High cytoplasmic expression of SALL4 predicts a malignant phenotype and poor prognosis of breast invasive ductal carcinoma

Higher expression of SALL4-A isoform is correlated with worse outcomes and progression of the disease in subtype of testicular germ cell tumours

BACKGROUND

The transcription factor SALL4 is associated with embryonic pluripotency and has proposed as a novel immunohistochemistry (IHC) marker for diagnosing germ cell tumours. SALL4 comprises three isoforms, and SALL4-A being the full-length isoform. Studying its isoforms could revolutionize testicular cancer prognosis and subtype differentiation.

METHODS

The expression and clinical significance of isoform 'A' of SALL4 was evaluated in 124 testicular germ cell tumours (TGCTs) subtypes, adjacent 67 normal tissues and 22 benign tumours, using immunohistochemistry on tissue microarrays (TMA).

RESULTS

A statistically significant higher expression of nuclear and cytoplasmic SALL4-A was detected in TGCTs histological subtypes and benign tumours compared to the normal tissues. Seminoma and yolk sac tumours had the highest nuclear and cytoplasmic expression of SALL4-A. A significant correlation was detected between the higher nuclear expression of SALL4-A and increased pT stages (P = 0.026) in seminomas. Whereas in embryonal carcinomas, cytoplasmic expression of SALL4-A was associated with the tumour recurrence (P = 0.04) and invasion of the epididymis (P = 0.011).

CONCLUSIONS

SALL4-A isoform expression in the cytoplasm and nucleus of TGCTs may be associated with histological differentiation. In the seminoma subtype of TGCTs, higher expression of SALL4-A may be used as a predictive indicator of poorer outcomes and prognosis.

Expression of stem cell markers SALL4, LIN28A, and KLF4 in ameloblastoma

BACKGROUND

Ameloblastoma (AME) is a benign odontogenic tumour of epithelial origin characterised by slow but aggressive growth, infiltration, and recurrence; it is capable of reaching large dimensions and invading adjacent structures. Stem cell research has proven to be significant in the sphere of tumour biology through these cells' possible involvement in the aetiopathogenesis of this tumour.

METHODS

Immunohistochemistry was performed on AME, dentigerous cyst (DC), and dental follicle (DF) samples, and indirect immunofluorescence was performed on the AME-hTERT cell line to determine the expression of SALL4, LIN28A, and KLF4.

RESULTS

Expression of proteins related to cellular pluripotency was higher in AME cells than in DC and DF cells. The analysis revealed that the proteins in question were mainly expressed in the parenchyma of AME tissue samples and were detected in the nuclei of AME-hTERT cells.

CONCLUSIONS

Stem cells may be related to the origin and progression of AME.

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.

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.

Production and characterization of a new specific monoclonal antibody against A-isoform of SALL4: A novel emerging testicular cancer marker

SALL4 transcription factor plays an important role to maintain the pluripotent and self-renewal of embryonic stem cells. It contributes to the growth of many cancers and embryonic development. With the exception of spermatogonia, SALL4 expression is silenced in most adult tissues after birth; nevertheless, it is re-expressed in a subset of different solid malignancies. SALL4 is a new, precise biomarker for testicular germ cell cancers that was just introduced. The whole isoform of SALL4 is called SALL4-A. Regarding the lack of antibody against human SALL4 isoforms, the pattern of expression, the role of each isoform remain unknown. Furthermore, in isoform specific evaluations, we aimed, for the first time, to produce and characterize mAb against human SALL4-A. Immunization of mice were performed with a selected 33-mer synthetic peptide of SALL4-A conjugated with KLH. Hybridoma cells were screened by ELISA for positive reactivity with SALL4-A peptide. From the ascites fluid of mice that had been injected with hybridoma cells, anti-SALL4-A mAbs were isolated using a protein G column. Reactivity of the mAbs was evaluated using the peptide and SALL4-A recombinant protein by ELISA and IHC on testicular cancer tissue as positive control, and normal kidney, stomach and prostate tissues as negative control. The produced mAb could well detect SALL4-A in testicular cancer tissues using IHC, while the reactivity was negative in normal kidney, stomach and prostate tissues. Using ELISA, the mAb affinity for the peptide and SALL4-A recombinant protein was assessed, and it was shown to be reasonably high. The mAb detected SALL4-A in nucleus and cytoplasm of several cancer cells and spermatogonia in testicular cancer tissue. In addition, it could recognize SALL4-A recombinant protein. Our produced monoclonal antibody against isoform-A of human SALL4 can specifically recognize SALL4-A using either IHC or ELISA. We hope that this mAb could help researchers in isoform-specific study of human SALL4.

SALL4: An Intriguing Therapeutic Target in Cancer Treatment

Spalt-Like Transcription Factor 4 (SALL4) is a critical factor for self-renewal ability and pluripotency of stem cells. On the other hand, various reports show tight relation of SALL4 to cancer occurrence and metastasis. SALL4 exerts its effects not only by inducing gene expression but also repressing a large cluster of genes through interaction with various epigenetic modifiers. Due to high expression of SALL4 in cancer cells and its silence in almost all adult tissues, it is an ideal target for cancer therapy. However, targeting SALL4 meets various challenges. SALL4 is a transcription factor and designing appropriate drug to inhibit this intra-nucleus component is challenging. On the other hand, due to lack of our knowledge on structure of the protein and the suitable active sites, it becomes more difficult to reach the appropriate drugs against SALL4. In this review, we have focused on approaches applied yet to target this oncogene and discuss the potential of degrader systems as new therapeutics to target oncogenes.

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.

Pseudogene-mediated DNA demethylation leads to oncogene activation

Pseudogenes, noncoding homologs of protein-coding genes, once considered nonfunctional evolutionary relics, have recently been linked to patient prognoses and cancer subtypes. Despite this potential clinical importance, only a handful of >12,000 pseudogenes in humans have been characterized in cancers to date. Here, we describe a previously unrecognized role for pseudogenes as potent epigenetic regulators that can demethylate and activate oncogenes. We focused on SALL4, a known oncogene in hepatocellular carcinoma (HCC) with eight pseudogenes. Using a locus-specific demethylating technology, we identified the critical CpG region for SALL4 expression. We demonstrated that SALL4 pseudogene 5 hypomethylates this region through interaction with DNMT1, resulting in SALL4 up-regulation. Intriguingly, pseudogene 5 is significantly up-regulated in a hepatitis B virus model before SALL4 induction, and both are increased in patients with HBV-HCC. Our results suggest that pseudogene-mediated demethylation represents a novel mechanism of oncogene activation in cancer.

Role of SALL4 and Nodal in the prognosis and tamoxifen resistance of estrogen receptor-positive breast cancer

Despite the discovery of a number of different mechanisms underlying tamoxifen resistance, its molecular pathway is not completely clear. The upregulation of SALL4 and Nodal has been reported in breast cancer. Nevertheless, their role in tamoxifen resistance has not been investigated. In the present study, we compared Nodal and SALL4 expression in 72 tamoxifen sensitive (TAMS) and tamoxifen-resistant (TAMR) patients. Afterward, the correlation of expression data with clinicopathological features and survival of patients was studied. Results showed that both SALL4 and Nodal were significantly upregulated in TAMR compared to TAMS patients. Besides, there was a positive association between Nodal and SALL4 expression. Furthermore, we evaluated their correlation with the expression of Oct4, Nanog and Sox2 stemness markers. The results demonstrated that in most tissue samples there was a positive correlation between Nodal and SALL4 expression with these stemness markers. Besides, the overexpression of SALL4 and Nodal significantly correlated with the N stage. Moreover, the overexpression of SALL4 was associated with extracapsular invasion and lymphatic invasion. High level expressions of SALL4 and Nodal had a significant association with worse disease-free survival (DFS) rates. In addition, increased level of Nodal expression provides a superior predictor factor for DFS. The multivariate Cox regression analysis also revealed that for DFS, perineural invasion (PNI) was independently an unfavorable prognostic value. These findings suggest that the high expression of SALL4 and Nodal could contribute to tamoxifen resistance and worse survival rates in tamoxifen-treated ER⁺ breast cancer patients.

Comparison of immunohistochemical profiles of ovarian germ cells in dysgerminomas of a captive maned wolf and domestic dogs

We characterized the immunohistochemical expression profiles of dysgerminomas from a 16-y-old maned wolf and 13 domestic dogs using the following biomarkers: Sal-like protein 4 (SALL4), octamer-binding transcription factor 3/4 (OCT3/4), placental alkaline phosphatase (PLAP), c-kit, and vimentin. The maned wolf had nonspecific and long-standing clinical signs of lethargy, anorexia, and weight loss, and was euthanized because of poor prognosis. At autopsy, the left ovary was effaced by a 12 × 8 × 6 cm mass, comprised of anaplastic cells with a mitotic count of 20 mitoses in 10 high power fields. Dysgerminomas from 7 of 13 domestic dogs had nuclear expression of SALL4. Dysgerminomas from the maned wolf and 2 domestic dogs had both nuclear and cytoplasmic expression of SALL4. Cytoplasmic expression of PLAP and OCT3/4 was present in dysgerminomas from the maned wolf and 3 (PLAP) or 4 (OCT3/4) domestic dogs. All dysgerminomas expressed vimentin. Membranous c-kit expression was rare in the dysgerminoma from the maned wolf, and variable in dysgerminomas from 4 domestic dogs. A dysgerminoma from a domestic dog had cytoplasmic expression of c-kit. SALL4 is a useful marker to confirm germ cell origin of dysgerminoma in canids.

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.

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.

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.

Upregulation of SALL4 by EGFR activation regulates the stemness of CD44-positive lung cancer

The transcriptional factor SALL4, an important stem cell regulator, is expressed in hematopoietic stem cells and various malignancies, but its role in EGFR-mutated NSCLCs has not been studied yet. Here, we report that the expression of Sal-like protein 4 (SALL4), was significantly higher in EGFR mutated lung tumors than in non-tumor tissue. SALL4-high lung cancer patients had poorer prognosis after surgery than SALL4-low patients. The expression of SALL4 could be induced by the activation of EGFR through the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. The knockdown of SALL4 expression could suppress spheroid formation and the expression of lung cancer stem cell marker CD44. More interestingly, the knockdown of SALL4 expression could suppress the migration, invasion, and metastasis of the lung cancer cells and significantly increase the sensitivity of EGFR mutated cells to Erlotinib. These results suggest that SALL4 may be a novel potential therapeutic target for the diagnosis and treatment of lung cancer.

MicroRNA-98 acts as a tumor suppressor in hepatocellular carcinoma via targeting SALL4

MicroRNAs (miRs) are involved in the development and progression of hepatocellular carcinoma (HCC), but the regulatory mechanism of miR-98 in HCC still remains unclear. Here we found that miR-98 was significantly downregulated in HCC tissues compared to matched adjacent normal tissues (ANTs). Low miR-98 expression was associated with tumor size, metastasis, portal vein tumor embolus, and poor overall survival. Ectopic expression of miR-98 decreased the proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) of HCC cells. SALL4 was identified as a novel target of miR-98, and the protein expression of SALL4 was inhibited by miR-98 in HCC cells. Overexpression of SALL4 reversed the suppressive effects of miR-98 on the malignant phenotypes of HCC cells. Besides, SALL4, upregulated in HCC tissues compared to the matched ANTs, was inversely correlated to the miR-98 levels in HCC tissues. In addition, overexpression of miR-98 markedly suppressed the tumor growth as well as tumor-induced death in nude mice. In summary, miR-98 plays a suppressive role in the proliferation, migration, invasion and EMT of HCC cells, partly at least, via directly inhibition of SALL4. Therefore, the miR-98/SALL4 axis may become a promising therapeutic target for HCC.

SALL4 - KHDRBS3 network enhances stemness by modulating CD44 splicing in basal-like breast cancer

Understanding the mechanism by which cancer cells enhance stemness facilitates cancer therapies. Here, we revealed that a stem cell transcription factor, SALL4, functions to enhance stemness in basal-like breast cancer cells. We used shRNA-mediated knockdown and gene overexpression systems to analyze gene functions. To evaluate stemness, we performed a sphere formation assay. In SALL4 knockdown cells, the sphere formation ability was reduced, indicating that SALL4 enhances stemness. CD44 is a membrane protein and is known as a stemness factor in cancer. CD44 splicing variants are involved in cancer stemness. We discovered that SALL4 modulates CD44 alternative splicing through the upregulation of KHDRBS3, a splicing factor for CD44. We cloned the KHDRBS3-regulated CD44 splicing isoform (CD44v), which lacks exons 8 and 9. CD44v overexpression prevented a reduction in the sphere formation ability by KHDRBS3 knockdown, indicating that CD44v is positively involved in cancer stemness. In addition, CD44v enhanced anoikis resistance under the control of the SALL4 - KHDRBS3 network. Basal-like breast cancer is an aggressive subtype among breast cancers, and there is no effective therapy so far. Our findings provide molecular targets for basal-like breast cancer therapy. In the future, this study may contribute to the establishment of drugs targeting cancer stemness.

Oncogenic protein SALL4 and ZNF217 as prognostic indicators in solid cancers: a meta‑analysis of individual studies

BACKGROUND

SALL4 and ZNF217 have been widely acknowledged as pivotal effectors stimulating embryonic immortalization as well as oncogenicity. Nevertheless, their prognostic worthiness towards solid tumors remains obscure. Hence we performed this comprehensive meta-analysis aiming to unveil the survival significance of both aberrantly expressed proteins.

RESULTS

Overall we included 22 eligible entries comprising of 3093 participants. Over-expression of SALL4 and ZNF217 were negatively correlated with clinical prognosis of 3-year, 5-year, 10-year and disease-free survival in solid malignancies, irrespective of cancer types, source regions, mean-age and sex predominance. Results of sensitivity analysis additionally verified the stability of the pooled outcomes. No publication bias was observed on the basis of Egger's test and Begg's test.

METHODS

Studies were eventually included via database searching and rigorous eligibility appraisal. Data extraction and methodological assessment were implemented under a standard manner. Review Manager 5.3 and STATA 12.0 were utilized as statistical platforms following the recommendations by Cochrane Collaboration protocols.

CONCLUSIONS

Aberrant amplification of SALL4 and ZNF217 serve as unfavorable predictors of survival expectancy among cancer sufferers, revealing great potential as targeted spots in future therapeutics.

MicroRNA-98 Plays a Suppressive Role in Non-Small Cell Lung Cancer Through Inhibition of SALL4 Protein Expression

MicroRNAs (miRs) have been demonstrated to be significantly associated with the development and progression of non-small cell lung cancer (NSCLC). However, the underlying mechanism of miR-98 in mediating the malignant phenotypes of NSCLC cells remains obscure. In this study, we found that miR-98 was significantly downregulated in NSCLC tissues compared to nontumor lung tissues. Downregulation of miR-98 was significantly associated with poor differentiation and advanced clinical stage. Restoration of miR-98 expression significantly decreased the proliferation, migration, and invasion of NSCLC A549 and H1229 cells. SALL4 was identified as a target gene of miR-98, and the protein expression of SALL4 was negatively regulated by miR-98 in NSCLC A549 and H1229 cells. Overexpression of SALL4 promoted A549 and H1229 cell proliferation, migration, and invasion and reversed the suppressive effects of miR-98 on the malignant phenotypes of A549 and H1229 cells. Moreover, SALL4 was found to be significantly upregulated in NSCLC tissues compared to the nontumor lung tissues. We then observed an inverse correlation between the miR-98 and SALL4 levels in NSCLC tissues. In vivo study revealed that miR-98 overexpression suppressed NSCLC growth. In summary, we demonstrate that miR-98 acts as a tumor suppressor in NSCLC cells by inhibiting the protein expression of its target gene SALL4. Therefore, our study highlights the importance of the miR-98/SALL4 axis in NSCLC.

Knockdown of Sall4 inhibits intrahepatic cholangiocarcinoma cell migration and invasion in ICC-9810 cells

In spite of improvements in surgical technology, the resectability and curability of intrahepatic cholangiocarcinoma (ICC) are still low. Our previous study showed that the strong Sal-like protein 4 (Sall4)-positive cases had shorter overall survival compared to Sall4-negative cases, indicating an oncogenic role of Sall4 in ICC. In this study, we aimed to explore the precise mechanism of Sall4 on ICC cell invasion and metastasis. We evaluated the expression of Sall4, PTEN, and Bmi-1 in 28 cases of adjacent tissues and 175 cases of ICC tissues by using immunohistochemical staining. We found that the expression of Sall4 and Bmi-1 was significantly increased in ICC tissues compared with the adjacent tissues, while PTEN expression was reduced in ICC tissues compared with the adjacent tissues, and there was a reverse relationship between Sall4 and PTEN in ICC, whereas there was a positive correlation in Sall4 and Bmi-1 expression in ICC. In addition, overall survival analysis showed that ICC patients with low PTEN exhibited a worse prognosis than ICC patients with high PTEN, and lower Bmi-1 expression showed a better prognosis than ICC patients with high Bmi-1. By a battery of experiments in vitro, we demonstrated that Sall4 promotes ICC cell proliferation, and progression of ICC might be through PTEN/PI3K/Akt and Bmi-1/Wnt/β-catenin signaling and enhancing epithelial-mesenchymal transition process. Thus, Sall4 may be a potential target for the treatment of ICC metastasis.

Characterization of Cancer Stem Cells in Moderately Differentiated Buccal Mucosal Squamous Cell Carcinoma

Aim

To identify and characterize cancer stem cells (CSC) in moderately differentiated buccal mucosa squamous cell carcinoma (MDBMSCC).

Methods

Four micrometer-thick, formalin-fixed, paraffin-embedded MDBMSCC samples from six patients underwent 3,3-diaminobenzidine (DAB) immunohistochemical (IHC) staining for the embryonic stem cell (ESC) markers, NANOG, OCT4, SALL4, SOX2, and pSTAT3; cancer stem cell marker, CD44; squamous cell carcinoma (SCC) marker, EMA; and endothelial marker, CD34. The transcriptional activities of the genes encoding NANOG, OCT4, SOX2, SALL4, STAT3, and CD44 were studied using NanoString gene expression analysis and colorimetric in situ hybridization (CISH) for NANOG, OCT4, SOX2, SALL4, and STAT3.

Results

Diaminobenzidine and immunofluorescent (IF) IHC staining demonstrated the presence of (1) an EMA⁺/CD44⁺/SOX2⁺/SALL4⁺/OCT4⁺/pSTAT3⁺/NANOG⁺ CSC subpopulation within the tumor nests; (2) an EMA⁻/CD44⁻/CD34⁻/SOX2⁺/OCT4⁺/pSTAT3⁺/NANOG⁺ subpopulation within the stroma between the tumor nests; and (3) an EMA⁻/CD44⁻/CD34⁺/SOX2⁺/SALL4⁺/OCT4⁺/pSTAT3⁺/NANOG⁺ subpopulation on the endothelium of the microvessels within the stroma. The expression of CD44, SOX2, SALL4, OCT4, pSTAT3, and NANOG was confirmed by the presence of mRNA transcripts, using NanoString analysis and NANOG, OCT4, SOX2, SALL4, and STAT3 by CISH staining.

Conclusion

This study demonstrated a novel finding of three separate CSC subpopulations within MDBMSCC: (1) within the tumor nests expressing EMA, CD44, SOX2, SALL4, OCT4, pSTAT3, and NANOG; (2) within the stroma expressing SOX2, SALL4, OCT4, pSTAT3, and NANOG; and (3) on the endothelium of the microvessels within the stroma expressing CD34, SOX2, SALL4, OCT4, pSTAT3, and NANOG.

SALL4, the missing link between stem cells, development and cancer

There is a growing body of evidence supporting that cancer cells share many similarities with embryonic stem cells (ESCs). For example, aggressive cancers and ESCs share a common gene expression signature that includes hundreds of genes. Since ESC genes are not present in most adult tissues, they could be ideal candidate targets for cancer-specific diagnosis and treatment. This is an exciting cancer-targeting model. The major hurdle to test this model is to identify the key factors/pathway(s) within ESCs that are responsible for the cancer phenotype. SALL4 is one of few genes that can establish this link. The first publication of SALL4 is on its mutation in a human inherited disorder with multiple developmental defects. Since then, over 300 papers have been published on various aspects of this gene in stem cells, development, and cancers. This review aims to summarize our current knowledge of SALL4, including a SALL4-based approach to classify and target cancers. Many questions about this important gene still remain unanswered, specifically, on how this gene regulates cell fates at a molecular level. Understanding SALL4's molecular functions will allow development of specific targeted approaches in the future.