosis in gastric cancer

Chemokine receptor, CXCR3, has been increasingly reported to be involved in tumorigenesis and tumor progression, but limited data are available regarding the expression of CXCR3 in gastric cancer (GC). In the present study, the expressions of CXCR3 and its variants were detected in 96 GC and corresponding nontumor gastric tissues by immunohistochemical staining, in 40 freshly frozen GC and nontumor gastric tissues by reverse-transcription polymerase chain reaction and quantitative real-time polymerase chain reaction, and in 10 freshly frozen GC and nontumor gastric tissues by Western blotting. Results revealed that an overexpression of CXCR3 occurs in GC tissues as compared to the nontumor gastric tissues. High level of CXCR3 expression was found to be inversely associated with invasion depth and metastasis (P = .030 and P = .019, respectively) and directly associated with improved overall survival (log-rank test, P < .001). Furthermore, multivariate analysis showed that high CXCR3 expression acts an independent prognostic factor for GC patients (hazard ratio, 0.379 [0.196-0.734]; P = .004). The messenger RNA expression of both the CXCR3 variants, CXCR3-A and CXCR3-B, were up-regulated in GC tissues (P = .006 and P = .002, respectively), although CXCR3-B messenger RNA expression was significantly higher than CXCR3-A, with an average CXCR3-B to CXCR3-A ratio of 1.80. CXCR3-B protein expression was also up-regulated in GC tissues (P = .023). In conclusion, our study suggested a potential use of CXCR3 overexpression as a prognostic marker for GC and involvement of the up-regulation of CXCR3-B in favorable prognosis of GC patients.

Trial Watch: Peptide-based anticancer vaccines

Malignant cells express antigens that can be harnessed to elicit anticancer immune responses. One approach to achieve such goal consists in the administration of tumor-associated antigens (TAAs) or peptides thereof as recombinant proteins in the presence of adequate adjuvants. Throughout the past decade, peptide vaccines have been shown to mediate antineoplastic effects in various murine tumor models, especially when administered in the context of potent immunostimulatory regimens. In spite of multiple limitations, first of all the fact that anticancer vaccines are often employed as therapeutic (rather than prophylactic) agents, this immunotherapeutic paradigm has been intensively investigated in clinical scenarios, with promising results. Currently, both experimentalists and clinicians are focusing their efforts on the identification of so-called tumor rejection antigens, i.e., TAAs that can elicit an immune response leading to disease eradication, as well as to combinatorial immunostimulatory interventions with superior adjuvant activity in patients. Here, we summarize the latest advances in the development of peptide vaccines for cancer therapy.

Trial Watch: Immunogenic cell death inducers for anticancer chemotherapy

The term "immunogenic cell death" (ICD) is now employed to indicate a functionally peculiar form of apoptosis that is sufficient for immunocompetent hosts to mount an adaptive immune response against dead cell-associated antigens. Several drugs have been ascribed with the ability to provoke ICD when employed as standalone therapeutic interventions. These include various chemotherapeutics routinely employed in the clinic (e.g., doxorubicin, epirubicin, idarubicin, mitoxantrone, bleomycin, bortezomib, cyclophosphamide and oxaliplatin) as well as some anticancer agents that are still under preclinical or clinical development (e.g., some microtubular inhibitors of the epothilone family). In addition, a few drugs are able to convert otherwise non-immunogenic instances of cell death into bona fide ICD, and may therefore be employed as chemotherapeutic adjuvants within combinatorial regimens. This is the case of cardiac glycosides, like digoxin and digitoxin, and zoledronic acid. Here, we discuss recent developments on anticancer chemotherapy based on ICD inducers.

Cell surface nucleolin interacts with CXCR4 receptor via the 212 c-terminal portion

Previously, we reported that CXCR4 receptor interacted with cell surface nucleolin, and the synergy of CXCR4 and nucleolin plays an essential role in malignant transformation. Here, we continued to conduct a structure-function analysis of nucleolin to identify which portion can efficaciously bind to CXCR4. In the present study, the expression of CXCR4 and nucleolin in 100 cases of papillary thyroid cancer (PTC) samples was investigated through immunohistochemistry (IHC). Subsequently, using nucleolin mutants and pull-down assay, we investigated precise interactions between CXCR4 and nucleolin in HEK-293 cells. A previous study demonstrated CXCR4 and nucleolin co-expressed in cell lines, and the present study further identified that CXCR4 and nucleolin co-expressed in PTC tissues, instead of normal tissues. The nucleolin mutant analysis revealed that nucleolin can efficaciously bind CXCR4 to activate CXCR4 signaling by 212 C-terminal domain. Conversely, N-terminal, RBD and GAR mutants of nucleolin showed no sign of activation of CXCR4 signaling, and differences were statistically insignificant (p > 0.05). In conclusion, these results suggested nucleolin is essential to activate CXCR4 signaling via 212 C-terminal domain, which is required for cell growth, migration, and invasiveness. Furthermore, nucleolin may interact with more G protein-coupled receptors, at least chemokine receptor. Our study will lay a new foundation for cancer therapy by antagonizing nucleolin and CXCR4.

Chemokine receptor-specific antibodies in cancer immunotherapy: achievements and challenges

The 1990s brought a burst of information regarding the structure, expression pattern, and role in leukocyte migration and adhesion of chemokines and their receptors. At that time, the FDA approved the first therapeutic antibodies for cancer treatment. A few years later, it was reported that the chemokine receptors CXCR4 and CCR7 were involved on directing metastases to liver, lung, bone marrow, or lymph nodes, and the over-expression of CCR4, CCR6, and CCR9 by certain tumors. The possibility of inhibiting the interaction of chemokine receptors present on the surface of tumor cells with their ligands emerged as a new therapeutic approach. Therefore, many research groups and companies began to develop small molecule antagonists and specific antibodies, aiming to neutralize signaling from these receptors. Despite great expectations, so far, only one anti-chemokine receptor antibody has been approved for its clinical use, mogamulizumab, an anti-CCR4 antibody, granted in Japan to treat refractory adult T-cell leukemia and lymphoma. Here, we review the main achievements obtained with anti-chemokine receptor antibodies for cancer immunotherapy, including discovery and clinical studies, proposed mechanisms of action, and therapeutic applications.