SLC39A4 as a Novel Prognosis Marker Promotes Tumor Progression in Esophageal Squamous Cell Carcinoma

UKLF/PCBP2 axis governs the colorectal cancer development by transcriptionally activating SLC39A4

Colorectal cancer (CRC) is one of the most prevalent malignant tumors with limited treatment options. Therefore, there is an urgent need to investigate new therapeutic targets against CRC. Ubiquitous Kruppel-like factor (UKLF) is involved in various cancer processes, but its effect and detailed molecular mechanism in CRC are not yet fully understood. Here, this study aimed to investigate the function and mechanism of UKLF in the development of CRC. The results showed that UKLF was highly expressed in CRC tissues from clinical patients and its high expression was related to poor prognosis. UKLF promoted cell proliferation, migration and invasion, and inhibited cell apoptosis. The promotion effect of UKLF on tumor growth was further confirmed in vivo. As far as the mechanism was concerned, poly (C) binding protein 2 (PCBP2) was verified to bind to the 3'-UTR of UKLF mRNA and enhance its mRNA stability. Moreover, UKLF modulated the expression of solute carrier family 39 member 4 (SLC39A4) at the transcriptional level. Taken together, these findings elucidated the regulatory mechanism of UKLF and uncovered the importance of the PCBP2/UKLF/SLC39A4 pathway. The targeting of UKLF may be a novel direction for molecular-targeted CRC therapy.

A cuproptosis-related gene expression signature predicting clinical prognosis and immune responses in intrahepatic cholangiocarcinoma detected by single-cell RNA sequence analysis

BACKGROUND

Cholangiocarcinoma represents a malignant neoplasm originating from the hepatobiliary tree, with a subset of tumors developing inside the liver. Intrahepatic cholangiocarcinomas (ICC) commonly exhibit an asymptomatic presentation, rendering both diagnosis and treatment challenging. Cuproptosis, an emerging regulated cell death pathway induced by copper ions, has garnered attention recently. As cancer cells show altered copper metabolism and comparatively higher copper needs, cuproptosis may play a role in the development of ICC. However, studies investigating this possibility are currently lacking.

METHODS

Single-cell and bulk RNA sequence data were analyzed, and correlations were established between the expression of cuproptosis-related molecules and ICC patient survival. Genes with predicting survival were used to create a CUPT score using Cox and LASSO regression and tumor mutation burden (TMB) analysis. The CIBERSORT software was employed to characterize immune cell infiltration within the tumors. Furthermore, immune infiltration prediction, biological function enrichment, and drug sensitivity analyses were conducted to explore the potential implications of the cuproptosis-related signature. The effects of silencing solute carrier family 39 member 4 gene (SLC39A4) expression using siRNA were investigated using assays measuring cell proliferation, colony formation, and cell migration. Key genes of cuproptosis were detected by western blotting.

RESULTS

The developed CUPT score divided patients into high and low CUPT score groups. Those with a low score had significantly better prognosis and longer survival. In contrast, high CUPT scores were associated with worse clinical outcomes and significantly higher TMB. Comparisons of the two groups also indicated differences in the immune infiltrate present in the tumors. Finally, we were able to identify 95 drugs potentially affecting the cuproptosis pathway. Some of these might be effective in the treatment of ICC. The in vitro experiments revealed that suppressing the expression of SLC39A4 in ICC cell lines resulted in reduced cell proliferation, colony formation, and cell migration. It also led to an increase in cell death and the upregulation of key genes associated with cuproptosis, namely ferredoxin 1 (FDX1) and dihydrolipoyl transacetylase (DLAT). These findings strongly suggest that this cuproptosis-associated molecule may play a pivotal role in the development and metastasis of ICC.

CONCLUSIONS

Changes in the expression of a cuproptosis-related gene signature can predict the clinical prognosis of ICC with considerable accuracy. This supports the notion that cuproptosis influences the diversity and complexity of the immune microenvironment, mutational landscape, and biological behavior of ICC. Understanding this pathway better may hold promise for the development of innovative strategies in the management of this disease.

The role of SLC39A4 in the prognosis, immune microenvironment, and contribution to malignant behavior in vivo and in vitro of cervical cancer

BACKGROUND

Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) are becoming more common in younger women. Solute carrier family 39 member 4 (SLC39A4) produces a zinc ion transporter involved in metastasis and invasion of tumors.

METHODS

The Cancer Genome Atlas RNA-seq data was used to investigate the expression of SLC39A4 and its prognostic potential. The assessment of the effect of SLC39A4 on cell growth and migration in CESC was conducted using MTT, colony formation, and Transwell assays. SLC39A4 was studied in vivo using a xenograft mouse model, and its functional involvement in oncogenesis was investigated by identifying the associated differentially expressed genes (DEGs). We evaluated the relationships among SLC39A4 levels, chemosensitivity, radiosensitivity and immune infiltration.

RESULTS

SLC39A4 was upregulated in CESC samples, and individuals with greater SLC39A4 mRNA expression had shorter overall survival. SLC39A4 has been identified to be a regulator of tumor cell metastasis and proliferation in vivo and in vitro, with an area under the curve of 0.874 for diagnosing CESC. In total, 948 DEGs were discovered to be enriched in key CESC progression-related signaling pathways. Additionally, intratumoral immune checkpoint and infiltration activity were associated with SLC39A4 expression. High SLC39A4 expression exhibited poor chemosensitivity and radiosensitivity profiles.

CONCLUSION

In conclusion, SLC39A4 is a key regulator of CESC development, prognosis, and the composition of the tumor immune microenvironment. SLC39A4 could be used as a prognostic or diagnostic screening tool and as a potential target for CESC treatment.

Zinc Transporters Serve as Prognostic Predictors and their Expression Correlates with Immune Cell Infiltration in Specific Cancer: A Pan-cancer Analysis

The disruption of zinc (Zn) homeostasis has been implicated in cancer development and progression through various signaling pathways. Maintaining intracellular zinc balance is crucial in the context of cancer. Human cells rely on two families of transmembrane transporters, SLC30A/ZNT and SLC39A/ZIP, to coordinate zinc homeostasis. While some ZNTs and ZIPs have been linked to cancer progression, limited information is available regarding the expression patterns of zinc homeostasis-related genes and their potential roles in predicting prognosis and developing therapeutic strategies for specific cancers. In this study, a systematic analysis was conducted to examine the expression of all genes from the SLC30A and SLC39A families at both mRNA and protein levels across different cancers. As a result, three SLC39A genes (SLC39A1, SLC39A4, and SLC39A8) were found to be significantly dysregulated in specific cancers, including cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), liver hepatocellular carcinoma (LIHC), pancreatic adenocarcinoma (PAAD), and kidney renal papillary cell carcinoma (KIRP). Moreover, the dysregulation of these genes was tightly associated with the prognosis of patients with those cancers. Furthermore, we found that the gene SLC39A8 exhibited the lowest mutation frequency in KIRP, whereas mutations in SLC39A4 were found to significantly impact overall survival (OS), disease-free (DF), and progress-free survival (PFS) in cancer patients, particularly in those with PAAD. Additionally, immune infiltration analysis revealed that SLC39A1, SLC39A4, and SLC39A8 may function as immune regulators in cancers. This provides new insights into understanding the complex relationship between zinc homeostasis and cancer progression.

The Transcription of ZIP9 Is Associated With the Macrophage Polarization and the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common digestive system cancers (DSCs) with a poor prognosis. Zinc‐regulated transporter (ZRT)/iron‐regulated transporter (IRT) like protein transporters (ZIPs) encode membrane transport proteins, which are responsible for the absorption of zinc and play important roles in the pathogenesis of various human cancers. Tumor-associated macrophages (TAMs) are important participants in the regulation of tumor microenvironment and the development of HCC. Individual role of each ZIP involved in hepatocarcinogenesis remains elusive. In this study, the transcription patterns of ZIPs in the DSCs were screened firstly through GEPIA2 database. Interestingly, the analysis of the DSCs data showed the distinct mRNA levels of ZIPs between DSCs tissues and healthy controls. Notably, the transcription levels of ZIP2, ZIP5, ZIP8, ZIP9 and ZIP14 were decreased significantly in the tissues of human liver cancer compared to paracarcinoma liver tissues. To further confirm the mRNA transcriptional changes of Zips in HCC, N-Nitrosodiethylamine (DEN) combined with carbon tetrachloride (CCl₄) inducing mouse model of HCC were established. Consistently, the mRNA levels of Zip2, Zip9, and Zip14 in liver tissues of HCC induced mice were also decreased compared with the healthy controls. In addition, mouse peritoneal elucidated macrophages (PEMs)-derived M1/M2 macrophages in vitro, as well as human patients of HCC-derived TAMs, were used to examine the transcription levels of ZIPs. Our results showed that both Zip2 and Zip9 were up-regulated in M2-polarized macrophages. Zip2 transcript was also up-regulated M1-polarized macrophages, but Zip9 was slightly down-regulated. TAMs generated from human liver cancer tissues also displayed a decrease in ZIP9 transcription compared to paracarcinoma tissues. To further explore the role of Zip9 in M1/M2 polarization, the siRNA knockdown results revealed that Zip9, but not Zip2, could promote M2 macrophage polarization and impair M1 macrophage polarization. Mechanistically, Zip9 enhances phosphorylated STAT6 to promote M2 macrophage polarization but suppresses the phosphorylation of IκBα/β to inhibit M1 macrophage polarization. Together, our results indicate that ZIP9 may involve in macrophages polarity in HCC development and may be a potent new biomarker for the diagnosis of HCC.

Knockdown of SLC39A4 Expression Inhibits the Proliferation and Motility of Gallbladder Cancer Cells and Tumor Formation in Nude Mice

Purpose

Gallbladder cancer (GBC) is a common malignancy of the biliary tract and is characterized by rapid progression and early metastasis. Elucidating the molecular mechanisms of GBC could help to develop better treatment strategies.

Materials and Methods

Human GBC cell lines (GBC-SD and NOZ) were applied to determine the capacity of the proliferation and migration of cells using the MTT assay, colony formation, wound-healing assay as well as the Transwell™ assay. A nude xenograft was used to evaluate tumor growth in vivo.

Results

Using two types of GBC cell lines, we found that absence of solute carrier family (SLC) 39A4 (which encodes the zinc transporter ZRT/IRT-like protein [ZIP]4), could suppress the proliferation and migration of cells. Additionally, absence of ZIP4 could impair growth of xenografts in nude mice. While, over-expression of SLC39A4 could promote the GBC cell proliferation and migration, and inhibit apoptosis. We revealed that SLC39A4 might affect GBC progression by modulating the signaling pathways responsible for the survival, energy supply and metastasis of cells, and indicated that SLC39A4 could serve as a novel therapeutic target for GBC.

Conclusion

SLC39A4 promoted the viability and motility of GBC cells, and tumor formation in nude mice. We demonstrated an oncogenic potential for SLC39A4.