Inhibition of SALL4 reduces tumorigenicity involving epithelial-mesenchymal transition via Wnt/β-catenin pathway in esophageal squamous cell carcinoma

Cancer stem cell biomarkers and related signalling pathways

Cancer stem cells (CSCs) represent a distinct subset of neoplastic cells characterised by their heightened capacity for tumorigenesis. These cells are implicated in the facilitation of cancer metastasis, recurrence, and resistance to conventional therapeutic interventions. Extensive scientific research has been devoted to the identification of biomarkers and the elucidation of molecular mechanisms in order to improve targeted therapeutic approaches. Accurate identification of cancer stem cells based on biomarkers can provide a theoretical basis for drug combinations of malignant tumours. Targeted biomarker-based therapies also offer a silver lining for patients with advanced malignancies. This review aims comprehensively to consolidate the latest findings on CSCs biomarkers, targeted agents as well as biomarkers associated signalling pathways in well-established cancer types, thereby contributing to improved prognostic outcomes.

SALL4 in gastrointestinal tract cancers: upstream and downstream regulatory mechanisms

Effective therapeutic targets and early diagnosis are major challenges in the treatment of gastrointestinal tract (GIT) cancers. SALL4 is a well-known transcription factor that is involved in organogenesis during embryonic development. Previous studies have revealed that SALL4 regulates cell proliferation, survival, and migration and maintains stem cell function in mature cells. Additionally, SALL4 overexpression is associated with tumorigenesis. Despite its characterization as a biomarker in various cancers, the role of SALL4 in GIT cancers and the underlying mechanisms are unclear. We describe the functions of SALL4 in GIT cancers and discuss its upstream/downstream genes and pathways associated with each cancer. We also consider the possibility of targeting these genes or pathways as potential therapeutic options for GIT cancers.

Potential markers of cancer stem-like cells in ESCC: a review of the current knowledge

In patients with esophageal squamous cell carcinoma (ESCC), the incidence and mortality rate of ESCC in our country are also higher than those in the rest of the world. Despite advances in the treatment department method, patient survival rates have not obviously improved, which often leads to treatment obstruction and cancer repeat. ESCC has special cells called cancer stem-like cells (CSLCs) with self-renewal and differentiation ability, which reflect the development process and prognosis of cancer. In this review, we evaluated CSLCs, which are identified from the expression of cell surface markers in ESCC. By inciting EMTs to participate in tumor migration and invasion, stem cells promote tumor redifferentiation. Some factors can inhibit the migration and invasion of ESCC via the EMT-related pathway. We here summarize the research progress on the surface markers of CSLCs, EMT pathway, and the microenvironment in the process of tumor growth. Thus, these data may be more valuable for clinical applications.

The tight junction protein claudin 6 is a potential target for patient-individualized treatment in esophageal and gastric adenocarcinoma and is associated with poor prognosis

BACKGROUND

The prognosis of esophageal adenocarcinoma (EAC) and gastric adenocarcinoma (GAC) remains poor, and new therapeutic approaches are urgently needed. Claudin 6 (CLDN6) is an oncofetal antigen that is largely absent in healthy tissues and upregulated in several cancers, making it a promising therapeutical target. In this study, the expression of CLDN6 was assessed in an large Caucasian EAC and GAC cohort.

METHODS

RNA-Seq data from 89 EACs and 371 GACs were obtained from The Cancer Genome Atlas project and EAC/GAC cases were stratified by CLDN6 mRNA expression based on a survival-associated cutoff. For groups with CLDN6 expression above or below this cutoff, differential gene expression analyses were performed using DESeq, and dysregulated biological pathways were identified using the Enrichr tool. Additionally, CLDN6 protein expression was assessed in more than 800 EACs and almost 600 GACs using a CLDN6-specific immunohistochemical antibody (clone 58-4B-2) that is currently used in Phase I/II trials to identify patients with CLDN6-positive tumors (NCT05262530; NCT04503278). The expression of CLDN6 was also correlated with histopathological parameters and overall survival (OS).

RESULTS

EACs and GACs with high CLDN6 mRNA levels displayed an overexpression of pathways regulating the cell cycle, DNA replication, and receptor / extracellular matrix interactions. CLDN6 protein expression was associated with shorter OS in EAC and GAC, both in treatment-naïve subgroups and cohorts receiving neoadjuvant therapy. In multivariate analysis, CLDN6 protein expression was an independent adverse prognostic factor in EAC associated with a shorter OS (HR: 1.75; p = 0.01) and GAC (HR: 2.74; p = 0.028).

CONCLUSIONS

High expression of CLDN6 mRNA is associated with the dysregulation of distinct biological pathways regulating cell growth, proliferation, and cell-matrix interactions. Clinically, the expression of CLDN6 protein is a valuable adverse prognostic marker in EAC and GAC.

The critical role of circular RNAs in drug resistance in gastrointestinal cancers

Nowadays, drug resistance (DR) in gastrointestinal (GI) cancers, as the main reason for cancer-related mortality worldwide, has become a serious problem in the management of patients. Several mechanisms have been proposed for resistance to anticancer drugs, including altered transport and metabolism of drugs, mutation of drug targets, altered DNA repair system, inhibited apoptosis and autophagy, cancer stem cells, tumor heterogeneity, and epithelial-mesenchymal transition. Compelling evidence has revealed that genetic and epigenetic factors are strongly linked to DR. Non-coding RNA (ncRNA) interferences are the most crucial epigenetic alterations explored so far, and among these ncRNAs, circular RNAs (circRNAs) are the most emerging members known to have unique properties. Due to the absence of 5' and 3' ends in these novel RNAs, the two ends are covalently bonded together and are generated from pre-mRNA in a process known as back-splicing, which makes them more stable than other RNAs. As far as the unique structure and function of circRNAs is concerned, they are implicated in proliferation, migration, invasion, angiogenesis, metastasis, and DR. A clear understanding of the molecular mechanisms responsible for circRNAs-mediated DR in the GI cancers will open a new window to the management of GI cancers. Hence, in the present review, we will describe briefly the biogenesis, multiple features, and different biological functions of circRNAs. Then, we will summarize current mechanisms of DR, and finally, discuss molecular mechanisms through which circRNAs regulate DR development in esophageal cancer, pancreatic cancer, gastric cancer, colorectal cancer, and hepatocellular carcinoma.

Dual-Regulated Mechanism of EZH2 and KDM6A on SALL4 Modulates Tumor Progression via Wnt/β-Catenin Pathway in Gastric Cancer

BACKGROUND

SALL4 has been demonstrated in many cancers and participated in tumorigenesis and tumor progression, however, its expression and function still remain ambiguous in GC, especially its upstream mechanistic modulators.

PURPOSE

We explored whether the dual mediation of EZH2 and KDM6A could be involved in upstream regulation of SALL4, which promotes GC cell progression via the Wnt/β-catenin pathway.

METHOD

Analysis of discrepant gene expression in GC and normal gastric tissues from The Cancer Genome Atlas (TCGA) dataset. GC cell lines were transfected by siEZH2 and siKDM6A, the transduction molecules of KDM6A/EZH2-SALL4-β-catenin signaling were quantified in the GC cells.

RESULTS

Here, we showed that only SALL4 levels of SALL family members were upregulated in nonpaired and paired GC tissues than those in corresponding normal tissues and were associated with its histological types, pathological stages, TNM stages including T stage (local invasion), N stage (lymph node metastasis), M stage (distant metastasis), and overall survival from the TCGA dataset. SALL4 level was elevated in GC cells compared to normal gastric epithelial cell line (GES-1) and was correlated to cancer cell progression and invasion through the Wnt/β-catenin pathway in GC, which levels would be separately upregulated or downregulated by KDM6A or EZH2.

CONCLUSION

We first proposed and demonstrated that SALL4 promoted GC cell progression via the Wnt/β-catenin pathway, which was mediated by the dual regulation of EZH2 and KDM6A on SALL4. This mechanistic pathway in gastric cancer represents a novel targetable pathway.

Salt-like transcription factor 4 promotes laryngeal cancer progression through transcriptional activation of ubiquitin-specific protease 21 to stabilize Yin Yang 1

Laryngeal cancer (LC) is a rare and challenging clinical problem. Our aim was to investigate the mechanism of salt-like transcription factor 4 (SALL4) in LC. LC tissue and paracancerous tissue were collected. Relative mRNA or protein levels were measured by quantitative real-time polymerase chain reaction or Western blot. MTT, wound healing, and transwell assay were performed to evaluate cell proliferation, migration and invasion. The binding relationship between SALL4 and USP21 promoter was verified by dual-luciferase assay and ChIP. Co-IP and glutathione-S-transferase (GST)-pull down were performed to measure the protein interaction between USP21 and YY1. Additionally, YY1 ubiquitination level was analyzed. It was found that SALL4 mRNA and SALL4 protein levels were elevated in LC clinical tissues and various LC cells. Knockdown of SALL4 inhibited epithelial-mesenchymal transition (EMT) of LC cells. USP21 was transcriptionally activated by SALL4. Co-IP and GST-pull down confirmed USP21 interacted with YY1. USP21 protected YY1 from degradation through deubiquitination. Furthermore, overexpression of USP21 reversed the effect of knockdown of SALL4 on YY1 and EMT in LC cells. In general, SALL4 facilitated EMT of LC cells through modulating USP21/YY1 axis.

IGF2BP2-induced circRUNX1 facilitates the growth and metastasis of esophageal squamous cell carcinoma through miR-449b-5p/FOXP3 axis

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most common digestive malignancies with relatively high morbidity and mortality. Emerging evidence suggests circular RNAs (circRNAs) play critical roles in tumor cell malignancy. However, the biological function and clinical significance of many circRNAs in ESCC remain elusive.

METHODS

The expression level and clinical implication of circRUNX1 in ESCC tissues were evaluated using qRT-PCR. In vitro and in vivo functional studies were conducted to investigate the underlying biological effects of circRUNX1 on ESCC cell growth and metastasis. Moreover, bioinformatics analysis, RNA sequencing (RNA-seq), RNA immunoprecipitation (RIP) assays, dual-luciferase reporter assays, and rescue experiments were performed to explore the relationships between circRUNX1, miR-449b-5p, Forkhead box protein P3 (FOXP3), and insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2).

RESULTS

CircRUNX1 was found to be significantly up-regulated in ESCC tissues and associated with TNM stage and differentiation grade. Functionally, circRUNX1 promoted ESCC cell proliferation and metastasis in vitro and in vivo. CircRUNX1 enhanced FOXP3 expression by competitively sponging miR-449b-5p. Notably, both miR-449b-5p mimics and FOXP3 knockdown restored the effects of circRUNX1 overexpression on cell proliferation and metastasis. Furthermore, IGF2BP2 binding to circRUNX1 prevented its degradation.

CONCLUSIONS

IGF2BP2 mediated circRUNX1 functions as an oncogenic factor to facilitate ESCC progression through the miR-449b-5p/FOXP3 axis, implying that circRUNX1 has the potential to be a promising diagnostic marker and therapeutic target for ESCC patients.

A more novel and robust gene signature predicts outcome in patients with esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a life-threatening thoracic tumor with a poor prognosis. The tumor microenvironment (TME) mainly comprises tumor cells and tumor-infiltrating immune cells mixed with stromal components. The latest research has displayed that tumor immune cell infiltration (ICI) is closely connected with the ESCC patients' clinical prognosis. This study was designed to construct a gene signature based on the ICI of ESCC to predict prognosis.

METHODS

Based on the selection criteria we set, the eligible ESCC cases from the GSE53625 and TCGA-ESCA datasets were chosen for the training cohort and the validation cohort, respectively. Unsupervised clustering detailed grouped ESCC cases of the training cohort based on the ICI profile. We determined the differential expression genes (DEGs) between the ICI clusters, and, subsequently, we adopted the univariate Cox analysis to recognize DEGs with prognostic potential. These screened DEGs underwent a Lasso regression, which then generated a gene signature. The harvested signature's predictive ability was further examined by the Kaplan-Meier analysis, Cox analysis, ROC, IAUC, and IBS. More importantly, we listed similar studies in the most recent year and compared theirs with ours. We performed the functional annotation, immune relevant signature correlation analysis, and immune infiltrating analysis to thoroughly understand the functional mechanism of the signature and the immune cells' roles in the gene signature's predicting capacity.

RESULTS

A sixteen-gene signature (ARSD, BCAT1, BIK, CLDN11, DLEU7-AS1, GGH, IGFBP2, LINC01037, LINC01446, LINC01497, M1AP, PCSK2, PCSK5, PPP2R2A, TIGD7, and TMSB4X) was generated from the Lasso model. We then confirmed the signature as having solid and stable prognostic capacity by several statistical methods. We revealed the superiority of our signature after comparing it to our predecessors, and the GSEA uncovered the specifically mechanism of action related to the gene signature. Two immune relevant signatures, including GZMA and LAG3 were identified associating with our signature. The immune-infiltrating analysis identified crucial roles of resting mast cells, which potentially support the sixteen-gene signature's prognosis ability.

CONCLUSIONS

We discovered a robust sixteen-gene signature that can accurately predict ESCC prognosis. The immune relevant signatures, GZMA and LAG3, and resting mast cells infiltrating were closely linked to the sixteen-gene signature's ability.

Role of SALL4 in HER2+ Breast Cancer Progression: Regulating PI3K/AKT Pathway

Treatment for the HER2+ breast cancer subtype is still unsatisfactory, despite breakthroughs in research. The discovery of various new molecular mechanisms of transcription factors may help to make treatment regimens more effective. The transcription factor SALL4 has been related to aggressiveness and resistance therapy in cancer. Its molecular mechanisms and involvement in various signaling pathways are unknown in the HER2+ breast cancer subtype. In this study, we have evaluated the implication of SALL4 in the HER2+ subtype through its expression in patients' samples and gain and loss of function in HER2+ cell lines. We found higher SALL4 expression in breast cancer tissues compared to healthy tissue. Interestingly, high SALL4 expression was associated with disease relapse and poor patient survival. In HER2+ cell lines, transient overexpression of SALL4 modulates PI3K/AKT signaling through regulating PTEN expression and BCL2, which increases cell survival and proliferation while reducing the efficacy of trastuzumab. SALL4 has also been observed to regulate the epithelial-mesenchymal transition and stemness features. SALL4 overexpression significantly reduced the epithelial markers E-cadherin, while it increased the mesenchymal markers β-catenin, vimentin and fibronectin. Furthermore, it has been also observed an increased expression of MYC, an essential transcription factor for regulating epithelial-mesenchymal transition and/or cancer stem cells. Our study demonstrates, for the first time, the importance of SALL4 in the HER2+ subtype and partial regulation of trastuzumab sensitivity. It provides a viable molecular mechanism-driven therapeutic strategy for an important subset of HER2-overexpressing patients whose malignancies are mediated by SALL4 expression.

Co-overexpression of self-renewal markers SALL4 and HIWI is correlated with depth of tumor invasion and metastasis in colorectal cancer

Background

SALL4 and HIWI are involved in the maintenance of self-renewal capacity of stem cells. Several scrutinizes have demonstrated that SALL4 and HIWI play a key role in cancer development. However, the correlation between these genes regarding different clinicopathological features of patients with colorectal cancer (CRC) is still unclear.

Methods

The expression of SALL4 and HIWI in different clinicopathological features of 46 CRC patients was analyzed using relative comparative real-time PCR.

Results

mRNA expression levels of SALL4 and HIWI genes were significantly correlated with each other in CRC (P = 0.013, Pearson correlation = 0.364). HIWI expression was notably increased in tumors with overexpression of SALL4 in comparison with other samples. This correlation was significant in non-metastatic CRCs compared to the metastatic tumors and in invaded tumors to the serosa (T3/T4) in comparison with non-invaded tumors (T1/T2).

Conclusions

Based on the significant association of SALL4 and HIWI in different indices of CRC poor prognosis, it may be concluded that simultaneous expression of these genes is notably contributed to the growth and development of the disease, and therefore, their co-overexpression may be considered for prognosis of aggressive CRCs.

Systematic analysis of expression profiles of HMGB family members for prognostic application in non-small cell lung cancer

Background: Lung cancer is a significant challenge to human health. Members of the high mobility group (HMG) superfamily (HMGB proteins) are implicated in a wide variety of physiological and pathophysiological processes, but the expression and prognostic value of HMGB family members in non-small cell lung cancer (NSCLC) have not been elucidated.

Methods: In this study, ONCOMINE, UALCAN, GEPIA, Kaplan–Meier Plotter, starBase, OncomiR databases, and GeneMANIA were utilized to evaluate the prognostic significance of HMGB family members in NSCLC.

Results: HMGB2/3 expression levels were higher in NSCLC patients. HMGB1 expression was higher in lung squamous cell carcinoma (LUSC) and was lower in lung adenocarcinoma (LUAD) tissue than in normal lung tissue. HMGB2 expression was related to cancer stage. Increased HMGB1 mRNA expression levels were associated with improved lung cancer prognosis, including overall survival (OS), first-progression survival (FP), and post-progression survival (PPS). There was no significant association between HMGB2 levels and prognostic indicators. HMGB3 expression was associated with poorer OS. GeneMANIA and GO/KEGG pathway analysis showed that HMGB family members mainly associated with chromosome condensation, regulation of chromatin organization, and nucleosome binding in NSCLC. HMGBs expression were closely correlated with infiltrating levels of specific types of immune cells in NSCLC, especially Th2 cells, Th17 cells, and mast cells. hsa-miR-25-3p, hsa-miR-374a-3p, and hsa-miR-93-5p were significantly positively correlated with HMGB1, HMGB2, and HMGB3, respectively. However, hsa-miR-30a-5p was predicted to significantly negatively regulate HMGB3 expression.

Conclusion: Our study revealed that HMGB1 is positively related to the improved prognosis in NSCLC, and demonstrate that HMGB3 might be a risk factor for poorer survival of NSCLC patients.

Low expression of PRDM5 predicts poor prognosis of esophageal squamous cell carcinoma

Background

The role of the PRDM5 in esophageal squamous cell carcinoma (ESCC) has not been revealed. This study investigated the relationship between PRDM5 expression and survival outcome in esophageal squamous cell carcinoma and explored the mechanism in tumor development.

Methods

In present study, expression of PRDM5 mRNA in esophageal squamous cell carcinoma patients was conducted using the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. The expression of PRDM5 was assessed by immunohistochemical staining. Kaplan-Meier curve and Cox regression analysis was performed to analyze the survival outcome and independent predictive factors. qRT-PCR and Methylation-specific PCR were performed to identify the mRNA level of PRDM5 and Methylation rate. Cibersort algorithm to analyze the relationship between PRDM5 expression and immune cell invasion. Western-blot was performed to confirm the expression of esophageal tumor tissues and adjacent tissues.

Results

The TCGA database and GEO database show that PRDM5 mRNA level in esophageal squamous cell carcinoma adjacent tissues was higher than that of cancer tissues, and ESCC patients with high expression of PRDM5 mRNA had better overall survival. Tissue microarray showed that the protein level of PRDM5 in the adjacent tissues of patients with ESCC was higher than that in cancer tissues, and the expression level of PRDM5 was significantly correlated with the grade of clinicopathological characteristics (P < 0.001). Patients with high expression of PRDM5 displayed a better OS and DFS. Cox regression analysis showed that PRDM5 was an independent risk factor and prognostic factor for ESCC patients (HR: 2.626, 95%CI: 1.824–3.781; P < 0.001). The protein level of PRDM5 matched with the transcriptional level, whereas the DNA methylation affected the transcriptional level. Cibersort showed that T cells CD4 memory resting, mast cells resting, eosinophils, M2 macrophages and mast cells activated were significantly positively correlated with PRDM5 expression (P < 0.05), while regulatory T cells, monocytes and dendritic cells negatively correlated with PRDM5 expression (P < 0.05).

Conclusion

PRDM5 can be used as a biomarker to predict the survival of ESCC patients. Furthermore, PRDM5 expression in ESCC cells may affect WNT/β-catenin signaling pathways, thus further affect the ESCC cell proliferation, migration, and invasion capacity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09787-8.

Intratumor microbiome in cancer progression: current developments, challenges and future trends

Cancer is a complicated disease attributed to multifactorial changes, which causes difficulties with treatment strategies. Various factors have been regarded as the main contributors, and infectious etiological factors have recently attracted interest. Several microbiomes contribute to carcinogenesis, cancer progression, and modulating cancer treatment by inducing cancerous epithelial cells and chronic inflammation. Most of our knowledge on the role of microbiota in tumor oncogenesis and clinical efficiency is associated with the intestinal microbiome. However, compelling evidence has also confirmed the contribution of the intratumor microbiome in cancer. Indeed, the findings of clinical tumor samples, animal models, and studies in vitro have revealed that many intratumor microbiomes promote tumorigenesis and immune evasion. In addition, the intratumor microbiome participates in regulating the immune response and even affects the outcomes of cancer treatment. This review summarizes the interplay between the intratumor microbiota and cancer, focusing on the contribution and mechanism of intratumor microbiota in cancer initiation, progression, and potential applications to cancer therapy.

RASSF10 exhibits tumor‑suppressing potential involving tumor proliferation, metastasis and epithelial‑mesenchymal transition in esophageal squamous cell carcinoma

Growing evidence indicates that Ras-association domain family 10 (RASSF10) is a novel tumor-suppressor gene that is involved in the inhibition of tumor progression and metastasis; however, the biological functions and molecular mechanisms of RASSF10 in esophageal squamous cell carcinoma (ESCC) have not yet been thoroughly elucidated. The expression of RASSF10 in ESCC tissues and adjacent non-tumor tissues was investigated employing quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) assays of tissue microarrays. The function of RASSF10 in ESCC cell growth, migration and invasion was determined by CCK-8, colony formation, scratch wound healing and Transwell invasion assays, respectively. The correlation between RASSF10 and markers related to epithelial-mesenchymal transition (EMT) was evaluated by tissue microarray (TMA)-IHC, western blotting and immunofluorescence staining. RASSF10 was found to be highly downregulated in ESCC tissues compared with that noted in the adjacent non-tumor tissues, and closely correlated with tumor progression and patient prognosis. Moreover, functional studies demonstrated that RASSF10 overexpression not only resulted in reduced cell growth and colony formation but also inhibited migration and invasion of the ESCC cells. Tumor RASSF10 expression was positively correlated with E-cadherin expression and negatively correlated with vimentin. In addition, it was demonstrated that the antineoplastic functions of RASSF10 mediate inactivation of the Wnt/β-catenin pathway in ESCC. Our findings revealed that RASSF10 may constitute a prognostic factor for ESCC patients and a crucial candidate for targeted therapy against ESCC.

Co-expression of cancer stem cell markers, SALL4/ALDH1A1, is associated with tumor aggressiveness and poor survival in patients with serous ovarian carcinoma

Background

Spalt-like transcription factor 4 (SALL4) and aldehyde dehydrogenase1 family member A1 (ALDH1A1) expressing cells have been characterized as possessing stem cell-like properties known as cancer stem cell marker in serous ovarian carcinoma (SOC).

Methods

The association between SALL4 and ALDH1A1 was observed based on literature review and bioinformatics tools. Therefore, this study aimed to investigate the association between the co-expression of SALL4/ALDH1A1 proteins and clinicopathological parameters and their prognostic value in SOC patients using immunohistochemical staining on tissue microarrays (TMAs). Furthermore, benign tumors and normal tissue samples were compared with the expression of the tumor tissue samples.

Results

Increased co-expression of SALL4/ALDH1A1 was found to be significantly associated with the advanced FIGO stage (P = 0.047), and distant metastasis (P = 0.028). The results of Kaplan–Meier survival analysis indicated significant differences between disease- specific survival (DSS; P = 0.034) or progression-free survival (PFS; P = 0.018) and the patients with high and low co-expression of SALL4/ALDH1A1, respectively. Furthermore, high level co-expression of SALL4/ALDH1A1 was a significant predictor of worse DSS and PFS in the univariate analysis. The data also indicated that the co-expression of SALL4/ALDH1A1 was an independent prognostic factor affecting PFS. Moreover, the co-expression of SALL4/ALDH1A1 added prognostic values of DSS in patients with SOC who had grade III versus grade I in multivariate analysis.

Conclusions

Our data demonstrated that high co-expression of SALL4/ALDH1A1 was found to be significantly associated with tumor aggressiveness and worse DSS or PFS in SOC patients. Therefore, co-expression of SALL4/ALDH1A1 may serve as a potential prognostic biomarker of cancer progression in these cases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00921-x.

SALL Proteins; Common and Antagonistic Roles in Cancer

Simple Summary

Transcription factors play essential roles in regulating gene expression, impacting the cell phenotype and function, and in the response of cells to environmental conditions. Alterations in transcription factors, including gene amplification or deletion, point mutations, and expression changes, are implicated in carcinogenesis, cancer progression, metastases, and resistance to cancer treatments. Not surprisingly, transcription factor activity is altered in numerous cancers, representing a unique class of cancer drug targets. This review updates and integrates information on the SALL family of transcription factors, highlighting the synergistic and/or antagonistic functions they perform in various cancer types.

Abstract

SALL proteins are a family of four conserved C2H2 zinc finger transcription factors that play critical roles in organogenesis during embryonic development. They regulate cell proliferation, survival, migration, and stemness; consequently, they are involved in various human genetic disorders and cancer. SALL4 is a well-recognized oncogene; however, SALL1–3 play dual roles depending on the cancer context and stage of the disease. Current reviews of SALLs have focused only on SALL2 or SALL4, lacking an integrated view of the SALL family members in cancer. Here, we update the recent advances of the SALL members in tumor development, cancer progression, and therapy, highlighting the synergistic and/or antagonistic functions they perform in similar cancer contexts. We identified common regulatory mechanisms, targets, and signaling pathways in breast, brain, liver, colon, blood, and HPV-related cancers. In addition, we discuss the potential of the SALL family members as cancer biomarkers and in the cancer cells’ response to therapies. Understanding SALL proteins’ function and relationship will open new cancer biology, clinical research, and therapy perspectives.

Infection with a hypervirulent strain of Helicobacter pylori primes gastric cells toward intestinal transdifferentiation

BACKGROUND

Intestinal metaplasia, gastric-to-intestinal transdifferentiation, occurs as a result of the misexpression of certain regulatory factors, leading to genetic reprogramming. Here, we have evaluated the H. pylori-induced expression patterns of these candidate genes.

METHODS

The expression levels of 1) tissue-specific transcription factors (RUNX3, KLF5, SOX2, SALL4, CDX1 and CDX2), 2) stemness factors (TNFRSF19, LGR5, VIL1) and 3) tissue-specific mucins (MUC5AC, MUC2) were evaluated by quantitative real-time PCR in gastric primary cells (GPCs), in parallel with two gastric cancer (MKN45 and AGS) cell lines, up to 96h following H. pylori infection.

RESULTS

Following H. pylori infection of GPCs, RUNX3 declined at 24h post infection (-6.2 ± 0.3) and remained downregulated for up to 96h. Subsequently, overexpression of self-renewal and pluripotency transcription factors, KLF5 (3.6 ± 0.2), SOX2 (7.6 ± 0.5) and SALL4 (4.3 ± 0.2) occurred. The expression of TNFRSF19 and LGR5, demonstrated opposing trends, with an early rise of the former (4.5 ± 0.3) at 8h, and a simultaneous fall of the latter (-1.8 ± 0.5). This trend was reversed at 96h, with the decline in TNFRSF19 (-5.5 ± 0.2), and escalation of LGR5 (2.6 ± 0.2) and VIL1 (1.8 ± 0.3). Ultimately, CDX1 and CDX2 were upregulated by 1.9 and 4.7-fold, respectively. The above scenario was, variably observed in MKN45 and AGS cells.

CONCLUSION

Our data suggests an interdependent gene regulatory network, induced by H. pylori infection. This interaction begins with the downregulation of RUNX3, upregulation of self-renewal and pluripotency transcription factors, KLF5, SOX2 and SALL4, leading to the downregulation of TNFRSF19, upregulation of LGR5 and aberrant expression of intestine-specific transcription factors, potentially facilitating the process of gastric-to-intestinal transdifferentiation.

Immuno-oncological role of 20S proteasome alpha-subunit 3 in aggravating the progression of esophageal squamous cell carcinoma

PSMA3, a member of the proteasome subunit, has been shown to play a major player in protein degradation. Reportedly, PSMA3 functions as a negative regulator in various cancers including colon, pancreatic and gastric cancers. However, the contributions of PSMA3 to the progression of esophageal squamous cell carcinoma (ESCC) and the underlying mechanism remain unclear. Therefore, in this study, we investigated whether PSMA3 is involved in ESCC progression and the potential underlying mechanism. The results revealed that PSMA3 was highly expressed in the ESCC tumor tissues and functioned as a negative indicator according to the data from The Cancer Genome Atlas (TCGA)/Gene Expression Omnibus (GEO) datasets and clinical patients' samples. Pathway enrichment analysis showed that PSMA3 was closely correlated with ESCC cancer stemness and the inflammatory response; however, this correlation was absent after knockdown of PSMA3 in vitro. We further demonstrated that PSMA3 suppressed CD8⁺ T-cells infiltration depending on the C-C motif chemokine ligand 3 (CCL3)/C-C motif chemokine receptor 5 (CCR5) axis. Collectively, these results demonstrate the role of PSMA3 in ESCC cancer stemness and the negative regulation of CD8 T-cells infiltration mediated by PSMA3. The results of this study may provide a potential target for the immuno-oncology effect of PSMA3 in ESCC therapy.

Pluripotency Stemness and Cancer: More Questions than Answers

Embryonic stem cells and induced pluripotent stem cells provided us with fascinating new knowledge in recent years. Mechanistic insight into intricate regulatory circuitry governing pluripotency stemness and disclosing parallels between pluripotency stemness and cancer instigated numerous studies focusing on roles of pluripotency transcription factors, including Oct4, Sox2, Klf4, Nanog, Sall4 and Tfcp2L1, in cancer. Although generally well substantiated as tumour-promoting factors, oncogenic roles of pluripotency transcription factors and their clinical impacts are revealing themselves as increasingly complex. In certain tumours, both Oct4 and Sox2 behave as genuine oncogenes, and reporter genes driven by composite regulatory elements jointly recognized by both the factors can identify stem-like cells in a proportion of tumours. On the other hand, cancer stem cells seem to be biologically very heterogeneous both among different tumour types and among and even within individual tumours. Pluripotency transcription factors are certainly implicated in cancer stemness, but do not seem to encompass its entire spectrum. Certain cancer stem cells maintain their stemness by biological mechanisms completely different from pluripotency stemness, sometimes even by engaging signalling pathways that promote differentiation of pluripotent stem cells. Moreover, while these signalling pathways may well be antithetical to stemness in pluripotent stem cells, they may cooperate with pluripotency factors in cancer stem cells - a paradigmatic example is provided by the MAPK-AP-1 pathway. Unexpectedly, forced expression of pluripotency transcription factors in cancer cells frequently results in loss of their tumour-initiating ability, their phenotypic reversion and partial epigenetic normalization. Besides the very different signalling contexts operating in pluripotent and cancer stem cells, respectively, the pronounced dose dependency of reprogramming pluripotency factors may also contribute to the frequent loss of tumorigenicity observed in induced pluripotent cancer cells. Finally, contradictory cell-autonomous and non-cell-autonomous effects of various signalling molecules operate during pluripotency (cancer) reprogramming. The effects of pluripotency transcription factors in cancer are thus best explained within the concept of cancer stem cell heterogeneity.

Epigenetic control of melanoma cell invasiveness by the stem cell factor SALL4

Melanoma cells rely on developmental programs during tumor initiation and progression. Here we show that the embryonic stem cell (ESC) factor Sall4 is re-expressed in the Tyr::NrasQ61K; Cdkn2a-/- melanoma model and that its expression is necessary for primary melanoma formation. Surprisingly, while Sall4 loss prevents tumor formation, it promotes micrometastases to distant organs in this melanoma-prone mouse model. Transcriptional profiling and in vitro assays using human melanoma cells demonstrate that SALL4 loss induces a phenotype switch and the acquisition of an invasive phenotype. We show that SALL4 negatively regulates invasiveness through interaction with the histone deacetylase (HDAC) 2 and direct co-binding to a set of invasiveness genes. Consequently, SALL4 knock down, as well as HDAC inhibition, promote the expression of an invasive signature, while inhibition of histone acetylation partially reverts the invasiveness program induced by SALL4 loss. Thus, SALL4 appears to regulate phenotype switching in melanoma through an HDAC2-mediated mechanism.

Elevated expression of the RNA-binding motif protein 43 predicts poor prognosis in esophageal squamous cell carcinoma

RNA-binding proteins (RBPs) play crucial roles in the post-transcriptional regulation of mRNA during numerous physiological and pathological processes, including tumor genesis and development. However, the role of RNA-binding motif protein 43 (RBM43) in esophageal squamous cell carcinoma (ESCC) has not been reported so far. The current study was the first to evaluate RBM43 protein expression by immunohistochemistry (IHC) in an independent cohort of 207 patients with ESCC, to explore its potential prognostic value and clinical relevance in ESCC. The results indicated that RBM43 protein levels were significantly elevated in ESCC tissues and increased RBM43 expression was associated with age and N categories. In addition, ESCC patients with high expression of RBM43 had shorter overall survival (OS) and disease‐free survival (DFS) than those with low RBM43 expression. Furthermore, when survival analyses were conducted at different clinical stages, overexpression of RBM43 was significantly correlated with shortened survival in patients with ESCC at early stages (TNM stage I–II and N0 stage). Cox regression analysis further proved that high RBM43 expression was an independent predictor of poor prognosis in ESCC patients. In conclusion, increased expression of RBM43 is correlated with malignant attributes to ESCC and predicts unfavorable prognosis, suggesting an effective prognostic biomarker and potential therapeutic target for ESCC.

Evaluation of the Prognostic Value of Solute Carrier Family 34 Member 2 "SLC34A2" in Papillary Thyroid Carcinoma: An Immunohistochemical Study

Background

Papillary thyroid carcinoma (PTC) usually has an indolent clinical course, yet a subset of patients might show an aggressive course. Thus, better stratification of at-risk patients is mandatory for proper management. Solute carrier family 34 member 2 (SLC34A2) is an independent prognostic indicator in several cancers. However, only a few studies have been conducted to evaluate the prognostic value of SLC34A2 in PTC, with none of them assessing its immunohistochemical (IHC) expression in a large cohort of patients with PTC or exploring its possible relationship with tumor progression. Aim of the Study. We aimed to evaluate the IHC expression of SLC34A2 in a large series of PTC patients, correlate its expression with established clinicopathological factors, and find any possible relationship between this marker and patient prognosis. Material and Methods. A total of 476 samples (including 238 samples of PTC and 238 samples of normal thyroid tissue) collected between 2002 and 2005 were extracted from the archives of the Pathology Lab, Ain Shams University Hospitals. IHC analysis was performed using an anti-SLC34A2 antibody. Follow-up data were obtained.

Results

High SLC34A2 expression significantly correlated with important adverse clinicopathological parameters of PTC—i.e., late tumor stage, positive extrathyroid extension, tumor size  >  4 cm, and age  ≥  55 years (p ≤ 0.001 for each). Kaplan–Meier analysis revealed that high SLC34A2 expression significantly correlated with shorter disease-free survival (DFS; p = 0.005), but not with overall survival (p = 0.111). Multivariate analysis showed SLC34A2 to be an independent prognostic factor affecting DFS.

Conclusions

High SLC34A2 IHC expression correlated with adverse clinicopathological prognostic parameters. Furthermore, SLC34A2 was identified as an independent factor for DFS that could serve to improve risk stratification of PTC patients for better management.

L1CAM overexpression promotes tumor progression through recruitment of regulatory T cells in esophageal carcinoma

OBJECTIVE

L1 cell adhesion molecule (L1CAM) exhibits oncogenic activity in tumors. However, the link between L1CAM and the tumor microenvironment remains poorly understood in patients with esophageal squamous cell carcinoma (ESCC). In this study, we investigated how L1CAM expression in ESCC affects the oncogenic characteristics of tumor cells and the tumor microenvironment.

METHODS

Human ESCC samples were collected, and the mRNA and protein levels of L1CAM were examined by real-time PCR and immunohistochemistry. Overexpression and knockdown gene expression assays were used for mechanistic studies. The cell proliferation and cell cycle were measured with CCK-8 assays and flow cytometry. Cell migration and invasion ability were measured with Transwell assays. Multiplex bead-based assays were performed to identity the factors downstream of L1CAM. Xenograft studies were performed in nude mice to evaluate the effects of L1CAM on tumor growth and regulatory T cell (Treg) recruitment.

RESULTS

L1CAM expression was significantly elevated in ESCC tissues (P < 0.001) and correlated with poorer prognosis (P < 0.05). Ablation of L1CAM in ESCC cells inhibited tumor growth and migration, and increased tumor cell apoptosis (P < 0.05). In the tumor microenvironment, L1CAM expression correlated with Treg infiltration in ESCC by affecting CCL22 secretion. Mechanistically, L1CAM facilitated CCL22 expression by activating the PI3K/Akt/NF-κB signaling pathway. Furthermore, CCL22 promoted Treg recruitment to the tumor site; the Tregs then secreted TGF-β, which in turn promoted L1CAM expression via Smad2/3 in a positive feedback loop.

CONCLUSIONS

Our findings provide new insight into the mechanism of immune evasion mediated by L1CAM, suggesting that targeting L1CAM-CCL22-TGF-β crosstalk between tumor cells and Tregs may offer a unique means to improve treatment of patients with ESCC.

NEDD9 promotes cancer stemness by recruiting myeloid-derived suppressor cells via CXCL8 in esophageal squamous cell carcinoma

OBJECTIVE

Esophageal squamous cell carcinoma (ESCC) has high morbidity and mortality rates worldwide. Cancer stem cells (CSCs) may cause tumor initiation, metastasis, and recurrence and are also responsible for chemotherapy and radiotherapy failures. Myeloid-derived suppressor cells (MDSCs), in contrast, are known to be involved in mediating immunosuppression. Here, we aimed to investigate the mechanisms of interaction of CSCs and MDSCs in the tumor microenvironment.

METHODS

ESCC tissues and cell lines were evaluated. Neural precursor cell expressed, developmentally downregulated 9 (NEDD9) was knocked down and overexpressed by lentiviral transfection. Quantitative PCR, Western blot, immunohistochemistry, cell invasion, flow cytometry, cell sorting, multiplex chemokine profiling, and tumor growth analyses were performed.

RESULTS

Microarray analysis revealed 10 upregulated genes in esophageal CSCs. Only NEDD9 was upregulated in CSCs using the sphere-forming method. NEDD9 expression was correlated with tumor invasion (P = 0.0218), differentiation (P = 0.0153), and poor prognosis (P = 0.0373). Additionally, NEDD9 was required to maintain the stem-like phenotype. Screening of chemokine expression in ESCC cells with NEDD9 overexpression and knockdown showed that NEDD9 regulated C-X-C motif chemokine ligand 8 (CXCL8) expression via the ERK pathway. CXCL8 mediated the recruitment of MDSCs induced by NEDD9 in vitro and in vivo. MDSCs promoted the stemness of ESCC cells through NEDD9 via the Notch pathway.

CONCLUSIONS

As a marker of ESCC, NEDD9 maintained the stemness of ESCC cells and regulated CXCL8 through the ERK pathway to recruit MDSCs into the tumor, suggesting NEDD9 as a therapeutic target and novel prognostic marker for ESCC.

Up-Regulation of SALL4 Is Associated With Survival and Progression via Putative WNT Pathway in Gastric Cancer

SALL4, a transcriptional factor involved in embryonic stem cell self-renewal and pluripotency, is overexpressed in gastric cancer (GC). However, the association of SALL4 with the survival of GC patients is not well-understood, and the role of SALL4 in cancer progression is still unknown. In the present study, a total of 1,815 GC patients who underwent radical resection at Peking Cancer Hospital were included consecutively from 2015 to 2018, confirming the prognostic value of SALL4 and validating by data from TCGA and GEO. The protein and mRNA expression levels of SALL4 were evaluated by immunohistochemistry and qPCR, respectively. Besides, GSEA and WGCNA were applied to explore the SALL4-related cancer-promoting signaling pathways and gene modules. Our results showed that overexpression of SALL4 was observed in 16.7% of GC patients. SALL4 positivity was associated with male, older age, mixed-type histology, late stages, lymphatic metastasis, vascular invasion, non-cardia location, high AFP level, and no EBV infection background. SALL4 could be served as a marker for prognostic prediction in GC, and SALL4-positive GC was significantly associated with shortened survival. Further, the bioinformatic analysis indicated that the Wnt/β-catenin signaling pathway was activated in SALL4-high cases compared with SALL4-low cases. Expression of SALL4 was also positively correlated with the expression of multiple co-expressed genes, such as TRIB3, which plays an important role in activating the Wnt/β-catenin pathway. Our findings indicate that SALL4 is associated with clinicopathological features related to cancer progression in GC and its function in the Wnt/β-catenin pathway.

Effect of SALL4 on the Proliferation, Invasion and Apoptosis of Breast Cancer Cells

Objective:

We aimed to identify the expression of Sal-like 4 (SALL4) in breast cancer tissues and to explore the role of this gene in the carcinogenesis of breast cancer cells.

Methods:

A total of 62 paired breast cancer and noncancerous tissue samples were obtained from patients with breast cancer. SALL4 expression patterns and their association with clinicopathological characteristics were investigated by qRT-PCR, western blotting, and immunochemistry in breast cancer tissues. After the knockdown of SALL4 by short hairpin RNAs (shRNAs), the proliferative, invasive, and apoptotic abilities of MDA-MB-435 and MDA-MB-468 cells (breast cancer cell lines) were measured by colony formation and CCK-8 assays, wound healing and transwell assays, and flow cytometry, respectively.

Results:

SALL4 expression was higher in breast cancer tissues than that in the paired noncancerous tissues, and increased SALL4 expression in tumor tissues was closely related to tumor size and lymphatic metastasis. Furthermore, functional experiments revealed that SALL4 knockdown inhibited the cell proliferation, induced cell cycle arrest in G0/G1phase and apoptosis, and decreased the ability of migration and invasion in breast cancer cells. Additionally, our study first demonstrated that SALL4 played a critical role in modulating the tumorigenicity of breast cancer cells via the WNT/β-catenin signaling pathway.

Conclusions:

Our results suggest that the expression of SALL4 is upregulated in breast cancer, and this upregulation is involved in the regulation of cell growth, invasion, and apoptosis. Hence, SALL4 may be a promising target for diagnosis and therapy in patients with breast cancer.

Spalt-like transcription factor 4 expression in oral epithelial dysplasia and oral squamous cell carcinoma: An immunohistochemical appraisal

BACKGROUND:

Spalt-like transcription factor 4 (SALL4) is a stem cell marker that plays a critical role in maintaining the pluripotency and self-renewal of embryonic and hematopoietic stem cells. Only a few studies have been done to apprehend the expression of SALL4 in the potentially malignant oral lesion (leukoplakia with dysplasia) and oral squamous cell carcinoma (OSCC).

AIM:

The aim of this study is to evaluate the expression of SALL4 in leukoplakia with dysplasia and OSCC and to correlate the expression of the marker (SALL4) with the various clinicopathological parameters and patient outcome.

MATERIALS AND METHODS:

Immunohistochemistry for SALL4 protein was performed on 140 cases: those histopathologically confirmed cases of leukoplakia with dysplasia (n = 30) and OSCC (n = 110). Ten cases of nonepithelial neoplasm (fibroepithelial hyperplasia and excised tissue surrounding impacted third molars) were taken as control. Statistical analyses were applied to evaluate correlations between SALL4 overexpression and clinicopathological features of leukoplakia and OSCC. Survival rates were analyzed using Kaplan–Meier method.

RESULTS:

SALL4 positivity was observed to be higher (P = 0.001) in the tumor cells of OSCC with Immuno Reactive Score (IRS) ranging from 0 to 9. Poorly differentiated squamous cell carcinoma (SCC) had paramount higher expression with a median IRS of 6. Similar IRS and above (IRS, 6–9) was observed in Stage I (five cases), which recurred and well-differentiated cases with metastasis (four cases) while in leukoplakia with dysplasia the SALL4 expression was weak with a range of 2–4.

CONCLUSIONS:

SALL4 being one of the cancer stem cell molecules plays an important role in the progression of oral cancer, which was evident in this study. This could also account for aggressive clinical behavior. Follow-up of these patients would relate this molecule could be responsible for cancer relapse. Patients diagnosed to have oral epithelial dysplasia had a low expression of SALL4, are under follow-up, although seven cases did transform to SCC. Thus, we conclude, SALL4 may be of prognostic relevance, but in oral epithelial dysplasia, it requires further investigations.

TRIM33 Overexpression Inhibits the Progression of Clear Cell Renal Cell Carcinoma In Vivo and In Vitro

Purpose

To evaluate the expression of tripartite motif-containing 33 (TRIM33) in ccRCC tissues and explore the biological effect of TRIM33 on the progress of ccRCC.

Method

The Cancer Genome Atlas (TCGA) database was used to examine the mRNA expression levels of TRIM33 in ccRCC tissues and its clinical relevance. Immunohistochemistry (IHC) was performed to evaluate its expression in ccRCC tissues obtained from our hospital. The correlation between TRIM33 expression and clinicopathological features of the patients was also investigated. The effects of TRIM33 on the proliferation of ccRCC cells were examined using the CCK-8 and colony formation assays. The effects of TRIM33 on the migration and invasion of ccRCC cells were explored through wound healing and transwell assays, along with the use of Wnt signaling pathway agonists in rescue experiments. Western blotting was used to explore the potential mechanism of TRIM33 in renal cancer cells. A xenograft model was used to explore the effect of TRIM33 on tumor growth.

Result

Bioinformatics analysis showed that TRIM33 mRNA expression in ccRCC tissues was downregulated, and low TRIM33 expression was related to poor prognosis in ccRCC patients. In agreement with this, low TRIM33 expression was detected in human ccRCC tissues. TRIM33 expression levels were correlated with clinical characteristics, including tumor size and Furman's grade. Furthermore, TRIM33 overexpression inhibited proliferation, migration, and invasion of 786-O and ACHN cell lines. The rescue experiment showed that the originally inhibited migration and invasion capabilities were restored. TRIM33 overexpression reduced the expression levels of β-catenin, cyclin D1, and c-myc, and inhibited tumor growth in ccRCC cells in vivo.

Conclusion

TRIM33 exhibits an abnormally low expression in human ccRCC tissues. TRIM33 may serve as a potential therapeutic target and prognostic marker for ccRCC.

SALL4 promotes tumor progression in breast cancer by targeting EMT

Sal-like protein 4 (SALL4) is overexpressed in breast cancer and might contribute to breast cancer progression, but the molecular mechanism remains unknown. Here, we found that within a group of 371 ethnic Chinese breast cancer patients, SALL4 was associated with lower grade (P = .002) and progesterone receptor positivity (P = .004) for overall cases; lower Ki67 (P = .045) and high vimentin (P = .007) for luminal cases. Patients with high SALL4 expression in lymph node metastasis showed a significantly worse survival than those with low expression. Knockout of SALL4 in a triple-negative breast cancer cell line MDA-MB-231-Red-FLuc-GFP led to suppressed ability in proliferation, clonogenic formation, migration, and mammosphere formation in vitro, tumorigenicity and lung colonization in vivo. On the other hand, overexpression of SALL4 enhanced migration and mammosphere formation in vitro and tumorigenicity in vivo. Mechanistically, there was a positive correlation between SALL4 expression and mesenchymal markers including Zinc finger E-box binding homeobox 1 (ZEB1), vimentin, Slug, and Snail in vivo. Chromatin immunoprecipitation experiment indicated that SALL4 can bind to the promoter region of vimentin (-778 to -550 bp). Taken together, we hypothesize that SALL4 promotes tumor progression in breast cancer by inducing the mesenchymal markers like vimentin through directly binding to its promoter. Increased SALL4 level in metastatic lymph node relative to the primary site is an important poor survival marker in breast cancer.

MiR-3622a-3p acts as a tumor suppressor in colorectal cancer by reducing stemness features and EMT through targeting spalt-like transcription factor 4

MicroRNAs are a class of small non-coding RNAs which act as oncogenes or tumor suppressors through targeting specific mRNAs. Colorectal cancer (CRC) is one of the most common malignancies worldwide. MiR-3622a-3p is found to be decreased in colorectal cancer (CRC) by analyzing data from TCGA database and there are few reports about the role of miR-3622a-3p in cancers. Our research aimed to explore the effects of miR-3622a-3p on CRC. MiR-3622a-3p was found to be down-regulated in CRC tissues and cells by qRT-PCR. The effect of miR-3622a-3p on proliferation, apoptosis, cell cycle, migration and invasion of CRC cells were investigated by a serious of biological function assays and the results revealed that miR-3622a-3p could inhibit the malignant biological properties of CRC. We performed dual luciferase assay, RNA immunoprecipitation (RIP) assay and pull-down assay to confirm the interaction between miR-3622a-3p and spalt-like transcription factor 4 (SALL4). Western blot was carried out to determine the effects of miR-3622a-3p and SALL4 on stemness features and EMT. We found that miR-3622a-3p suppressed stemness features and EMT of CRC cells by SALL4 mRNA degradation. MiR-3622a-3p could inhibit CRC cell proliferation and metastasis in vivo with tumor xenograft model and in vivo metastasis model. The CRC organoid model was constructed with fresh CRC tissues and the growth of organoids was suppressed by miR-3622a-3p. Taken together, the results of our study indicate miR-3622a-3p exerts antioncogenic role in CRC by downregulation of SALL4. The research on miR-3622a-3p might provide a new insight into treatment of CRC.

Linking Cancer Stem Cell Plasticity to Therapeutic Resistance-Mechanism and Novel Therapeutic Strategies in Esophageal Cancer

Esophageal cancer (EC) is an aggressive form of cancer, including squamous cell carcinoma (ESCC) and adenocarcinoma (EAC) as two predominant histological subtypes. Accumulating evidence supports the existence of cancer stem cells (CSCs) able to initiate and maintain EAC or ESCC. In this review, we aim to collect the current evidence on CSCs in esophageal cancer, including the biomarkers/characterization strategies of CSCs, heterogeneity of CSCs, and the key signaling pathways (Wnt/β-catenin, Notch, Hedgehog, YAP, JAK/STAT3) in modulating CSCs during esophageal cancer progression. Exploring the molecular mechanisms of therapy resistance in EC highlights DNA damage response (DDR), metabolic reprogramming, epithelial mesenchymal transition (EMT), and the role of the crosstalk of CSCs and their niche in the tumor progression. According to these molecular findings, potential therapeutic implications of targeting esophageal CSCs may provide novel strategies for the clinical management of esophageal cancer.

VHL mutation-mediated SALL4 overexpression promotes tumorigenesis and vascularization of clear cell renal cell carcinoma via Akt/GSK-3β signaling

Background

Although ongoing development of therapeutic strategies contributes to the improvements in clinical management, clear cell renal cell carcinoma (ccRCC) deaths originate mainly from radiochemoresistant and metastatic disease. Transcription factor SALL4 has been implicated in tumorigenesis and metastasis of multiple cancers. However, it is not known whether SALL4 is involved in the pathogenesis of ccRCC.

Methods

Analyses of clinical specimen and publicly available datasets were performed to determine the expression level and clinical significance of SALL4 in ccRCC. The influence of SALL4 expression on ccRCC tumor growth, metastasis and vascularity was evaluated through a series of in vitro and in vivo experiments. Western blotting, immunofluorescence staining and integrative database analysis were carried out to investigate the underlying mechanism for SALL4-mediated oncogenic activities in ccRCC.

Results

SALL4 expression was increased in ccRCC and positively correlated with tumor progression and poor prognosis. SALL4 could promote ccRCC cell proliferation, colony formation, cell cycle progression, migration, invasion and tumorigenicity and inhibit cell senescence. Further investigation revealed a widespread association of SALL4 with individual gene transcription and the involvement of SALL4 in endothelium development and vasculogenesis. In the context of ccRCC, SALL4 promoted tumor vascularization by recruiting endothelial cells. In addition, we found that SALL4 could exert its tumor-promoting effect via modulating Akt/GSK-3β axis and VEGFA expression. VHL mutation and DNA hypomethylation may be involved in the upregulation of SALL4 in ccRCC.

Conclusions

Overall, our results provide evidence that upregulated SALL4 can function as a crucial regulator of tumor pathogenesis and progression in ccRCC, thus offering potential therapeutic strategies for future treatment.

Expression and clinical value of SALL4 in renal cell carcinomas

The aim of the present study was to investigate the expression of spalt like transcription factor 4 (SALL4) in the three most common types of renal cell carcinomas (RCC) [clear cell RCC (ccRCC), papillary renal cell carcinoma (pRCC) and chromophobe RCC (chRCC)], and the association with the overall survival (OS) of patients. The Cancer Genome Atlas (TCGA) database and RCC samples were used to investigate the expression levels of the SALL4 gene and its association with the OS in the three types of RCC based on the analysis of the transcriptome, copy number and survival data. It was found that SALL4 was highly expressed in ccRCC and pRCC tumor tissue, and low mRNA expression level of SALL4 indicated a prolonged survival in both ccRCC and pRCC. This mRNA expression level was associated with pathological Tumor-Node-Metastasis stage, M and T stages in both ccRCC and pRCC. The analysis of the enriched pathway results suggested that SALL4 may act via translation initiation, and that the related genes promoted the progression of RCC. Moreover, the high expression level of SALL4 was detected in RCC samples and serum from patients. It was demonstrated that SALL4 promotes increased viability in RCC cells. Therefore, the present results suggest that SALL4 may be a sensitive and specific cancer biomarker in ccRCC and pRCC. Furthermore, targeting of SALL4 may improve RCC therapy and prolong the survival of patients with ccRCC or pRCC.

Crosstalk between MEIS1 and markers of different cell signaling pathways in esophageal squamous cell carcinoma

The homeobox transcription factor MEIS1 is involved in cell fate decision, stem cells properties, gastrointestinal (GI) tract development, and progression of several malignancies such as esophageal squamous cell carcinoma (ESCC). Increasing evidences suggest the crosstalk between MEIS1 and cell signaling pathways. Therefore, our aim in present study was to investigate the probable linkage of MEIS1 expression with key genes of different cell signaling pathways in ESCC tumorigenesis, and their correlation with clinicopathological feature of the patients. The gene expression profiling of MEIS1 and different cell signaling genes including SALL4, SIZN1, and HEY1 (stemness state, BMP, and NOTCH signaling pathways, respectively) was performed using quantitative real-time reverse transcription polymerase chain reaction (PCR) in fresh tumoral compared to margin normal tissues of 50 treatment-naive ESCC samples. The mRNA expression of MEIS1/SIZN1, SIZN1/HEY1, and SIZN1/SALL4 were significantly associated to each other (P < 0.05). There were remarkable correlations between concomitant mRNA expression of MEIS1 and SIZN1 in tumors with invasion to adventitia, early stages of tumor progression and poorly differentiated tumors. Moreover, expression of MEIS1 and HEY1 was correlated to each other in primary stages of tumor progression and non-invaded tumors. Expression of MEIS1 was significantly associated with SALL4 in poorly differentiated tumors. Our results indicated that correlation between different cell signaling pathway-related genes may lead to esophageal tumorigenesis. It is illustrated that MEIS1 as a HOX gene has a significant correlation with stemness state, BMP, and NOTCH signaling pathways via the SIZN1.

Overexpression of Sal-like protein 4 in head and neck cancer: epigenetic effects and clinical correlations

BACKGROUND

Sal-like protein 4 (SALL4), an embryonic stem cell factor, has been reported to play an essential role in embryogenesis and oncogenesis. As yet, however, the expression and role of this transcription factor in head and neck squamous cell carcinoma (HNSCC) has not been established.

METHODS

We assessed SALL4 mRNA expression in a well-characterised dataset of 230 HNSCC samples (test cohort 110 cases and validation cohort 120 cases). We also transfected HNSCC cells (FaDu and UM-SCC-6) with SALL4 siRNA and assessed its effects on proliferation and expression of specific epigenetic factors in order to uncover the role of SALL4 in HNSCC.

RESULTS

Overexpression of SALL4 was detected in tumour samples of both cohorts. HNSCC cells treated with SALL4 siRNA showed a reduction in growth and a decrease in DNA methyltransferase 3 alpha (DNMT3A) expression. In the patient cohorts, SALL4 overexpression was found to significantly correlate with disease recurrence (p < 0.001) and SALL4 methylation status (p = 0.002). We also found that DNMT3A was significantly upregulated upon SALL4 upregulation (p < 0.001). High expression levels of SALL4 correlated with decreases in disease-free survival (DFS) rates (log-rank test, p < 0.001). Multivariate analysis revealed that SALL4 expression served as an independent prognostic factor for DFS (hazard ratio: 2.566, 95% confidence interval: 1.598-4.121; p < 0.001).

CONCLUSIONS

Our findings indicate that SALL4 upregulation correlates with HNSCC tumour aggressiveness and an adverse patient outcome. Our findings also indicate that DNMT3A may synergistically contribute to the regulatory effects of SALL4. Our findings provide insight into SALL4-mediated HNSCC development via epigenetic modulation.

Spalt-Like Protein 4 (SALL4) Promotes Angiogenesis by Activating Vascular Endothelial Growth Factor A (VEGFA) Signaling

Background

Spalt-like protein 4 (SALL4) is a nuclear transcription factor central to early embryonic development, especially for regulating pluripotency of embryonic stem cells (ESCs) and sustaining ESCs self-renewal. Aberrant re-expression of SALL4 in adult tissues is involved in tumorigenesis and cancer progression. However, the role of SALL4 in angiogenesis remains elusive. Here, we determined the potential action of SALL4 on proliferation, migration, and tube formation of endothelial cells.

Material/Methods

HUVECs were infected with lentiviral particles expressing shRNA against SALL4. QRT-PCR and immunoblotting analysis were carried out to evaluate knockdown efficiency at mRNA and protein levels. Cell proliferation was measured by CCK-8 assay and flow cytometry was conducted to analyze cell cycle distribution. Wound-healing and Transwell migration assays were performed to evaluate cell motility. In addition, we determined the role of SALL4 on angiogenesis by tube formation assay, and Western blot analysis was used to assess the effect of SALL4 downregulation on VEGFA expression.

Results

We found that SALL4 downregulation resulted in decreased proliferation. Cell cycle analysis revealed that SALL4 knockdown impeded cell cycle progression and induced cell cycle arrest at G1 phase. We also found that silencing of SALL4 decreased the capacity of wound healing and cell migration in HUVECs. Furthermore, tube formation assay showed that loss of SALL4 inhibited HUVECs angiogenesis. We also observed that SALL4 knockdown reduced the level of VEGFA in HUVECs.

Conclusions

In conclusion, these results support that by promoting proliferation, cell cycle progression, migration, and tube formation, SALL4 is involved in the process of angiogenesis through modulating VEGFA expression.

SLC34A2 simultaneously promotes papillary thyroid carcinoma growth and invasion through distinct mechanisms

Thyroid cancer is the fastest growing cancer among all solid tumors in recent decades. Papillary thyroid carcinoma (PTC) is the most predominant type of thyroid cancer. Around 30% of PTC patients with distant metastases and local invasion receive poor prognosis. Thus, the identification of new druggable biological targets is of great importance. Accumulating evidence indicates that solute carrier family numbers have emerged as obligate effectors during the progression of multiple malignancies. Here, we uncovered the functional significance, molecular mechanisms, and clinical impact of solute carrier family 34 member A2 (SLC34A2) in PTC. SLC34A2 was markedly overexpressed in PTC tissues at both mRNA and protein levels compared with matched adjacent normal tissues due to promoter hypomethylation mediated by the DNA methyltransferase 3 beta (DNMT3B). Furthermore, a series of in vivo and in vitro gain- or loss-of-functional assays elucidated the role of SLC34A2 in boosting cell proliferation, cell cycle progression, migration, invasion, and adhesion of PTC cells. Using immunoprecipitation and mass spectrometry, we discovered that SLC34A2 bound to the actin-binding repeats domain of Cortactin (CTTN), thereby inducing the invadopodia formation of PTC cells to promote the metastasis potential of PTC cells. Besides, our mechanistic studies, as well as gene set enrichment analysis (GSEA), have pinpointed the PTEN/AKT/FOXO3a pathway as a major signaling functioning downstream of SLC34A2 regulated cell growth. Taken together, our results highlighted that SLC34A2 plays a pivotal oncogenic role during carcinogenesis and metastasis through distinct mechanisms in PTC.

cPLA2α reversibly regulates different subsets of cancer stem cells transformation in cervical cancer

Cervical cancer stem cells (CCSCs) are considered major causes of chemoresistance/radioresistance and metastasis. Although several cell surface antigens have been identified in CCSCs, these markers vary among tumors because of CSC heterogeneity. However, whether these markers specifically distinguish CCSCs with different functions is unclear. Here, we demonstrated that CCSCs exist in two biologically distinct phenotypes characterized by different levels of cytosolic phospholipase A2α (cPLA2α) expression. Overexpression of cPLA2α results in a CD44⁺ CD24^- phenotype associated with mesenchymal traits, including increased invasive and migration abilities, whereas CCSCs with cPLA2α downregulation express CD133 and show quiescent epithelial characteristics. In addition, cPLA2α regulates the reversible transition between mesenchymal and epithelial CCSC states through PKCζ, an atypical protein kinase C, which governs cancer cell state changes and the maintenance of various embryonic stem cell characteristics, further inhibiting β-catenin-E-cadherin interaction in membrane and promoting β-catenin translocation into the nucleus to affect the transcriptional regulation of stemness signals. We propose that reversible transitions between mesenchymal and epithelial CCSC states regulated by cPLA2α are necessary for cervical cancer metastasis and recurrence. Thus, cPLA2α might be an attractive therapeutic target for eradicating different states of CCSCs to eliminate tumors more effectively.

Tissue-guided LASSO for prediction of clinical drug response using preclinical samples

Prediction of clinical drug response (CDR) of cancer patients, based on their clinical and molecular profiles obtained prior to administration of the drug, can play a significant role in individualized medicine. Machine learning models have the potential to address this issue but training them requires data from a large number of patients treated with each drug, limiting their feasibility. While large databases of drug response and molecular profiles of preclinical in-vitro cancer cell lines (CCLs) exist for many drugs, it is unclear whether preclinical samples can be used to predict CDR of real patients. We designed a systematic approach to evaluate how well different algorithms, trained on gene expression and drug response of CCLs, can predict CDR of patients. Using data from two large databases, we evaluated various linear and non-linear algorithms, some of which utilized information on gene interactions. Then, we developed a new algorithm called TG-LASSO that explicitly integrates information on samples' tissue of origin with gene expression profiles to improve prediction performance. Our results showed that regularized regression methods provide better prediction performance. However, including the network information or common methods of including information on the tissue of origin did not improve the results. On the other hand, TG-LASSO improved the predictions and distinguished resistant and sensitive patients for 7 out of 13 drugs. Additionally, TG-LASSO identified genes associated with the drug response, including known targets and pathways involved in the drugs' mechanism of action. Moreover, genes identified by TG-LASSO for multiple drugs in a tissue were associated with patient survival. In summary, our analysis suggests that preclinical samples can be used to predict CDR of patients and identify biomarkers of drug sensitivity and survival.

CircRNA_100367 regulated the radiation sensitivity of esophageal squamous cell carcinomas through miR-217/Wnt3 pathway

Background: Circular RNAs (circRNAs) play important roles in regulating the radioresistance of esophageal squamous cell carcinoma (ESCC). This study aimed to determine the role of hsa_circRNA_100367 in regulating radioresistance of ESCC.

Results: Higher expression and potency of endothelial to mesenchymal transformation (EMT) was found in radioresistant ESCC cells (KYSE-150R) than in ESCC cells (KYSE-150). Silencing circRNA_100367 inhibited the proliferation and migration of KYSE-150R cells, and decreased the expression of β-catenin (an important molecule in Wnt pathway) in KYSE-150R cells. Additionally, circRNA_100367 bound to miR-217, and miR-217 targeted Wnt3. Low Wnt3 expression was associated with the short survival time in patients with ESCC and Wnt3 knockdown inhibited the proliferation and migration of KYSE-150R cells. CircRNA_100367 enhanced the radioresistance of KYSE-150R cells through miR-217/Wnt3 pathway. In vivo, circRNA_100367 silence reduced the growth of KYSE-150R cells under radiation.

Conclusion: Our results revealed that circRNA_100367 attenuated radioresistance of ESCC through miR-217/Wnt3 pathway.

Methods: CircRNAs related with the radioresistance of ESCC were analyzed by hierarchical cluster analysis. The relationship between circRNA_100367 and miR-217, Wnt3 was detected by RNA immunoprecipitation (RIP), RNA pull-down and luciferase reporte assays. The proliferation and migration ESCC cells were detected by MTT, Transwell and colony formation assays.

LncRNA SNHG4 promotes the proliferation, migration, invasiveness, and epithelial–mesenchymal transition of lung cancer cells by regulating miR-98-5p

Long noncoding RNA small nucleolar RNA host gene 4 (SNHG4) is usually up-regulated in cancer and regulates the malignant behavior of cancer cells. However, its role in lung cancer remains elusive. In this study, we silenced the expression of SNHG4 in NCI-H1437 and SK-MES-1, two representative non-small-cell lung cancer cell lines, by transfecting them with siRNA (small interfering RNA) that specifically targets SNHG4. We observed significantly inhibited cell proliferation in vitro and reduced tumor growth in vivo after SNHG4 silencing. SNHG4 knockdown also led to cell cycle arrest at the G1 phase, accompanied with down-regulation of cyclin-dependent kinases CDK4 and CDK6. The migration and invasiveness of these two cell lines were remarkably inhibited after SNHG4 silencing. Moreover, our study revealed that the epithelial–mesenchymal transition (EMT) of lung cancer cells was suppressed by SNHG4 silencing, as evidenced by up-regulated E-cadherin and down-regulated SALL4, Twist, and vimentin. In addition, we found that SNHG4 silencing induced up-regulation of miR-98-5p. MiR-98-5p inhibition abrogated the effect of SNHG4 silencing on proliferation and invasion of lung cancer cells. In conclusion, our findings demonstrate that SNHG4 is required by lung cancer cells to maintain malignant phenotype. SNHG4 probably exerts its pro-survival and pro-metastatic effects by sponging anti-tumor miR-98-5p.

SALL4 promotes the tumorigenicity of cervical cancer cells through activation of the Wnt/β-catenin pathway via CTNNB1

SALL4 is overexpressed in many cancers and is found to be involved in tumorigenesis and tumor progression. However, the function of SALL4 in cervical cancer remains unknown. Here, we showed that the expression of SALL4 was gradually increased from normal cervical tissue to high-grade squamous intraepithelial lesions and then to squamous cervical carcinoma. SALL4 was upregulated or downregulated in cervical cancer cells by stably transfecting a SALL4-expressing plasmid or a shRNA plasmid targeting SALL4, respectively. In vitro, cell growth curves and MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) assays showed that SALL4 promoted the cell proliferation of cervical cancer cells. In vivo, xenograft experiments verified that SALL4 enhanced the tumor formation of cervical cancer cells in female BALB/c Nude mice. Cell cycle analysis by fluorescence-activated cell sorting found that SALL4 accelerates cell cycle transition from the G0 /G1 phase to the S phase. TOP/FOP-Flash reporter assay revealed that SALL4 significantly upregulates the activity of Wnt/β-catenin pathway. Western blotting showed that the expression levels of β-catenin and important downstream genes, including c-Myc and cyclin D1, were increased by SALL4 in cervical cancer cells. Furthermore, dual-luciferase reporter and chromatin immunoprecipitation assays confirmed that SALL4 transcriptionally activated CTNNB1 by physically interacting with its promoters. Taken together, The results of this study demonstrated that SALL4 may promote cell proliferation and tumor formation of cervical cancer cells by upregulating the activity of the Wnt/β-catenin signaling pathway by directly binding to the CTNNB1 promoter and trans-activating CTNNB1.

The research advances of exosomes in esophageal cancer

Esophageal carcinoma (EC) is one of the most common human digestive tract tumors, with high morbidity and mortality. It is necessary to elucidate the mechanism of cancer progression and seek early EC diagnostic markers for prompt detection and intervention. Exosomes are membrane nanovesicles secreted from many nucleated cells, 30-100 nm in diameter, containing various proteins, lipids and nucleic acids. They exist in peripheral blood, urine, ascites and other body fluids, widely engaged with intercellular material exchange and signal communication. Exosomes secreted from EC cells or tissues conduct important functions in tumor growth and progression. The detection and analysis of tumor-derived or tumor-associated exosomes has potential for EC early diagnosis and prognosis assessment. In the present paper, the exosomes' biological behaviors, isolation, detection and functions in EC progression - using as potential biomarkers for EC diagnosis or prognosis - are reviewed.

Association between quantitative parameters of CEUS and Sall4/Wnt/β-catenin signaling in patients with hepatocellular carcinoma

Objectives: In this study, we aim to investigate the correlations of quantitative parameters of contrast-enhanced ultrasonography (CEUS) and Spalt-Like Transcription Factor 4 (Sall4)/Wnt/β-catenin signaling pathway with clinicopathological features and prognosis of patients with hepatocellular carcinoma (HCC).

Methods: The CEUS was performed to detect the liver function and the prognosis of patients. The expression of Sall4, WNT3a and β-catenin was evaluated using immunohistochemical staining. Sall4, WNT3a and β-catenin mRNA expression was measured by SYBR green qPCR assay.

Results: We found that the mRNA and protein expression of Sall4, WNT3a and β-catenin in the HCC tissues were significantly upregulated compared with the adjacent normal tissues. Upregulation of these proteins was associated with tumor differentiation, TNM stage, tumor size, vascular invasion and liver cirrhosis of HCC patients. In addition, we found that decreased time to peak and washout time and increased peak intensity and area under the curve of CEUS in the HCC were also correlated with TNM stage, tumor size and vascular invasion. Moreover, Sall4, WNT3a and β-catenin protein were significantly associated with the TTP, PI, AUC, and WOT.

Conclusion: This study suggests that quantitative parameters of CEUS and Sall4/Wnt/β-catenin signaling may be helpful for early diagnosis and prognosis prediction of HCC patients.

SALL4 induces radioresistance in nasopharyngeal carcinoma via the ATM/Chk2/p53 pathway

Radiotherapy is the mainstay and primary curative treatment modality in nasopharyngeal carcinoma (NPC), whose efficacy is limited by the development of intrinsic and acquired radioresistance. Thus, deciphering new molecular targets and pathways is essential for enhancing the radiosensitivity of NPC. SALL4 is a vital factor in the development and prognosis of various cancers, but its role in radioresistance remains elusive. This study aimed to explore the association of SALL4 expression with radioresistance of NPC. It was revealed that SALL4 expression was closely correlated with advanced T classification of NPC patients. Inhibition of SALL4 reduced proliferation and sensitized cells to radiation both in vitro and in vivo. Furthermore, SALL4 silencing increased radiation-induced DNA damage, apoptosis, and G2/M arrest in CNE2 and CNE2R cells. Moreover, knockdown of SALL4 impaired the expression of p-ATM, p-Chk2, p-p53, and anti-apoptosis protein Bcl-2, while pro-apoptosis protein was upregulated. These findings indicate that SALL4 could induce radioresistance via ATM/Chk2/p53 pathway and its downstream proteins related to apoptosis. Targeting SALL4 might be a promising approach for the development of novel radiosensitizing therapeutic agents for radioresistant NPC patients.