SALL4, a novel marker for human gastric carcinogenesis and metastasis

Strategies for the Isolation and Identification of Gastric Cancer Stem Cells

Gastric cancer stem cells (GCSCs) originate from both gastric adult stem cells and bone marrow cells and are conspicuously present within the histological milieu of gastric cancer tissue. GCSCs play pivotal and multifaceted roles in the initiation, progression, and recurrence of gastric cancer. Hence, the characterization of GCSCs not only facilitates precise target identification for prospective therapeutic interventions in gastric cancer but also has significant implications for targeted therapy and the prognosis of gastric cancer. The prevailing techniques for GCSC purification involve their isolation using surface-specific cell markers, such as those identified by flow cytometry and immunomagnetic bead sorting techniques. In addition, in vitro culture and side-population cell sorting are integral methods in this context. This review discusses the surface biomarkers, isolation techniques, and identification methods of GCSCs, as well as their role in the treatment of gastric cancer.

PGD2/PTGDR2 Signal Affects the Viability, Invasion, Apoptosis, and Stemness of Gastric Cancer Stem Cells and Prevents the Progression of Gastric Cancer

BACKGROUND

Prostaglandin D2 (PGD2) has been shown to restrict the occurrence and development of multiple cancers; nevertheless, its underlying molecular mechanism has not been fully elucidated. The present study investigated the effect of PGD2 on the biological function of the enriched gastric cancer stem cells (GCSCs), as well as its underlying molecular mechanism, to provide a theoretical basis and potential therapeutic drugs for gastric cancer (GC) treatment.

METHODS

The plasma PGD2 levels were detected by Enzyme-linked immunosorbent assay (ELISA). Silencing of lipocalin prostaglandin D synthetases (L-PTGDS) and prostaglandin D2 receptor 2 (PTGDR2) was carried out in GCSCs from SGC-7901 and HGC-27 cell lines. Cell Counting Kit-8, transwell, flow cytometry, and western blotting assays were used to determine cell viability, invasion, apoptosis, and stemness of GCSCs. In vivo xenograft models were used to assess tumor growth.

RESULTS

Clinically, it was found that the plasma PGD2 level decreased significantly in patients with GC. PGD2 suppressed viability, invasion, and stemness and increased the apoptosis of GCSCs. Downregulating L-PTGDS and PTGDR2 promoted viability, invasion, and stemness and reduced the apoptosis of GCSCs. Moreover, the inhibition of GCSCs induced by PGD2 was eliminated by downregulating the expression of PTGDR2. The results of in vivo experiments were consistent with those of in vitro experiments.

CONCLUSION

Our data suggest that PGD2 may be an important marker and potential therapeutic target in the clinical management of GC. L-PTGDS/PTGDR2 may be one of the critical targets for GC therapy. The PGD2/PTGDR2 signal affects the viability, invasion, apoptosis, and stemness of GCSCs and prevents the progression of GC.

SALL4 advances the proliferation and tumor cell stemness of colon cancer cells through the transcription and regulation of ROBO2

SALL4 is a transcription factor highly expressed in diverse cancers and is implicated in the development of cancer. SALL4 has been implied to play a cancer-promoting role in colon cancer (CC), but the molecular mechanism remains unclear. Chromatin immunoprecipitation assay and dual-luciferase assay were conducted to verify the binding relationship of SALL4 and ROBO2. qRT-PCR detected the mRNA expression levels of SALL4 and ROBO2, and the flow cytometry analyzed the cell cycle distribution. Western blot examined SALL4 expression, and cell cycle/cell stemness-related proteins. The impact of SALL4 and ROBO2 on the proliferation capacity of cells and tumor cell stemness was elucidated by MTT, colony formation, and sphere-forming assays. SALL4 and ROBO2 were up-regulated in CC, and SALL4 could activate the transcription of ROBO2. Down-regulated SALL4 was able to significantly restrain the proliferation capacity of CC cells and arrest the cell cycle in G0/G1 phase by repressing the expression of cyclin B, cyclin E, and cyclin D1. Besides, the rescue assay results indicated that up-regulated ROBO2 could reverse the repressive impact of down-regulated SALL4 on the proliferation of CC cells and accelerate the progression of the cell cycle, thus promoting the sphere-forming of tumor stem cells. SALL4 advanced the proliferation of CC and cell stemness through direct activation of ROBO2 expression, implied the novel mechanism of SALL4 in CC, and pointed out that SALL4/ROBO2 axis was likely to be a potential target for clinical treatment of CC.

SALL4 promotes angiogenesis in gastric cancer by regulating VEGF expression and targeting SALL4/VEGF pathway inhibits cancer progression

BACKGROUND

Spalt-like protein 4 (SALL4) is a stemness-related transcription factor whose abnormal re-expression contributes to cancer initiation and progression. However, the role of SALL4 in cancer angiogenesis remains unknown.

METHODS

Analyses of clinical specimens via TCGA datasets were performed to determine the expression level and clinical significance of SALL4 in STAD (Stomach Adenocarcinoma). SALL4 knockdown, knockout, and overexpression were achieved by siRNA, CRISPR/Cas9, and plasmid transfection. The effects of conditioned medium (CM) from SALL4 knockdown or overexpression of gastric cancer cells on endothelial cell proliferation, migration, and tube formation were investigated by CCK-8 assay, transwell migration assay, and tube formation assay. The regulation of VEGF gene expression by SALL4 was studied by qRT-PCR, western blot, chromatin immunoprecipitation (ChIP) assay, and electrophoretic mobility shift assay (EMSA). Engineered exosomes from 293T cells loaded with si-SALL4-B and thalidomide were produced to test their therapeutic effect on gastric cancer progression.

RESULTS

SALL4 expression was increased in STAD and positively correlated with tumor progression and poor prognosis. SALL4-B knockdown or knockout decreased while over-expression increased the promotion of human umbilical vein endothelial cells (HUVEC) cell proliferation, migration, and tube formation by gastric cancer cell-derived CM. Further investigation revealed a widespread association of SALL4 with angiogenic gene transcription through the TCGA datasets. Additionally, SALL4-B knockdown reduced, while over-expression enhanced the expression levels of VEGF-A, B, and C genes. The results of ChIP and EMSA assays indicated that SALL4 could directly bind to the promoters of VEGF-A, B, and C genes and activate their transcription, which may be associated with increased histone H3-K79 and H3-K4 modifications in their promoter regions. Furthermore, si-SALL4-B and thalidomide-loaded exosomes could be efficiently uptaken by gastric cancer cells and significantly reduced SALL4-B and Vascular Endothelial Growth Factor (VEGF) expression levels in gastric cancer cells, thus inhibiting the pro-angiogenic role of their derived CM.

CONCLUSION

These findings suggest that SALL4 plays an important role in angiogenesis by transcriptionally regulating VEGF expression. Co-delivery of the functional siRNA and anticancer drug via exosomes represents a useful approach to inhibiting cancer angiogenesis by targeting SALL4/VEGF pathway.

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.

Early hepatoid adenocarcinoma of the stomach with signet ring cell carcinoma: A case report and clinicopathological features

Background

Hepatoid adenocarcinoma of the stomach (HAS) is a rare subtype of gastric cancer with poor prognosis, and its clinicopathological features are not well understood, so the pathology from the clinical biopsy is easily misdiagnosed, especially for special or atypical HAS. We present an extremely rare early HAS with signet ring cell carcinoma and evaluate its clinicopathological features.

Case presentation

A 51-year-old female patient of Chinese Han ethnicity with upper abdominal pain for 5 years and worsened abdominal pain for 1 month was admitted to our hospital. Esophagogastroduodenoscopy showed a submucosal tumor-like elevated lesion with central depression in the greater curvature of the junction between the antrum and body. Histopathological examination from the biopsy revealed medium-low-differentiation adenocarcinoma with signet ring cell carcinoma. Radical gastrectomy was performed, and the final diagnosis was early HAS with signet ring cell carcinoma.

Conclusions

HAS with signet ring cell carcinoma is a special type of HAS and extremely rare. It is first presented for this extremely rare type of HAS, which contributes to strengthen the understanding for the clinicopathological characteristics of HAS and especially promote early detection of HAS.

Clinicopathological and prognostic significance of SWI/SNF complex subunits in undifferentiated gastric carcinoma

BACKGROUND

The switch/sucrose nonfermentable (SWI/SNF) complex is an evolutionarily conserved chromatin remodeling complex that displays dysfunction in many tumors, especially undifferentiated carcinoma. Cancer stem cells (CSC), a special type of undifferentiated cancer cells with stem cell-like properties, play an essential role in tumor cell proliferation, invasion, and metastasis. In undifferentiated gastric carcinomas, the association of SWI/SNF complexes with clinicopathological features, CSC phenotype, and the prognosis is not fully understood.

METHODS

We collected a cohort of 21 patients with undifferentiated/dedifferentiated gastric carcinoma. We next performed immunohistochemistry staining for the five subunits of the SWI/SNF complex (ARID1A, ARID1B, SMARCA2, SMARCA4, and SMARCB1), and four mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6), as well as other markers such as p53, PD-L1, and cancer stem cell (CSC) markers (SOX2, SALL4). Then, we investigated the correlation of SWI/SNF complex subunits with clinicopathological characters and performed prognostic analysis.

RESULTS

We observed SMARCA2 loss in 12 cases (57.14%), followed by ARID1A (5 cases, 23.81%) and SMARCA4 (3 cases, 14.29%). Fourteen cases (66.67%) lost any one of the SWI/SNF complex subunits, including 3 cases with SMARCA2 and ARID1A co-loss, and 3 cases with SMARCA2 and SMARCA4 co-loss. Correlation analysis revealed that the CSC phenotype occurred more frequently in the SWI/SNF complex deficient group (P = 0.0158). Survival analysis revealed that SWI/WNF complex deficiency, undifferentiated status, CSC phenotype, and the loss of SMARCA2 and SMARCA4 resulted in worse survival. Univariate and multivariate Cox regression analyses screened out three independent factors associated with worse prognosis: undifferentiated status, SWI/SNF complex deficiency, and lymph node metastasis.

CONCLUSIONS

The SWI/SNF complex deficiency was more likely to result in a CSC phenotype and worse survival and was an independent prognostic factor in undifferentiated/dedifferentiated gastric carcinoma.

Demethylation and Up-Regulation of an Oncogene after Hypomethylating Therapy

BACKGROUND

Although hypomethylating agents are currently used to treat patients with cancer, whether they can also reactivate and up-regulate oncogenes is not well elucidated.

METHODS

We examined the effect of hypomethylating agents on SALL4, a known oncogene that plays an important role in myelodysplastic syndrome and other cancers. Paired bone marrow samples that were obtained from two cohorts of patients with myelodysplastic syndrome before and after treatment with a hypomethylating agent were used to explore the relationships among changes in SALL4 expression, treatment response, and clinical outcome. Leukemic cell lines with low or undetectable SALL4 expression were used to study the relationship between SALL4 methylation and expression. A locus-specific demethylation technology, CRISPR-DNMT1-interacting RNA (CRISPR-DiR), was used to identify the CpG island that is critical for SALL4 expression.

RESULTS

SALL4 up-regulation after treatment with hypomethylating agents was observed in 10 of 25 patients (40%) in cohort 1 and in 13 of 43 patients (30%) in cohort 2 and was associated with a worse outcome. Using CRISPR-DiR, we discovered that demethylation of a CpG island within the 5' untranslated region was critical for SALL4 expression. In cell lines and patients, we confirmed that treatment with a hypomethylating agent led to demethylation of the same CpG region and up-regulation of SALL4 expression.

CONCLUSIONS

By combining analysis of patient samples with CRISPR-DiR technology, we found that demethylation and up-regulation of an oncogene after treatment with a hypomethylating agent can indeed occur and should be further studied. (Funded by Associazione Italiana per la Ricerca sul Cancro and others.).

Aberrant ARMCX1 Expression Is an Independent Predictor of Poor Prognosis in Gastric Cancer

ARMCX1 (Armadillo repeat containing X-linked 1) is identified to be the novel tumor suppressor gene related to multiple tumor types. Nonetheless, its effect on gastric cancer (GC) is still poorly understood. The present work determined ARMCX1 level within GC and the relation with clinicopathological characteristics. This work also collected relevant information in The Cancer Genome Atlas (TCGA) database for investigating associations of ARMCX1 with clinicopathologic variables and then validated in our GC cohort. Receiver operating characteristic (ROC) curves were plotted for assessing whether ARMCX1 expression was significant in diagnosing GC. Kaplan-Meier (KM) and Cox regression analyses were conducted for assessing clinicopathological characteristics associated with overall survival (OS) of GC cases. The data from the Human Protein Atlas (HPA) and Gene Expression Omnibus (GEO) databases was also analyzed for further validation, and biological processes (BPs) were identified by gene set enrichment analysis (GSEA). GC tissues showed markedly decreased ARMCX1 level relative to healthy counterparts (P < 0.001). Interestingly, ARMCX1 upregulation predicted low differentiation, poor OS, increased invasion, and late tumor stage. In addition, the area under ROC curve (AUC) and P value were 0.747 and <0.001, separately. Cases showing ARMCX1 upregulation showed significantly poor prognostic outcome compared with patients showing downregulation (P = 0.007). Furthermore, multivariate analysis showed that ARMCX1 upregulation independently predicted the risk of OS (P = 0.0017, hazard ratio, 1.089). GSEA analysis identified that several cancer-related pathways, such as focal adhesion, ECM receptor interaction, JAK/STAT, melanoma, WNT, and cancer, were enriched in GCs. We conclude that ARMCX1 serves as the possibly independent biomarker to diagnose and predict GC prognostic outcome.

Computing microRNA-gene interaction networks in pan-cancer using miRDriver

DNA copy number aberrated regions in cancer are known to harbor cancer driver genes and the short non-coding RNA molecules, i.e., microRNAs. In this study, we integrated the multi-omics datasets such as copy number aberration, DNA methylation, gene and microRNA expression to identify the signature microRNA-gene associations from frequently aberrated DNA regions across pan-cancer utilizing a LASSO-based regression approach. We studied 7294 patient samples associated with eighteen different cancer types from The Cancer Genome Atlas (TCGA) database and identified several cancer-specific and common microRNA-gene interactions enriched in experimentally validated microRNA-target interactions. We highlighted several oncogenic and tumor suppressor microRNAs that were cancer-specific and common in several cancer types. Our method substantially outperformed the five state-of-art methods in selecting significantly known microRNA-gene interactions in multiple cancer types. Several microRNAs and genes were found to be associated with tumor survival and progression. Selected target genes were found to be significantly enriched in cancer-related pathways, cancer hallmark and Gene Ontology (GO) terms. Furthermore, subtype-specific potential gene signatures were discovered in multiple cancer types.

SALL4 Oncogenic Function in Cancers: Mechanisms and Therapeutic Relevance

SALL4, a member of the SALL family, is an embryonic stem cell regulator involved in self-renewal and pluripotency. Recently, SALL4 overexpression was found in malignant cancers, including lung cancer, hepatocellular carcinoma, breast cancer, gastric cancer, colorectal cancer, osteosarcoma, acute myeloid leukemia, ovarian cancer, and glioma. This review updates recent advances of our knowledge of the biology of SALL4 with a focus on its mechanisms and regulatory functions in tumors and human hematopoiesis. SALL4 overexpression promotes proliferation, development, invasion, and migration in cancers through activation of the Wnt/β-catenin, PI3K/AKT, and Notch signaling pathways; expression of mitochondrial oxidative phosphorylation genes; and inhibition of the expression of the Bcl-2 family, caspase-related proteins, and death receptors. Additionally, SALL4 regulates tumor progression correlated with the immune microenvironment involved in the TNF family and gene expression through epigenetic mechanisms, consequently affecting hematopoiesis. Therefore, SALL4 plays a critical oncogenic role in gene transcription and tumor growth. However, there are still some scientific hypotheses to be tested regarding whether SALL4 is a therapeutic target, such as different tumor microenvironments and drug resistance. Thus, an in-depth understanding and study of the functions and mechanisms of SALL4 in cancer may help develop novel strategies for cancer therapy.

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.

The Relationship Between D-dimer and Prognosis in the Patients with Serum Alpha-Fetoprotein-Positive Gastric Cancer: A Retrospective Cohort Study

Background:

Alpha-fetoprotein-positive gastric cancer (AFPGC) is a subtype of gastric cancer that is rare in clinical practice and extremely malignant. Malignant tumors are often associated with hemorrhage, thrombosis, and even disseminated intravascular coagulation (DIC). The D-dimer test is used as a sensitive index in the diagnosis of DIC and fresh thrombosis in malignant tumors. Therefore, this study aims to investigate the relationship between D-dimer values and the clinical characteristics and prognosis of patients with serum AFPGC (AFP ⩾ 15 μg/L) patients.

Methods:

Overall, 120 healthy subjects and 120 AFP-negative gastric cancer (AFP < 15μg/L) patients from May 2017 to July 2018 at the Shanxi Cancer Hospital served as the control group in this retrospective cohort study. Additionally, 120 patients with pretreatment advanced serum AFP were chosen to analyze clinicopathologic features and factors that affect prognosis. The predictor was the D-dimer, and the outcome variable was overall survival (OS). Other variables included age, sex, tumor site, T-stage, distant metastasis, and preoperative serum tumor biomarkers. Differences in OS rate were analyzed by GraphPad Prism 9.2.0.332. The Cox regression model was used for univariate and multivariate analysis.

Results:

In comparison to AFP-negative gastric cancer, we discovered that D-dimer had a meaningfully higher presentation in patients with AFPGC (P < .001). Based on D-dimer median levels, the AFPGC patients were divided into two groups, including 39 patients with low D-dimer (<1000 ng/mL) and 81 patients with high D-dimer (⩾1000 ng/mL). The variables, including T-stage, distant metastasis, and expression of HER2, were associated with the value of D-dimer. The D-dimer levels were weakly related to the levels of tumor markers. The differences in AFPGC patients, with an OS rate of 30.76% for patients with low D-dimer (<1000) and 12.30% with high D-dimer (⩾1000; P = .0027), were statistically significant. Cox multivariate analysis of various parameters indicated that T-stage, distant metastasis, vascular embolism, level of D-dimer, and tumor biomarkers of AFP were independent risk factors for survival.

Conclusion:

Serum D-dimer levels may be a valuable indicator for predicting AFPGC metastasis and progression.

Clinicopathological and molecular characteristics of the alpha-fetoprotein-producing gastric cancer: emphasis on two major subtypes

Alpha-fetoprotein-producing gastric cancer (AFPGC) is associated with high invasion and poor prognosis, but has not been well-documented due to its rarity. To develop the understanding of AFPGC, and further facilitate its clinical decision-making and treatment, we performed clinicopathological and molecular characterization of AFPGC and its two major subtypes, namely, gastric adenocarcinoma with enteroblastic differentiation (GAED) and hepatoid adenocarcinoma (HAC). The clinicopathological and molecular characteristics of AFPGC patients (n = 54) were mainly investigated by immunohistochemistry and next-generation sequencing (NGS) approaches. AFPGC exhibited a higher incidence of lymphatic and vascular invasion than conventional gastric adenocarcinoma (CGA). Despite various morphological patterns, there was mostly no evident difference in clinicopathological characteristics between the GAED and HAC subtypes. Target-enriched NGS profiling of disease mutation landscapes discovered 17 differentially mutated genes between AFPGC and CGA. The AFPGC patients carrying ZNF217 mutations had poorer overall survival than the ZNF217 wildtype. Furthermore, ATR showed a significantly higher mutation rate in GAED than in HAC. Overall, our study of clinicopathological characteristics shed light on the differences between CGA and AFPGC, as well as the relationships between the GAED and HAC subtypes of AFPGC. Furthermore, mutation landscape profiling revealed potential diagnostic and prognostic markers for AFPGC and its two subtypes.

Targeting an Inducible SALL4-Mediated Cancer Vulnerability with Sequential Therapy

Oncofetal protein SALL4 is critical for cancer cell survival. Targeting SALL4, however, is only applicable in a fraction of cancer patients who are positive for this gene. To overcome this limitation, we propose to induce a cancer vulnerability by engineering a partial dependency upon SALL4. Following exogenous expression of SALL4, SALL4-negative cancer cells became partially dependent on SALL4. Treatment of SALL4-negative cells with the FDA-approved hypomethylating agent 5-aza-2'-deoxycytidine (DAC) resulted in transient upregulation of SALL4. DAC pretreatment sensitized SALL4-negative cancer cells to entinostat, which negatively affected SALL4 expression through a microRNA, miRNA-205, both in culture and in vivo. Moreover, SALL4 was essential for the efficiency of sequential treatment of DAC and entinostat. Overall, this proof-of-concept study provides a framework whereby the targeting pathways such as SALL4-centered therapy can be expanded, sensitizing cancer cells to treatment by transient target induction and engineering a dependency. SIGNIFICANCE: These findings provide a therapeutic approach for patients harboring no suitable target by induction of a SALL4-mediated vulnerability.

Long Non-coding RNA DANCR in Cancer: Roles, Mechanisms, and Implications

Long non-coding RNA (lncRNA) DANCR (also known as ANCR)—differentiation antagonizing non-protein coding RNA, was first reported in 2012 to suppress differentiation of epithelial cells. Emerging evidence demonstrates that DANCR is a cancer-associated lncRNA abnormally expressed in many cancers (e.g., lung cancer, gastric cancer, breast cancer, hepatocellular carcinoma). Increasing studies suggest that the dysregulation of DANCR plays critical roles in cancer cell proliferation, apoptosis, migration, invasion, and chemoresistance in vitro and tumor growth and metastasis in vivo. Mechanistic analyses show that DANCR can serve as miRNA sponges, stabilize mRNAs, and interact with proteins. Recent research reveals that DANCR can be detected in many body fluids such as serum, plasma, and exosomes, providing a quick and convenient method for cancer monitor. Thus DANCR can be used as a promising diagnostic and prognostic biomarker and therapeutic target for various types of cancer. This review focuses on the role and mechanism of DANCR in cancer progression with an emphasis on the clinical significance of DANCR in human cancers.

A pan-cancer study of spalt-like transcription factors 1/2/3/4 as therapeutic targets

Spalt-like transcription factors (SALLs) are evolutionarily conserved proteins that participate in embryonic development. Four members of the SALL family, SALL1, SALL2, SALL3, and SALL4, are involved in cellular apoptosis, angiogenesis, invasion, and metastasis of tumors. We used the TCGA pan-cancer data to conduct a comprehensive analysis of SALL genes. High heterogeneity in the expression of these genes was observed across various cancers, SALL1 and SALL2 were downregulated, whereas SALL4 was upregulated. Moreover, we verified that SALL4 was commonly associated with survival disadvantage, whereas others were linked to a better prognosis. In renal cancer, SALL1, SALL2, and SALL3 showed downregulation, suggesting that they acted as tumor suppressors. Furthermore, SALLs were associated with immune infiltrate subtypes, with a close association between different degrees of infiltration of stromal cells and immune cells. DNA and RNA analyses in different tumors suggested different degrees of negative or positive correlation with tumor stem cell-like features. Finally, we revealed that SALLs were related to cancer cell resistance. Our results highlight the necessity to further study each SALL gene as a separate entity in specific types of cancer. Although this article showed that SALLs could be promising targets for cancer therapy, it needs further studies to validate the findings.

Advances of Tumorigenesis, Diagnosis at Early Stage, and Cellular Immunotherapy in Gastrointestinal Malignancies

Globally, in 2018, 4.8 million new patients have a diagnosis of gastrointestinal (GI) cancers, while 3.4 million people died of such disorders. GI malignancies are tightly relevant to 26% of the world-wide cancer incidence and occupies 35% of all cancer-associated deaths. In this article, we principally investigated molecular and cellular mechanisms of tumorigenesis in five major GI cancers occurring at esophagus, stomach, liver, pancreas, and colorectal region that illustrate high morbidity in Eastern and Western countries. Moreover, through this investigation, we not only emphasize importance of the tumor microenvironment in development and treatment of malignant tumors but also identify significance of M2PK, miRNAs, ctDNAs, circRNAs, and CTCs in early detection of GI cancers, as well as systematically evaluate contribution of personalized precision medicine including cellular immunotherapy, new antigen and vaccine therapy, and oncolytic virotherapy in treatment of GI cancers.

Identification of Clinical Relevant Molecular Subtypes of Pheochromocytoma

Pheochromocytoma (PCC) is a rare neuroendocrine tumor of the adrenal gland with a high rate of mortality if diagnosed at a late stage. Common symptoms of pheochromocytoma include headache, anxiety, palpitation, and diaphoresis. Different treatments are under observation for PCC but there is still no effective treatment option. Recently, the gene expression profiling of various tumors has provided new subtype-specific options for targeted therapies. In this study, using data sets from TCGA and the GSE19422 cohorts, we identified two distinct PCC subtypes with distinct gene expression patterns. Genes enriched in Subtype I PCCs were involved in the dopaminergic synapse, nicotine addiction, and long-term depression pathways, while genes enriched in subtype II PCCs were involved in protein digestion and absorption, vascular smooth muscle contraction, and ECM receptor interaction pathways. We further identified subtype specific genes such as ALK, IGF1R, RET, and RSPO2 for subtype I and EGFR, ESR1, and SMO for subtype II, the overexpression of which led to cell invasion and tumorigenesis. These genes identified in the present research may serve as potential subtype-specific therapeutic targets to understand the underlying mechanisms of tumorigenesis. Our findings may further guide towards the development of targeted therapies and potential molecular biomarkers against PCC.

Integrated clinicopathological and immunohistochemical analysis of gastric adenocarcinoma with hepatoid differentiation: an exploration of histogenesis, molecular characteristics, and prognostic markers

In addition to hepatoid adenocarcinoma (HAC), gastric adenocarcinoma with enteroblastic differentiation (GAED) and common adenocarcinoma (COM) could also show hepatoid differentiation, which presents a poor prognosis. To elucidate the histogenesis and development of gastric cancer with hepatoid differentiation, we identified 55 cases by histological morphology and a panel of markers, including α-fetoprotein (AFP), Glypican 3 (GPC3) and SALL4, then clinicopathological parameters, pathomorphological characteristics, mucin phenotypes, molecular features, Immunoscore and survival analysis were assessed. A mixture of three types (COM + GAED + HAC) was most commonly observed in the same case, and typical transitions between each histological subtype were frequently seen. Hyaline globule and pink amorphous substance were often present. HER2 was amplified in 21.8% of cases. All the tumors showed intestinal phenotype (69.1%) and mixed gastric/intestinal phenotype (30.9%) and were all defined to chromosomal instable (CIN)/genomically stable (GS) group. Considering that 83.6% cases presented TP53 gene mutation phenotype and 61.8% cases showed ≥10% aberrant E-cadherin expression, the precise molecule classification is ambiguous. Survival analysis showed that patients with high SALL4 expression, high preoperative serum AFP level, or low Immunoscore had a significantly poor overall survival (OS). Moreover, SALL4, HER2, and Immunoscore had an independent influence on OS. In conclusion, we suggest that the development of gastric adenocarcinoma with hepatoid differentiation might a continuously progressive profile: from intestinal-type COM adenocarcinoma to GAED and then HAC. CIN/GS subtypes might be where they belonged. SALL4, HER2, and Immunoscore may be potential therapeutic targets.

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.

Silencing SALL-4 Gene by Transfecting Small Interfering RNA with Targeted Aminoglycoside-Carboxyalkyl Polyethylenimine Nano-Polyplexes Reduced Migration of MCF-7 Breast Cancer Cells

Background:

The application of non-viral systems for delivering genes to cells is becoming a very interesting issue, especially in the treatment of neoplasms such as Breast Cancer (BC). Polymer-based non-viral systems are safe and feasible gene carriers to be used in targeted cancer therapy. SALL4 gene encodes a transcription factor and is overexpressed in some cancers.

Methods:

In this study, carboxyalkylated-PEI25 (25 kDa) was used to deliver plasmids expressing SALL4-siRNA into MCF-7 cells. DLS and AFM were applied to determine the size of nanoparticles. The MTT method was used to assess cytotoxicity, and the efficiency of transfection was confirmed both qualitatively and quantitatively. Finally, the effect of silencing SALL4 was investigated on the migration of MCF7 cells using the scratch test.

Results:

The results showed that transferring the SALL4-siRNA using PEI25G10C50 reduced the expression of the corresponding transcription factor by 14 folds which attenuated the migration of MCF-7 cells by 58%.

Conclusion:

In conclusion, PEI25G10C50 can serve as an effective gene delivery system for treating BC by targeting SALL-4.

MYC as a Multifaceted Regulator of Tumor Microenvironment Leading to Metastasis

The Myc family of oncogenes is deregulated in many types of cancer, and their over-expression is often correlated with poor prognosis. The Myc family members are transcription factors that can coordinate the expression of thousands of genes. Among them, c-Myc (MYC) is the gene most strongly associated with cancer, and it is the focus of this review. It regulates the expression of genes involved in cell proliferation, growth, differentiation, self-renewal, survival, metabolism, protein synthesis, and apoptosis. More recently, novel studies have shown that MYC plays a role not only in tumor initiation and growth but also has a broader spectrum of functions in tumor progression. MYC contributes to angiogenesis, immune evasion, invasion, and migration, which all lead to distant metastasis. Moreover, MYC is able to promote tumor growth and aggressiveness by recruiting stromal and tumor-infiltrating cells. In this review, we will dissect all of these novel functions and their involvement in the crosstalk between tumor and host, which have demonstrated that MYC is undoubtedly the master regulator of the tumor microenvironment. In sum, a better understanding of MYC’s role in the tumor microenvironment and metastasis development is crucial in proposing novel and effective cancer treatment strategies.

YAP promotes self-renewal of gastric cancer cells by inhibiting expression of L-PTGDS and PTGDR2

INTRODUCTION

Cancer stem cells have been implicated angiogenesis of tumor and invasiveness, drug resistance in tumors. Yes-associated protein 1 (YAP) owns carcinogenic roles in various organs, but the role of YAP in cancer stem cells of gastric cancer (GC) remains unclear. In this study, we explored the function and mechanism of YAP in GC cancer stem cells.

MATERIALS AND METHODS, AND RESULTS

First, we confirmed that the expression of YAP mRNA and protein in GC tissues was higher than in adjacent tissues by RT-PCR, western blot and immunohistochemistry. Immunofluorescence staining of the GC tissues revealed that the region of YAP expression coincided with the region of expression of the cancer stem cell marker SALL4 but did not overlap with that of the epithelial marker cytokeratin 14 (CK14). Additional research revealed that spherical cells expressed relatively high levels of YAP protein, and YAP overexpression reinforced self-renewal and expression of stem cell markers in the GC cells. Knockdown the expression of YAP reversed this phenomenon. Second, we examined the expression patterns of lipocalin-type prostaglandin D2 synthase (L-PTGDS) and prostaglandin D2 receptor 2 (PTGDR2) in GC tissues and proved that there was negatively correlation between the expression of L-PTGDS and PTGDR2 and YAP in GC tissues. Finally, we confirmed that YAP inhibited the expression of L-PTGDS and PTGDR2 by gain- and loss-of-function experiments. Moreover, the overexpression of L-PTGDS and PTGDR2 suppressed the proliferation and self-renewal induced by YAP in vitro and reversed the pro-tumor effect of YAP in vivo.

CONCLUSION

Our results revealed a novel function of YAP and the mechanism underlying cancer stem cell regulation by YAP.

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.

MEIS1 promotes expression of stem cell markers in esophageal squamous cell carcinoma

BACKGROUND

MEIS1 (Myeloid ecotropic viral integration site 1) as a homeobox (HOX) transcription factor plays regulatory roles in a variety of cellular processes including development, differentiation, survival, apoptosis and hematopoiesis, as well as stem cell regulation. Few studies have established pluripotency and self-renewal regulatory roles for MEIS1 in human esophageal squamous cell carcinoma (ESCC), and our aim in this study was to evaluate the functional correlation between MEIS1 and the stemness markers in ESCC patients and cell line KYSE-30.

METHODS

Expression pattern of MEIS1 and SALL4 gene expression was analyzed in different pathological features of ESCC patients. shRNA in retroviral vector was used for constantly silencing of MEIS1 mRNA in ESCC line (KYSE-30). Knockdown of MEIS1 gene and the expression pattern of selected stemness markers including SALL4, OCT4, BMI-1, HIWI, NANOG, PLK1, and KLF4 were evaluated using real-time PCR.

RESULTS

Significant correlations were observed between MEIS1 and stemness marker SALL4 in different early pathological features of ESCC including non-invaded tumors, and the tumors with primary stages of progression. Retroviral knockdown of MEIS1 in KYSE-30 cells caused a noteworthy underexpression of both MEIS1 and major involved markers in stemness state of the cells including SALL4, OCT4, BMI-1, HIWI and KLF4.

CONCLUSIONS

The results highlight the important potential role of MEIS1 in modulating stemness properties of ESCCs and cells KYSE-30. These findings may confirm the linkage between MEIS1 and self-renewal capacity in ESCC and support probable oncogenic role for MEIS1 in the disease.

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.

The Relevance of Transcription Factors in Gastric and Colorectal Cancer Stem Cells Identification and Eradication

Gastric and colorectal cancers have a high incidence and mortality worldwide. The presence of cancer stem cells (CSCs) within the tumor mass has been indicated as the main reason for tumor relapse, metastasis and therapy resistance, leading to poor overall survival. Thus, the elimination of CSCs became a crucial goal for cancer treatment. The identification of these cells has been performed by using cell-surface markers, a reliable approach, however it lacks specificity and usually differs among tumor type and in some cases even within the same type. In theory, the ideal CSC markers are those that are required to maintain their stemness features. The knowledge that CSCs exhibit characteristics comparable to normal stem cells that could be associated with the expression of similar transcription factors (TFs) including SOX2, OCT4, NANOG, KLF4 and c-Myc, and signaling pathways such as the Wnt/β-catenin, Hedgehog (Hh), Notch and PI3K/AKT/mTOR directed the attention to the use of these similarities to identify and target CSCs in different tumor types. Several studies have demonstrated that the abnormal expression of some TFs and the dysregulation of signaling pathways are associated with tumorigenesis and CSC phenotype. The disclosure of common and appropriate biomarkers for CSCs will provide an incredible tool for cancer prognosis and treatment. Therefore, this review aims to gather the new insights in gastric and colorectal CSC identification specially by using TFs as biomarkers and divulge promising drugs that have been found and tested for targeting these cells.

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.

SALL4 promotes gastric cancer progression via hexokinase II mediated glycolysis

Background

The stem cell factor SALL4 is reactivated in human cancers. SALL4 plays diverse roles in tumor growth, metastasis, and drug resistance, but its role in tumor metabolism has not been well characterized.

Methods

The glycolytic levels of gastric cancer cells were detected by glucose uptake, lactate production, lactate dehydrogenase activity, ATP level, and hexokinase activity. QRT-PCR and western blot were used to detect the changes in the expression of glycolytic genes and proteins. The downstream target genes of SALL4 were identified by microarray. The regulation of hexokinase II (HK-2) by SALL4 was analyzed by luciferase reporter assay and chromatin immunoprecipitation assay. Transwell migration assay, matrigel invasion assay, cell counting assay and colony formation assay were used to study the roles of HK-2 regulation by SALL4 in gastric cancer cells in vitro. The effects of SALL4 on glycolysis and gastric cancer progression in vivo were determined by subcutaneous xenograft and peritoneal metastasis tumor models in nude mice.

Results

SALL4 knockdown inhibited glucose uptake, lactate production, lactate dehydrogenase activity, ATP level and hexokinase activity in gastric cancer cells, and decreased the expression of glycolytic genes and proteins. Microarray analysis showed that SALL4 knockdown affected glycolysis-related pathway. The regulation of HK-2 gene expression by SALL4 was confirmed by luciferase reporter assay and chromatin immunoprecipitation assay. HK-2 knockdown abrogated the promotion of glycolysis by SALL4 in gastric cancer cells, indicating that HK-2 acts as a downstream effector of SALL4. Moreover, HK-2 knockdown reversed the promoting role of SALL4 in gastric cancer cell proliferation, migration and invasion, suggesting that SALL4 drives gastric cancer progression by upregulating HK-2.

Conclusions

SALL4 promotes gastric cancer progression through HK-2-mediated glycolysis, which reveals a new mechanism for the oncogenic roles of SALL4 in cancer.

The transcription factor Spalt and human homologue SALL4 induce cell invasion via the dMyc-JNK pathway in Drosophila

Cancer cell metastasis is a leading cause of mortality in cancer patients. Therefore, revealing the molecular mechanism of cancer cell invasion is of great significance for the treatment of cancer. In human patients, the hyperactivity of transcription factor Spalt-like 4 (SALL4) is sufficient to induce malignant tumorigenesis and metastasis. Here, we found that when ectopically expressing the Drosophila homologue spalt (sal) or human SALL4 in Drosophila, epithelial cells delaminated basally with penetration of the basal lamina and degradation of the extracellular matrix, which are essential properties of cell invasion. Further assay found that sal/SALL4 promoted cell invasion via dMyc-JNK signaling. Inhibition of the c-Jun N-terminal kinase (JNK) signaling pathway through suppressing matrix metalloprotease 1, or basket can achieve suppression of cell invasion. Moreover, expression of dMyc, a suppressor of JNK signaling, dramatically blocked cell invasion induced by sal/SALL4 in the wing disc. These findings reveal a conserved role of sal/SALL4 in invasive cell movement and link the crucial mediator of tumor invasion, the JNK pathway, to SALL4-mediated cancer progression.This article has an associated First Person interview with the first author of the paper.

Sal-Like Protein 4 Transcription Factor: A Significant Diagnostic Biomarker Involved in Childhood ALL Resistance and Relapse

Purpose

Sal‐like protein 4 transcription factor (SALL4) is a stem cell transcription factor that plays an essential role in the maintenance and self-renewal of embryonic and hematopoietic stem cells, functioning as an oncogene in several cancers. However, the role of SALL4 in the biological behavior of childhood acute lymphoblastic leukemia and its relationship with multidrug resistance and relapse has remained largely unknown.

Patients and Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to characterize the expression pattern of SALL4 in the bone marrow samples of 43 patients with Philadelphia negative ALL and 18 children in the non-cancer control group. The presence of minimal residual disease was measured a year after the initial therapy using SSCP (single-strand conformation polymorphism). In addition, the correlation between the expression of SALL4 and ABCA3 in relapsed patients was analyzed statistically.

Results

Results showed an overexpression of SALL4 in de novo patients compared with the control group (P=0.0001, AUC= 0.93), indicating the importance of this gene in the induction of leukemia. A significant increase in the ABCA3 expression levels was revealed in the relapsed patients, in comparison with the drug-sensitive group (P = 0.0005). The leukemogenetic effect of SALL4 can be related to the effect of this gene on the maintenance of pluripotency in cancer stem cells. Results also suggest that the expression of SALL4 can be considered as a diagnostic marker for pediatric ALL. Moreover, SALL4 expression levels in the minimal residual disease positive (mrd+) ALL group was significantly higher than those in the mrd− group (p=0.0001, AUC= 0.92).

Conclusion

These data demonstrate the prognostic impact of SALL4 in childhood ALL. Our findings also indicated a direct correlation between the mRNA expression levels of SALL4 and ABCA3 transporter in the relapsed group of ALL patients (r=0.7). These results describe a possible mechanism by which SALL4 may lead to the development of multidrug resistance.

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.

Identifying critical state of complex diseases by single-sample Kullback-Leibler divergence

Background

Developing effective strategies for signaling the pre-disease state of complex diseases, a state with high susceptibility before the disease onset or deterioration, is urgently needed because such state usually followed by a catastrophic transition into a worse stage of disease. However, it is a challenging task to identify such pre-disease state or tipping point in clinics, where only one single sample is available and thus results in the failure of most statistic approaches.

Methods

In this study, we presented a single-sample-based computational method to detect the early-warning signal of critical transition during the progression of complex diseases. Specifically, given a set of reference samples which were regarded as background, a novel index called single-sample Kullback–Leibler divergence (sKLD), was proposed to explore and quantify the disturbance on the background caused by a case sample. The pre-disease state is then signaled by the significant change of sKLD.

Results

The novel algorithm was developed and applied to both numerical simulation and real datasets, including lung squamous cell carcinoma, lung adenocarcinoma, stomach adenocarcinoma, thyroid carcinoma, colon adenocarcinoma, and acute lung injury. The successful identification of pre-disease states and the corresponding dynamical network biomarkers for all six datasets validated the effectiveness and accuracy of our method.

Conclusions

The proposed method effectively explores and quantifies the disturbance on the background caused by a case sample, and thus characterizes the criticality of a biological system. Our method not only identifies the critical state or tipping point at a single sample level, but also provides the sKLD-signaling markers for further practical application. It is therefore of great potential in personalized pre-disease diagnosis.

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.

[Clinicopathological and molecular characteristics of Epstein-Barr virus associated gastric cancer: a single center large sample case investigation]

OBJECTIVE

Epstein-Barr virus associated gastric cancer (EBVaGC) is different from the traditional gastric cancer (Epstein-Barr virus non-associated gastric cancer, EBVnGC), and has unique clinicopathological features. This study investigated the largest single center cancer series so as to establish the clinicopathological and molecular characteristics of EBVaGC in China.

METHODS

A retrospective analysis was conducted on EBVaGC and EBVnGC patients diagnosed at Peking University Cancer Hospital from 2003 to 2018 by comparing their clinicopathological features and prognosis. The gastric cancer (GC) dataset of public database was analyzed to obtain differentially expressed genes. The expression of important genes and their association with prognosis of GC were verified in GC tissues from our hospital.

RESULTS

In this study, 3 241 GC patients were included, and a total of 163 EBVaGC (5.0%) patients were identified. Compared with EBVnGC, EBVaGC was higher in male and younger patients, and positively associated with remnant GC, poorly differentiated adenocarcinoma, and mixed type GC. EBVaGC was inversely related to lymph node metastasis. The 5-year survival rate of EBVnGC and EBVaGC was 59.6% and 63.2% respectively (P<0.05). In order to explore molecular features of EBVaGC, the Cancer Genome Atlas (TCGA) dataset was analyzed (n=240), and 7 404 significant differentially expressed genes were obtained, involving cell proliferation, apoptosis, invasion and metastasis. The down-regulated invasion/metastasis gene SALL4 and the up-regulated immune checkpoint gene PD-L1 were important molecular features of EBVaGC. Validation of these two genes in large GC series showed that the majority of the EBVaGC was SALL4 negative (1/92, 1.1%, lower than EBVnGC, 303/1 727, 17.5%), and that PD-L1 was mostly positive in EBVaGC (81/110, 73.6%, higher than EBVnGC, 649/2 350, 27.6%). GC patients with SALL4 negative and PD-L1 positive were often associated with better prognosis.

CONCLUSION

EBVaGC is a unique subtype of GC with less metastasis and a good prognosis. It also has a distinct molecular background. The down-regulation of invasion/metastasis gene SALL4 and up-regulation of immune checkpoint gene PD-L1 are important molecular features.

IDO1 Maintains Pluripotency of Primed Human Embryonic Stem Cells by Promoting Glycolysis

Human embryonic stem cells (hESCs) depend on glycolysis for energy supply and pluripotency and switch to oxidative phosphorylation upon differentiation. The underlying mechanisms remain unclear. Here, we demonstrate that indoleamine 2,3-dioxygenase 1 (IDO1) is expressed in primed hESCs and its expression rapidly downregulated upon hESC differentiation. IDO1 is required to maintain pluripotency by suppressing mitochondria activity and promoting glycolysis through the increase of NAD⁺ /NADH ratio. The upregulation of IDO1 during hESC differentiation suppresses the differentiation of hESCs into certain lineages of cells such as cardiomyocytes, which depend on oxidative phosphorylation to satisfy their high energy demand. Therefore, IDO1 plays important roles in maintaining the pluripotency of hESCs. Stem Cells 2019;37:1158-1165.

miR-188-5p emerges as an oncomiRNA to promote gastric cancer cell proliferation and migration via upregulation of SALL4

MicroRNAs (miRNAs) play pivotal roles in modulating key biological processes in gastric cancer (GC). As a newly identified miRNA, the function and potential mechanism of miR-188-5p in GC has not been thoroughly elucidated. Here, quantitative real-time polymerase chain reaction detection showed abnormally higher expression of miR-188-5p in GC cells and tissues. Gain-of-function analysis in vitro showed that miR-188-5p promoted GC cell proliferation and migration, while loss-of-function studies showed the reverse. Targetscan has predicted that phosphatase and tensin homolog (PTEN) was a potential target gene of miR-188-5p. miR-188-5p suppressed PTEN messenger RNA and protein expression and activated downstream AKT/mTOR signaling in GC cells, but luciferase reporter analysis showed that PTEN was not regulated by miR-188-5p via the 3' untranslated region. Furthermore, we observed that miR-188-5p overexpression promoted Sal-like protein 4 (SALL4) protein expression, cellular nuclear translocation, and transcription. Knockdown of SALL4 eliminated the effect of miR-188-5p in GC cells as well as suppression of PTEN. Taken together, our results demonstrate that miR-188-5p promotes GC cell proliferation and migration while suppressing tumor suppressor gene PTEN expression via transcriptional upregulation of oncogene SALL4. We conclude that miR-188-5p acts as an oncomiRNA in GC and may be a promising therapeutic target for GC.

[Aloin induces apoptosis via regulating the activation of MAPKs signaling pathway in human gastric cancer cells in vitro]

OBJECTIVE

To investigate the effect of aloin on apoptosis of human gastric cancer cells and explore the molecular mechanism.

METHODS

Gastric cancer MKN-28 and HGC-27 cells were cultured routinely in 1640 medium supplemented with 10% fetal bovine serum and 10% non-essential amino acids (for HGC-27 cells) and treated with different concentrations of aloin for different durations. The cell viability, cell nuclear morphology, and apoptotic rate of the cells were detected using CCK-8 assay, DAPI staining and AnnexinV-FITC/PI, respectively; Western blotting was used to detect the expression levels of PARP, procaspase 3 and the phosphorylation of p38, ERK and JNK. The cells were treated with specific inhibitors of p38, ERK and JNK, and the inhibitory effects on these pathways were detected with Western blotting; DAPI staining was used to detect the effects of inhibitors on apoptosis of gastric cancer cells.

RESULTS

Aloin dose-dependently inhibited the viability and induced apoptosis of HGC-27 and MKN-28 cells. Alion treatment obvious enhanced the phosphorylation of p38 and JNK but decreased ERK phosphorylation in the cells. Blocking ERK activation with the ERK inhibitor obviously enhanced aloin-induced cell apoptosis, where inhibiting p38 and JNK activation partly reversed alion-induced apoptosis in the cells.

CONCLUSIONS

Aloin induces apoptosis of human gastric cancer cells in vitro by activating p38 and JNK signaling pathways and inhibiting ERK signaling pathway.

Hepatoid adenocarcinoma of the stomach: a unique subgroup with distinct clinicopathological and molecular features

OBJECTIVES

Hepatoid adenocarcinoma of the stomach (HAS) is characterized by histological resemblance to hepatocellular carcinoma and a poor prognosis. The aim of this study is to elucidate the clinicopathological and molecular characteristics of HAS.

METHODS

Forty-two patients with HAS who received gastrectomy were enrolled in this study. Based on a panel of 483 cancer-related genes, targeted sequencing of 24 HAS and 22 clinical parameter-matched common gastric cancer (CGC) samples was performed. Prognostic factors for overall survival (OS) and disease-free survival (DFS) were analysed with the Kaplan-Meier method.

RESULTS

The most frequently mutated gene in both HAS and CGC was TP53, with a mutation rate of 30%. Additionally, CEBPA, RPTOR, WISP3, MARK1, and CD3EAP were identified as genes with high-frequency mutations in HAS (10-20%). Copy number gains (CNGs) at 20q11.21-13.12 occurred frequently in HAS, nearly 50% of HAS tumours harboured at least one gene with a CNG at 20q11.21-13.12. This CNG tended to be related to more adverse biobehaviour, including poorer differentiation, greater vascular and nerve invasion, and greater liver metastasis. Pathway enrichment analysis revealed that the HIF-1 signalling pathway and signalling pathways regulating stem cell pluripotency were specifically enriched in HAS. The survival analysis showed that a preoperative serum AFP level ≥ 500 ng/ml was significantly associated with poorer OS (p = 0.007) and tended to be associated with poorer DFS (p = 0.05).

CONCLUSION

CNGs at 20q11.21-13.12 happened frequently in HAS and tended to be related to more adverse biobehaviour. The preoperative serum AFP level was a sensitive prognostic biomarker for DFS and OS.

Knockdown of sal-like 4 expression by small interfering RNA induces apoptosis in breast cancer cells

Breast cancer is the most prevalent cancers worldwide and causes a significant amount of deaths annually. Spalt-like transcription factor 4 is known as a transcription factor, which has an important role in the proliferation of cancerous cells. Small interfering RNA (siRNA) is a short-chain molecule of 20 to 25 nucleotides that protrude on two sides of the 3', two nucleotides. In this study, using a specific sequence of siRNA against the sequence of this gene, its activity is investigated in the cell line of breast cancer. The breast cancer cells (MCF-7) were cultured and then, using a specific anti-sal-like 4 (SALL4) siRNA, their toxic doses were determined. Then, the gene is transfected into the cell. Proliferation and expression of the SALL4 and BCL-2 gene were measured using the real-time polymerase chain reaction method. The specific concentration of siRNA IC₅₀ of the SALL4 gene was 40.35 nmole. Gene expression results indicated that the expression of the Bcl-2 gene in the siRNA group was significantly reduced ( P < 0.05). SiRNA can increase the apoptosis of breast cancer cells by reducing the gene expression of SALL4 gene and Bcl-2; it can be used as a novel targeted therapy. This strategy, in addition to increasing the specificity of the drug, also reduces the side effects when compared with conventional chemotherapy.

Platelets enhance the ability of bone-marrow mesenchymal stem cells to promote cancer metastasis

Background

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have been identified to be closely associated with cancer progression. Our previous experimental results showed that BM-MSCs promote tumor growth and metastasis of gastric cancer through paracrine-soluble cytokines or exosomes. However, the elements that affect the role of BM-MSCs in promoting tumor metastasis are not clear. It is known that thrombocytosis in cancer patients is very common. Recently, platelets are recognized to play a critical role in tumor progression.

Purpose

This study aims to observe the effect of BM-MSCs which were co-cultured with platelets on tumor cell metastasis.

Methods

Platelet aggregation rate and the expression of P-selectin of platelets co-incubated with conditioned medium of SGC-7901 cells and BM-MSCs were detected by flow cytometry and platelet aggregometer. We also analyzed the change of BM-MSCs after co-incubation with platelets or platelets which were treated with SGC-7901 cells using transwell assay and Western blot analysis. The proliferation and migration ability and expression of VEGF, c-Myc, and sall-4 in SGC-7901 cells treated with medium of BM-MSCs which were co-cultured with platelets were detected. SGC-7901 cells were injected into Balb/c nude mice and the extent of lung metastasis was observed. Both in vitro and in vivo assays were used to analyze the effect of platelets on enhancing the ability of BM-MSCs to promote cancer metastasis.

Results

Results suggested that BM-MSCs and tumor cells can promote platelet aggregation rate and the expression of P-selectin. The protein levels of α-smooth muscle actin, vimentin, and fibroblast activation protein in BM-MSCs were higher after co-incubation with platelets, and SB431542 was used to confirm the effect of TGF-β on transdifferentiation of BM-MSCs into cancer-associated fibroblasts. Medium of BM-MSCs treated with platelets enhanced the proliferation and migration ability of SGC-7901 cells. More lung metastases were found in mice which were injected with SGC-7901 cells treated with conditioned medium from BM-MSCs co-incubated with platelets.

Conclusion

Tumor cells and BM-MSCs activate platelets which can change the characteristics of BM-MSCs through secretion of TGF-β. Moreover, we found that platelets enhanced the effect of BM-MSCs on tumor metastasis, which suggested a potential target and approach for gastric cancer therapy.

miR-103/miR-195/miR-15b Regulate SALL4 and Inhibit Proliferation and Migration in Glioma

Glioma is the common highly malignant primary brain tumor. However, the molecular pathways that result in the pathogenesis of glioma remain elusive. In this study, we found that microRNA-103 (miR-103), microRNA-195 (miR-195), or microRNA-15b (miR-15b), which all have the same 5' "seed" miRNA portion and share common binding sites in the SALL4 3'-untranslated region (UTR), were downregulated in glioma tissues and cell lines. These miRNAs suppressed glioma cell proliferation, migration, and invasion, induced cell apoptosis, and decreased the level of the SALL4 protein, but not that of SALL4 mRNA, which was identified as a direct target of all three miRNAs. The caspase-3/7 activity expression in U251 cells overexpressing these miRNAs was rescued during SALL4 upregulation. An obvious inverse correlation was observed between SALL4 and miR-103 or miR-195 expression levels in clinical glioma samples. Moreover, enforced expression of SALL4 stimulated cell proliferation, migration, and invasion. In conclusion, these data suggest that miR-103, miR-195, and miR-15b post-transcriptionally downregulated the expression of SALL4 and suppressed glioma cell growth, migration, and invasion, and increased cell apoptosis. These results provide a potential therapeutic target that may downregulate SALL4 in glioma.