SALL4 suppresses PTEN expression to promote glioma cell proliferation via PI3K/AKT signaling pathway

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.

SALL4 is a CRL3REN/KCTD11 substrate that drives Sonic Hedgehog-dependent medulloblastoma

The Sonic Hedgehog (SHH) pathway is crucial regulator of embryonic development and stemness. Its alteration leads to medulloblastoma (MB), the most common malignant pediatric brain tumor. The SHH-MB subgroup is the best genetically characterized, however the molecular mechanisms responsible for its pathogenesis are not fully understood and therapeutic benefits are still limited. Here, we show that the pro-oncogenic stemness regulator Spalt-like transcriptional factor 4 (SALL4) is re-expressed in mouse SHH-MB models, and its high levels correlate with worse overall survival in SHH-MB patients. Proteomic analysis revealed that SALL4 interacts with REN/KCTD11 (here REN), a substrate receptor subunit of the Cullin3-RING ubiquitin ligase complex (CRL3REN) and a tumor suppressor lost in ~30% of human SHH-MBs. We demonstrate that CRL3REN induces polyubiquitylation and degradation of wild type SALL4, but not of a SALL4 mutant lacking zinc finger cluster 1 domain (ΔZFC1). Interestingly, SALL4 binds GLI1 and cooperates with HDAC1 to potentiate GLI1 deacetylation and transcriptional activity. Notably, inhibition of SALL4 suppresses SHH-MB growth both in murine and patient-derived xenograft models. Our findings identify SALL4 as a CRL3REN substrate and a promising therapeutic target in SHH-dependent cancers.

LncRNA CAI2 Contributes to Poor Prognosis of Glioma through the PI3K-Akt Signaling Pathway

AIMS

We aim to explore new potential therapeutic targets and markers in human glioma.

BACKGROUND

Gliomas are the most common malignant primary tumor in the brain.

OBJECTIVE

In the present research, we evaluated the effect of CAI2, a long non-coding RNA, on the biological behaviors of glioma and explored the related molecular mechanism.

METHODS

The expression of CAI2 was analyzed using qRT-PCR in 65 cases of glioma patients. The cell proliferation was determined with MTT and colony formation assays, and the PI3K-AKt signaling pathway was analyzed using western blot.

RESULTS

CAI2 was upregulated in human glioma tissue compared with the matched, adjacent nontumor tissue and was correlated with WHO grade. Survival analyses proved that the overall survival of patients with high CAI2 expression was poor compared to that of patients with low CAI2 expression. High CAI2 expression was an independent prognostic factor in glioma. The absorbance values in the MTT assay after 96 h were .712 ± .031 for the si-control and .465 ± .018 for the si- CAI2-transfected cells, and si-CAI2 inhibited colony formation in U251 cells by approximately 80%. The levels of PI3K, p-AKt, and AKt in si-CAI2-treated cells were decreased.

CONCLUSION

CAI2 may promote glioma growth through the PI3K-AKt signaling pathway. This research provided a novel potential diagnostic marker for human glioma.

Immunotherapy, targeted therapy, and their cross talks in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a challenging malignancy with limited treatment options beyond surgery and chemotherapy. Recent advancements in targeted therapies and immunotherapy, including PD-1 and PD-L1 monoclonal antibodies, have shown promise, but their efficacy has not met expectations. Biomarker testing and personalized medicine based on genetic mutations and other biomarkers represent the future direction for HCC treatment. To address these challenges and opportunities, this comprehensive review discusses the progress made in targeted therapies and immunotherapies for HCC, focusing on dissecting the rationales, opportunities, and challenges for combining these modalities. The liver's unique physiology and the presence of fibrosis in many HCC patients pose additional challenges to drug delivery and efficacy. Ongoing efforts in biomarker development and combination therapy design, especially in the context of immunotherapies, hold promise for improving outcomes in advanced HCC. Through exploring the advancements in biomarkers and targeted therapies, this review provides insights into the challenges and opportunities in the field and proposes strategies for rational combination therapy design.

Role of exosomal miRNA-19a/19b and PTEN in brain tumor diagnosis

Aim: The current study was designed to evaluate the diagnostic significance of the exosomal miRNAs miR-19a and miR-19b and the PTEN gene in brain tumor patients versus controls. Methods: Exosomes were extracted from the serum samples of 400 brain tumor patients and 400 healthy controls. The exosomes were characterized by scanning electron microscopy, dynamic light scattering and ELISA. Quantitative PCR was used to analyze selected exosome miRNAs and gene expression levels. Results: Analysis showed significant deregulated expression of miR-19a (p < 0.0001), miR-19b (p < 0.0001) and PTEN (p < 0.001) in patients versus controls. Spearman correlation showed a significant correlation among the selected exosomal miRNAs and the PTEN gene. Conclusion: Receiver operating characteristic curve analysis showed the good diagnostic value of exosomal miRNAs and the PTEN gene in brain tumor patients.

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.

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.

Signaling Pathways Regulating the Expression of the Glioblastoma Invasion Factor TENM1

Glioblastoma (GBM) is one of the most aggressive cancers, with dismal prognosis despite continuous efforts to improve treatment. Poor prognosis is mostly due to the invasive nature of GBM. Thus, most research has focused on studying the molecular players involved in GBM cell migration and invasion of the surrounding parenchyma, trying to identify effective therapeutic targets against this lethal cancer. Our laboratory discovered the implication of TENM1, also known as ODZ1, in GBM cell migration in vitro and in tumor invasion using different in vivo models. Moreover, we investigated the microenvironmental stimuli that promote the expression of TENM1 in GBM cells and found that macrophage-secreted IL-6 and the extracellular matrix component fibronectin upregulated TENM1 through activation of Stat3. We also described that hypoxia, a common feature of GBM tumors, was able to induce TENM1 by both an epigenetic mechanism and a HIF2α-mediated transcriptional pathway. The fact that TENM1 is a convergence point for various cancer-related signaling pathways might give us a new therapeutic opportunity for GBM treatment. Here, we briefly review the findings described so far about the mechanisms that control the expression of the GBM invasion factor TENM1.

LncRNA MBNL1-AS1 Represses Proliferation and Cancer Stem-Like Properties of Breast Cancer through MBNL1-AS1/ZFP36/CENPA Axis

Background

Emerging studies have revealed long noncoding RNAs (lncRNAs) were key regulators of cancer progression. In this research, the expression and roles of MBNL1-AS1 were explored in breast cancer (BC).

Methods

In this study, the MBNL1-AS1 expression in breast cancer tissue, as well as in cell line, was studied by qRT-PCR assays. The effects of MBNL1-AS1 on proliferation and stemness were evaluated by MTT assays, colony formation assays, orthotopic breast tumor mice models, extreme limiting dilution analysis (ELDA), fluorescence in situ hybridization (FISH), flow cytometry assays, and sphere formation assays. Flexmap 3D assays were performed to show that MBNL1-AS1 downregulated the centromere protein A (CENPA) secretion in BC cells. Western blot, RNA pull-down assays, RNA immunoprecipitation (RIP) assays, and FISH were conducted to detect the mechanism.

Results

The results showed that the expression levels of MBNL1-AS1 were downregulated in breast cancer tissues and cell lines. In vitro and in vivo studies demonstrated that overexpression of MBNL1-AS1 markedly inhibited BC cells proliferation and stemness. RNA pull-down assay, RIP assay, western blot assay, and qRT-PCR assay showed that MBNL1-AS1 downregulated CENPA mRNA via directly interacting with Zinc Finger Protein 36 (ZFP36) and subsequently decreased the stability of CENPA mRNA. Restoration assays also confirmed that MBNL1-AS1 suppressed the CENPA-mediated proliferation and stemness in breast cancer cells.

Conclusions

The new mechanism of how MBNL1-AS1 regulates BC phenotype is elucidated, and the MBNL1-AS1/ZFP36/CENPA axis may be served as a therapeutic target for BC patients.

A Tumor Suppressor Gene, N-myc Downstream-Regulated Gene 1 (NDRG1), in Gliomas and Glioblastomas

The development of potent and selective therapeutic approaches to glioblastoma (GBM) requires the identification of molecular pathways that critically regulate the survival and proliferation of GBM. Glioblastoma stem-like cells (GSCs) possess stem-cell-like properties, self-renewal, and differentiation into multiple neural cell lineages. From a clinical point of view, GSCs have been reported to resist radiation and chemotherapy. GSCs are influenced by the microenvironment, especially the hypoxic condition. N-myc downstream-regulated gene 1 (NDRG1) is a tumor suppressor with the potential to suppress the proliferation, invasion, and migration of cancer cells. Previous studies have reported that deregulated expression of NDRG1 affects tumor growth and clinical outcomes of patients with GBM. This literature review aimed to clarify the critical role of NDRG1 in tumorigenesis and acquirement of resistance for anti-GBM therapies, further to discussing the possibility and efficacy of NDRG1 as a novel target of treatment for GBM. The present review was conducted by searching the PubMed and Scopus databases. The search was conducted in February 2022. We review current knowledge on the regulation and signaling of NDRG1 in neuro-oncology. Finally, the role of NDRG1 in GBM and potential clinical applications are discussed.

SALL4 Oncogenic Function in Cancers: Mechanisms and Therapeutic Relevance

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

Microrchidia family CW‑type zinc finger 2 promotes the proliferation, invasion, migration and epithelial‑mesenchymal transition of glioma by regulating PTEN/PI3K/AKT signaling via binding to N‑myc downstream regulated gene 1 promoter

Glioma is a common malignant tumor of the central nervous system with high incidence and mortality. The present study aimed to investigate the role of Microrchidia family CW‑type zinc finger 2 (MORC2) in the development of glioma. Firstly, MORC2 expression was detected in several glioma cell lines (U251, SHG44, LN229 and T98G). Following MORC2 silencing, cell proliferation was evaluated using the Cell Counting Kit‑8 assay and the expression of proliferation‑related proteins was assessed via immunofluorescence staining or western blotting. Cell invasion and migration were assessed using transwell and wound healing assays, respectively. Western blotting and immunofluorescence staining were employed to determine the expression of epithelial‑mesenchymal transition (EMT)‑associated proteins. The protein expression of N‑myc downstream regulated gene 1 (NDRG1) and PTEN/PI3K/AKT signaling was determined with western blot analysis. Then, the luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay were employed to evaluate the binding between MORC2 and NDRG1 promoter. Subsequently, cellular functional experiments were performed to assess the effects of NDRG1 on the progression of glioma after NDRG1 and MORC2 overexpression. In addition, tumor‑bearing experiments were conducted using a U251 tumor‑bearing nude mice model to detect tumor growth. The expression of proliferation (proliferating cell nuclear antigen, cyclin‑dependent kinase 2 and cyclin E1), migration [matrix metalloproteinase (MMP)2 and MMP9], EMT (E‑cadherin, N‑cadherin and Vimentin) and PTEN/PI3K/AKT signaling proteins in tumor tissues was examined with immunohistochemistry assay or western blotting. Results revealed that MORC2 was notably unregulated in glioma cells compared with the normal human astrocyte. Loss‑function of MORC2 inhibited the proliferation, invasion, migration and EMT of glioma cells. Importantly, MORC2 silencing upregulated NDRG1 expression and inactivated PTEN/PI3K/AKT signaling. Additionally, the luciferase reporter‑ and ChIP assays confirmed that MORC2 could bind to the NDRG1 promoter. NDRG1 upregulation suppressed the progression of glioma and these effects were partially reversed by MORC2 overexpression. Results of tumor‑bearing experiments suggested that gain‑function of NDRG1 inhibited tumor growth and downregulated the expression of proliferation, migration and EMT‑related proteins in tumorous tissue in U251 tumor‑bearing mice, which was partially counteracted after MORC2 overexpression. In addition, MORC2 overexpression abrogated the inhibitory effect of NDRG1 on PTEN/PI3K/AKT signaling. In summary, MORC2 promoted the progression of glioma by inactivation of PTEN/PI3K/AKT signaling via binding to NDRG1 promoter, providing a novel and potent target for the treatment of glioma.

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.

Exosome-mediated transfer of MIF confers temozolomide resistance by regulating TIMP3/PI3K/AKT axis in gliomas

Temozolomide (TMZ) resistance is an important cause of clinical treatment failure and poor prognosis in gliomas. Increasing evidence indicates that cancer-derived exosomes contribute to chemoresistance; however, the specific contribution of glioma-derived exosomes remains unclear. The aim of this study was to explore the role and underlying mechanisms of exosomal macrophage migration inhibitory factor (MIF) on TMZ resistance in gliomas. We first demonstrated that MIF was upregulated in the exosomes of TMZ-resistant cells, engendering the transfer of TMZ resistance to sensitive cells. Our results indicated that exosomal MIF conferred TMZ resistance to sensitive cells through the enhancement of cell proliferation and the repression of cell apoptosis upon TMZ exposure. MIF knockdown enhanced TMZ sensitivity in resistant glioma cells by upregulating Metalloproteinase Inhibitor 3 (TIMP3) and subsequently suppressing the PI3K/AKT signaling pathway. Additionally, exosomal MIF promoted tumor growth and TMZ resistance of glioma cells in vivo, while IOS-1 (MIF inhibitor) promotes glioma TMZ sensitive in vivo. Taken together, our study demonstrated that exosome-mediated transfer of MIF enhanced TMZ resistance in glioma through downregulating TIMP3 and further activating the PI3K/AKT signaling pathway, highlighting a prognostic biomarker and promising therapeutic target for TMZ treatment in gliomas.

LncRNA ANCR promotes glioma cells invasion, migration, proliferation and inhibits apoptosis via interacting with EZH2 and repressing PTEN expression

Recently, the role of long noncoding RNA (lncRNA) has been identified in human diseases, and we aim to explore the role of lncRNA antidifferentiation noncoding RNA (ANCR) in glioma. Expression of lncRNA ANCR, enhancer of zeste homolog 2 (EZH2), and phosphatase and tensin homolog (PTEN) in glioma tissues and cells was determined by RT-PCR or western blot assay. The correlation between expression of ANCR, EZH2, and PTEN in glioma tissues was analyzed using Pearson test. The apoptosis, transwell invasion, migration, colony formation, and proliferation assays were conducted to evaluate the influences of lncRNA ANCR depletion, EZH2 reduction, or PTEN elevation on the cell biology of glioma cells. The relationships between ANCR and EZH2, and between EZH2 and PTEN were confirmed through RIP, RNA pull-down, and chromatin immunoprecipitation assays. Our results indicated that ANCR and EZH2 were upregulated and PTEN was downregulated in glioma tissues and cell lines. ANCR expression was positively related to EZH2 expression, while PTEN expression was negatively related to ANCR/EZH2 expression. Inhibited ANCR, reduced EZH2, or elevated PTEN could reduce the ability of invasion, migration, and proliferation, and promote apoptosis of glioma cells. PTEN overexpression or EZH2 inhibition reversed the promotive role of ANCR upregulation in glioma cell growth and metastasis. Mechanistically, PTEN was upregulated in ANCR knockdown glioma cells. EZH2 interacted with ANCR in glioma cells. In conclusion, we have found that restrained ANCR could repress invasion, migration, and proliferation, as well as promote apoptosis of glioma cells through interacting with EZH2 and regulating the expression of PTEN, offering an effective therapeutic target for patients with glioma.

EZH2-Inhibited MicroRNA-454-3p Promotes M2 Macrophage Polarization in Glioma

Glioma is a primary intracranial tumor with high incidence and mortality. The oncogenic role of EZH2 has been reported in glioma. EZH2 inhibited microRNA-454-3p (miR-454-3p) by binding to its promoter in chondrosarcoma cells. Therefore, our study aimed to identify whether EZH2 regulated M2 macrophage polarization in glioma via miR-454-3p. Clinical samples of different grades of glioma and glioma cells were collected and immunohistochemistry and RT-qPCR demonstrated that EZH2 was highly expressed in glioma tissues. Expression of EZH2 was positively correlated with the degree of M2 macrophage polarization in glioma tissues. EZH2 was silenced by lentivirus in glioma cells, which were subsequently co-cultured with macrophages to evaluate its effect on macrophage polarization. miR-454-3p, a down-regulated miR in glioma, was found to be increased after silencing of EZH2. Furthermore, MethPrimer analysis showed that EZH2 silencing inhibited the DNA methylation level of miR-454-3p. Additionally, MS-PCR, dual-luciferase reporter, RIP and RNA pull down assays revealed that miR-454-3p promoted PTEN expression by inhibiting m⁶A modification through binding to the enzyme YTHDF2. Either inhibition of miR-454-3p or PTEN resulted in promotion of M2 macrophage polarization. Collectively, histone methyltransferase EZH2 inhibited miR-454-3p through methylation modification and promoted m⁶A modification of PTEN to induce glioma M2 macrophage polarization.

MiR-24 Promotes Cell Growth in Human Glioma by CDX1/PI3K/Akt Signaling Pathway

MicroRNA-24 (miR-24) has been identified to be related to the development of glioma. However, the exact molecular mechanism of miR-24 in glioma progression remains vague. The aim of the present study was to investigate the role of miR-24 in sepsis and to reveal the associated mechanisms. Quantitative real-time polymerase chain reaction was used to compare the levels of miR-24 in glioma and normal tissue. The miR-24 inhibitor or miR-24 mimic was transfected into glioma cells, and then the effects of miR-24 on cell proliferation and apoptosis were detected using CCK-8 (Cell Counting Kit-8) assay and flow cytometry, respectively. Western blot was used to examine the levels of CDX1 (caudal-type homeobox 1), PI3K, p-PI3K, Akt, p-Akt, Cyclin D1, p27, proliferating cell nuclear antigen, Bcl-2, Bax, and Cleaved-casp3. Luciferase assay was used to identify the target gene of miR-24. An animal model was established in mice to detect the role of miR-24 in vivo. These results suggested that miR-24 was elevated in glioma, and miR-24 could promote glioma progression by facilitating cell proliferation and inducing cell apoptosis through CDX1/PI3K/Akt signaling pathway, indicating a novel pathway underlying progression in glioma cells and providing a potential target for glioma treatment.

Metformin enhances the sensitivity of colorectal cancer cells to cisplatin through ROS-mediated PI3K/Akt signaling pathway

Metformin and cisplatin have been widely studied as antitumor agents. However, the effect of metformin combined with cisplatin has not been investigated in colorectal cancer (CRC) cells. This study was aimed to explore the effect of metformin or/and cisplatin on cell viability, apoptosis, and the related signaling pathways in CRC SW480 and SW620 cells. We found that metformin or cisplatin inhibited cell viability of SW480 and SW620 cells in a concentration- and time-dependent manner. Furthermore, metformin combined with cisplatin obviously inhibited cell viability, decreased colony formation, induced apoptosis, mediated cleavage of caspase-9, caspase-3 and PARP, activated mitochondrial membrane potential, downregulated Mcl-1 and Bcl-2 expression, upregulated Bak and Bax expression, and increased reactive oxygen species (ROS) production, compared to the individual agent in SW480 and SW620 cells, which were attenuated by N-acetyl-L-cysteine (NAC), a ROS scavenger. Moreover, NAC could recover the downregulation of p-PI3K and p-Akt treated with combination of metformin and cisplatin, which subsequently activated the PI3K/Akt signaling pathway. Taken together, our results demonstrated that metformin enhanced the sensitivity of CRC cells to cisplatin through ROS-mediated PI3K/Akt signaling pathway.

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.

AOC1 Contributes to Tumor Progression by Promoting the AKT and EMT Pathways in Gastric Cancer

Background

AOC1 is a copper-containing amine oxidase that is responsible for catalyzing the deamination of polyamines, which produces reactive oxygen species. Previous studies have demonstrated that polyamines are involved in the regulation of proliferation, migration, and apoptosis of cells. However, very little is known about the functions and regulatory mechanisms of AOC1 in tumors.

Methods

Based on GEPIA data, we found that AOC1 was significantly upregulated in human gastric cancer tissues. We knocked down AOC1 in human AGS and MKN45 cells using siRNA transfection, then utilized qRT-PCR assay and Western blot to verify the effectiveness of AOC1 knockdown in gastric cancer cells.

Results

Function analysis demonstrated that knockdown of AOC1 inhibited the proliferation, invasion, and migration of human gastric cancer cells. Flow cytometry detection suggested that AOC1 knockdown induced apoptosis in human gastric cancer cells. Mechanism investigation suggested that AOC1 knockdown increased the ratio of Bax/Bcl2 and induced activation of the caspase cascade. Furthermore, the AKT signaling pathway was inactivated when AOC1 was silenced, including downregulated phosphorylation level of AKT and expression of downstream effectors, Cyclin D1, and p70S6K. Finally, we found that knockdown of AOC1 inhibited the epithelial–mesenchymal transition (EMT) in human gastric cancer by increasing the expression of epithelial markers E-cadherin, as well as decreasing mesenchymal marker N-cadherin, SNAIL and Slug.

Conclusion

Our study suggests that AOC1 functions as an oncogene in human gastric cancer by activating the AKT signaling pathway and EMT process and maybe a target of 6-mercaptopurine, which provides new insight in the clinical use of AOC1 in gastric cancer therapy.

The Mechanisms Underlying PTEN Loss in Human Tumors Suggest Potential Therapeutic Opportunities

In this review, we will first briefly describe the diverse molecular mechanisms associated with PTEN loss of function in cancer. We will then proceed to discuss the molecular mechanisms linking PTEN loss to PI3K activation and demonstrate how these mechanisms suggest possible therapeutic approaches for patients with PTEN-null tumors.

Transcriptional alterations in glioma result primarily from DNA methylation-independent mechanisms

In cancer cells, aberrant DNA methylation is commonly associated with transcriptional alterations, including silencing of tumor suppressor genes. However, multiple epigenetic mechanisms, including polycomb repressive marks, contribute to gene deregulation in cancer. To dissect the relative contribution of DNA methylation–dependent and –independent mechanisms to transcriptional alterations at CpG island/promoter-associated genes in cancer, we studied 70 samples of adult glioma, a widespread type of brain tumor, classified according to their isocitrate dehydrogenase (IDH1) mutation status. We found that most transcriptional alterations in tumor samples were DNA methylation–independent. Instead, altered histone H3 trimethylation at lysine 27 (H3K27me3) was the predominant molecular defect at deregulated genes. Our results also suggest that the presence of a bivalent chromatin signature at CpG island promoters in stem cells predisposes not only to hypermethylation, as widely documented, but more generally to all types of transcriptional alterations in transformed cells. In addition, the gene expression strength in healthy brain cells influences the choice between DNA methylation- and H3K27me3-associated silencing in glioma. Highly expressed genes were more likely to be repressed by H3K27me3 than by DNA methylation. Our findings support a model in which altered H3K27me3 dynamics, more specifically defects in the interplay between polycomb protein complexes and the brain-specific transcriptional machinery, is the main cause of transcriptional alteration in glioma cells. Our study provides the first comprehensive description of epigenetic changes in glioma and their relative contribution to transcriptional changes. It may be useful for the design of drugs targeting cancer-related epigenetic defects.

Molecular and Clinical Insights into the Invasive Capacity of Glioblastoma Cells

The invasive capacity of GBM is one of the key tumoral features associated with treatment resistance, recurrence, and poor overall survival. The molecular machinery underlying GBM invasiveness comprises an intricate network of signaling pathways and interactions with the extracellular matrix and host cells. Among them, PI3k/Akt, Wnt, Hedgehog, and NFkB play a crucial role in the cellular processes related to invasion. A better understanding of these pathways could potentially help in developing new therapeutic approaches with better outcomes. Nevertheless, despite significant advances made over the last decade on these molecular and cellular mechanisms, they have not been translated into the clinical practice. Moreover, targeting the infiltrative tumor and its significance regarding outcome is still a major clinical challenge. For instance, the pre- and intraoperative methods used to identify the infiltrative tumor are limited when trying to accurately define the tumor boundaries and the burden of tumor cells in the infiltrated parenchyma. Besides, the impact of treating the infiltrative tumor remains unclear. Here we aim to highlight the molecular and clinical hallmarks of invasion in GBM.

LINC00673 silencing inhibits cell migration and invasion by suppressing PI3K/AKT signaling in glioma

LINC00673 is an oncogene that plays a key role in various cancer types. However, the role of LINC00673 in glioma remains unclear. In this study, we examined its expression in glioma cells by quantitative real-time PCR and found higher expression of LINC00673 in glioma cells compared with that in normal human astrocytes. Furthermore, LINC00673 silencing inhibited the migration and invasion of U87MG and U118MG cells, phosphoinositide 3-kinase (PI3K) expression, and AKT phosphorylation. Moreover, activation of the PI3K/AKT signaling pathway by insulin-like Growth factor-1 abolished the inhibitory effect of LINC00673 silencing on the migration and invasion of U87MG and U118MG cells. In conclusion, LINC00673 silencing inhibits glioma cell migration and invasion by suppressing the PI3K/AKT signaling pathway, and it is a potential therapeutic target for the treatment of metastatic glioma.

IL-17 induces the proliferation and migration of glioma cells through the activation of PI3K/Akt1/NF-κB-p65

Interleukin 17 (IL-17), as a pro-inflammatory cytokine, is up-regulated in the sera and tumor tissues of glioma patients; however the effects of IL-17 on glioma proliferation and migration remain unclear. In this study, the roles of IL-17 in the proliferation and migration of glioma cells and their potential mechanisms were determined. The results showed that IL-17 could not only enhance the proliferation and migration of cultured glioma cells (in vitro), but also promote the tumor formation of glioma cells in BALB/c nude mice (in vivo). Mechanical exploration revealed that IL-17 stimulation could increase the phosphorylation levels of Akt1 and NF-κB-p65 in glioma cells, and knockdown or inhibition of PI3K, Akt1 and NF-κB-p65 could also reduce the IL-17-induced proliferation and migration of the glioma cells. Moreover, PI3K/Akt1 was the upstream regulator of NF-κB-p65 activation in IL-17-incubated glioma cells. Furthermore, the inhibition of PI3K, Akt1 and NF-κB-p65 markedly suppressed the tumor formation of glioma cells induced by IL-17. Together, these data indicate that IL-17 can promote the proliferation and migration of glioma cells via PI3K/Akt1/NF-κB-p65 activation, and these findings might provide a new insight into glioma pathogenesis.

miRNA-19 promotes non-small-cell lung cancer cell proliferation via inhibiting CBX7 expression

Background

miR-19 is a critical carcinogenic miRNA that participates in important biological processes of human malignancies. CBX7 plays a key role in lung cancer development and progression. In the present study, for the first time, we investigated the correlation between miR-19 and CBX7 in non-small-cell lung cancer (NSCLC).

Methods

miR-19 expression in NSCLC tissues and lung cancer cell lines was detected using quantitative reverse transcriptase PCR (qRT-PCR). Luciferase reporter assay, qRT-PCR, Western blot, and immunohistochemical assay were conducted to identify the target reaction of miR-19 and CBX7. Moreover, the influence of miR-19 on lung cancer cell proliferation, migration, and invasion was studied including cell counting kit-8 assay, scratch assay, transwell assay, flow cytometry assay, and staining assays.

Results

miR-19 was overexpressed in NSCLC tissues and lung cancer cell lines. Luciferase reporter assay demonstrated that miR-19 could inhibit CBX7 expression via binding to the 3′-UTR of CBX7. Furthermore, miR-19 remarkably decreased CBX7 protein and mRNA expression. Additionally, overexpression of miR-19 could significantly enhance lung cancer cell proliferation and migration.

Conclusion

miR-19 functions as a tumor accelerator promoting lung cancer cell proliferation through targeting CBX7 and inhibiting its expression.

miR‑494‑3p promotes the progression of endometrial cancer by regulating the PTEN/PI3K/AKT pathway

MicroRNAs (miRs) are essential regulators in the development and progression of cancer. The role of miR-494-3p in endometrial cancer (EC) has not yet been investigated. In the present study, the expression levels of miR‑494‑3p were significantly upregulated in EC tissues compared with adjacent normal tissues. Furthermore, upregulation of miR‑494‑3p in patients with EC indicated poorer prognosis; miR‑494‑3p overexpression significantly promoted the proliferation, migration and invasion of HHUA and JEC cells in vitro. Consistently, inhibition of miR‑494‑3p in HHUA cells significantly suppressed tumor growth in vivo in a xenograft model. Additionally, phosphatase and tensin homolog (PTEN) was revealed to be a direct target of miR‑494‑3p in EC cells. Furthermore, overexpression of miR‑494‑3p inhibited PTEN expression and consequently activated the downstream phosphoinositide 3‑kinase/protein kinase B (PI3K/AKT) signialing pathway. Restoration of PTEN or inhibition of PI3K/AKT pathway also abolished miR‑494‑3p‑mediated proliferation, migration and invasion of HHUA and JEC cells. In summary, the results of the present study revealed the importance of the miR‑494‑3p/PTEN/PI3K/AKT axis in the progression of EC, which may provide novel insight into potential therapeutic targets for the treatment of EC.

The emerging role of miR-19 in glioma

Glioma has been regarded as the most common, highly proliferative and invasive brain tumour. Advances in research of miRNAs in glioma are toward further understanding of the pathogenesis of glioma. MiR‐19, a member of miR‐17~92 cluster, was reported to play an oncogenic role in tumourigenesis. Here we review the identified data about the effect of miR‐19 on proliferation, apoptosis, migration and invasion of glioma cells, the target genes regulated by miR‐19, and correlation of miR‐19 with the sensitivity of glioma cells to chemotherapy and radiotherapy. It is concluded that miR‐19 plays an important role in the pathogenesis of glioma and can be a potential target for gene therapy of glioma.

FOXK1 promotes cell growth through activating wnt/β-catenin pathway and emerges as a novel target of miR-137 in glioma

Glioma is the most common primary malignant brain tumor in adults. Forkhead box k1 (FOXK1) was reported to be dysregulated and play important roles in multiple human cancers. However, the expression pattern and roles of FOXK1 in glioma has never been investigated. In this study, we firstly observed that the expression of FOXK1 was significantly increased in glioma tissue samples and cell lines. Functional assays demonstrated that overexpression of FOXK1 promoted proliferation, cell cycle transition and inhibited apoptosis in glioma cell lines. On the contrary, knockdown of FOXK1 exhibited an opposite effect on glioma cells proliferation, cell cycle and apoptosis. Data of western blot indicated that FOXK1 overexpression increased while FOXK1 knockdown decreased the levels of β-catenin, c-myc and cyclinD1 in glioma cells. Moreover, we demonstrated that FOXK1 was a novel target of miR-137 in glioma and FOXK1 restoration abolished the tumor suppressive effect of miR-137 in glioma cells. Statistical analysis showed that the mRNA level of FOXK1 was inversely correlated with miR-137 expression in glioma tissues. In conclusion, the present study demonstrated that FOXK1 promoted cell growth through activating wnt/β-catenin pathway and is negatively regulated by miR-137 in glioma.

Epigenetic modification of SALL1 as a novel biomarker for the prognosis of early stage head and neck cancer

This study examined Sal-like protein (SALL)1 methylation profiles in head and neck squamous-cell carcinoma (HNSCC) patients at diagnosis and follow-up, and evaluated their prognostic significance and value as a biomarker. SALL1 expression was examined in a panel of cell lines by quantitative reverse transcription PCR (qRT-PCR). Promoter methylation was determined by quantitative methylation-specific polymerase chain reaction (qMSP) and was compared to the clinical characteristics of 205 samples. SALL1 promoter methylation was associated with transcriptional inhibition and was correlated with disease recurrence in 31.7% of cases, with an odds ratio of 1.694 (95% confidence interval: 1.093-2.626; P = 0.018) by multivariate Cox proportional hazard regression analysis. SALL1 promoter hypermethylation showed highly discriminatory receiver operator characteristic curve profiles that clearly distinguished HNSCC from adjacent normal mucosal tissue, and was correlated with reduced disease-free survival in early stage T1 and T2 patients (log-rank test, P < 0.001). SALL1 methylation was significantly correlated with the methylation status of both SALL3 and CDH1. This study suggests that CpG hypermethylation is a likely mechanism of SALL1 gene inactivation, supporting the hypothesis that SALL1 might play a role in HNSCC tumorigenesis and could serve as an important biomarker.