IL-37 promotes cell apoptosis in cervical cancer involving Bim upregulation

In vivo study on IL-37 inhibition of malignant melanoma metastasis

OBJECTIVES

Malignant melanoma is highly aggressive, prone to early metastasis, and associated with extremely poor prognosis, posing a serious threat to human health. Identifying molecular mechanisms that inhibit metastasis is of great significance for improving treatment and prognosis. Interleukin-37 (IL-37), an anti-inflammatory cytokine, has not only been linked to various inflammatory diseases but also exhibits anti-tumor properties. This study aims to explore the effect of IL-37 on melanoma metastasis in vivo by establishing a murine model of pulmonary metastasis.

METHODS

Mouse melanoma B16F1 cells were transfected with either IL-37 overexpression plasmid (IL-37 oe) or empty vector. Three groups were set: An IL-37 oe group (transfection reagent+IL-37 oe plasmid), a Vector group (transfection reagent+vector plasmid), and a Blank group (transfection reagent only). C57 mice were randomly divided into 3 groups (n=3 per group) and injected intravenously with logarithmic-phase B16F1 cells under sterile conditions. Mice were weighed every 3 days. After 1 month, mice were euthanized by cervical dislocation, and organs including lungs, heart, liver, spleen, and kidneys were harvested. Lung metastases were photographed and counted. Organs were fixed in 4% paraformaldehyde, embedded in paraffin, and stained with hematoxylin and eosin (HE).

RESULTS

Western blotting confirmed successful plasmid transfection. There were no significant differences in body weight among the 3 groups over the 28-day period (P>0.05). Lung tumors were observed upon dissection, indicating successful metastasis modeling. HE staining showed no morphological differences in the heart, liver, spleen, and kidneys between groups. The numbers of lung metastases in the Blank, Vector, and IL-37 oe groups were (24.00±2.08), (24.67±0.88), and (5.33±1.45), respectively. The IL-37 oe group had significantly fewer lung metastases than the other 2 groups (P<0.05), while no difference was observed between the Blank and Vector groups.

CONCLUSIONS

IL-37 significantly inhibits lung metastasis of malignant melanoma cells in mice without affecting body weight or major organs. It may serve as a potential molecular target for gene therapy or immunotherapy of malignant melanoma.

Recombinant expression, downstream optimization, and therapeutic evaluation of recombinant human interleukin-37 for cancer therapy

Interleukin-37 is a cytokine with potent immunosuppressive properties that has been shown to have potential to treat autoimmune and chronic inflammatory diseases, as well as certain types of cancer. IL-37 is a 19 kDa protein which interacts with proteins in receptor-dependent and receptor-independent pathways. The expression of the IL-37 protein cloned into the pET-28a vector was optimized in Rosetta 2(DE3) after comparing its expression with Rosetta-gami 2(DE3) and Rosetta 2(DE3) pLysS, which was then used for the large-scale production of IL-37. IMAC purification of IL-37 yielded > 97% pure 0.9 mg/mL protein from auto-induced fermentation. The IC50 value of IL-37 was < 1 µM, which was similar to that of doxorubicin, and proliferation of > 80% of all cancer cells was inhibited by 100 µg/mL of IL-37 protein. IL-37 may be a promising theragnostic target for cancer due to its comparable IC50 value with that of doxorubicin.

Agree to disagree: The contradiction between IL-18 and IL-37 reveals shared targets in cancer

IL-37 is a newly discovered member of the IL-1 cytokine family which plays an important role in regulating inflammation and maintaining physiological homeostasis. IL-37 showed a close relationship with IL-18, another key cytokine in inflammation regulation and cancer development. IL-37 affects the function of IL-18 either by binding to IL-18Rα, a key subunit of both IL-37 and IL-18 receptor, or by drastically neutralizing the IL-18 protein expression of IL-18 binding protein, an important natural inhibitory molecule of IL-18. Moreover, as another subunit receptor of IL-37, IL-1R8 can suppress IL-18Rα expression, functioning as a surveillance mechanism to prevent overactivation of both IL-18 and IL-37 signaling pathways. While IL-18 and IL-37 share the same receptor subunit, IL-18 would in turn interfere with IL-37 signal transduction by binding to IL-18Rα. It is also reported that IL-18 and IL-37 demonstrated opposing effects in a variety of cancers, such as glioblastoma, lung cancer, leukemia, and hepatocellular cancer. Although the mutual regulation of IL-18 and IL-37 and their diametrically opposed effects in cancers has been reported, IL-18 has not been taken into consideration when interpreting clinical findings and conducting mechanism investigations related to IL-37 in cancer. We aim to review the recent progress in IL-18 and IL-37 research in cancer and summarize the correlation between IL-18 and IL-37 in cancer based on their expression level and underlying mechanisms, which would provide new insights into elucidating the conflicting roles of IL-18 and IL-37 in cancer and bring new ideas for translational research related to IL-18 and IL-37.

Novel insights into IL-37: an anti-inflammatory cytokine with emerging roles in anti-cancer process

Interleukin-37 (IL-37) is a newly discovered member of IL-1 family. The cytokine was proved to have extensive protective effects in infectious diseases, allergic diseases, metabolic diseases, autoimmune diseases and tumors since its discovery. IL-37 was mainly produced by immune and some non-immune cells in response to inflammatory stimulus. The IL-37 precursors can convert into the mature forms after caspase-1 cleavage and activation intracellularly, and then bind to Smad-3 and transfer to the nucleus to inhibit the production and functions of proinflammatory cytokines; extracellularly, IL-37 binds to cell surface receptors to form IL-37/IL-18Rα/IL-1R8 complex to exert immunosuppressive function via inhibiting/activating multiple signal pathways. In addition, IL-37 can attenuate the pro-inflammatory effect of IL-18 through directly or forming an IL-37/IL-18BP/IL-18Rβ complex. Therefore, IL-37 has the ability to suppress innate and acquired immunity of the host, and effectively control inflammatory stimulation, which was considered as a new hallmark of cancer. Specifically, it is concluded that IL-37 can inhibit the growth and migration of tumor cells, prohibit angiogenesis and mediate the immunoregulation in tumor microenvironment, so as to exert effective anti-tumor effects. Importantly, latest studies also showed that IL-37 may be a novel therapeutic target for cancer monitoring. In this review, we summarize the immunoregulation roles and mechanisms of IL-37 in anti-tumor process, and discuss its progress so far and potential as tumor immunotherapy.

Circular RNA ARHGAP5 inhibits cisplatin resistance in cervical squamous cell carcinoma by interacting with AUF1

Cervical squamous cell carcinoma (CSCC) is one of the leading causes of cancer death in women worldwide. Patients with advanced cervical carcinoma always have a poor prognosis once resistant to cisplatin due to the lack of effective treatment. It is urgent to investigate the molecular mechanisms of cisplatin resistance. Circular RNAs (circRNAs) are known to exert their regulatory functions in a series of malignancies. However, their effects on CSCC remain to be elucidated. Here, we found that cytoplasmic circARHGAP5, derived from second and third exons of the ARHGAP5 gene, was downregulated in cisplatin-resistant tissues compared with normal cervix tissues and untreated cervical cancer tissues. In addition, experiments from overexpression/knockdown cell lines revealed that circARHGAP5 could inhibit cisplatin-mediated cell apoptosis in CSCC cells both in vitro and in vivo. Mechanistically, circARHGAP5 interacted with AU-rich element RNA-binding protein (AUF1) directly. Overexpression of AUF1 could also inhibit cell apoptosis mediated by cisplatin. Furthermore, we detected the potential targets of AUF1 related to the apoptotic pathway and found that bcl-2-like protein 11 (BIM) was not only negatively regulated by AUF1 but positively regulated by circARHGAP5, which indicated that BIM mRNA might be degraded by AUF1 and thereby inhibited tumor cell apoptosis. Collectively, our data indicated that circARHGAP5 directly bound to AUF1 and prevented AUF1 from interacting with BIM mRNA, thereby playing a pivotal role in cisplatin resistance in CSCC. Our study provides insights into overcoming cancer resistance to cisplatin treatment.

Dual role of IL-37 in the progression of tumors

Interleukin (IL)-37 is a novel defined cytokine that belongs to IL-1 family, which possesses potent anti-inflammatory and immunosuppressive properties. The IL-37 protein mainly exists in the cytoplasm of monocytes and is also expressed in epithelial cells and T cells. IL-37 is produced as a precursor which works in mature or immature isoforms without a classic signal peptide, and negatively regulates TLR agonist- mediated signaling pathway, proinflammatory cytokines, and IL-1R ligands. IL-37 has been found to be elevated and plays an anti-tumor role in various types of tumors, such as hepatocellular carcinoma, non-small cell lung cancer, and cervical cancer. The tumor microenvironment (TME) refers to the cellular environment where the tumor or cancer stem cells exist. At present, growing evidence shows that changes in TME can regulate metabolism, immunity, secretion, and function, so as to inhibit or promote the progression of the tumor. Therefore, a thorough understanding of the TME is essential for the occurrence and development of tumors. In this review, we will summarize the role of IL-37 in the microenvironment of different tumors, hoping to provide novel perspectives towards the mechanism, prevention, and treatment of tumors.

Extracellular IL-37 promotes osteogenic and odontogenic differentiation of human dental pulp stem cells via autophagy

The osteogenic and odontogenic differentiation of dental pulp stem cells (DPSCs) contribute to restoration and regeneration of dental tissue. Previous study indicated that interleukin-37 (IL-37) was an anti-inflammatory factor that affected other pro-inflammatory signals. The aim of this study was to explore the effects of IL-37 on the differentiation of DPSCs. DPSCs were cultured in growth medium with different concentrations of IL-37. We selected the optimal concentration for the following experiments by alkaline phosphatase (ALP) activity analysis, quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and Western blot. Cell counting kit assay (CCK-8) and 5-Ethynyl-2'-Deoxyuridine (EdU) assay were conducted to assess the effects of IL-37 on the proliferation of DPSCs. ALP activity assay and staining, alizarin red S (ARS) staining, qRT-PCR, Western blot as well as immunofluorescence staining were conducted to assess differentiation ability of DPSCs. Western blot, immunofluorescence staining and transmission electron microscopy (TEM) were utilized to examine cell autophagy. Results showed that IL-37 enhanced the osteogenic and odontogenic differentiation ability of DPSCs with no significant influence on the proliferation of DPSCs. Autophagy in DPSCs was activated by IL-37. Activation of autophagy enhanced osteogenesis and odontogenesis of DPSCs, whereas inhibition of autophagy suppressed DPSCs osteogenic and odontogenic differentiation. In conclusion, IL-37 increased osteogenic and odontogenic differentiation via autophagy.

In situ immunopathological events in human cervical intraepithelial neoplasia and cervical cancer: Review

Neoplasia of the cervix represents one of the most common cancers in women. Clinical and molecular research has identified immunological impairment in squamous intraepithelial cervical lesions and cervical cancer patients. The in-situ expression of several cytokines by uterine epithelial cells and by infiltrating leukocytes occurs during the cervical intraepithelial neoplasia and cervical cancer. Some of these cytokines can prevent and others can induce the progression of the neoplasm. The infiltrating leukocytes also produce cytokines and growth factors relate to angiogenesis, chemotaxis, and apoptosis capable of modulating the dysplasia progression. In this review we analyzed several interleukins with an inductive effect or blocking effect on the neoplastic progression. We also analyze the genetic polymorphism of some cytokines and their relationship with the risk of developing cervical neoplasia. In addition, we describe the leukocyte cells that infiltrate the cervical uterine tissue during the neoplasia and their effects on neoplasia progression.

Decreased IL-37 expression in hepatocellular carcinoma tissues and liver cancer cell lines

The role of IL-37 in cancer is currently largely unknown. The present study aimed to investigate IL-37 expression in hepatocellular carcinoma (HCC), paracancerous tissues (PT) and liver cancer cell lines, and their associations between IL-37 and NF-κB. A total of 65 HCC and 65 PT tissues were collected. The expression of IL-37 and NF-κB in tissues was detected by immunohistochemistry (IHC) and the data was analyzed using SPSS software. In the in vitro studies, IL-37 gene was transfected into HepG2 and MHCC97H cell lines with Lipofectamine 3000, and the protein regulation of NF-κB by IL-37 was verified by immunofluorescence (IF) and western blotting. In HCC, the positive expression rates of IL-37 and NF-kB were 21.5 and 95.4%, respectively. In PT, strong positive staining of IL-37and weak positive staining of NF-κB were observed. The normal expression levels of IL-37 and NF-κB, the increased IL-37 and decreased NF-κB induced by IL-37 gene transfection were observed through IF in cell lines. In terms of clinical significance, the difference in IL-37 expression between HCC and PT was statistically significant (χ²=55.05; P<0.001). IL-37 expression in HCC but not PT was negatively associated with serum AFP (χ²=6.522; P=0.039). IL-37 expression in PT was associated with sex (χ²=13.12; P=0.003) and tumor size (χ²=7.996; P=0.045). NF-κB expression in PT was associated with age, sex and BCLC stage. Notably, there was a negative correlation between IL-37 and NF-κB in HCC (r=-0.277; P=0.029) but not in PT (P>0.05). IL-37 overexpression downregulated the NF-κB protein by 56.50% in HepG2 cells (P<0.05) and 30.52% in MHCC97H cells (P<0.05). In conclusion, the expression of IL-37 in HCC and PT was specifically associated with serum AFP and tumor size, respectively. IL-37 expression was negatively correlated with NF-κB protein expression in HCC tissues and liver cancer cell lines.

Low expression of IL-37 protein is correlated with high Oct4 protein expression in hepatocellular carcinoma

OBJECTIVE

The function of IL-37 in cancer remains largely unclear. The present research was to probe the protein expression of IL-37 and Oct4 in hepatocellular carcinoma (HCC), para-cancerous tissues (PT) and cancer cell lines, and discuss their relationship.

METHODS

Forty-nine HCC specimens and forty-nine PT samples were collected for immunohistochemical staining of IL-37 and Oct4 protein. Then, the correlations among IL-37, Oct4 and the clinical indicators were analyzed. In further in vitro studies, IL-37 was over expressed in HepG2 and MHCC97H cancer cell lines by gene transfection using a lipo3000 kit. Finally, the protein expression of IL-37 and Oct4 was detected by immunofluorescence and western blot to verify the in vivo correlation between IL and 37 and Oct4.

RESULTS

In HCC, IL-37 protein expression was weakly positive with a positive rate of 12.2% while Oct4 expression was strongly positive with a positive rate of 91.8%. In PT, strong positive IL-37 (83.7%) and weakly positive Oct4 (91.8%) were shown. The increased IL-37 and decreased Oct4 induced by IL-37 gene transfection were observed through IF in cells. In terms of clinical significance, the difference of IL-37 expression between HCC and PT was statistically significant (χ² = 51.815, P = 3.2796 × 10^-11). IL-37 in tumor tissues was associated with serum AFP (χ² = 5.515, P = 0.048) and cirrhosis (χ² = 7.451, P = 0.014). IL-37 expression of PT was link to gender (χ² = 10.376, P = 0.013) and tumor size (χ² = 8.118, P = 0.04). The expression of Oct4 in HCC was related to the patient's gender and cirrhosis. Importantly, there was a negative correlation between IL and 37 and Oct4 in tumor tissues (r = -0.299, P = 0.047) but not in PT (P > 0.05). Oct4 protein expression was down-regulated by IL-37 by 63.35% in HepG2 cells (P < 0.05) and 95.20% in MHCC97H cells (P < 0.05).

CONCLUSION

IL-37 expression in tumor tissues and PT was related to serum AFP and liver cirrhosis, tumor size, respectively. IL-37 protein expression was correlated with Oct4 in cancer cell lines and tumor tissues but not PT. The present study indicated that IL-37 might play a role in the development of HCC.

Inhibition of human cervical cancer cell invasion by IL-37 involving runt related transcription factor 2 suppression

Background

IL-37 is a newly anti-inflammatory cytokine whose function is largely unknown in cancer. Our preliminary experiment found IL-37 could inhibit the invasion of human cervical cancer (CC) cells and influence the expression of RUNX family whose function was also unclear in CC. The present study aims to further investigate the effects of IL-37 on cell invasion and runt related transcription factor 2 (RUNX2) expression in CC cell lines.

Methods

Firstly, plasmid overexpressing IL-37 or RUNX2 was transfected into Siha and C33A cells by Hilymax. Then, the effects of IL-37 on the mRNA expression of RUNX1, RUNX2 and RUNX3 gene were detected by quantitative real-time polymerase chain reaction. Protein expression was measured by Western blot and the grayscale scanning analysis. Finally, the effects of IL-37 or RUNX2 on cell invasion were tested by transwell assay.

Results

IL-37 inhibited the mRNA expression of RUNX1 and RUNX2, and increased that of RUNX3 in CC cells. Among the three RUNX genes, RUNX2 showed the most significant change in mRNA expression (decreased by78.5% in Siha cells and by 61.5% in C33A cells) and thus was chosen for the following study. Overexpressed IL-37 inhibited cell invasion by 36.23% in Siha cells (P<0.05) and 26.21% in C33A cells (P<0.01). Overexpression of RUNX2 promoted cell invasion. Up-regulation of IL-37 suppressed markedly the mRNA and protein expression of RUNX2. Furthermore, overexpressed RUNX2 partially restored the inhibited cell invasion by IL-37 to 86.62% in Siha cells (P<0.01) and 87.08% in C33A cells (P<0.01).

Conclusions

IL-37 can significantly inhibit the cell invasion of Siha and C33A cells, which involves the suppression of RUNX2.