Sal-like protein 4 (SALL4), a stem cell biomarker in liver cancers

SALL4 in gastrointestinal tract cancers: upstream and downstream regulatory mechanisms

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

BEX1 supports the stemness of hepatoblastoma by facilitating Warburg effect in a PPARγ/PDK1 dependent manner

BACKGROUND

Hepatoblastoma (HB) is a highly aggressive paediatric malignancy that exhibits a high presence of cancer stem cells (CSCs), which related to tumour recurrence and chemotherapy resistance. Brain expressed X-linked protein 1 (BEX1) plays a pivotal role in ciliogenesis, axon regeneration and differentiation of neural stem cells. However, the role of BEX1 in metabolic and stemness programs in HB remains unclear.

METHODS

BEX1 expression in human and mouse HB was analyzed using gene expression profile data from NCBI GEO and immunohistochemical validation. Seahorse extracellular flux analyzer, ultra-high-performance liquid-chromatography mass spectrometry (LC-MS), flow cytometry, qRT-PCR, Western Blot, sphere formation assay, and diluted xenograft tumour formation assay were used to analyze metabolic and stemness features.

RESULTS

Our results indicated that overexpression of BEX1 significantly enhanced the Warburg effect in HB cells. Furthermore, glycolysis inhibition largely attenuated the effects of BEX1 on HB cell growth and self-renewal, suggesting that BEX1 promotes stemness maintenance of HB cells by regulating the Warburg effect. Mechanistically, BEX1 enhances Warburg effect through the downregulation of peroxisome proliferator-activated receptor-gamma (PPARγ). Furthermore, pyruvate dehydrogenase kinase isozyme 1 (PDK1) is required for PPARγ-induced inhibition of Warburg effect in HB. In addition, BEX1 supports the stemness of HB by enhancing Warburg effect in a PPARγ/PDK1 dependent manner.

CONCLUSIONS

HB patients with high BEX1 and PDK1 expression had a poor prognosis. BEX1 promotes the stemness maintenance of HB cells via modulating the Warburg effect, which depends on PPARγ/PDK1 axis. Pioglitazone could be used to target BEX1-mediated stemness properties in HB by upregulating PPARγ.

Fibrolamellar carcinomas-growth arrested by paracrine signals complexed with synthesized 3-O sulfated heparan sulfate oligosaccharides

Fibrolamellar carcinomas (FLCs), lethal tumors occurring in children to young adults, have genetic signatures implicating derivation from biliary tree stem cell (BTSC) subpopulations, co-hepato/pancreatic stem cells, involved in hepatic and pancreatic regeneration. FLCs and BTSCs express pluripotency genes, endodermal transcription factors, and stem cell surface, cytoplasmic and proliferation biomarkers. The FLC-PDX model, FLC-TD-2010, is driven ex vivo to express pancreatic acinar traits, hypothesized responsible for this model's propensity for enzymatic degradation of cultures. A stable ex vivo model of FLC-TD-2010 was achieved using organoids in serum-free Kubota's Medium (KM) supplemented with 0.1% hyaluronans (KM/HA). Heparins (10 ng/ml) caused slow expansion of organoids with doubling times of ∼7-9 days. Spheroids, organoids depleted of mesenchymal cells, survived indefinitely in KM/HA in a state of growth arrest for more than 2 months. Expansion was restored with FLCs co-cultured with mesenchymal cell precursors in a ratio of 3:7, implicating paracrine signaling. Signals identified included FGFs, VEGFs, EGFs, Wnts, and others, produced by associated stellate and endothelial cell precursors. Fifty-three, unique heparan sulfate (HS) oligosaccharides were synthesized, assessed for formation of high affinity complexes with paracrine signals, and each complex screened for biological activity(ies) on organoids. Ten distinct HS-oligosaccharides, all 10-12 mers or larger, and in specific paracrine signal complexes elicited particular biological responses. Of note, complexes of paracrine signals and 3-O sulfated HS-oligosaccharides elicited slowed growth, and with Wnt3a, elicited growth arrest of organoids for months. If future efforts are used to prepare HS-oligosaccharides resistant to breakdown in vivo, then [paracrine signal-HS-oligosaccharide] complexes are potential therapeutic agents for clinical treatments of FLCs, an exciting prospect for a deadly disease.

Dyrk2 gene transfer suppresses hepatocarcinogenesis by promoting the degradation of Myc and Hras

Background & Aims

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and has a poor prognosis. However, the molecular mechanisms underlying hepatocarcinogenesis and progression remain unknown. In vitro gain- and loss-of-function analyses in cell lines and xenografts revealed that dual-specificity tyrosine-regulated kinase 2 (DYRK2) influences tumour growth in HCC.

Methods

To investigate the role of Dyrk2 during hepatocarcinogenesis, we developed liver-specific Dyrk2 conditional knockout mice and an in vivo gene delivery system with a hydrodynamic tail vein injection and the Sleeping Beauty transposon. The antitumour effects of Dyrk2 gene transfer were investigated in a murine autologous carcinogenesis model.

Results

Dyrk2 expression was reduced in tumours, and that its downregulation was induced before hepatocarcinogenesis. Dyrk2 gene transfer significantly suppressed carcinogenesis. It also suppresses Myc-induced de-differentiation and metabolic reprogramming, which favours proliferative, and malignant potential by altering gene profiles. Dyrk2 overexpression caused Myc and Hras degradation at the protein level rather than at the mRNA level, and this degradation mechanism was regulated by the proteasome. Immunohistochemical analyses revealed a negative correlation between DYRK2 expression and MYC and longer survival in patients with HCC with high-DYRK2 and low-MYC expressions.

Conclusions

Dyrk2 protects the liver from carcinogenesis by promoting Myc and Hras degradation. Our findings would pave the way for a novel therapeutic approach using DYRK2 gene transfer.

Impact and Implications

Hepatocellular carcinoma (HCC) is one of the most common cancers, with a poor prognosis. Hence, identifying molecules that can become promising targets for therapies is essential to improve mortality. No studies have clarified the association between DYRK2 and carcinogenesis, although DYRK2 is involved in tumour growth in various cancer cells. This is the first study to show that Dyrk2 expression decreases during hepatocarcinogenesis and that Dyrk2 gene transfer is an attractive approach with tumour suppressive activity against HCC by suppressing Myc-mediated de-differentiation and metabolic reprogramming that favours proliferative and malignant potential via Myc and Hras degradation.

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.

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

Background

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

Methods

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

Results

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

Conclusions

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

All-Trans-Retinoic Acid Plus Oxaliplatin/Fluorouracil/Leucovorin for Advanced Hepatocellular Carcinoma with Pulmonary Metastasis: A Multicenter Retrospective Study

Aim

To study the impact of All-trans-retinoic acid (ATRA) plus FOLFOX4 compared to FOLFOX4 alone in patients with advanced hepatocellular carcinoma (HCC) with pulmonary metastasis.

Methods

The data of patients with advanced HCC who underwent systemic chemotherapy using FOLFOX4 or ATRA plus FOLFOX4 at the Eastern Hepatobiliary Surgery Hospital, First Hospital of Jilin University, Zhejiang Sian International Hospital and Fujian Cancer Hospital were retrospectively analyzed. The survival outcomes in the 2 groups were compared.

Results

From May 2014 to July 2020, 66 patients were suitable to enter into this study. The median survival (14.0 vs 8.0 months, p=0.012), and the median time to progression in the ATRA plus FOLFOX4 group were both significantly longer than those in the FOLFOX4 group (8.7 vs 3.2 months, p=0.002). The 6 month-, 1 year- and 2 year- overall survival rates were also significantly better in the ATRA plus FOLFOX4 group (100.0%, 64.7% and 20.5%; respectively) than the FOLFOX4 group (59.4%, 21.9%, and 12.5%, respectively; p<0.001). Leukocytopenia, fatigue, anorexia, nausea, were the most common acute toxicities, but these were mostly NCI CTCAE Grade 1 or 2. There was no significant difference in adverse events between the two groups.

Conclusion

ATRA plus FOLFOX4 significantly improved the survival outcomes in patients with advanced HCC with pulmonary metastasis.

Hepatoid carcinoma and related entities of the extrahepatic bile duct: A clinicopathological study of four cases

Hepatoid carcinoma or related entities (HPC/RTs) are extremely rare, especially in the extrahepatic bile duct (EHBD). Only a few case reports have been published. We analyzed the clinicopathological features of HPCs/RTs in EHBD. HPC/RT of extrahepatic cholangiocarcinoma (eCCA) cases were selected based on the histological characteristics and immunohistochemical detection of spalt-like transcription factor 4 (SALL4) and/or alpha-fetoprotein (AFP). Four HPC/RT cases arose in the distal but not in the perihilar EHBD. The four patients with HPC/RT included one female and three males with a median age of 77 years. There are various macroscopic types of HPC/RT. The predominant histological features were two solid-type carcinomas that mimicked hepatocellular carcinoma and two well-differentiated tubular adenocarcinomas. Immunohistochemically, SALL4 and glypican-3 were expressed in all cases, and AFP was expressed in one case. Cancer cell phenotypes included intestinal, pancreatobiliary, and mixed pancreatobiliary and intestinal types. Focal neuroendocrine differentiation and severe perineural and lymphovascular invasions were also observed. HPC/RT recurred in two patients within 2 years, and one patient died 13 months postoperatively. It is suggested that the HPC/RT of EHBD shares common characteristics with HPC/RT arising in various organs, and has some unique characteristics. HPC/RT of EHBD might be more aggressive than conventional eCCA.

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.

Cancer stem cells in hepatocellular carcinoma - from origin to clinical implications

Hepatocellular carcinoma (HCC) is an aggressive disease with a poor clinical outcome. The cancer stem cell (CSC) model states that tumour growth is powered by a subset of tumour stem cells within cancers. This model explains several clinical observations in HCC (as well as in other cancers), including the almost inevitable recurrence of tumours after initial successful chemotherapy and/or radiotherapy, as well as the phenomena of tumour dormancy and treatment resistance. The past two decades have seen a marked increase in research on the identification and characterization of liver CSCs, which has encouraged the design of novel diagnostic and treatment strategies for HCC. These studies revealed novel aspects of liver CSCs, including their heterogeneity and unique immunobiology, which are suggestive of opportunities for new research directions and potential therapies. In this Review, we summarize the present knowledge of liver CSC markers and the regulators of stemness in HCC. We also comprehensively describe developments in the liver CSC field with emphasis on experiments utilizing single-cell transcriptomics to understand liver CSC heterogeneity, lineage-tracing and cell-ablation studies of liver CSCs, and the influence of the CSC niche and tumour microenvironment on liver cancer stemness, including interactions between CSCs and the immune system. We also discuss the potential application of liver CSC-based therapies for treatment of HCC.

SALL Proteins; Common and Antagonistic Roles in Cancer

Simple Summary

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

Abstract

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

Pluripotency Stemness and Cancer: More Questions than Answers

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

Enhanced penetrative siRNA delivery by a nanodiamond drug delivery platform against hepatocellular carcinoma 3D models

Small interfering RNA (siRNA) can cause specific gene silencing and is considered promising for treating a variety of cancers, including hepatocellular carcinoma (HCC). However, siRNA has many undesirable physicochemical properties that limit its application. Additionally, conventional methods for delivering siRNA are limited in their ability to penetrate solid tumors. In this study, nanodiamonds (NDs) were evaluated as a nanoparticle drug delivery platform for improved siRNA delivery into tumor cells. Our results demonstrated that ND-siRNA complexes could effectively be formed through electrostatic interactions. The ND-siRNA complexes allowed for efficient cellular uptake and endosomal escape that protects siRNA from degradation. Moreover, ND delivery of siRNA was more effective at penetrating tumor spheroids compared to liposomal formulations. This enhanced penetration capacity makes NDs ideal vehicles to deliver siRNA against solid tumor masses as efficient gene knockdown and decreased tumor cell proliferation were observed in tumor spheroids. Evaluation of ND-siRNA complexes within the context of a 3D cancer disease model demonstrates the potential of NDs as a promising gene delivery platform against solid tumors, such as HCC.

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.

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.

Zinc Finger Protein SALL4 Functions through an AT-Rich Motif to Regulate Gene Expression

The zinc finger transcription factor SALL4 is highly expressed in embryonic stem cells, downregulated in most adult tissues, but reactivated in many aggressive cancers. This unique expression pattern makes SALL4 an attractive therapeutic target. However, whether SALL4 binds DNA directly to regulate gene expression is unclear, and many of its targets in cancer cells remain elusive. Here, through an unbiased screen of protein binding microarray (PBM) and cleavage under targets and release using nuclease (CUT&RUN) experiments, we identify and validate the DNA binding domain of SALL4 and its consensus binding sequence. Combined with RNA sequencing (RNA-seq) analyses after SALL4 knockdown, we discover hundreds of new SALL4 target genes that it directly regulates in aggressive liver cancer cells, including genes encoding a family of histone 3 lysine 9-specific demethylases (KDMs). Taken together, these results elucidate the mechanism of SALL4 DNA binding and reveal pathways and molecules to target in SALL4-dependent tumors.

In this paper, Kong et al. elucidate the DNA binding mechanisms of the transcription factor SALL4 and an epigenetic pathway that it regulates. Due to its important role in driving aggressive cancers, better understanding of SALL4 function will lead to strategies to target this protein in cancer.

A Comprehensive Prognostic and Immunological Analysis of a New Three-Gene Signature in Hepatocellular Carcinoma

There are few reports on the role of genes associated with the mRNA expression-based stemness index (mRNAsi) in the prognosis and immune regulation of hepatocellular carcinoma (HCC). This study is aimed at analyzing the expression profile and prognostic significance of a new mRNAsi-based three-gene signature in HCC. This three-gene signature was identified by analyzing mRNAsi data from the Cancer Genome Atlas (TCGA) HCC dataset. The prognostic value of the risk score based on the three-gene signature was evaluated by Cox regression and Kaplan-Meier analysis and then verified in the International Cancer Genome Consortium (ICGC) database. Meanwhile, the correlations between the risk score and immune cell infiltration patterns, microsatellite instability (MSI), tumor mutation burden (TMB), immune checkpoint molecules, hypoxia-related genes, immunotherapy response, and compounds targeting the gene signature were explored, respectively. The results showed that compared with normal liver tissues, the mRNAsi score of HCC tissues was significantly increased. PTDSS2, MRPL9, and SOCS were the genes most related to mRNAsi in HCC tissues. Survival analysis results suggested the risk score based on the three-gene signature was an independent predictor of the prognosis for patients with HCC. The nomogram combining the risk score and pathological stage showed a good predictive ability for the overall survival of patients with HCC patients. Meanwhile, the risk score was significantly related to immune cell infiltration patterns, MSI, TMB, several immune checkpoint molecules, and hypoxia-related genes. In addition, the risk score was associated with the immunotherapy response, and fifteen potential therapeutic drugs targeting the three-gene signature were identified. Therefore, we propose to use this three-gene signature including PTDSS2, MRPL9, and SOCS as a potential prognostic biomarker for HCC.

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.

Integrating Genomics Into Clinical Practice in Hepatocellular Carcinoma: The Challenges Ahead

The incidence and mortality related to hepatocellular carcinoma (HCC) continue to increase in the United States, with most patients presenting at advanced stages where curative therapy and long-term survival is unlikely. Fortunately, significant progress has been made in identifying the landscape of HCC mutations due to advances in whole genome expression profiling. Drug development has also evolved in recent years with multiple first- and second-line systemic chemotherapy agents approved for HCC for the first time in over a decade. However, despite advances in molecular profiling, mutations that were identified at the highest frequency were not amenable to drug development, and curative therapy for advanced HCC remains elusive. This review focuses on the current understanding of HCC genomics and the limitations of translating the current HCC molecular profiling into clinical practice and examines the effectiveness and benefits of approved systemic therapies for advanced HCC.

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.

Embryonal Rhabdomyosarcoma of the Ovary and Fallopian Tube: Rare Neoplasms Associated With Germline and Somatic DICER1 Mutations

DICER1 mutations (somatic or germline) are associated with a variety of uncommon neoplasms including cervical and genitourinary embryonal rhabdomyosarcoma (ERMS). We report a primary ovarian and 2 primary fallopian tube ERMS occurring in 60-, 13-, and 14-year-olds, respectively. The 3 neoplasms exhibited a similar morphologic appearance being polypoid and containing edematous hypocellular areas and hypercellular foci composed of small cells with scant cytoplasm exhibiting rhabdomyoblastic differentiation (desmin, myogenin, myoD1 positive). There was cellular cartilage in all cases and extensive foci of anaplasia, eosinophilic globules, and bone/osteoid in 1 case each. All 3 neoplasms exhibited DICER1 mutations; in 1 of the tubal cases, the patient had a germline mutation and in the other 2 cases, the DICER1 mutations were somatic. Accompanying DICER1 "second hits" were identified in all cases. In 2 of the neoplasms, SALL4-positive glandular structures were present which we speculate may represent an unusual primitive "metaplastic" phenomenon. Our study adds to the literature on ERMS at unusual sites associated with DICER1 mutations. ERMS arising at such sites, especially when they contain cartilage or bone/osteoid, are especially likely to be associated with DICER1 mutations. Pathologists should be aware of this as these may be the sentinel neoplasms in patients with DICER1 syndrome and confirming a germline mutation can facilitate the screening of the individual and affected family members for other neoplasms which occur in this syndrome.

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.

Mechanisms of cancer stem cell therapy

Cancer stem cells (CSCs) are responsible for carcinogenesis and tumorigenesis and are involved in drug and radiation resistance, metastasis, tumor relapse and initiation. Remarkably, they have other abilities such as inheritance of self-renewal and de-differentiation. Hence, targeting CSCs is considered a potential anti-cancer therapeutic strategy. Recent advances in the identification of biomarkers to recognize CSCs and the development of new techniques to evaluate tumorigenic and carcinogenic roles of CSCs are instrumental to this approach. Elucidation of signaling pathways that regulate CSCs colony progression and drug resistance are critical in establishing effective targeted therapies. CSCs play a central key role in immunomodulation, immune evasion and effector immunity, which alters immune system balancing. These include mTOR, SHH, NOTCH and Wnt/β-catering in cancer progression. In this review article, we discuss the importance of these CSCs pathways in cancer therapy.

CK19-positive Hepatocellular Carcinoma is a Characteristic Subtype

The heterogeneity of hepatocellular carcinoma (HCC) commonly leads to therapeutic failure of HCC. Cytokeratin 19 (CK19) is well acknowledged as a biliary/progenitor cell marker and a marker of tumor stem cell. CK19-positive HCCs demonstrate aggressive behaviors and poor outcomes which including worse overall survival and early tumor recurrence after hepatectomy and liver transplantation. CK19-positive HCCs are resistant to chemotherapies as well as local treatment. This subset of HCC is thought to derive from liver progenitor cells and can be induced by extracellular stimulation such as hypoxia. Besides being a stemness marker, CK19 plays an important role in promoting malignant property of HCC. The regulatory network associated with CK19 expression has been summarized that extracellular stimulations which transmit into cytoplasm through signal transduction pathways (TGF-β, MAKP/JNK and MEK-ERK1/2), further induce important nuclear transcriptional factors (SALL4, AP1, SP1) to activate CK19 promoter. Novel noncoding RNAs are also involved in the regulation of CK19 expression. TGFβR1 becomes a therapeutic target for CK19-positive HCC. In conclusion, CK19 can be a potential biomarker for predicting poor prognosis after surgical and adjuvant therapies. CK19-pisitive HCCs exhibit distinctive molecular profiling, should be diagnosed and treated as a separate subtype of HCCs.

Telomerase reverse transcriptase (TERT) promoter mutation correlated with intratumoral heterogeneity in hepatocellular carcinoma

Telomerase reverse transcriptase (TERT) promoter mutations are frequently observed in hepatocellular carcinoma (HCC); however, the impact of TERT promoter mutations (TPMs) on clinical features and morphological patterns in HCC remains unresolved. Using DNA extracted from 97 HCCs, correlations between TPM status and both the clinical features of HCC and the immunohistochemically-based subgroups were evaluated. Morphological tumor patterns were semi-quantitatively analyzed using hematoxylin and eosin-stained slides of the whole tumor cross-sectional area. The percentages of tumor area occupied by early, well, moderate and poor histological patterns were calculated as a homogeneity index. TPMs were observed in 53 of 97 (55%) HCCs and were significantly associated with older age (P = 0.018) and HCV-related background (P = 0.048). The biliary/stem cell marker-positive subgroup was less likely to have TPMs (29%) compared to the Wnt/β-catenin signaling marker-positive subgroup (60%). In contrast to TPM-negative HCCs, TPM-positive HCCs clearly exhibited intratumoral morphological heterogeneity (0.800 ± 0.117 vs 0.927 ± 0.096, P < 0.0001), characterized by two or more heterogeneous histological patterns (P < 0.0001) and had more well or early differentiated histological patterns (P = 0.024). Our findings showed that intratumoral heterogeneity was strongly related to TPM-positive HCCs, which established novel roles of TPMs, and may improve our understanding particularly about HCC development and diagnosis.

Cancer Stem Cell Functions in Hepatocellular Carcinoma and Comprehensive Therapeutic Strategies

Hepatocellular carcinoma (HCC) is a significant cause of cancer-related mortality owing to resistance to traditional treatments and tumor recurrence after therapy, which leads to poor therapeutic outcomes. Cancer stem cells (CSC) are a small subset of tumor cells with the capability to influence self-renewal, differentiation, and tumorigenesis. A number of surface markers for liver cancer stem cell (LCSC) subpopulations (EpCAM, CD133, CD44, CD13, CD90, OV-6, CD47, and side populations) in HCC have been identified. LCSCs play critical roles in regulating HCC stemness, self-renewal, tumorigenicity, metastasis, recurrence, and therapeutic resistance via genetic mutations, epigenetic disruption, signaling pathway dysregulation, or alterations microenvironment. Accumulating studies have shown that biomarkers for LCSCs contribute to diagnosis and prognosis prediction of HCC, supporting their utility in clinical management and development of therapeutic strategies. Preclinical and clinical analyses of therapeutic approaches for HCC using small molecule inhibitors, oncolytic measles viruses, and anti-surface marker antibodies have demonstrated selective, efficient, and safe targeting of LCSC populations. The current review focuses on recent reports on the influence of LCSCs on HCC stemness, tumorigenesis, and multiple drug resistance (MDR), along with LCSC-targeted therapeutic strategies for HCC.

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.

Mitochondrial DNA alterations may influence the cisplatin responsiveness of oral squamous cell carcinoma

Cisplatin is the first-line chemotherapeutic agent for the treatment of oral squamous cell carcinoma (OSCC). However, the intrinsic or acquired resistance against cisplatin remains a major obstacle to treatment efficacy in OSCC. Recently, mitochondrial DNA (mtDNA) alterations have been reported in a variety of cancers. However, the role of mtDNA alterations in OSCC has not been comprehensively studied. In this study, we evaluated the correlation between mtDNA alterations (mtDNA content, point mutations, large-scale deletions, and methylation status) and cisplatin sensitivity using two OSCC cell lines, namely SAS and H103, and stem cell-like tumour spheres derived from SAS. By microarray analysis, we found that the tumour spheres profited from aberrant lipid and glucose metabolism and became resistant to cisplatin. By qPCR analysis, we found that the cells with less mtDNA were less responsive to cisplatin (H103 and the tumour spheres). Based on the findings, we theorised that the metabolic changes in the tumour spheres probably resulted in mtDNA depletion, as the cells suppressed mitochondrial respiration and switched to an alternative mode of energy production, i.e. glycolysis. Then, to ascertain the origin of the variation in mtDNA content, we used MinION, a nanopore sequencer, to sequence the mitochondrial genomes of H103, SAS, and the tumour spheres. We found that the lower cisplatin sensitivity of H103 could have been caused by a constellation of genetic and epigenetic changes in its mitochondrial genome. Future work may look into how changes in mtDNA translate into an impact on cell function and therefore cisplatin response.

miR-296-5p suppresses stem cell potency of hepatocellular carcinoma cells via regulating Brg1/Sall4 axis

Epithelial-mesenchymal transition (EMT), a pivotal event during cancer progression such as relapse and metastasis, is positively correlated with the stemness potency of tumor cells. Our previous study showed that miR-296-5p attenuated EMT program of hepatocellular carcinoma cells (HCC) through NRG1/ERBB2/ERBB3 signaling. In the present study, we uncovered that miR-296-5p was able to inhibit the stemness potency of HCC by decreasing the number and size of tumorspheres, downregulating the expression of CSC biomarkers and hampering the ability of tumorigenesis in NOD/SCID mice. Brahma-related gene-1 (Brg1), as the target protein of miR-296-5p detected by bioinformatics methods, activates a series of downstream cascades through directly binding to Sall4 promoter and enhancing Sall4 transcription. Importantly, the higher expressions of Brg1 and Sall4 in tumor tissues of HCC patients suggest poorer prognoses after surgical extraction. In conclusion, miR-296-5p exerts an inhibitory effect on stemness potency of HCC cells via Brg1/Sall4 axis.

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.

Lipoprotein-Like Nanoparticle Carrying Small Interfering RNA Against Spalt-Like Transcription Factor 4 Effectively Targets Hepatocellular Carcinoma Cells and Decreases Tumor Burden

Patients with advanced hepatocellular carcinoma (HCC) are often unable to tolerate chemotherapy due to liver dysfunction in the setting of cirrhosis. We investigate high-density lipoprotein (HDL)-mimicking peptide phospholipid scaffold (HPPS), which are nanoparticles that capitalize on normal lipoprotein metabolism and transport, as a solution for directed delivery of small interfering RNA (siRNA) cargo into HCC cells. Spalt-like transcription factor 4 (SALL4), a fetal oncoprotein expressed in aggressive HCCs, is specifically targeted as a case study to evaluate the efficacy of HPPS carrying siRNA cargo. HPPS containing different formulations of siRNA therapy against SALL4 were generated specifically for HCC cells. These were investigated both in vitro and in vivo using fluorescence imaging. HPPS-SALL4 effectively bound to scavenger receptor, class B type 1 (SR-BI) and delivered the siRNA cargo into HCC cells, as seen in vitro. HPPS-SALL4 effectively inhibited HCC tumor growth (P < 0.05) and induced a 3-fold increase in apoptosis of the cancer cells in vivo compared to HPPS-scramble. Additionally, there was no immunogenicity associated with HPPS-SALL4 as measured by cytokine production. Conclusion: We have developed unique HDL-like nanoparticles that directly deliver RNA interference (RNAi) therapy against SALL4 into the cytosol of HCC cells, effectively inhibiting HCC tumor growth without any systemic immunogenicity. This therapeutic modality avoids the need for hepatic metabolism in this cancer, which develops in the setting of cirrhosis and liver dysfunction. These natural lipoprotein-like nanoparticles with RNAi therapy are a promising therapeutic strategy for HCC.

Activation of extracellular signal-regulated kinase is associated with hepatocellular carcinoma with aggressive phenotypes

AIM

Sorafenib inhibits multiple kinase signaling pathways, including the rat sarcoma virus (Ras)/rapidly accelerated fibrosarcoma (Raf)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway, and is a promising therapy for hepatocellular carcinoma (HCC). However, the role of ERK activation in HCC remains unclear. This study was designed to investigate the potential link between ERK activation and aggressive HCC phenotypes.

METHODS

We evaluated nuclear ERK expression by immunohistochemistry in 154 resected HCC nodules from 136 patients. We then investigated the associations of ERK expression with the clinicopathological characteristics of HCC, c-MET expression, and the molecular subclass biomarkers Ki-67, keratin 19 (KRT19, CK19, or K19), and sal-like protein 4. Multivariate Cox regression analysis was carried out to determine independent prognostic factors for overall survival and recurrence-free survival. The effects of ERK activation by hepatocyte growth factor (HGF) on eight HCC cell lines were further examined.

RESULTS

High-level nuclear expression of ERK was observed in 20 (13%) of 154 nodules and was significantly associated with higher serum alpha-fetoprotein levels (P = 0.034), poorer differentiation (P = 0.003), a higher Ki-67 index (P < 0.001), high-level expression of c-MET (P = 0.008), KRT19 (P = 0.002), or sal-like protein 4 (P < 0.001), and shorter overall survival (multivariate hazard ratio 3.448; P = 0.028) and recurrence-free survival (multivariate hazard ratio 2.755; P = 0.004). HCC cells treated with hepatocyte growth factor showed enhanced cell proliferation together with ERK activation and upregulated KRT19 expression, both of which were inhibited by sorafenib.

CONCLUSIONS

High-level ERK activation is associated with a KRT19-positive highly proliferative subtype of HCC with a dismal prognosis. These findings support the key role of the hepatocyte growth factor/c-MET/ERK axis in HCC progression.

The Roles Of Angiogenesis And Cancer Stem Cells In Sorafenib Drug Resistance In Hepatocellular Carcinoma

Background

An increasing number of studies support cancer stem cells as the reason for chemoresistance to sorafenib therapy in hepatocellular carcinoma (HCC), but the mechanism is still unclear. In this study, the mechanism of sorafenib resistance in cancer stem cells was examined by in vitro experiments and xenograft mouse model.

Methods

The expression of cancer stem cell markers in the Chang liver cell line and PLC/PRF/5 and HepG2 hepatoma cell lines were compared by immunoblot assay before and after sorafenib treatment in vitro. As a xenograft mouse model, subcutaneous injection of hepatoma cells followed by sorafenib therapy was performed in NU/NU mice. The effects of sorafenib therapy on tumor growth and cancer stem cell markers were studied. Angiogenesis associated with cancer stem cells was studied by immunoblot and immunohistochemistry assay.

Results

The expression of cancer stem cell markers was higher in PLC/PRF/5 and HepG2 cells than Chang liver cells, indicating that these hepatoma cells had more stemness-related characteristics. The cancer stem cell markers were upregulated in the hepatoma cell lines following sorafenib treatment in vitro. In the xenograft model, tumors from PLC/PRF/5 and HepG2 cells with high E-cadherin expression were more resistance to sorafenib therapy. However, the expression of cancer stem cell markers was not significantly different after sorafenib therapy in these tumors. Furthermore, we found that sorafenib therapy induced angiogenesis within tumors from high E-cadherin expressing hepatoma cells.

Conclusion

The mechanism of chemoresistance in sorafenib therapy in HCC may be the tumor angiogenesis associated with high E-cadherin expression in cancer stem cells.

Inflammatory Micro-environment Contributes to Stemness Properties and Metastatic Potential of HCC via the NF-κB/miR-497/SALL4 Axis

Increasing evidence has demonstrated the essential role of inflammatory micro-environment in tumorigenesis and tumor progression. Some cancer cells in tumor maintain typical stemness properties and, with the capacity of self-renewal, are thought to be crucial for the initiation and maintenance of tumors as well as their metastasis. Although both inflammatory micro-environment and stemness properties played crucial roles in tumor initiation and development, currently it is still unclear whether and how the inflammatory micro-environment promotes cancer stemness properties. Here, we show the first evidence that the inflammatory micro-environment promotes the stemness properties and metastatic potential of hepatocellular carcinoma (HCC) via the NF-κB/miR-497/SALL4 axis. We discover that miR-497 directly targets SALL4, negatively regulates its expression, and further inhibits the self-renewal and metastasis of HCC; more importantly, inflammatory factor TNF-α inhibits the expression of miR-497 via NF-kB-mediated negative transcriptional regulation and simultaneously upregulates the expression of SALL4 and promotes the self-renewal and metastasis phenotypes of HCC cells. Moreover, lower expression of miR-497 is significantly associated with poor prognosis in HCC patients. Taken together, our findings not only revealed a novel signaling pathway (NF-κB/miR-497/SALL4 axis) to connect inflammation with stemness properties, and clarified the molecular mechanisms underlying the inflammation-mediated self-renewal and metastasis phenotypes, but also provided novel molecular targets for developing new anticancer strategies.

NAP1L1 is a prognostic biomarker and contribute to doxorubicin chemotherapy resistance in human hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most fatal cancers, and its molecular basis needs to be delineated to identify biomarkers for its potential treatment. The purpose of this study was to identify a novel gene, nucleosome assembly proteins 1-like 1 protein (NAP1L1), associated with aggressive phenotypes of HCC.

Methods

Immunohistochemical staining was used to detect NAP1L1 protein expression in HCC tissues. The prognostic value of NAP1L1 expression was determined using Kaplan–Meier analysis and the Cox proportional hazards model. CCK-8 and apoptosis assays were used to detect the chemosensitivity in vitro. Xenograft tumor models were used to evaluate tumor cell proliferation and chemosensitivity in vivo.

Results

NAP1L1 expression was significantly upregulated in tumor tissues as compared to adjacent non-tumor tissues. High NAP1L1 expression in HCC tissues was associated with aggressive clinicopathologic features, such as serum AFP levels, tumor size and tumor number. Patients with high NAP1L1 expression had poor overall survival in our cohort and in the extra-validation cohort analyzed by TCGA microarray dataset and was further identified as an independent prognostic factor in HCC patients treated with radical resection. Both in vitro and in vivo assays showed that NAP1L1 promoted HCC cell proliferation and contribute to chemotherapy resistance. Further analyses found that some certain stemness associated genes were decreased concurrently with NAP1L1 down-regulation in HCC cell lines.

Conclusions

Our findings support that NAP1L1 is a prognostic biomarker and may contribute to chemotherapy resistance in human hepatocellular carcinoma.

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.

Role of Cancer Stem Cells in Cholangiocarcinoma and Therapeutic Implications

Cholangiocarcinoma (CCA) is the second most common type of liver cancer, and is highly aggressive with very poor prognosis. CCA is classified into intrahepatic cholangiocarcinoma (iCCA) and extra-hepatic cholangiocarcinoma (eCCA), which is further stratified into perihilar (pCCA) and distal (dCCA). Cancer stem cells (CSCs) are a subpopulation of cancer cells capable of tumor initiation and malignant growth, and are also responsible for chemoresistance. Thus, CSCs play an important role in CCA carcinogenesis. Surface markers such as CD133, CD24, CD44, EpCAM, Sox2, CD49f, and CD117 are important for identifying and isolating CCA CSCs. CSCs are present in the tumor microenvironment (TME), termed ‘CSC niche’, where cellular components and soluble factors interact to promote tumor initiation. Epithelial-to-mesenchymal transition (EMT) is another important mechanism underlying carcinogenesis, involved in the invasiveness, metastasis and chemoresistance of cancer. It has been demonstrated that EMT plays a critical role in generating CSCs. Therapies targeting the surface markers and signaling pathways of CCA CSCs, proteins involved in TME, and immune checkpoint proteins are currently under investigation. Therefore, this review focuses on recent studies on the roles of CSCs in CCA; the possible therapeutic strategies targeting CSCs of CCA are also discussed.

Forced expression of DYRK2 exerts anti-tumor effects via apoptotic induction in liver cancer

Liver cancer is highly aggressive and globally exhibits a poor prognosis. Therefore, the identification of novel molecules that can become targets for future therapies is urgently required. We have reported that dual-specificity tyrosine-regulated kinase 2 (DYRK2) functions as a tumor suppressor by regulating cell survival, differentiation, proliferation and apoptosis. However, the research into its clinical application as a molecular target has remained to be explored. Here we showed that DYRK2 knockdown enhanced tumor growth of liver cancer cells. Conversely and more importantly, adenovirus-mediated overexpression of DYRK2 resulted in inhibition of cell proliferation and tumor growth, and induction of apoptosis both in vitro and in vivo. Furthermore, we found that liver cancer patients with low DYRK2 expression had a significantly shorter overall survival. Given the findings that DYRK2 regulates proliferation and apoptosis of cancer cells, DYRK2 expression could be a promising predictive marker of the prognosis in liver cancer. Stabilized or forced expression of DYRK2 may become thus a potential target for novel gene therapy against liver cancer.

Diverse perspectives to address for the future treatment of heterogeneous hepatocellular carcinoma

Hepatocellular carcinomas (HCCs), which often arise from chronic liver damage, have poor conditional 5-year survival and are recognized as heterogeneous tumors. Considering the heterogeneity of HCCs, diverse perspectives need to be addressed for treating such tumors, besides the findings of conventional imaging modalities and tumor markers. Data from the latest technologies, such as liquid biopsy, and the detection of the presence of cancer cells with stem/progenitor cell markers, gene mutations and diverse pathways, crosstalk with immune cells and cancer-associated fibroblasts, and mechanisms of epithelial–mesenchymal transition provide diverse lines of information. Integration of these data with clinical data might be necessary to develop effective therapies for precision medicine. Here, we review several aspects of dealing with the complexity of heterogeneous HCCs.

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.

The Role of Gene Therapy in Premature Ovarian Insufficiency Management

Premature ovarian insufficiency (POI) is a highly prevalent disorder, characterized by the development of menopause before the age of 40. Most cases are idiopathic; however, in some women the cause of this condition (e.g.; anticancer treatment, genetic disorders, and enzymatic defects) could be identified. Although hormone-replacement therapy, the principal therapeutic approach for POI, helps alleviate the related symptoms, this does not effectively solve the issue of fertility. Assisted reproductive techniques also lack efficacy in these women. Thus, an effective approach to manage patients with POI is highly warranted. Several mechanisms associated with POI have been identified, including the lack of function of the follicle-stimulating hormone (FSH) receptor, alterations in apoptosis control, mutations in Sal-like 4 genes, and thymulin or basonuclin-1 deficiency. The above mentioned may be good targets for gene therapy in order to correct defects leading to POI. The goal of this review is to summarize current experiences on POI studies that employed gene therapy, and to discuss possible future directions in this field.

SALL4 activates TGF-β/SMAD signaling pathway to induce EMT and promote gastric cancer metastasis

Background

Increasing evidence suggests that SALL4 plays oncogenic roles in cancer development and progression. We have previously shown that SALL4 is highly expressed in gastric cancer, and its upregulation is associated with lymph node metastasis and poor prognosis. The role of SALL4 in gastric cancer metastasis and the underlying mechanism remain unclear.

Materials and methods

The biological roles of SALL4 in gastric cancer cell mobility, migration, and invasion were investigated by wound healing, transwell migration assay, and Matrigel invasion assay. The effects of SALL4 on epithelial-mesenchymal transition (EMT) in gastric cancer cells were examined by quantitative real-time PCR and Western blot. The downstream target genes of SALL4 were identified by microarray. The regulation of TGF-β1 by SALL4 in gastric cancer cells was analyzed by luciferase reporter assay and chromatin immunoprecipitation assay.

Results

SALL4 knockdown inhibited, while SALL4 overexpression promoted the motility, migration, and invasion abilities of gastric cancer cells in vitro. SALL4 knockdown also suppressed the peritoneal metastasis of gastric cancer cells in nude mice. SALL4 knockdown suppressed, while SALL4 overexpression induced the activation of TGF-β/SMAD signaling pathway and triggered EMT in gastric cancer cells. TGF-β1 was identified as a direct target gene of SALL4. The results of chromatin immunoprecipitation study and luciferase reporter assay further confirmed that SALL4 bound to the promoter of TGF-b1 gene and activated its expression. TGF-β1 knockdown reversed SALL4-mediated promotion of gastric cancer cell motility, migration, and invasion, indicating that TGF-β1 acts as a downstream effector of SALL4. Furthermore, the expression of TGF-β1 was found to be closely associated with that of SALL4 in gastric cancer tissues.

Conclusion

SALL4 promotes the metastasis of gastric cancer, at least partly, by directly activating TGF-β1, suggesting that SALL4 may serve as a new target for gastric cancer therapy.

Cancer Stem Cells or Tumor Survival Cells?

Research endeavors originally generated stem cell definitions for the purpose of describing normally sustainable developmental and tissue turnover processes in various species, including humans. The notion of investigating cells that possess a vague capacity of “stamm (phylum)” can be traced back to the late 19th century, mainly concentrating on cells that could produce the germline or the entire blood system. Lately, such undertakings have been recapitulated for oncogenesis, tumor growth, and cancer cell resistance to oncolytic therapies. However, due to the complexity and basic life-origin mechanisms comprising the genetic and epigenetic repertoire of the stemness in every developing or growing cell, presently there are ongoing debates regarding the biological essentials of the stem cell-like tumor initiation cells (ie, cancer stem cells; CSCs). This conceptual analysis focuses on the potential pitfalls of extrapolating that CSCs bear major traits of stemness. We propose a novel nomenclature of Tumor Survival Cells (TSCs) to further define tumor cells behaving like CSCs, based on the ruthless and detrimental features of Cancer Cell Survivology that appears fundamentally different from stem cell biology. Hence, precise academic separation of TSCs from all the stem cell-related labels applied to these unique tumor cells may help to improve scientific reasoning and strategies to decode the desperado-like survival behaviors of TSCs to eventually overcome cancer.

Evaluation of NCAM and c-Kit as hepatic progenitor cell markers for intrahepatic cholangiocarcinomas

BACKGROUND

Intrahepatic cholangiocarcinomas (ICCs) are primary liver malignancies and are the second most common type of malignancy after hepatocellular carcinoma. ICCs are heterogeneous in clinical features, genotype, and biological behavior, suggesting that ICCs can initiate in different cell lineages.

AIM

We investigated intrahepatic cholangiocarcinoma RBE cell lines for the markers neural cell adhesion molecule (NCAM) and c-Kit, which possess hepatic progenitor cells properties.

METHODS

NCAM + c-Kit + cells were tested for hepatic progenitor cell properties including proliferation ability, colony formation, spheroid formation, and invasiveness in NOD/SCID mice. The Agilent Whole Human Genome Microarray Kit was used to evaluate differences in gene expression related to stem cell signaling pathways between NCAM + c-Kit + and NCAM-c-Kit- subset cells. Microarray results were further confirmed by real-time RT-PCR.

RESULTS

NCAM + c-Kit + cells showed hepatic progenitor cell-like traits including the abilities to self-renew and differentiate and tumorigenicity in NOD/SCID mice. Differences were observed in the expression of 421 genes related to stem cell signaling pathways (fc ≥ 2 or fc ≤ 0.5), among which 231 genes were upregulated and 190 genes were downregulated.

CONCLUSION

NCAM + c-Kit + subset cells in RBE may have properties of hepatic progenitor cells. NCAM combined with c-Kit may be a valuable marker for isolating and purifying ICC stem/progenitor cells.

Poly(ethylene glycol)-poly(lysine) block copolymer-ubenimex conjugate targets aminopeptidase N and exerts an antitumor effect in hepatocellular carcinoma stem cells

Previous studies highlighted that aminopeptidase N (APN)/CD13 acts as a scavenger in the survival of hepatocellular carcinoma (HCC) stem cells by reducing reactive oxygen species (ROS) levels. Hence, it has been proposed that APN/CD13 inhibition can increase cellular ROS levels and sensitize cells to chemotherapeutic agents. Although ubenimex, also known as bestatin, competitively inhibits proteases such as APN/CD13 on the cellular membrane and it is clinically used for patients with acute myeloid leukemia and lymphedema, research has demonstrated that higher concentrations of the agent induce the death of APN/CD13⁺ HCC stem cells. In this study, we developed a poly(ethylene glycol)-poly(lysine) block copolymer-ubenimex conjugate (PEG-b-PLys(Ube)) to increase the efficacy of reagents in APN/CD13⁺ cancer stem cells. Exposure to PEG-b-PLys(Ube) increased the intracellular ROS concentration by inhibiting APN enzyme activity, permitting the induction of apoptosis and attenuation of HCC cell proliferation. In addition, PEG-b-PLys(Ube) exhibited a relatively stronger antitumor effect in mice than PEG-b-PLys alone or phosphate-buffered saline. Moreover, an isobologram analysis revealed that combinations of fluorouracil, cisplatin, or doxorubicin with PEG-b-PLys(Ube) exhibited synergistic effects. This study demonstrated that PEG-b-PLys(Ube) does not impair the properties of ubenimex and exerts a potent antitumor effect.