The ELR+CXCL chemokines and their receptors CXCR1/CXCR2: A signaling axis and new target for the treatment of renal cell carcinoma

A Potent Solution for Tumor Growth and Angiogenesis Suppression via an ELR+CXCL-CXCR1/2 Pathway Inhibitor

CXCR1/2 biomolecules play vital roles in cancer cell proliferation, tumor inflammation, and angiogenesis, making them attractive drug targets. In clear cell renal cell carcinoma (RCC) and head and neck squamous cell carcinoma (HNSCC), where CXCR1/2 is overexpressed, inhibition studies are limited. Building upon previous research efforts, we investigated new N,N'-diarylurea analogues as ELR+CXCL-CXCR1/2 inhibitors. Evaluations on RCC and HNSCC cell lines and 3D spheroid cultures identified compound 10 as a lead molecule, exhibiting significant inhibition of invasion, migration, and neo-angiogenesis. It demonstrated strong interference with the signaling pathway, with high selectivity toward kinases. In vivo studies on zebrafish embryos and RCC xenografted mice showed notable anticancer, antimetastatic, and antiangiogenic effects after oral administration and minimal toxicity. Compound 10 emerges as a promising candidate for further preclinical development as an oral anticancer and antiangiogenic drug targeting the ELR+CXCL-CXCR1/2 pathway.

Tumor-Associated Macrophages Affect the Tumor Microenvironment and Radioresistance via the Upregulation of CXCL6/CXCR2 in Hepatocellular Carcinoma

BACKGROUND

Hepatocellular carcinoma is the sixth most diagnosed malignancy and the fourth most common cause of cancer-related mortality globally. Despite progress in the treatment of liver cancer, nonsurgical treatments remain unsatisfactory, and only 15% of early-stage cases are surgically operable. Radiotherapy (RT) is a non-surgical treatment option for liver cancer when other traditional treatment methods are ineffective. However, RT has certain limitations, including eliciting poor therapeutic effects in patients with advanced and recurrent tumors. Tumor-associated macrophages (TAMs) are major inflammatory cells in the tumor microenvironment that are key to tumor development, angiogenesis, invasion, and metastasis, and they play an essential role in RT responses.

METHODS

We used big data analysis to determine the potential of targeting CXCL6/CXCR2. We enrolled 50 patients with liver cancer who received RT at our hospital. Tumor tissue samples were examined for any relationship between CXCL6/CXCR2 activity and patient prognosis. Using a cell coculture system (Transwell), we cocultured Huh7 liver cancer cells and THP-1 monocytes with and without CXCL6/CXCR2 small interfering RNA for 72 h.

RESULTS

The overexpression of CXCL6/CXCR2 was highly correlated with mortality. Our tissue study indicated a positive correlation between CXCL6/CXCR2 and M2-TAMs subsets. The coculture study demonstrated that THP-1 monocytes can secrete CXCL6, which acts on the CXCR2 receptor on the surface of Huh7 cells and activates IFN-g/p38 MAPK/NF-κB signals to promote the epithelial-mesenchymal transition and radio-resistance.

CONCLUSIONS

Modulating the TAM/CXCL6/CXCR2 tumor immune signaling axis may be a new treatment strategy for the effective eradication of radiotherapy-resistant hepatocellular carcinoma cells.

A transcriptional program associated with cell cycle regulation predominates in the anti-inflammatory effects of CX-5461 in macrophage

CX-5461, a novel selective RNA polymerase I inhibitor, shows potential anti-inflammatory and immunosuppressive activities. However, the molecular mechanisms underlying the inhibitory effects of CX-5461 on macrophage-mediated inflammation remain to be clarified. In the present study, we attempted to identify the systemic biological processes which were modulated by CX-5461 in inflammatory macrophages. Primary peritoneal macrophages were isolated from normal Sprague Dawley rats, and primed with lipopolysaccharide or interferon-γ. Genome-wide RNA sequencing was performed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases were used for gene functional annotations. Enrichment analysis was conducted using the ClusterProfiler package of R software. We found that CX-5461 principally induced a molecular signature related to cell cycle inhibition in primed macrophages, featuring downregulation of genes encoding cell cycle mediators and concomitant upregulation of cell cycle inhibitors. At the same concentration, however, CX-5461 did not induce a systemic anti-inflammatory transcriptional program, although some inflammatory genes such as IL-1β and gp91phox NADPH oxidase were downregulated by CX-5461. Our data further highlighted a central role of p53 in orchestrating the molecular networks that were responsive to CX-5461 treatment. In conclusion, our study suggested that limiting cell proliferation predominated in the inhibitory effects of CX-5461 on macrophage-mediated inflammation.

Chemokines in the Landscape of Cancer Immunotherapy: How They and Their Receptors Can Be Used to Turn Cold Tumors into Hot Ones?

Over the last decade, monoclonal antibodies to immune checkpoint inhibitors (ICI), also known as immune checkpoint blockers (ICB), have been the most successful approach for cancer therapy. Starting with mAb to cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors in metastatic melanoma and continuing with blockers of the interactions between program cell death 1 (PD-1) and its ligand program cell death ligand 1 (PDL-1) or program cell death ligand 2 (PDL-2), that have been approved for about 20 different indications. Yet for many cancers, ICI shows limited success. Several lines of evidence imply that the limited success in cancer immunotherapy is associated with attempts to treat patients with "cold tumors" that either lack effector T cells, or in which these cells are markedly suppressed by regulatory T cells (Tregs). Chemokines are a well-defined group of proteins that were so named due to their chemotactic properties. The current review focuses on key chemokines that not only attract leukocytes but also shape their biological properties. CXCR3 is a chemokine receptor with 3 ligands. We suggest using Ig-based fusion proteins of two of them: CXL9 and CXCL10, to enhance anti-tumor immunity and perhaps transform cold tumors into hot tumors. Potential differences between CXCL9 and CXCL10 regarding ICI are discussed. We also discuss the possibility of targeting the function or deleting a key subset of Tregs that are CCR8+ by monoclonal antibodies to CCR8. These cells are preferentially abundant in several tumors and are likely to be the key drivers in suppressing anti-cancer immune reactivity.

Prognostic and predictive role of intra-tumoral CXCR1 expression in patients receiving tyrosine kinase inhibitors for metastatic clear-cell renal cell carcinoma

Objective:

We aimed to evaluate the role of intra-tumoral CXCR1 expression in predicting prognosis and treatment response in metastatic clear-cell renal cell carcinoma patients receiving tyrosine kinase inhibitors.

Materials and methods:

Patients with metastatic clear-cell renal cell carcinoma presented between February 2018–December 2019 were studied for the CXCR1 expression in tumor tissues before starting tyrosine kinase inhibitors. Primary outcome measure was progression-free survival. Secondary outcome measures included overall survival and prediction of treatment response.

Results:

The study included 35 patients with a mean age of 53.6±9.6 years. At a mean follow-up of 12.2±4.1 months, 17 (48.6%) patients had disease progression including eight (22.9%) deaths. Patients with high CXCR1 expression, compared to those with low CXCR1 expression, had a significantly shorter 12-month progression-free survival (35.4% vs 77.9%, p=0.01) and an insignificant impact on 12-month overall survival. The CXCR1 expression scores significantly differed between patients with progressive and nonprogressive disease (20.1 vs 15.1, p=0.01) and patients with high CXCR1 expression had a reduced benefit from tyrosine kinase inhibitors. The multivariate Cox regression analysis showed CXCR1 expression as a significant predictor of progression-free survival.

Conclusion:

High intra-tumoral CXCR1 expression before tyrosine kinase inhibitors can be an independent prognostic factor for progression-free survival and predictor of reduced benefit in patients with metastatic clear-cell renal cell carcinoma.

Level of evidence:

Level 2b.

Galectin-3 promotes CXCR2 to augment the stem-like property of renal cell carcinoma

Although targeted therapy is usually the first‐line treatment for advanced renal cell carcinoma (RCC), some patients can experience drug resistance. Cancer stem cells are tumour‐initiating cells that play a vital role in drug resistance, metastasis and cancer relapse, while galectins (Gal) participate in tumour progression and drug resistance. However, the exact role of galectins in RCC stemness is yet unknown. In this study, we grew a subpopulation of RCC cells as tumour spheres with higher levels of stemness‐related genes, such as Oct4, Sox2 and Nanog. Among the Gal family, Gal‐3 in particular was highly expressed in RCC tumour spheres. To further investigate Gal‐3's role in the stemness of RCC, lentivirus‐mediated knockdown and overexpression of Gal‐3 in RCC cells were used to examine both in vitro and in vivo tumorigenicity. We further assessed Gal‐3 expression in RCC tissue microarray using immunohistochemistry. Upon suppressing Gal‐3 in parental RCC cells, invasion, colony formation, sphere‐forming ability, drug resistance and stemness‐related gene expression were all significantly decreased. Furthermore, CXCL6, CXCL7 and CXCR2 were down‐regulated in Gal‐3‐knockdown tumour spheres, while CXCR2 overexpression in Gal‐3‐knockdown RCC restored the ability of sphere formation. Gal‐3 overexpression in RCC promoted both in vitro and in vivo tumorigenicity, and its expression was correlated with CXCR2 expression and tumour progression in clinical tissues. RCC patients with higher co‐expressions of Gal‐3 and CXCR2 demonstrated a worse survival rate. These results indicate that highly expressed Gal‐3 may up‐regulate CXCR2 to augment RCC stemness. Gal‐3 may be a prognostic and innovative target of combined therapy for treating RCC.

Chemokine (C-X-C motif) ligand 1 is a myokine induced by palmitate and is required for myogenesis in mouse satellite cells

AIM

The functional significance of the myokines, cytokines and peptides produced and released by muscle cells has not been fully elucidated. The purpose of this study was to identify a myokine with increased secretion levels in muscle cells due to saturated fatty acids and to examine the role of the identified myokine in the regulation of myogenesis.

METHODS

Human primary myotubes and mouse C2C12 myotubes were used to identify the myokine; its secretion was stimulated by palmitate loading. The role of the identified myokine in the regulation of the activation, proliferation, differentiation and self-renewal was examined in mouse satellite cells (skeletal muscle stem cells).

RESULTS

Palmitate loading promoted the secretion of chemokine (C-X-C motif) ligand 1 (CXCL1) in human primary myotubes, and it also increased CXCL1 gene expression level in C2C12 myotubes in a dose- and time-dependent manner. Palmitate loading increased the production of reactive oxygen species along with the activation of nuclear factor-kappa B (NF-κB) signalling. Pharmacological inhibition of NF-κB signalling attenuated the increase in CXCL1 gene expression induced by palmitate and hydrogen peroxide. Palmitate loading significantly increased CXC receptor 2 gene expression in undifferentiated cells. CXCL1 knockdown attenuated proliferation and myotube formation by satellite cells, with reduced self-renewal. CXCL1 knockdown also significantly decreased the Notch intracellular domain protein level.

CONCLUSION

These results suggest that secretion of the myokine CXCL1 is stimulated by saturated fatty acids and that CXCL1 promotes myogenesis from satellite cells to maintain skeletal muscle homeostasis.

High CXC chemokine receptor 1 level represents an independent negative prognosticator in non-metastatic clear-cell renal cell carcinoma patients

CXC chemokine receptor 1 (CXCR1) signaling has been shown as an essential molecular nexus regarding cancer cell proliferation, tumor inflammation, and angiogenesis in clear cell renal cell carcinoma (ccRCC). The aim of this study was to investigate the prognostic significance of CXCR1 in patients with non-metastatic ccRCC. Data from 446 consecutive non-metastatic ccRCC patients, operated between 2003 and 2008 at a single institution, were evaluated retrospectively. The cohort was split into a training set (n = 223) and a validation set (n = 223). CXCR1 expression was assessed by immunohistochemistry staining and its association with clinicopathologic features and prognosis were evaluated. High CXCR1 epithelial expression presented prognostic value, and indicated poor overall survival (OS) (P = 0.010 and P = 0.015, respectively) and recurrence-free survival (P = 0.011 and P = 0.019, respectively) in the training and validation sets. The incorporation of CXCR1 into the T stage and SSIGN score would help to refine individual risk stratification. Multivariate analysis identified increased epithelial CXCR1 was statistically significantly associated with a poor outcome for OS (HR [95% CI] 1.808 [1.184-2.761]; P = 0.006) and RFS (HR [95% CI] 1.570 [1.076-2.290]; P = 0.019) in all non-metastatic ccRCC patients. Predictive nomograms were generated with identified independent prognosticators to assess patient overall survival and recurrence-free survival at 3, 5 and 10 y. Furthermore, high CXCR1 expression were correlated with elevated infiltrated neutrophils and enriched MMP family gene expression. To conclude, high CXCR1 level within epithelial area represented a potential independent negative prognostic factor regarding OS and RFS in non-metastatic ccRCC patients after nephrectomy.

Identification of differentially expressed inflammatory factors in Wilms tumors and their association with patient outcomes

The present study aimed to identify differentially expressed inflammatory factors observed in Wilms tumors (WT), and to investigate the association of these factors with clinical stage, pathological type, lymph node metastasis and vascular involvement of WT. Surface-enhanced laser desorption/ionization-time of flight mass spectrometry was performed to screen differentially expressed proteins among WT and normal tissue pairs. Upregulated proteins in WT were separated and purified by solid phase extraction and Tricine SDS-PAGE, respectively. Following in-gel digestion, the peptide mixture was subjected to liquid chromatography mass spectrometry to identify proteins on the basis of their amino acid sequences. Immunohistochemistry was used to confirm the expression of differentially expressed inflammatory proteins. Of the proteins that were upregulated in WT, two proteins with mass/charge (m/z) ratio of 12,138 and 13,462 were identified as macrophage migration inhibitory factor (MIF) and C-X-C motif ligand 7 (CXCL7) chemokine, respectively. The expression of these two proteins was increased in WT compared with adjacent normal tissues and normal renal tissues, and increased with increasing clinical stage. In addition, their expression was significantly increased in patients with unfavorable pathological type, lymph node metastasis and vascular involvement compared with the groups with favorable type, and without lymph node metastasis or vascular involvement (P<0.05). Increased pro-inflammatory MIF and CXCL7 expression in WT is closely associated with the clinical stage, pathological type, lymph node metastasis and vascular involvement, and may represent biomarkers for the clinical diagnosis of WT.