Epigenetically regulated PAX6 drives cancer cells toward a stem-like state via GLI-SOX2 signaling axis in lung adenocarcinoma

Inhibition of ERN1 affects the expression of TGIF1 and other homeobox gene expressions in U87MG glioblastoma cells

BACKGROUND

The ERN1 (endoplasmic reticulum to nucleus signaling 1) pathway plays an important role in the regulation of gene expression in glioblastoma, but molecular mechanism has not yet been fully elucidated. The aim of this study was to evaluate the relative relevance of ERN1 activity as a kinase in comparison to its endoribonuclease activity in the regulation of homeobox gene expression.

METHODS

Two sublines of U87MG glioblastoma cells with different ways of ERN1 inhibition were used: dnERN1 (overexpressed transgene without protein kinase and endoribonuclease) and dnrERN1 (overexpressed transgene with mutation in endoribonuclease). ERN1 suppression was also done using siRNA for ERN1. Silencing of XBP1 mRNA by specific siRNA was used for suppression of ERN1 endoribonuclease function mediated by XBP1s. The expression levels of homeobox genes and microRNAs were evaluated by qPCR.

RESULTS

The expression of TGIF1 and ZEB2 genes was downregulated in both types of glioblastoma cells with inhibition of ERN1 showing the ERN1 endoribonuclease-dependent mechanism of their regulation. However, the expression of PBX3 and PRPRX1 genes did not change significantly in dnrERN1 glioblastoma cells but was upregulated in dnERN1 cells indicating the dependence of these gene expressions on the ERN1 protein kinase. At the same time, the changes in PAX6 and PBXIP1 gene expressions introduced in glioblastoma cells by dnrERN1 and dnERN1 were different in direction and magnitude indicating the interaction of ERN1 protein kinase and endoribonuclease activities in regulation of these gene expressions. The impact of ERN1 and XBP1 silencing on the expression of studied homeobox genes is similar to that observed in dnERN1 and dnrERN1 glioblastoma cells, correspondingly.

CONCLUSION

The expression of TGIF1 and other homeobox genes is dependent on the ern1 signaling pathways by diverse mechanisms because inhibition of ERN1 endoribonuclease and both ERN1 enzymatic activities had dissimilar impacts on the expression of most studied genes showing that ERN1 protein kinase plays an important role in controlling homeobox gene expression associated with glioblastoma cell invasion.

Dissecting SOX2 expression and function reveals an association with multiple signaling pathways during embryonic development and in cancer progression

SRY (Sex Determining Region) box 2 (SOX2) is an essential transcription factor that plays crucial roles in activating genes involved in pre- and post-embryonic development, adult tissue homeostasis, and lineage specifications. SOX2 maintains the self-renewal property of stem cells and is involved in the generation of induced pluripotency stem cells. SOX2 protein contains a particular high-mobility group domain that enables SOX2 to achieve the capacity to participate in a broad variety of functions. The information about the involvement of SOX2 with gene regulatory elements, signaling networks, and microRNA is gradually emerging, and the higher expression of SOX2 is functionally relevant to various cancer types. SOX2 facilitates the oncogenic phenotype via cellular proliferation and enhancement of invasive tumor properties. Evidence are accumulating in favor of three dimensional (higher order) folding of chromatin and epigenetic control of the SOX2 gene by chromatin modifications, which implies that the expression level of SOX2 can be modulated by epigenetic regulatory mechanisms, specifically, via DNA methylation and histone H3 modification. In view of this, and to focus further insights into the roles SOX2 plays in physiological functions, involvement of SOX2 during development, precisely, the advances of our knowledge in pre- and post-embryonic development, and interactions of SOX2 in this scenario with various signaling pathways in tumor development and cancer progression, its potential as a therapeutic target against many cancers are summarized and discussed in this article.

PAX6 promotes neuroendocrine phenotypes of prostate cancer via enhancing MET/STAT5A-mediated chromatin accessibility

BACKGROUND

Neuroendocrine prostate cancer (NEPC) is a lethal subset of prostate cancer which is characterized by neuroendocrine differentiation and loss of androgen receptor (AR) signaling. Growing evidence reveals that cell lineage plasticity is crucial in the failure of NEPC therapies. Although studies suggest the involvement of the neural transcription factor PAX6 in drug resistance, its specific role in NEPC remains unclear.

METHODS

The expression of PAX6 in NEPC was identified via bioinformatics and immunohistochemistry. CCK8 assay, colony formation assay, tumorsphere formation assay and apoptosis assay were used to illustrate the key role of PAX6 in the progression of in vitro. ChIP and Dual-luciferase reporter assays were conducted to confirm the binding sequences of AR in the promoter region of PAX6, as well as the binding sequences of PAX6 in the promoter regions of STAT5A and MET. For in vivo validation, the xenograft model representing NEPC subtype underwent pathological analysis to verify the significant role of PAX6 in disease progression. Complementary diagnoses were established through public clinical datasets and transcriptome sequencing of specific cell lines. ATAC-seq was used to detect the chromatin accessibility of specific cell lines.

RESULTS

PAX6 expression was significantly elevated in NEPC and negatively regulated by AR signaling. Activation of PAX6 in non-NEPC cells led to NE trans-differentiation, while knock-down of PAX6 in NEPC cells inhibited the development and progression of NEPC. Importantly, loss of AR resulted in an enhanced expression of PAX6, which reprogramed the lineage plasticity of prostate cancer cells to develop NE phenotypes through the MET/STAT5A signaling pathway. Through ATAC-seq, we found that a high expression level of PAX6 elicited enhanced chromatin accessibility, mainly through attenuation of H4K20me3, which typically causes chromatin silence in cancer cells.

CONCLUSION

This study reveals a novel neural transcription factor PAX6 could drive NEPC progression and suggest that it might serve as a potential therapeutic target for the management of NEPC.

LncRNA MIR31HG fosters stemness malignant features of non-small cell lung cancer via H3K4me1- and H3K27Ace-mediated GLI2 expression

Non-coding RNAs are responsible for oncogenesis and the development of stemness features, including multidrug resistance and metastasis, in various cancers. Expression of lncRNA MIR31HG in lung cancer tissues and peripheral sera of lung cancer patients were remarkably higher than that of healthy individuals and indicated a poor prognosis. Functional analysis showed that MIR31HG fosters stemness-associated malignant features of non-small cell lung cancer cells. Further mechanistic investigation revealed that MIR31HG modulated GLI2 expression via WDR5/MLL3/P300 complex-mediated H3K4me and H3K27Ace modification. In vivo MIR31HG repression with an antisense oligonucleotide attenuated tumor growth and distal organ metastasis, whereas MIR31HG promotion remarkably encouraged cellular invasion in lung and liver tissues. Our data suggested that MIR31HG is a potential diagnostic indicator and druggable therapeutic target to facilitate multiple strategic treatments for lung cancer patients.

Transcriptional regulation of cancer stem cell: regulatory factors elucidation and cancer treatment strategies

Cancer stem cells (CSCs) were first discovered in the 1990s, revealing the mysteries of cancer origin, migration, recurrence and drug-resistance from a new perspective. The expression of pluripotent genes and complex signal regulatory networks are significant features of CSC, also act as core factors to affect the characteristics of CSC. Transcription is a necessary link to regulate the phenotype and potential of CSC, involving chromatin environment, nucleosome occupancy, histone modification, transcription factor (TF) availability and cis-regulatory elements, which suffer from ambient pressure. Especially, the expression and activity of pluripotent TFs are deeply affected by both internal and external factors, which is the foundation of CSC transcriptional regulation in the current research framework. Growing evidence indicates that regulating epigenetic modifications to alter cancer stemness is effective, and some special promoters and enhancers can serve as targets to influence the properties of CSC. Clarifying the factors that regulate CSC transcription will assist us directly target key stem genes and TFs, or hinder CSC transcription through environmental and other related factors, in order to achieve the goal of inhibiting CSC and tumors. This paper comprehensively reviews the traditional aspects of transcriptional regulation, and explores the progress and insights of the impact on CSC transcription and status through tumor microenvironment (TME), hypoxia, metabolism and new meaningful regulatory factors in conjunction with the latest research. Finally, we present opinions on omnidirectional targeting CSCs transcription to eliminate CSCs and address tumor resistance.

PARD3 drives tumorigenesis through activating Sonic Hedgehog signalling in tumour-initiating cells in liver cancer

BACKGROUND

Par-3 Family Cell Polarity Regulator (PARD3) is a cellular protein essential for asymmetric cell division and polarized growth. This study aimed to study the role of PARD3 in hepatic tumorigenesis.

METHODS

The essential role of PARD3 in mediating hepatic tumorigenesis was assessed in diet-induced spontaneous liver tumour and syngeneic tumour models. The mechanism of PARD3 was delineated by bulk and single-cell RNA sequencing. The clinical significance of PARD3 was identified by tissue array analysis.

RESULTS

PARD3 was overexpressed in tumour tissues and PARD3 overexpression was positively correlated with high tumour stage as well as the poor prognosis in patients. In models of spontaneous liver cancer induced by choline-deficient, amino acid-defined (CDAA) and methionine-choline-deficient (MCD) diets, upregulation of PARD3 was induced specifically at the tumorigenesis stage rather than other early stages of liver disease progression. Site-directed knockout of PARD3 using an adeno-associated virus 8 (AAV8)-delivered CRISPR/Cas9 single-guide RNA (sgRNA) plasmid blocked hepatic tumorigenesis, while PARD3 overexpression accelerated liver tumour progression. In particular, single-cell sequencing analysis suggested that PARD3 was enriched in primitive tumour cells and its overexpression enhanced tumour-initiating cell (TICs). Overexpression of PARD3 maintained the self-renewal ability of the CD133+ TIC population within hepatocellular carcinoma (HCC) cells and promoted the in vitro and in vivo tumorigenicity of CD133+ TICs. Transcriptome analysis revealed that Sonic Hedgehog (SHH) signalling was activated in PARD3-overexpressing CD133+ TICs. Mechanistically, PARD3 interacted with aPKC to further activate SHH signalling and downstream stemness-related genes. Suppression of SHH signalling and aPKC expression attenuated the in vitro and in vivo tumorigenicity of PARD3-overexpressing CD133+ TICs. Tissue array analysis revealed that PARD3 expression was positively associated with the phosphorylation of aPKC, SOX2 and Gli1 and that the combination of these markers could be used to stratify HCC patients into two clusters with different clinicopathological characteristics and overall survival prognoses. The natural compound berberine was selected as a potent suppressor of PARD3 expression and could be used as a preventive agent for liver cancer that completely blocks diet-induced hepatic tumorigenesis in a PARD3-dependent manner.

CONCLUSION

This study revealed PARD3 as a potential preventive target of liver tumorigenesis via TIC regulation.

Potent molecular-targeted therapies for gastro-entero-pancreatic neuroendocrine carcinoma

Neuroendocrine neoplasms (NENs), which are characterized by neuroendocrine differentiation, can arise in various organs. NENs have been divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs) based on morphological differentiation, each of which has a distinct etiology, molecular profile, and clinicopathological features. While the majority of NECs originate in the pulmonary organs, extrapulmonary NECs occur most predominantly in the gastro-entero-pancreatic (GEP) system. Although platinum-based chemotherapy is the main therapeutic option for recurrent or metastatic GEP-NEC patients, the clinical benefits are limited and associated with a poor prognosis, indicating the clinically urgent need for effective therapeutic agents. The clinical development of molecular-targeted therapies has been hampered due to the rarity of GEP-NECs and the paucity of knowledge on their biology. In this review, we summarize the biology, current treatments, and molecular profiles of GEP-NECs based on the findings of pivotal comprehensive molecular analyses; we also highlight potent therapeutic targets for future precision medicine based on the most recent results of clinical trials.

Exploring the molecular mechanism of linagliptin in osteosarcoma cell lines for anti-cancer activity

BACKGROUND

Finding new applications for widely used current drugs is a fast and effective technique for discovering new anticancer chemicals. Osteosarcoma (OS), the most prevalent form of bone cancer, has several side effects that significantly lower patients' quality of life. This study aims to systematically examine the anti-cancer activity of linagliptin (LG) in the osteosarcoma cell line Saos-2.

METHODS

MTT assays and flow cytometry were used to assess cell viability and apoptosis, respectively. qPCR array experiments were carried out to determine target gene expressions and explain the molecular mechanism of LG's action.

RESULTS

Linagliptin treatment significantly decreased the viability of Saos-2 cells and hFOB1.19 cells (p < 0.001). The treatment also induced increased apoptotic effects in both Saos-2 cells (p < 0.001) and hFOB1.19 cells (p < 0.05). qPCR assays were conducted to assess cancer pathway analysis after applying specific quantities of LG to Saos-2 and hFOB1.19 cells.

CONCLUSION

The findings of this study demonstrate that LG inhibits the proliferation of Saos-2 cells and induces cell death. LG supports cell death by suppressing the expression of specific genes involved in cancer pathways.

HOPX is a tumor-suppressive biomarker that corresponds to T cell infiltration in skin cutaneous melanoma

BACKGROUND

Skin cutaneous melanoma (SKCM) is the most threatening type of skin cancer. Approximately 55,000 people lose their lives every year due to SKCM, illustrating that it seriously threatens human life and health. Homeodomain-only protein homeobox (HOPX) is the smallest member of the homeodomain family and is widely expressed in a variety of tissues. HOPX is involved in regulating the homeostasis of hematopoietic stem cells and is closely related to the development of tumors such as breast cancer, nasopharyngeal carcinoma, and head and neck squamous cell carcinoma. However, its function in SKCM is unclear, and further studies are needed.

METHODS

We used the R language to construct ROC (Receiver-Operating Characteristic) curves, KM (Kaplan‒Meier) curves and nomograms based on databases such as the TCGA and GEO to analyze the diagnostic and prognostic value of HOPX in SKCM patients. Enrichment analysis, immune scoring, GSVA (Gene Set Variation Analysis), and single-cell sequencing were used to verify the association between HOPX expression and immune infiltration. In vitro experiments were performed using A375 cells for phenotypic validation. Transcriptome sequencing was performed to further analyze HOPX gene-related genes and their signaling pathways.

RESULTS

Compared to normal cells, SKCM cells had low HOPX expression (p < 0.001). Patients with high HOPX expression had a better prognosis (p < 0.01), and the marker had good diagnostic efficacy (AUC = 0.744). GO/KEGG (Gene Ontology/ Kyoto Encyclopedia of Genes and Genomes) analysis, GSVA and single-cell sequencing analysis showed that HOPX expression is associated with immune processes and high enrichment of T cells and could serve as an immune checkpoint in SKCM. Furthermore, cellular assays verified that HOPX inhibits the proliferation, migration and invasion of A375 cells and promotes apoptosis and S-phase arrest. Interestingly, tumor drug sensitivity analysis revealed that HOPX also plays an important role in reducing clinical drug resistance.

CONCLUSION

These findings suggest that HOPX is a blocker of SKCM progression that inhibits the proliferation of SKCM cells and promotes apoptosis. Furthermore, it may be a new diagnostic and prognostic indicator and a novel target for immunotherapy in SKCM patients.

DNA Repair and Therapeutic Strategies in Cancer Stem Cells

First-line cancer treatments successfully eradicate the differentiated tumour mass but are comparatively ineffective against cancer stem cells (CSCs), a self-renewing subpopulation thought to be responsible for tumour initiation, metastasis, heterogeneity, and recurrence. CSCs are thus presented as the principal target for elimination during cancer treatment. However, CSCs are challenging to drug target because of numerous intrinsic and extrinsic mechanisms of drug resistance. One such mechanism that remains relatively understudied is the DNA damage response (DDR). CSCs are presumed to possess properties that enable enhanced DNA repair efficiency relative to their highly proliferative bulk progeny, facilitating improved repair of double-strand breaks induced by radiotherapy and most chemotherapeutics. This can occur through multiple mechanisms, including increased expression and splicing fidelity of DNA repair genes, robust activation of cell cycle checkpoints, and elevated homologous recombination-mediated DNA repair. Herein, we summarise the current knowledge concerning improved genome integrity in non-transformed stem cells and CSCs, discuss therapeutic opportunities within the DDR for re-sensitising CSCs to genotoxic stressors, and consider the challenges posed regarding unbiased identification of novel DDR-directed strategies in CSCs. A better understanding of the DDR mediating chemo/radioresistance mechanisms in CSCs could lead to novel therapeutic approaches, thereby enhancing treatment efficacy in cancer patients.

Differential role of Pax6 and its interaction with Shh-Gli1-IDH2 axis in regulation of glioma growth and chemoresistance

Glioma is a major brain tumor, and the associated mortality rate is very high. Contemporary therapies provide a chance of survival for 9-12 months. Therefore, a novel approach is essential to improve the survival rate. Sonic hedgehog (Shh) cell signaling is critical for early development in various tumors. This investigation attempted to explore the potential interaction and regulation of Shh-Gli1 cell signaling in association with paired box 6 (Pax6) and isocitrate dehydrogenase 2 (IDH2). The expression pattern of Shh, Gli1, Pax6, and IDH2 was examined by transcriptome analysis, immunohistochemistry, and confocal images. The results suggest the interaction of Shh-Gli1 cell signaling pathway with Pax6 and IDH2 and potential regulation. Thereafter, we performed protein-protein docking and molecular dynamic simulations (MDS) of Gli1 with Pax6 and IDH2. The results suggest differential dynamic interactions of Gli1-IDH2 and Gli1-Pax6. Gli1 knockdown downregulated the expression of Pax6 and upregulated the expression of IDH2. Moreover, Gli1 knockdown decreased the expression of the drug resistance gene MRP1. The knockdown of Pax6 gene in glioma cells downregulated the expression of Gli1 and IDH2 and promoted cell proliferation. Moreover, the efficacy of the treatment of glioma cells with temozolomide (TMZ) and Gli1 inhibitor GANT61 was higher than that of TMZ alone. MDS results revealed that the interactions of Gli1 with IDH2 were stronger and more stable than those with Pax6. Intriguingly, inhibition of Pax6 promoted glioma growth even in the presence of TMZ. However, the tumor-suppressive nature of Pax6 was altered when Gli1 was inhibited by GANT61, and it showed potential oncogenic character, as observed in other cancers. Therefore, we conclude that Pax6 interacted with IDH2 and Gli1 in glioma. Moreover, the Shh-Gli1-IDH2/Pax6 cell signaling axis provides a new therapeutic approach for inhibiting the progression of the disease and mitigating drug resistance in glioma.

Inhibitory Effect and Mechanism of Ursolic Acid on Cisplatin-Induced Resistance and Stemness in Human Lung Cancer A549 Cells

The survival rate of lung cancer patients remains low largely due to chemotherapy resistance during treatment, and cancer stem cells (CSCs) may hold the key to targeting this resistance. Cisplatin is a chemotherapy drug commonly used in cancer treatment, yet the mechanisms of intrinsic cisplatin resistance have not yet been determined because lung CSCs are hard to identify. In this paper, we proposed a mechanism relating to the function of ursolic acid (UA), a new drug, in reversing the cisplatin resistance of lung cancer cells regulated by CSCs. Human lung cancer cell line A549 was selected as the model cell and treated to become a cisplatin-resistant lung cancer cell line (A549-CisR), which was less sensitive to cisplatin and showed an enhanced capability of tumor sphere formation. Furthermore, in the A549-CisR cell line expression, levels of pluripotent stem cell transcription factors Oct-4, Sox-2, and c-Myc were increased, and activation of the Jak2/Stat3 signaling pathway was promoted. When UA was applied to the cisplatin-resistant cells, levels of the pluripotent stem cell transcription factors were restrained by the inhibition of the Jak2/Stat3 signaling pathway, which reduced the enrichment of tumor stem cells, and in turn, reversed cisplatin resistance in lung cancer cells. Hence, as a potential antitumor drug, UA may be able to inhibit the enrichment of the lung CSC population by inhibiting the activation of the Jak2-Stat3 pathway and preventing the resistance of lung cancer cells to cisplatin.

ERN1 dependent impact of glucose and glutamine deprivations on PBX3, PBXIP1, PAX6, MEIS1, and MEIS2 genes expression in U87 glioma cells

Objective. Homeobox genes play a fundamental role in the embryogenesis, but some of them have been linked to oncogenesis. The present study is aimed to investigate the impact of glucose and glutamine deprivations on the expression of homeobox genes such as PAX6 (paired box 6), PBX3 (PBX homeobox 3), PBXIP1 (PBX homeobox interacting protein 1), MEIS1 (MEIS homeobox 1), and MEIS2 in ERN1 knockdown U87 glioma cells with the intent to reveal the role of ERN1 (endoplasmic reticulum to nucleus signaling 1) signaling pathway on the endoplasmic reticulum stress dependent regulation of homeobox genes. Methods. The control (transfected by empty vector) and ERN1 knockdown (transfected by dominant-negative ERN1) U87 glioma cells were exposed to glucose and glutamine deprivations for 24 h. The cells RNA was extracted and reverse transcribed. The expression level of PAX6, PBX3, PBXIP1, MEIS1, and MEIS2 genes was evaluated by a real-time quantitative polymerase chain reaction analysis and normalized to ACTB. Results. It was found that glucose deprivation down-regulated the expression level of PAX6, MEIS1, and MEIS2 genes in control glioma cells, but did not significantly alter PBX3 and PBXIP1 genes expression. At the same time, ERN1 knockdown significantly modified the sensitivity of all studied genes to glucose deprivation. Other changes in gene expression were detected in control glioma cells under the glutamine deprivation. The expression of PBX3 and MEIS2 genes was down- while PAX6 and PBXIP1 genes up-regulated. Furthermore, ERN1 knockdown significantly modified the effect of glutamine deprivation on the majority of studied genes expression in U87 glioma cells. Conclusion. The results of the present study demonstrate that the exposure of U87 glioma cells under glucose and glutamine deprivations affected the expression of the majority of the studied homeobox genes and that the sensitivity of PAX6, PBX3, PBXIP1, MEIS1, and MEIS2 genes expression under these experimental conditions is mediated by ERN1, the major pathway of the endoplasmic reticulum stress signaling.

Expression analysis and regulation of GLI and its correlation with stemness and metabolic alteration in human brain tumor

GLI gene-mediated hedgehog (Hh) signaling pathway plays a substantial role in brain cancer development and growth including glioblastoma multiforme (GBM), lower-grade glioma (LGG), and medulloblastoma (MB). GLI2 and GLI3 gene expression levels are extremely enhanced in these cancers with poor patient survival. Moreover, GLI genes are correlated with stemness-related factors SOX2, SOX9, POU5F1, and NANOG that work as the driving factors for brain cancer stem cells (CSCs) progression. It's critical to find new ways to combat this deadly malignancy and CSCs. Using in silico approaches, our study explored the role of GLI genes (GLI1, GLI2, and GLI3), the primary transcription factors of the sonic hedgehog (SHH) signaling pathway, in GBM, LGG, MB, and glioblastoma stem-like cells (GSCs). Additionally, we found strong association of angiogenic-related gene VEGFA, metabolic genes ENO1, ENO2, and pluripotency-related genes SOX2, SOX9, NANOG, POU5F1 with GLI genes, suggesting their role in brain tumor initiation and progression. We also studied their transcriptional network and functional category enrichment analysis about brain tumor development to find a better therapeutic strategy against brain cancer and their stem cells.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03419-5.

Inside the stemness engine: Mechanistic links between deregulated transcription factors and stemness in cancer

Cell identity is largely determined by its transcriptional profile. In tumour, deregulation of transcription factor expression and/or activity enables cancer cell to acquire a stem-like state characterised by capacity to self-renew, differentiate and form tumours in vivo. These stem-like cancer cells are highly metastatic and therapy resistant, thus warranting a more complete understanding of the molecular mechanisms downstream of the transcription factors that mediate the establishment of stemness state. Here, we review recent research findings that provide a mechanistic link between the commonly deregulated transcription factors and stemness in cancer. In particular, we describe the role of master transcription factors (SOX, OCT4, NANOG, KLF, BRACHYURY, SALL, HOX, FOX and RUNX), signalling-regulated transcription factors (SMAD, β-catenin, YAP, TAZ, AP-1, NOTCH, STAT, GLI, ETS and NF-κB) and unclassified transcription factors (c-MYC, HIF, EMT transcription factors and P53) across diverse tumour types, thereby yielding a comprehensive overview identifying shared downstream targets, highlighting unique mechanisms and discussing complexities.

ADAMTS9-AS1 Long Non‑coding RNA Sponges miR‑128 and miR-150 to Regulate Ras/MAPK Signaling Pathway in Glioma

Glioma is a malignancy of the central nervous system with a poor prognosis. Therefore, the elaboration of its molecular features creates therapeutic opportunities. Looking for the regulatory non-coding RNAs (lncRNAs and miRNAs) that are involved in glioma incidence/progression, RNA-seq analysis introduced upregulated ADAMTS9-AS1 as a bona fide candidate that sponges miR-128 and miR-150 and shows the negative correlation of expression with them. Then, RT-qPCR verified the upregulation of ADAMTS9-AS1 in glioma tissues and cell lines. Furthermore, dual-luciferase assay supported that cytoplasmic ADAMTS9-AS1 is capable of sponging miR-128 and miR-150, which are known as regulators of Ras/MAPK, PI3K, and Wnt pathways. Following the overexpression of ADAMTS9-AS1 in 1321N1 and U87 glioma cells, tyrosine kinase receptors (IGF1R and TrkC), as well as Wnt receptors (Lrp6 and Fzd) were upregulated, detected by RT-qPCR. Furthermore, downstream genes of both Ras/MAPK and Wnt pathways were upregulated. Finally following the ADAMTS9-AS1 overexpression, upregulation of Ras/MAPK and Wnt signaling pathways was verified through western blotting and Top/Fop flash assay, respectively. At the cellular level, ADAMTS9-AS1 overexpression brought about reduced sub-G1 cell population, increased proliferation rate, reduced apoptosis level, increased migration rate, shortened Bax/Bcl2 ratio, induced EMT, and stemness characteristics of transfected cells, detected by flow cytometry, MTT assay, scratch test, and RT-qPCR. Overall, these results introduced ADAMTS9-AS1 as an oncogene that upregulates Ras/MAPK and Wnt pathways through sponging of the miR-128 and miR-150 in glioma cells. The outcome of ADAMTS9-AS1 expression is more aggression of the glioma cells through increased EMT and stemness characteristics. These features candidate ADAMTS9-AS1 locus for glioma therapy. As a result, we discovered the oncogenic properties of ADAMTS9-AS1 in glioma cancer. It sponges miR-128 and miR-150 and subsequently overstimulates RAS/MAPK and Wnt signaling pathways, particularly at the receptors level. Thus, ADAMTS9-AS1 increases proliferation, migration, and stemness in glioma cell lines. A schematic representation showing the functional effect of ADAMTS9-AS1.

The transcription factor PAX8 promotes angiogenesis in ovarian cancer through interaction with SOX17

PAX8 is a master transcription factor that is essential during embryogenesis and promotes neoplastic growth. It is expressed by the secretory cells lining the female reproductive tract, and its deletion during development results in atresia of reproductive tract organs. Nearly all ovarian carcinomas express PAX8, and its knockdown results in apoptosis of ovarian cancer cells. To explore the role of PAX8 in these tissues, we purified the PAX8 protein complex from nonmalignant fallopian tube cells and high-grade serous ovarian carcinoma cell lines. We found that PAX8 was a member of a large chromatin remodeling complex and preferentially interacted with SOX17, another developmental transcription factor. Depleting either PAX8 or SOX17 from cancer cells altered the expression of factors involved in angiogenesis and functionally disrupted tubule and capillary formation in cell culture and mouse models. PAX8 and SOX17 in ovarian cancer cells promoted the secretion of angiogenic factors by suppressing the expression of SERPINE1, which encodes a proteinase inhibitor with antiangiogenic effects. The findings reveal a non-cell-autonomous function of these transcription factors in regulating angiogenesis in ovarian cancer.

KLF3 and PAX6 are candidate driver genes in late-stage, MSI-hypermutated endometrioid endometrial carcinomas

Endometrioid endometrial carcinomas (EECs) are the most common histological subtype of uterine cancer. Late-stage disease is an adverse prognosticator for EEC. The purpose of this study was to analyze EEC exome mutation data to identify late-stage-specific statistically significantly mutated genes (SMGs), which represent candidate driver genes potentially associated with disease progression. We exome sequenced 15 late-stage (stage III or IV) non-ultramutated EECs and paired non-tumor DNAs; somatic variants were called using Strelka, Shimmer, SomaticSniper and MuTect. Additionally, somatic mutation calls were extracted from The Cancer Genome Atlas (TCGA) data for 66 late-stage and 270 early-stage (stage I or II) non-ultramutated EECs. MutSigCV (v1.4) was used to annotate SMGs in the two late-stage cohorts and to derive p-values for all mutated genes in the early-stage cohort. To test whether late-stage SMGs are statistically significantly mutated in early-stage tumors, q-values for late-stage SMGs were re-calculated from the MutSigCV (v1.4) early-stage p-values, adjusting for the number of late-stage SMGs tested. We identified 14 SMGs in the combined late-stage EEC cohorts. When the 14 late-stage SMGs were examined in the TCGA early-stage data, only Krüppel-like factor 3 (KLF3) and Paired box 6 (PAX6) failed to reach significance as early-stage SMGs, despite the inclusion of enough early-stage cases to ensure adequate statistical power. Within TCGA, nonsynonymous mutations in KLF3 and PAX6 were, respectively, exclusive or nearly exclusive to the microsatellite instability (MSI)-hypermutated molecular subgroup and were dominated by insertions-deletions at homopolymer tracts. In conclusion, our findings are hypothesis-generating and suggest that KLF3 and PAX6, which encode transcription factors, are MSI target genes and late-stage-specific SMGs in EEC.

Zinc-finger protein 750 mitigates malignant biological behavior of oral CSC-like cells enriched from parental CAL-27 cells

Oral squamous cell carcinoma (OSCC) is the most commonly occurring oral malignancy. Cancer stem cells (CSCs) are known to be responsible for cancer recurrence and metastasis. Zinc-finger protein 750 (ZNF750) has been reported to inhibit OSCC cell proliferation and invasion. The present study aimed to elucidate the role of ZNF750 in the inhibition of the renewal ability of CSCs derived from the OSCC cell line, CAL-27. The effects of ZNF750 on CSC-like properties were examined using aldehyde dehydrogenase (ALDH), tumor sphere formation and colony formation assays. Reverse transcription-quantitative PCR and western blotting were performed to detect the expression levels of octamer-binding transcription factor 4, sex-determining region Y-box 2, the enhancer of zeste homolog 2 (Ezh2), embryonic ectoderm development (EED) and SUZ12 polycomb repressive complex 2 subunit (SUZ12), and for the identification of genes associated with metastasis. ZNF750 effectively attenuated CSC-like cell self-renewal abilities; ZNF750 decreased the ALDH-positive cell population, tumor sphere and colony formation abilities, cell viability and stemness factors. Furthermore, the expression levels of Ezh2, EED and SUZ12 were decreased by ZNF750. ZNF750 inhibited MMP1, 3, 9 and 13 expression levels, and decreased the cell invasion and migratory abilities. Moreover, the expression of tissue inhibitors of matrix metalloproteinases-1 was increased by ZNF750. However, opposite effects were observed following the knockdown of the ZNF750 gene. Overall, the present study demonstrated that ZNF750 has the potential to inhibit the renewal of CSC-like cells enriched from parental CAL-27 cells.

SOX2 maintains the stemness of retinoblastoma stem-like cells through Hippo/YAP signaling pathway

PURPOSE

To explore the mechanisms underlying stemness maintenance of retinoblastoma (RB) stem cells (RSCs).

METHODS

The retinoblastoma stem-like cells (RSLCs) were isolated by single cell cloning in combination of examination of sphere-forming capacities. The stemness of the cells were characterized by the sphere-forming capacity and the expression levels of RSCs markers. Gene manipulation was performed by lentivirus system. Transcriptional regulation was identified by qRT-PCR, luciferase reporter, nuclear run-on and DNA pull-down assay. Spearman analysis was employed for correlation analysis of genes in tumor tissues of RB patients.

RESULTS

The isolated RSLCs exhibited enhanced sphere-forming capacity and constantly higher levels of CD44, ABCG2, SOX2 and PAX6, but not CD133. SOX2 positively regulated the stemness of RSLCs. SOX2 directly binds to the promoters of WWTR1 and YAP and transcriptionally activates WWTR1 and YAP. Knockdown of WWTR1 or YAP partially abolished the effect of SOX2 on the stemness of RSLCs.

CONCLUSIONS

SOX2, as a key deriver, maintains RB stemness by activating Hippo/YAP signaling. Inhibition of Hippo/YAP signaling would be an effective strategy for human RB caused by SOX2 upregulation.

Induction of Apoptosis in Human Pancreatic Cancer Stem Cells by the Endoplasmic Reticulum-Targeted Alkylphospholipid Analog Edelfosine and Potentiation by Autophagy Inhibition

Pancreatic cancer is one of the most lethal malignancies with a poor and gloomy prognosis and the highest mortality-to-incidence ratio. Pancreatic cancer remains an incurable malignancy, and current therapies are ineffective. We isolated cancer stem cells (CSCs) from the human PANC-1 pancreatic cancer cell line as CD44⁺CD24⁺EpCAM⁺ cells. These CSCs form pancreatic cancer spheres or spheroids and develop tumors in SCID mice after subcutaneous injection of as few as 100 cells per mouse. Here, we found that the alkylphospholipid analog edelfosine inhibited CSC pancreatic cancer spheroid formation and induced cell death, as assessed by an increase in the percentage of cells in the sub-G₀/G₁ region by means of flow cytometry, indicative of DNA breakdown and apoptosis. This correlated with an increase in caspase-3 activity and PARP breakdown, as a major substrate of caspase-3, following PANC-1 CSC treatment with edelfosine. The antitumor ether lipid edelfosine colocalized with the endoplasmic reticulum in both PANC-1 cells as well as PANC-1 CSCs by using a fluorescent edelfosine analog, and induced an endoplasmic reticulum stress response in both PANC-1 cells and PANC-1 CSCs, with a potent CHOP/GADD153 upregulation. Edelfosine elicited a strong autophagy response in both PANC-1 cells and PANC-1 CSCs, and preincubation of CSCs with autophagy inhibitors, chloroquine or bafilomycin A1, enhanced edelfosine-induced apoptosis. Primary cultures from pancreatic cancer patients were sensitive to edelfosine, as well as their respective isolated CSCs. Nontumorigenic pancreatic human cell line HPNE and normal human fibroblasts were largely spared. These data suggest that pancreatic CSCs isolated from established cell lines and pancreatic cancer patients are sensitive to edelfosine through its accumulation in the endoplasmic reticulum and induction of endoplasmic reticulum stress.

LncRNA DUXAP10 Upregulation and the Hedgehog Pathway Activation Are Critically Involved in Chronic Cadmium Exposure-Induced Cancer Stem Cell-Like Property

Cadmium (Cd) is a well-known lung carcinogen. However, the mechanism of Cd carcinogenesis remains to be clearly defined. Cd has been shown to act as a weak mutagen, suggesting that it may exert tumorigenic effect through nongenotoxic ways, such as epigenetic mechanisms. Long noncoding RNAs (lncRNAs) refer to RNA molecules that are longer than 200 nucleotides in length but lack protein-coding capacities. Regulation of gene expressions by lncRNAs is considered as one of important epigenetic mechanisms. The goal of this study is to investigate the mechanism of Cd carcinogenesis focusing on the role of lncRNA dysregulations. Cd-induced malignant transformation of human bronchial epithelia BEAS-2B cells was accomplished by a 9-month low-dose Cd (CdCl2, 2.5 µM) exposure. The Cd-exposed cells formed significantly more colonies in soft agar, displayed cancer stem cell (CSC)-like property, and formed tumors in nude mice. Mechanistically, chronic low-dose Cd exposure did not cause significant genotoxic effects but dysregulated lncRNA expressions. Further Q-PCR analysis confirmed the significant upregulation of the oncogenic lncRNA DUXAP10 in Cd-transformed cells. DUXAP10 knockdown in Cd-transformed cells significantly reduced their CSC-like property. Further mechanistic studies showed that the Hedgehog pathway is activated in Cd-transformed cells and inhibition of this pathway reduces Cd-induced CSC-like property. DUXAP10 knockdown caused the Hedgehog pathway inactivation in Cd-transformed cells. Furthermore, Pax6 expression was upregulated in Cd-transformed cells and Pax6 knockdown significantly reduced their DUXAP10 levels and CSC-like property. In summary, these findings suggest that the lncRNA DUXAP10 upregulation may play an important role in Cd carcinogenesis.

The multiple faces of NANOG in cancer: a therapeutic target to chemosensitize therapy-resistant cancers

The transcription factor NANOG regulates self-renewal and pluripotency in embryonic cells, and its downregulation leads to cell differentiation. Recent studies have linked upregulation of NANOG in various cancers and the regulation of expression of different molecules, and vice versa, to induce proliferation, metastasis, invasion and chemoresistance. Thus NANOG is an oncogene that functions by inducing stem cells' circuitries and heterogeneity in cancers. Understanding NANOG's role in various cancers may lead to it becoming a therapeutic target to halt cancer progression. The NANOG network can also be targeted to resensitize resistant cancer cells to conventional therapies. The current review focuses on NANOG regulation in the various signaling networks leading to cancer progression and chemoresistance, and highlights the therapeutic aspect of targeting NANOG in various cancers.

No Need to Stick Together to Be Connected: Multiple Types of Enhancers' Networking

Simple Summary

Transcription regulation programs require the functional interaction of distal and proximal regulatory regions, interacting by specific 3D chromatin configurations. Enhancers are cis-acting regulatory elements able to promote gene expression regardless their orientation and distance from the transcription starting site. Their systematic mapping by genome-wide chromatin profiling and chromosome conformation analysis, combined with the development of gene-editing approaches to modulate their function, revealed that many enhancers work together to fine-tune the expression of their target genes. This review aim to describe the functions of different types of enhancers and the modalities of enhancers’ interaction, focusing on their role in the regulation of complex biological processes like cancer development.

Abstract

The control of gene expression at a transcriptional level requires a widespread landscape of regulatory elements. Central to these regulatory circuits are enhancers (ENHs), which are defined as cis-acting DNA elements able to increase the transcription of a target gene in a distance- and orientation-independent manner. ENHs are not independent functional elements but work in a complex and dynamic cooperative network, constituting the building blocks of multimodular domains of gene expression regulation. The information from each of these elements converges on the target promoter, contributing to improving the precision and sharpness of gene modulation. ENHs’ interplay varies in its nature and extent, ranging from an additive to redundant effect depending on contexts. Moving from super-enhancers that drive the high expression levels of identity genes, to shadow-enhancers, whose redundant functions contribute to buffering the variation in gene expression, this review aims to describe the different modalities of ENHs’ interaction and their role in the regulation of complex biological processes like cancer development.

Heterogeneous distribution of PD-L1 expression in the IASLC/ATS/ERS classification of lung adenocarcinoma

BACKGROUND

PD-L1 expression in tumor cells can predict the efficacy of PD-1/PD-L1 inhibitors and prognosis in patients. However, the correlation between the PD-L1 expression and the novel lung adenocarcinoma classification are obscure.

METHODS

94 lung adenocarcinoma cases were reviewed in the Third Affiliated Hospital of Soochow University from January to December 2019. PD-L1 (DAKO 22C3) was used to test the PD-L1 expression in lung cancer tissue.

RESULT

TPS was used to interpret the PD-L1 expression. The negative, low positive and high positive of PD-L1 were 52 cases (55.30%), 29 cases (30.90%) and 13 cases (13.80%). The subtype ratio of acinar, lepidic and solid in adenocarcinoma were correlation with the PD-L1 TPS (r =  - 0.37, P < 0.001; r =  - 0.22, P = 0.013; r = 0.68, P < 0.001). The results of χ² test showed the PD-L1 expression had the significant difference with gender (P = 0.027), age (P = 0.018), smoking history (P = 0.021), lymph node metastasis (P = 0.001), TNM stage (P = 0.002), acinar structure (P = 0.017) and solid structure (P < 0.001). Multi-factor linear regression results suggested that solid structure, TNM stage and smoking history were associated with PD-L1 expression (P < 0.05). The solid structure showed more capability to PD-L1 expression (β = 0.398).

CONCLUSION

PD-L1 expression was heterogeneity in lung adenocarcinoma. The solid structure, TNM stage and smoking history were correlation to up-regulation of PD-L1 expression, and solid structure was the most importance factor.

Oncogenic PAX6 elicits CDK4/6 inhibitor resistance by epigenetically inactivating the LATS2-Hippo signaling pathway

Intrinsic resistance to CDK4/6 inhibitors hinders their clinical utility in cancer treatment. Furthermore, the predictive markers of CDK4/6 inhibitors in gastric cancer (GC) remain incompletely described. Here, we found that PAX6 expression was negatively correlated with the response to palbociclib in vitro and in vivo in GC. We observed that the PAX6 expression level was negatively correlated with the overall survival of GC patients and further showed that PAX6 can promote GC cell proliferation and the cell cycle. The cell cycle is regulated by the interaction of cyclins with their partner serine/threonine cyclin-dependent kinases (CDKs), and the G1/S-phase transition is the main target of CDK4/6 inhibitors. Therefore, we tested whether PAX6 expression was correlated with the GC response to palbociclib. We found that PAX6 hypermethylates the promoter of LATS2 and inactivates the Hippo pathway, which upregulates cyclin D1 (CCND1) expression. This results in a suppressed response to palbociclib in GC. Furthermore, we found that the induction of the Hippo signaling pathway or treatment with a DNA methylation inhibitor could overcome PAX6-induced palbociclib resistance in GC. These findings uncover a tumor promoter function of PAX6 in GC and establish overexpressed PAX6 as a mechanism of resistance to palbociclib.

JARID2 promotes stemness and cisplatin resistance in non-small cell lung cancer via upregulation of Notch1

Increased stemness is causally linked to development of drug resistance in cancers. JARID2 is a member of the Jumonji family of proteins and regulates differentiation of embryonic stem cells. However, the role of JARID2 in lung cancer stemness and drug resistance is still unclear. In this study, we investigated the expression of JARID2 in parental and cisplatin (CDDP) resistant non-small cell lung cancer (NSCLC) cells. The function of JARID2 in modulating CDDP sensitivity of NSCLC cells was determined. It was found that JARID2 is upregulated in CDDP resistant NSCLC cells, which depends on SOX2 expression. JARID2 overexpression promotes CDDP resistance in NSCLC cells, whereas JARID2 depletion restores CDDP sensitivity in CDDP resistant NSCLC cells. Moreover, JARID2 overexpression enhances cancer stem cell-like properties in NSCLC cells, which is coupled with increased expression of cancer stem cell markers. Mechanistically, JARID2-induced stemness and CDDP resistance is mediated by upregulation of Notch1. In clinical settings, high expression of JARID2 is significantly associated with advanced TNM stage, shorter overall survival, and poor chemotherapeutic response. These findings point toward an important role of JARID2 in CDDP resistance and stemness of NSCLC and provide a promising target for overcoming CDDP resistance.

Exploring Potential Carcinogenic Activity of Per- and Polyfluorinated Alkyl Substances Utilizing High-Throughput Toxicity Screening Data

Per- and polyfluorinated alkyl substances (PFAS) are ubiquitous, persistent, and toxic chemicals that pose public health risks. Recent carcinogenicity concerns have arisen based on epidemiological studies, animal tumor findings, and mechanistic data. Thousands of PFAS exist; however, current understanding of their toxicity is informed by studies of a select few, namely, perfluorooctanoic acid and perfluorooctanesulfonic acid. Hence, the computational, high-throughput screening tool, the US EPA CompTox Chemical Dashboard's ToxCast, was utilized to explore the carcinogenicity potential of PFAS. Twenty-three major PFAS that had sufficient in vitro ToxCast data and covered a range of structural subclasses were analyzed with the visual analytics software ToxPi, yielding a qualitative and quantitative assessment of PFAS activity in realms closely linked with carcinogenicity. A comprehensive literature search was also conducted to check the consistency of analyses with other mechanistic data streams. The PFAS were found to induce a vast range of biological perturbations, in line with several of the International Agency for Research on Cancer-defined key carcinogen characteristics. Patterns observed varied by length of fluorine-bonded chains and/or functional group within and between each key characteristic, suggesting some structure-based variability in activity. In general, the major conclusions drawn from the analysis, that is, the most notable activities being modulation of receptor-mediated effects and induction of oxidative stress, were supported by literature findings. The study helps enhance understanding of the mechanistic pathways that underlie the potential carcinogenicity of various PFAS and hence could assist in hazard identification and risk assessment for this emerging and relevant class of environmental toxicants.

An integrated epigenomic-transcriptomic landscape of lung cancer reveals novel methylation driver genes of diagnostic and therapeutic relevance

Background: Aberrant DNA methylation occurs commonly during carcinogenesis and is of clinical value in human cancers. However, knowledge of the impact of DNA methylation changes on lung carcinogenesis and progression remains limited.

Methods: Genome-wide DNA methylation profiles were surveyed in 18 pairs of tumors and adjacent normal tissues from non-small cell lung cancer (NSCLC) patients using Reduced Representation Bisulfite Sequencing (RRBS). An integrated epigenomic-transcriptomic landscape of lung cancer was depicted using the multi-omics data integration method.

Results: We discovered a large number of hypermethylation events pre-marked by poised promoter in embryonic stem cells, being a hallmark of lung cancer. These hypermethylation events showed a high conservation across cancer types. Eight novel driver genes with aberrant methylation (e.g., PCDH17 and IRX1) were identified by integrated analysis of DNA methylome and transcriptome data. Methylation level of the eight genes measured by pyrosequencing can distinguish NSCLC patients from lung tissues with high sensitivity and specificity in an independent cohort. Their tumor-suppressive roles were further experimentally validated in lung cancer cells, which depend on promoter hypermethylation. Similarly, 13 methylation-driven ncRNAs (including 8 lncRNAs and 5 miRNAs) were identified, some of which were co-regulated with their host genes by the same promoter hypermethylation. Finally, by analyzing the transcription factor (TF) binding motifs, we uncovered sets of TFs driving the expression of epigenetically regulated genes and highlighted the epigenetic regulation of gene expression of TCF21 through DNA methylation of EGR1 binding motifs.

Conclusions: We discovered several novel methylation driver genes of diagnostic and therapeutic relevance in lung cancer. Our findings revealed that DNA methylation in TF binding motifs regulates target gene expression by affecting the binding ability of TFs. Our study also provides a valuable epigenetic resource for identifying DNA methylation-based diagnostic biomarkers, developing cancer drugs for epigenetic therapy and studying cancer pathogenesis.

LncRNA SNHG17 promotes the progression of oral squamous cell carcinoma by modulating miR-375/PAX6 axis

BACKGROUND

The prognosis of patients with recurrent and/or metastatic oral squamous cell carcinoma (OSCC) remains poor, and its incidence is especially high in developing countries. Multiple long non-coding RNAs (lncRNAs) are recently identified as crucial oncogenic factors or tumor suppressors. This study aimed to probe into the role of lncRNA small nucleolar RNA host gene 17 (SNHG17) on the progression of OSCC.

METHODS

The expression level of SNHG17 in OSCC samples was tested using quantitative real-time polymerase chain reaction (qRT-PCR). Human OSCC cell lines CAL-27 and Tca8113 were used in in vitro studies. Cell counting kit-8 (CCK-8) and BrdU assays were used to assess the effect of SNHG17 on OSCC cell proliferation. Flow cytometry was used to study the effect of SNHG17 on OSCC cell apoptosis. Transwell assay was conducted to detect the effect of SNHG17 on migration and invasion. Moreover, luciferase reporter assay was employed to confirm targeting relationship between miR-375 and SNHG17. Additionally, Western blot was used to observe the regulatory function of SNHG17 on PAX6.

RESULTS

SNHG17 expression in OSCC clinical samples was significantly increased and was correlated with unfavorable pathological indexes. Its overexpression remarkably accelerated proliferation and metastasis of OSCC cells, while reduced apoptosis. Accordingly, knockdown of SNHG17 suppressed the malignant phenotypes of OSCC cells. Overexpression of SNHG17 significantly reduced the expression of miR-375 by sponging it, but enhanced the expression of PAX6.

CONCLUSION

SNHG17 is a sponge of tumor suppressor miR-375 in OSCC, enhances the expression of PAX6 indirectly, and functions as an oncogenic lncRNA.

Scutellariabarbata D. Don extraction selectively targets stemness-prone NSCLC cells by attenuating SOX2/SMO/GLI1 network loop

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellariabarbata D. Don extraction (SBE), a traditional Chinese medicine, has been proved effective against various malignant disorders in clinics with tolerable side-effects when administered alone or in combination with conventional chemotherapeutic regimens.

AIM OF THIS STUDY

Multi-drug resistance of cancer is attributed to existence of cancer stemness-prone cells that harbor aberrantly high activation of Sonic Hedgehog (SHH) cascade. Our previous study has demonstrated that SBE sensitized non-small cell lung cancer (NSCLC) cells to Cisplatin (DDP) treatment by downregulating SHH pathway. Yet, whether SBE could prohibit proliferation of cancer stemness-prone cells and its underlying molecular mechanisms remain to be investigated. In this article, we further investigated intervention of SBE on NSCLC cell stemness-associated phenotypes and its potential mode of action.

MATERIALS AND METHODS

CCK-8 and clonal formation detection were used to measure the anti-proliferative potency of SBE against NSCLC and normal epithelial cells. Sphere formation assay and RQ-PCR were used to detect proliferation of cancer stemness cells and associated marker expression upon SBE incubation. Mechanistically, DARTS-WB and SPR were used to unveil binding target of SBE. Immunodeficient mice were implanted with patient derived tumor bulk for in vivo validation of anti-cancer effect of SBE.

RESULTS

SBE selectively attenuated proliferation and stemness-like phenotypes of NSCLC cells rather than bronchial normal epithelial cells. Drug-protein interaction analysis revealed that SBE could directly bind with stem cell-specific transcription factor sex determining region Y-box 2 (SOX2) and interfere with the SOX2/SMO/GLI1 positive loop. In vivo assay using patient-derived xenografts (PDXs) model further proved that SBE diminished tumor growth and SOX2 expression in vivo.

CONCLUSION

Our data indicate that SBE represses stemness-related features of NSCLC cells via targeting SOX2 and may serve as an alternative therapeutic option for clinic treatment.

E2F1-induced ferritin heavy chain 1 pseudogene 3 (FTH1P3) accelerates non-small cell lung cancer gefitinib resistance

Long noncoding RNAs (lncRNAs) have been identified to be critical regulator for various human diseases and emerging evidence illustrate the essential function of lncRNAs in the non-small cell lung cancer (NSCLC). Here, our research team tried to identify the roles of lncRNA ferritin heavy chain 1 pseudogene 3 (FTH1P3) in the NSCLC, as well as its molecular mechanism. LncRNA microarray analysis revealed that ferritin heavy chain 1 pseudogene 3 (FTH1P3) was up-regulated in the gefitinib-resistant cells (PC9/GR). Clinically, lncRNA FTH1P3 high-expression was closely correlated with NSCLC patients' unfavorable prognosis. Gain and loss of functional experiments revealed that FTH1P3 promoted the proliferation and invasion of NSCLC cells in vitro, and FTH1P3 knockdown repressed the tumor growth in vivo. Mechanistically, transcription factor E2F1 accelerated the transcription of FTH1P3. RNA immunoprecipitation and chromatin immunoprecipitation experiments showed that FTH1P3 can recruit lysine-specific demethylase 1 (LSD1) and epigenetically repress the TIMP3, thereby accelerating the tumorigenesis of NSCLC. In summary, these findings suggest that FTH1P3 plays a critical role in the gefitinib resistance and progression of NSCLC, providing a potential novel prognostic marker for NSCLC.

Arsenic trioxide inhibits the growth of cancer stem cells derived from small cell lung cancer by downregulating stem cell-maintenance factors and inducing apoptosis via the Hedgehog signaling blockade

Background

Small cell lung cancer (SCLC) is the most deadly and aggressive type of primary lung cancer, with the 5-year survival rate lower than 5%. The FDA has approved arsenic trioxide (As₂O₃) for acute promyelocytic leukemia (APL) treatment. However, its role in SCLC-derived cancer stem cells (CSCs) remains largely unknown.

Methods

CSCs were enriched from SCLC cell lines by culturing them as spheres in conditioned serum-free medium. Then, qPCR, western blot, serial passage, limiting dilution, Transwell, and tumorigenesis assay were performed to verify the cells' stem phenotypic characteristics. Anticancer efficiency of As₂O₃ was assessed in these cells using CCK8, colony formation, sphere formation, flow cytometry, qPCR, western blot analysis in vitro, and tumor growth curve, immunofluorescence, and TUNEL staining analyses in vivo.

Results

The fifth-passage SCLC spheres showed a potent self-renewal capacity, higher clonal formation efficiency (CFE), SOX2, c-Myc, NANOG, and OCT4 levels, and invasion ability, and stronger tumorigenesis capacity than the parental SCLC cells, indicating that the SCLC sphere cells displayed CSC features. As₂O₃ inhibited the proliferation, clonality and sphere forming ability of SCLC-derived CSCs and suppressed the tumor growth of CSCs-derived xenograft tumors. As₂O₃ induced apoptosis and downregulation of SOX2 and c-Myc in vitro and in xenografts. Besides, SOX2 knockdown suppressed SCLC-derived CSCs to self-renew and induced apoptosis. Mechanistically, expression of GLI1 (a key transcription factor of Hedgehog pathway) and its downstream genes increased in SCLC-derived CSCs, compared to the parental cells. As₂O₃ dramatically downregulated GLI1 and its downstream genes in vitro and in vivo. The GLI inhibitor (GANT-61) recapitulated and enhanced the effects of As₂O₃ on SCLC-derived CSCs, including growth suppression, apoptosis induction, and GLI1, SOX2 and c-Myc downregulation.

Conclusions

Altogether, As₂O₃ effectively suppressed SCLC-derived CSCs growth by downregulating stem cell-maintenance factors and inducing apoptosis. These effects are mediated at least partly via the Hedgehog signaling blockade.

Identification and validation of novel DNA methylation markers for early diagnosis of lung adenocarcinoma

Lung cancer has the highest mortality of all cancers worldwide. Epigenetic alterations have emerged as potential biomarkers for early diagnosis of various cancer tissue types. To identify methylation markers for early diagnosis of lung adenocarcinoma, we aimed to integrate genome‐wide DNA methylation and gene expression data from The Cancer Genome Atlas. To this end, we first examined the global DNA methylation pattern of lung adenocarcinoma and investigated the relationship between DNA methylation subtypes and clinical features. We then extracted differentially methylated and expressed genes, and adopted feature selection techniques to determine the final methylation markers. The performance of the markers in predicting lung adenocarcinoma was evaluated on three independent datasets from Gene Expression Omnibus. Protein levels of marker genes were validated by immunohistochemistry, and their biological function was further verified in vivo. We identified three novel methylation markers in lung adenocarcinoma including cg08032924, cg14823851, and cg19161124, mapping to CMTM2, TBX4, and DPP6, respectively. Validating these results on three independent datasets indicated that the three markers can achieve extremely high sensitivity and specificity in distinguishing lung adenocarcinoma from normal samples. Immunohistochemistry quantification results confirmed that markers are weakly expressed in human lung adenocarcinoma, and CMTM2 decreased tumor growth of mouse Lewis lung carcinoma in vivo. Overall, our study identified three novel methylation markers in lung adenocarcinoma which may contribute toward an improved diagnosis potentially leading to a better outcome for patients with lung adenocarcinoma.

LINC01619 promotes non-small cell lung cancer development via regulating PAX6 by suppressing microRNA-129-5p

This article explored LINC01619 impact on non-small cell lung cancer (NSCLS) development. LINC01619 expression in tumor tissues/normal tissues of NSCLS patients was detected by qRT-PCR and in situ hybridization. PAX6 expression in clinical tissues was researched by immunohistochemistry. After transfection, SPCA1 and A549 cells were subjected to CCK-8 assay and cell colony formation experiment. Xenograft tumor experiment was conducted. ALDH⁺ cells from SPCA1 and A549 cells were separated and transfected. ALDH⁺ cells percentage, sphere number and cancer stem cell markers expression was determined by flow cytometry, sphere culture and Western blot respectively. Luciferase reporter gene assay and RNA binding protein immunoprecipitation assay was conducted. The colocalization of LINC01619 and miR-129-5p in cells was determined by RNA fluorescence in situ hybridization experiment. Gene expression in tissues and cells were assessed by qRT-PCR and Western blot. As a result, aberrantly up-regulated LINC01619 and PAX6 in NSCLC patients predicted poor prognosis. LINC01619 overexpression in SPCA1 cells enhanced cell viability, cloning ability, and xenograft tumors volume and weigh, whereas LINC01619 silencing in A549 cells weakened the above indicators. LINC01619 overexpression promoted cancer stem cells characteristics including increasing percentage of ALDH⁺ cells, sphere number and cancer stem cell markers expression. LINC01619 directly inhibited miR-129-5p and the two genes were mainly colocalized in the cytoplasm. PAX6 was up-regulated in NSCLC and directly suppressed by miR-129-5p. LINC01619 promoted cells viability, cloning ability and cancer stem cells characteristics in NSCLC via the miR-129-5p/PAX6 axis. Thus, LINC01619 promotes NSCLC development via regulating PAX6 by suppressing miR-129-5p.

PAX6 contributes to the activation and proliferation of hepatic stellate cells via activating Hedgehog/GLI1 pathway

Aberrant activation of Hedgehog signaling is considered as the key player in hepatic stellate cell (HSC) activation involved in liver fibrosis (LF). The glioma-associated protein gene (GLI) has a predicted paired box 6 (PAX6)-binding site within its transcribed region. Therefore, this study aimed to investigate the relationship between PAX6 and GLI and their contribution to HSC activation and proliferation. PAX6 expression was upregulated in platelet-derived growth factor-BB (PDGF-BB)-induced LX-2 cells. The activation and proliferation of HSC were inhibited by interference of PAX6 with short hairpin RNA (shPAX6) via curbing Hedgehog signaling. Notably, PAX6 directly bound to the promoter sequence of GLI1 independent of the PTCH/SMO axis. Therefore, we propose that PAX6 upregulation induces HSC activation and proliferation through crosstalk with GLI1 signaling. Thus, these novel mechanistic insights involving the PAX6-mediated regulation of the activation and proliferation of HSC may provide a new therapeutic target for LF.

An evolving paradigm of cancer stem cell hierarchies: therapeutic implications

Over a decade of research has confirmed the critical role of cancer stem-like cells (CSCs) in tumor initiation, chemoresistance, and metastasis. Increasingly, CSC hierarchies have begun to be defined with some recurring themes. This includes evidence that these hierarchies are 'flexible,' with both cell state transitions and dedifferentiation events possible. These findings pose therapeutic hurdles and opportunities. Here, we review cancer stem cell hierarchies and their interactions with the tumor microenvironment. We also discuss the current therapeutic approaches designed to target CSC hierarchies and initial clinical trial results for CSC targeting agents. While cancer stem cell targeted therapies are still in their infancy, we are beginning to see encouraging results that suggest a positive outlook for CSC-targeting approaches.

Lactate-fueled oxidative metabolism drives DNA methyltransferase 1-mediated transcriptional co-activator with PDZ binding domain protein activation

Activity of transcriptional co‐activator with PDZ binding domain (TAZ) protein is strongly implicated in the pathogenesis of human cancer and is influenced by tumor metabolism. High levels of lactate concentration in the tumor microenvironment as a result of metabolic reprogramming are inversely correlated with patient overall survival. Herein, we investigated the role of lactate in the regulation of the activity of TAZ and showed that glycolysis‐derived lactate efficiently increased TAZ expression and activity in lung cancer cells. We showed that the reactive oxygen species (ROS) generated by lactate‐fueled oxidative phosphorylation (OXPHOS) in mitochondria activated AKT and thereby inhibited glycogen synthase kinase 3 beta/beta‐transducin repeat‐containing proteins (GSK‐3β/β‐TrCP)‐mediated ubiquitination and degradation of DNA methyltransferase 1 (DNMT1). Upregulation of DNMT1 by lactate caused hypermethylation of TAZ negative regulator of the LATS2 gene promoter, leading to TAZ activation. Moreover, TAZ binds to the promoter of DNMT1 and is necessary for DNMT1 transcription. Our study showed a molecular mechanism of DNMT1 in linking tumor metabolic reprogramming to the Hippo‐TAZ pathway and functional significance of the DNMT1‐TAZ feedback loop in the migratory and invasive potential of lung cancer cells.

Treating tumors with minimally invasive therapy: A review

With high level of morbidity and mortality, tumor is one of the deadliest diseases worldwide. Aiming to tackle tumor, researchers have developed a lot of strategies. Among these strategies, the minimally invasive therapy (MIT) is very promising, for its capability of targeting tumor cells and resulting in a small incision or no incisions. In this review, we will first illustrate some mechanisms and characteristics of tumor metastasis from the primary tumor to the secondary tumor foci. Then, we will briefly introduce the history, characteristics, and advantages of some of the MITs. Finally, emphasis will be, respectively, focused on an overview of the state-of-the-art of the HIFU-, PDT-, PTT-and SDT-based anti-tumor strategies on each stage of tumor metastasis.

Targeting Cancer Stem Cells: A Strategy for Effective Eradication of Cancer

Cancer stem cells (CSCs) are subpopulations of tumor cells with the ability to self-renew, differentiate, and initiate and maintain tumor growth, and they are considered to be the main drivers of intra- and inter-tumoral heterogeneity. While conventional chemotherapy can eradicate the majority of non-CSC tumor cells, CSCs are often drug-resistant, leading to tumor recurrence and metastasis. The heterogeneity of CSCs is the main challenge in developing CSC-targeting therapy; therefore, we and other investigators have focused on developing novel therapeutic strategies that combine conventional chemotherapy with inhibitors of CSC-regulating pathways. Encouraging preclinical findings have suggested that CSC pathway blockade can indeed enhance cellular sensitivity to non-targeted conventional therapy, and this work has led to several ongoing clinical trials of CSC pathway inhibitors. Our studies in bladder cancer and lung adenocarcinoma have demonstrated a crucial role of YAP1, a transcriptional regulator of genes that promote cell survival and proliferation, in regulating CSC phenotypes. Moreover, using cell lines and patient-derived xenograft models, we showed that inhibition of YAP1 enhances the efficacy of conventional therapies by attenuating CSC stemness features. In this review, we summarize the therapeutic strategies for targeting CSCs in several cancers and discuss the potential and challenges of the approach.