Zebrafish Models to Study the Crosstalk between Inflammation and NADPH Oxidase-Derived Oxidative Stress in Melanoma

Association between inflammatory factors and melanoma: a bidirectional Mendelian randomization study

PURPOSE

This study performed a bidirectional Mendelian randomization (MR) analysis to elucidate the causal relationships of C-reactive protein and 41 inflammatory regulators with melanoma, including data from UK Biobank, Cardiovascular Risk in Young Finns Study, and Cohorts for Inflammation Work Group.

METHODS

We selected the inverse variance weighting (IVW) to merge the estimated causal effects of multiple SNPs into a weighted average. To evaluate the heterogeneities of IVW, the Cochran Q statistic, and I2 index were used. What's more, several sensitivity analyses were employed, including IVW, MR-Egger, weighted median, and Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO).

RESULTS

With SNPs reaching P < 5 × 10-8, the analyses findings revealed that IL-16 had a significant positively association with genetically risk of melanoma (ORIVW: 1.05; 95% CI: 1.03-1.07; P < 0.001), and high levels of MCP1 (ORIVW: 1.13; 95% CI: 1.03-1.23; P = 0.01) were suggestively associated with melanoma susceptibility. What's more, TNF-β (ORIVW: 1.07; 95% CI: 1.01-1.13; P = 0.02) and IL-8 (ORIVW: 1.08, 95% CI: 1.01-1.16; P = 0.03) were demonstrated a positive association with the risk of melanoma under a less stringent cut-off (P < 5 × 10-6). Conversely, we found a facilitative effect of melanoma susceptibility on IP-10 and inhibitory effects on IL-6, IL-1b, and GRO-α.

CONCLUSION

The genetic evidence that we have uncovered indicates a potential association between the levels of specific inflammatory markers (IL-16, IL-8, MCP-1, and TNF-β) and the risk of melanoma. Further research is imperative to translate these findings into clinical applications.

Smad4 Loss in the Mouse Intestinal Epithelium Alleviates the Pathological Fibrotic Response to Injury in the Colon

Mucosal healing is associated with better clinical outcomes in patients with inflammatory bowel diseases (IBDs). Unresolved injury and inflammation, on the other hand, increases pathological fibrosis and the predisposition to cancer. Loss of Smad4, a tumor suppressor, is known to increase colitis-associated cancer in mouse models of chronic IBD. Since common biological processes are involved in both injury repair and tumor growth, we sought to investigate the effect of Smad4 loss on the response to epithelial injury. To this end, Smad4 was knocked out specifically in the intestinal epithelium and transcriptomic and morphological changes compared between wild type mice and Smad4 knock out mice after DSS-induced injury. We find that Smad4 loss alleviates pathological fibrosis and enhances mucosal repair. The transcriptomic changes specific to epithelium indicate molecular changes that affect epithelial extracellular matrix (ECM) and promote enhanced mucosal repair. These findings suggest that the biological processes that promote wound healing alleviate the pathological fibrotic response to DSS. Therefore, these mucosal repair processes could be exploited to develop therapies that promote normal wound healing and prevent fibrosis.

NEW AND NOTEWORTHY

We show that transcriptomic changes due to Smad4 loss in the colonic epithelium alleviates the pathological fibrotic response to DSS in an IBD mouse model of acute inflammation. Most notably, we find that collagen deposition in the epithelial ECM, as opposed to that in the lamina propria, correlates with epithelial changes that enhance wound healing. This is the first report on a mouse model providing alleviated fibrotic response in a DSS-IBD mouse model in vivo .

Dual Role of DUOX1-Derived Reactive Oxygen Species in Melanoma

Melanoma is the most serious type of skin cancer. Inflammation and oxidative stress play an essential role in the development of several types of cancer, including melanoma. Although oxidative stress promotes tumor growth, once cells escape from the primary tumor, they are subjected to a more hostile environment, with higher levels of oxidative stress typically killing most cancer cells. As Dual Oxidase 1 (DUOX1) is a major producer of reactive oxygen species (ROS) in epithelia, we used allotransplantation and autochthonous melanoma models in zebrafish together with in silico analysis of the occurrence and relevance of DUOX1 expression of the skin cutaneous melanoma (SKCM) cohort of The Cancer Genome Atlas (TCGA) to address the role of this enzyme in the aggressiveness of melanoma cells in vivo. It was found that high transcript levels of the gene encoding DUOX1 were associated with the poor prognosis of patients in the early-stage melanoma of TCGA cohort. However, DUOX1 transcript levels were not found to be associated to the prognosis of late-stage SKCM patients. In addition, the transcript level of DUOX1 in metastatic SKCM was lower than in primary SKCM. Using zebrafish primary melanoma and allotransplantation models, we interrogated the role of DUOX1 in vivo. Our results confirmed a dual role of DUOX1, which restrains melanoma proliferation but promotes metastasis. As this effect is only observed in immunocompromised individuals, the immune system appears to be able to counteract this elevated metastatic potential of DUOX1-deficient melanomas.

Hypoxia-Nitric Oxide Axis and the Associated Damage Molecular Pattern in Cutaneous Melanoma

Hypoxia was intensively studied in cancer during the last few decades, being considered a characteristic of the tumor microenvironment. The aim of the study was to evaluate the capacity of tumor cells to adapt to the stress generated by limited oxygen tissue in cutaneous melanoma. We developed a case-control prospective study that included 52 patients with cutaneous melanoma and 35 healthy subjects. We focused on identifying and monitoring hypoxia, the dynamic of nitric oxide (NO) serum metabolites and posttranslational metabolic disorders induced by NO signaling according to the clinical, biological and tumoral characteristics of the melanoma patients. Our study showed high levels of hypoxia-inducible factor-1a (HIF-1a) and hypoxia-inducible factor-2a (HIF-2a) in the melanoma patients. Hypoxia-inducible factors (HIFs) control the capacity of tumor cells to adapt to low levels of oxygen. Hypoxia regulated the nitric oxide synthase (NOS) expression and activity. In the cutaneous melanoma patients, disorders in NO metabolism were detected. The serum levels of the NO metabolites were significantly higher in the melanoma patients. NO signaling influenced the tumor microenvironment by modulating tumoral proliferation and sustaining immune suppression. Maintaining NO homeostasis in the hypoxic tumoral microenvironment could be considered a future therapeutic target in cutaneous melanoma.