Tumor suppressive BTB/POZ zinc-finger protein ZBTB28 inhibits oncogenic BCL6/ZBTB27 signaling to maintain p53 transcription in multiple carcinogenesis

LASS2 suppresses metastasis in multiple cancers by regulating the ferroptosis signalling pathway through interaction with TFRC

BACKGROUND

As a key enzyme in ceramide synthesis, longevity assurance homologue 2 (LASS2) has been indicated to act as a tumour suppressor in a variety of cancers. Ferroptosis is involved in a variety of tumour processes; however, the role of LASS2 in regulating ferroptosis has yet to be explored. This article explores the potential underlying mechanisms involved.

METHODS

Bioinformatics tools and immunohistochemical staining were used to evaluate LASS2 expression, and the results were analysed in relation to overall survival and clinical association in multiple cancers. Coimmunoprecipitation-coupled liquid chromatography-mass spectrometry (co-IP LC-MS) was performed to identify potential LASS2-interacting proteins in thyroid, breast, and liver cancer cell lines. Transcriptomics, proteomics and metabolomics analyses of multiple cancer cell types were performed using MS or LC-MS to further explore the underlying mechanisms involved. Among these tumour cells, the common LASS2 interaction partner transferrin receptor (TFRC) was analysed by protein-protein docking and validated by coimmunoprecipitation western blot, immunofluorescence, and proximity ligation assays. Then, we performed experiments in which tumour cells were treated with Fer-1 or erastin or left untreated, with or without inducing LASS2 overexpression, and assessed the molecular biological and cellular functions by corresponding analyses.

RESULTS

Low LASS2 expression is correlated with adverse clinical characteristic and poor prognosis in patients with thyroid cancer, breast cancer or HCC. Multiomics analyses revealed significant changes in the ferroptosis signalling pathway, iron ion transport and iron homeostasis. Our in vitro experiments revealed that LASS2 overexpression regulated ferroptosis status in these tumour cells by affecting iron homeostasis, which in turn inhibited tumour migration, invasion and EMT. In addition, LASS2 overexpression reversed the changes in tumour cell metastasis induced by either Fer-1 or erastin. Mechanistically, LASS2 interacts directly with TFRC to regulate iron homeostasis in these tumour cells.

CONCLUSIONS

In summary, our study reveals for the first time that LASS2 can inhibit tumour cell metastasis by interacting with TFRC to regulate iron metabolism and influence ferroptosis status in thyroid, breast, and liver cancer cells, these results suggest potential universal therapeutic targets for the treatment of these cancers.

Zinc finger protein 831 promotes apoptosis and enhances chemosensitivity in breast cancer by acting as a novel transcriptional repressor targeting the STAT3/Bcl2 signaling pathway

Emerging evidence suggested that zinc finger protein 831 (ZNF831) was associated with immune activity and stem cell regulation in breast cancer. Whereas, the roles and molecular mechanisms of ZNF831 in oncogenesis remain unclear. ZNF831 expression was significantly diminished in breast cancer which was associated with promoter CpG methylation but not mutation. Ectopic over-expression of ZNF831 suppressed breast cancer cell proliferation and colony formation and promoted apoptosis in vitro, while knockdown of ZNF831 resulted in an opposite phenotype. Anti-proliferation effect of ZNF831 was verified in vivo. Bioinformatic analysis of public databases and transcriptome sequencing both showed that ZNF831 could enhance apoptosis through transcriptional regulation of the JAK/STAT pathway. ChIP and luciferase report assays demonstrated that ZNF831 could directly bind to one specific region of STAT3 promoter and induce the transcriptional inhibition of STAT3. As a result, the attenuation of STAT3 led to a restraint of the transcription of Bcl2 and thus accelerated the apoptotic progression. Augmentation of STAT3 diminished the apoptosis-promoting effect of ZNF831 in breast cancer cell lines. Furthermore, ZNF831 could ameliorate the anti-proliferation effect of capecitabine and gemcitabine in breast cancer cell lines. Our findings demonstrate for the first time that ZNF831 is a novel transcriptional suppressor through inhibiting the expression of STAT3/Bcl2 and promoting the apoptosis process in breast cancer, suggesting ZNF831 as a novel biomarker and potential therapeutic target for breast cancer patients.

Transcription Factor Zbtb20 as a Regulator of Malignancy and Its Practical Applications

Zbtb20 (zinc finger and BTB domain-containing protein 20) is a transcription factor with a zinc finger DNA binding domain and a BTB domain responsible for protein-protein interaction. Recently, this TF has received attention because new data showed its pivotal involvement in normal neural development and its regulatory effects on proliferation and differentiation in different tissues. Zbtb20 was shown to increase proliferation and migration and confer resistance to apoptosis in the contexts of many malignant tumors like hepatocellular carcinoma, non-small-cell lung carcinoma, gastric adenocarcinoma, glioblastoma multiforme, breast cancer, and acute myeloid leukemia. The involvement of Zbtb20 in tumor biology is best studied in hepatocellular carcinoma, where it is a promising candidate as an immunohistochemical tumor marker or may be used in patient screening. Here we review the current data connecting Zbtb20 with malignant tumors.

ZBTB40 is a telomere-associated protein and protects telomeres in human ALT cells

Alternative lengthening of telomeres (ALTs) mechanism is activated in some somatic, germ cells, and human cancer cells. However, the key regulators and mechanisms of the ALT pathway remain elusive. Here we demonstrated that ZBTB40 is a novel telomere-associated protein and binds to telomeric dsDNA through its N-terminal BTB (BR-C, ttk and bab) or POZ (Pox virus and Zinc finger) domain in ALT cells. Notably, the knockout or knockdown of ZBTB40 resulted in the telomere dysfunction-induced foci and telomere lengthening in the ALT cells. The results also show that ZBTB40 is associated with ALT-associated promyelocytic leukemia nuclear bodies, and the loss of ZBTB40 induces the accumulation of the ALT-associated promyelocytic leukemia nuclear bodies in U2OS cells. Taken together, our results implicate that ZBTB40 is a key player of telomere protection and telomere lengthening regulation in human ALT cells.

Identification of ZBTB9 as a potential therapeutic target against dysregulation of tumor cells proliferation and a novel biomarker in Liver Hepatocellular Carcinoma

BACKGROUND

Zinc finger and bric-a-brac/tramtrack/broad (ZBTB) domain-containing proteins have been reported to be associated with many tumors' development. However, in tumor initiation and progression, the role of ZBTB9, one of the protein family, and its prognostic value were yet to be elucidated in Liver Hepatocellular Carcinoma (LIHC).

METHODS

We used R software and online bioinformatics analysis tools such as GEPIA2, cBioPortal, TIMER2, Metascape, UALCAN, STRING, TISIDB, and COSMIC to investigate ZBTB9's characteristics and function in LIHC, including abnormal expression, carcinogenic role, related signaling pathways and prognostic value. Furthermore, cell experiments (such as formation, wound healing, and transwell assays) and analyses based on clinical samples (such as immunohistochemistry (IHC) and promoter methylation analysis) were conducted to verify pivotal conclusions.

RESULTS

ZBTB9 was overexpressed in LIHC samples compared to adjacent normal tissues. Through the analysis of genomic alteration and promoter hypomethylation, the clinical value and etiology of abnormal expression of ZBTB9 were preliminarily exlpored. Subsequent evidence showed that it could result in tumor progression and poor prognosis via activating cell cycle, DNA repair, MYC, and KRAS-associated signaling pathways as well as rendering immune dysregulation. After the knockdown of ZBTB9, evidently inhibited capacities of tumor cells proliferation and migration were observed. These results together indicated that ZBTB9 could be a promising prognostic biomarker and had the potential value to offer novel therapeutic targets for LIHC treatment.

CONCLUSIONS

ZBTB9 was identified as a novel biomarker to predict the prognosis and tumor progression in LIHC, and a promising therapeutic target to invert tumor development.

PCDH20 inhibits esophageal squamous cell carcinoma proliferation and migration by suppression of the mitogen-activated protein kinase 9/AKT/β-catenin pathway

Aberrant protocadherins (PCDHs) expression trigger tumor invasion and metastasis. PCDH20 anti-tumor functions in various tumor have been identified. Tumor suppression is due to Wnt/β-catenin pathway antagonism and may be suppressed caused by PCDH20 downregulation through promotor methylation, whereas PCDH20 effects and regulation mechanism in esophageal squamous cell carcinoma (ESCC) remains elusive. We analyzed PCDH20 effects on ESCC and underlying action mechanisms for PCDH20. We test PCDH20 expression in ESCC tissues and cells by semi-quantitative PCR (RT-PCR) and q-PCR (real-time quantitative polymerase chain reaction). MSP (methylation-specific PCR) was carried out to assess the methylation of PCDH20 in ESCC cells and tissues. Anti-tumor effects of PCDH20 in vitro were assessed by clone formation assay, CCK8 assay, Transwell assay, and flow cytometry. Nude mice tumorigenicity was used to assess PCDH20 anti-tumor effect in vivo. Online database, qPCR, and Western blotting were used to identify the downregulation of MAP3K9 by PCDH20, associated with AKT/β-catenin signaling inactivation. We found that PCDH20 expression was dramatically attenuated in esophageal cancer tissues and cells, maybe due to promotor methylation, and ectopic PCDH20 expression suppressed ESCC malignant biological phenotypes. PCDH20 exerted anti-tumor effects by MAP3K9 downregulation, which suppressed AKT/β-catenin signaling in ESCC cells.

Conclusion

PCDH20 was a tumor suppressor gene, which antagonized AKT/β-catenin signaling pathway in ESCC by decreasing MAP3K9.

BTBD10 inhibits glioma tumorigenesis by downregulating cyclin D1 and p-Akt

The aim of this study was to investigate the role of BTBD10 in glioma tumorigenesis. The mRNA and protein levels of BTBD10 in 52 glioma tissues and eight normal brain tissues were determined using reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis, respectively. U251 human glioblastoma cells were infected with BTBD10-expressing or control lentiviruses. Cell growth was evaluated using the methyl thiazolyl tetrazolium (MTT) assay. Cell apoptosis and cell cycle distribution were analyzed using flow cytometry. Cyclin D1 and p-Akt levels were determined using western blot analysis. The results showed that BTBD10 mRNA and protein levels were significantly lower in glioma tissues than in normal brain tissues. Additionally, BTBD10 levels were significantly lower in high-grade gliomas than in low-grade tumors. Compared with control cells, U251 cells overexpressing BTBD10 exhibited decreased cell proliferation, increased cell accumulation at the G0/G1 phase, increased cell apoptosis, and decreased levels of cyclin D1 and p-Akt. These findings show that BTBD10 is downregulated in human glioma tissue and that BTBD10 expression negatively correlates with the pathological grade of the tumor. Furthermore, BTBD10 overexpression inhibits proliferation, induces G0/G1 arrest, and promotes apoptosis in human glioblastoma cells by downregulating cyclin D1- and Akt-dependent signaling pathways.

ZBTB28 inhibits breast cancer by activating IFNAR and dual blocking CD24 and CD47 to enhance macrophages phagocytosis

Breast cancer is the leading cause of cancer death in female. Until now, advanced breast cancer is still lack effective treatment strategies and reliable prognostic markers. In the present article, we introduced the physiologic and pathologic functions and regulation mechanisms of ZBTB28, a tumor suppressor gene, in breast cancer. ZBTB28 is frequently silenced in breast cancer due to promoter CpG methylation, and its expression is positively correlated with breast cancer patient survival. The antineoplastic effect of ZBTB28 in breast cancer was elucidated through a series of in vitro and in vivo measurements, including cell proliferation, apoptosis, cell cycle, epithelial mesenchymal transition (EMT), and growth of xenografts. Furthermore, ZBTB28 can directly regulate IFNAR to activate interferon-stimulated genes and potentiate macrophage activation. Ectopic ZBTB28 expression in breast cancer cells was sufficient to downregulate CD24 and CD47 to promote phagocytosis of macrophages, demonstrating that ZBTB28 was beneficial for the combination treatment of anti-CD24 and anti-CD47. Collectively, our results reveal a mode of action of ZBTB28 as a tumor suppressor gene and suggest that ZBTB28 is an important regulator of macrophage phagocytosis in breast cancer, holding promise for the development of novel therapy strategies for breast cancer patients.

The A to I editing landscape in melanoma and its relation to clinical outcome

RNA editing refers to non-transient RNA modifications that occur after transcription and prior to translation by the ribosomes. RNA editing is more widespread in cancer cells than in non-transformed cells and is associated with tumorigenesis of various cancer tissues. However, RNA editing can also generate neo-antigens that expose tumour cells to host immunosurveillance. Global RNA editing in melanoma and its relevance to clinical outcome currently remain poorly characterized. The present study compared RNA editing as well as gene expression in tumour cell lines from melanoma patients of short or long metastasis-free survival, patients relapsing or not after immuno- and targeted therapy and tumours harbouring BRAF or NRAS mutations. Overall, our results showed that NTRK gene expression can be a marker of resistance to BRAF and MEK inhibition and gives some insights of candidate genes as potential biomarkers. In addition, this study revealed an increase in Adenosine-to-Inosine editing in Alu regions and in non-repetitive regions, including the hyperediting of the MOK and DZIP3 genes in relapsed tumour samples during targeted therapy and of the ZBTB11 gene in NRAS mutated melanoma cells. Therefore, RNA editing could be a promising tool for identifying predictive markers, tumour neoantigens and targetable pathways that could help in preventing relapses during immuno- or targeted therapies.

C2orf40 inhibits hepatocellular carcinoma through interaction with UBR5

BACKGROUND AND AIM

Hepatocellular carcinoma (HCC) urgently needs a marker for early diagnosis and targeted treatment. C2orf40 has been identified as a tumor suppressor gene in many cancers. However, the precise role and regulatory mechanism by C2orf40 contribute to HCC remain elusive and merit exploration.

METHODS

Reverse-transcription PCR, quantitative real-time PCR, and methylation-specific PCR were used to detect expression and methylation of C2orf40 in HCC cell lines or tissues. The effects of C2orf40 in liver cancer cells were examined via colony formation, CCK8, transwell, and flow cytometric assays. The effect of C2orf40 on tumorigenesis in vivo was determined by xenografts and immunohistochemical analysis. Western blot, indirect immunofluorescence, Co-IP, and cycloheximide (CHX) were used to further investigate the potential mechanism of C2orf40.

RESULTS

The down-regulation of C2orf40 in hepatocellular cancer tissue samples is often related to the degree of methylation of its promoter CpG. The recovery of C2orf40 expression in HCC cell lines can induce G0/G1 phase arrest and apoptosis and also inhibit cell migration and invasion by reversing the epithelial-mesenchymal transition (EMT) process, both in vivo and in vitro. In addition, C2orf40 can increase the expression of p21 through interaction with UBR5.

CONCLUSIONS

Low expression levels of C2orf40 are related to the hypermethylation of its promoter. C2orf40 can inhibit HCC through UBR5-dependent or p53-independent mechanisms. C2orf40 may be a diagnostic biomarker and a potential therapeutic target in HCC.

Molecular response uncovers neurotoxicity of Pardosa pseudoannulata exposed to cadmium pressure

Cadmium (Cd) is a widely distributed heavy metal in south of China. Growing evidence indicates that systemic exposure to Cd, particularly the long-term exposure, may cause neurotoxic effects. Nevertheless, mechanisms underlying Cd neurotoxicity remain not completely understood. In this report, we investigated the neural alterations in the spider Pardosa pseudoannulata (Bösenberg and Strand, 1906) exposed to long-term Cd (LCd) and short-term Cd (SCd) pressure. Cd stress lowered foraging ability and prey consuming time in the spiders. In addition, enzymatic analysis results indicated that Cd exposure reduced the level of acetylcholinesterase at subcellular level. We then identified differentially expressed genes (DEGs) in the Cd exposed spiders using pairwise comparisons and found that a large number of DEGs were related to neurotransmitter receptors and ion transport and binding proteins. Notably, LCd exposure harbored more altered genes in ion transporter activity comparing with SCd exposure. From six K-means clusters, 53 putative transcriptional factors (TFs) belonging to 21 families were characterized, and ZBTB subfamily displayed the most distinctive alterations in the characterized genes, which is assumed to play a key role in the regulation of ion transmembrane process under Cd stress. A protein-to-protein interaction network constructed by the yielded DEGs also showed that ion and receptor binding activities were affected under long-term Cd exposure. Four key modules from the network indicated that Cd may further down-regulate energy metabolism pathway in spiders. Collectively, this comprehensive analysis provides multi-dimensional insights to understand the molecular response of spiders to Cd exposure.

Epigenetic silencing of ZBTB28 promotes renal cell carcinogenesis

AIM

Zinc finger and BTB domain-containing protein 28 (ZBTB28) is a potential tumor suppressor for some cancers. However, its epigenetic regulation and functions in renal cell carcinoma (RCC) remain to be elucidated.

METHODS

The expression of ZBTB28 mRNA was analyzed by semi-quantitative reverse transcription polymerase chain reaction (PCR) in nine RCC cell lines and normal kidney tissues. Methylation status of ZBTB28 promoter was assessed by methylation-specific PCR in RCC cell lines, primary RCC, tumors and adjacent tissues. The involvement of ZBTB28 in cell proliferation and migration was investigated.

RESULTS

ZBTB28 promoter was hypermethylated in 88.9% (8/9) of RCC cell lines with reduced ZBTB28 mRNA expression, and could be reversed by DNA methyltransferase inhibitors. The methylation of ZBTB28 promoter was detected in 73.5% (36/49) of primary RCC tissues, compared with 7.1% (1/14) in normal tissues. Overexpression of ZBTB28 significantly inhibited RCC cell proliferation and migration, and induced apoptosis. Further analyses revealed that ZBTB28 upregulation could inhibit multiple oncogenic signaling transduction pathways.

CONCLUSION

ZBTB28 is frequently silenced by promoter methylation in RCC pathogenesis and functions as a novel tumor suppressive gene. ZBTB28 may be a potential target for the development of RCC therapeutic strategies.

ZBTB28 induces autophagy by regulation of FIP200 and Bcl-XL facilitating cervical cancer cell apoptosis

Background

Among the common preventable cancers of women, cervical cancer has the highest morbidity. It is curable if detected at an early stage. However, reliable diagnostic and prognostic markers, which relate to physiologic and pathologic regulation of cervical cancer, are not available. In this study, one such potential marker, ZBTB28, was evaluated for its potential usefulness in cervical cancer assessment.

Methods

Public database analysis, reverse-transcription polymerase chain reaction (PCR), and methylation-specific PCR were employed to analyze ZBTB28 expression and promoter methylation. The importance of ZBTB28 in cervical cancer cells was assessed by cellular and molecular analysis in vitro and in vivo.

Results

This study assessed the anti-tumor effects of the transcription factor, ZBTB28, which is often silenced in cervical cancer due to CpG methylation of its promoter. We found ZBTB28 to directly affect cervical cancer cell proliferation, apoptosis, autophagy, and tumorigenesis. Also, it increased cancer cell chemosensitivity to Paclitaxel, Cisplatin, and 5-fluorouracil. Ectopic ZBTB28 expression inhibited the growth of cervical cancer xenografts in nude mice. Furthermore, electron microscopy demonstrated ZBTB28 to induce autophagosomes in cervical cancer cells. ZBTB28 induced cellular autophagy by the degradation of Bcl-XL, reduction of the Bcl-XL-BECN1 complex, and by interaction with the autophagy-related gene FIP200. ZBTB28-induced autophagy of cervical cancer cells was shown to mediate cellular apoptosis through the regulation of FIP200.

Conclusion

These findings identify ZBTB28 as a tumor suppressor gene that can induce autophagy-related apoptosis in cervical cancer cells. As such, ZBTB28 may be a target for the treatment of uterine-cervical carcinoma. Further, ZBTB28 promoter methylation analysis may offer a new objective strategy for cervical cancer screening.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01948-0.

Tumor suppressor DRD2 facilitates M1 macrophages and restricts NF-κB signaling to trigger pyroptosis in breast cancer

Rationale: Breast cancer (BrCa) is the most common cancer worldwide, and the 5-year relative survival rate has declined in patients diagnosed at stage IV. Advanced BrCa is considered as incurable, which still lack effective treatment strategies. Identifying and characterizing new tumor suppression genes is important to establish effective prognostic biomarkers or therapeutic targets for late-stage BrCa.

Methods: RNA-seq was applied in BrCa tissues and normal breast tissues. Through analyzing differentially expressed genes, DRD2 was selected for further analysis. And expression and promoter methylation status of DRD2 were also determined. DRD2 functions were analyzed by various cell biology assays in vitro. Subcutaneous tumor model was used to explore DRD2 effects in vivo. A co-cultivated system was constructed to investigate interactions of DRD2 and macrophages in vitro. WB, IHC, IF, TUNEL, qRT-PCR, Co-IP, Antibody Array, and Mass Spectrum analysis were further applied to determine the detailed mechanism.

Results: In BrCa, DRD2 was found to be downregulated due to promoter methylation. Higher expression of DRD2 positively correlated with longer survival times especially in HER2-positive patients. DRD2 also promoted BrCa cells sensitivity to Paclitaxel. Ectopic expression of DRD2 significantly inhibited BrCa tumorigenesis. DRD2 also induced apoptosis as well as necroptosis in vitro and in vivo. DRD2 restricted NF-κB signaling pathway activation through interacting with β-arrestin2, DDX5 and eEF1A2. Interestingly, DRD2 also regulated microenvironment as it facilitated M1 polarization of macrophages, and triggered GSDME-executed pyroptosis.

Conclusion: Collectively, this study novelly manifests the role of DRD2 in suppressing BrCa tumorigenesis, predicting prognosis and treatment response. And this study further reveals the critical role of DRD2 in educating M1 macrophages, restricting NF-κB signaling pathway and triggering different processes of programmed cell death in BrCa. Taking together, those findings represent a predictive and therapeutic target for BrCa.

Cancer cells escape p53's tumor suppression through ablation of ZDHHC1-mediated p53 palmitoylation

The inactivation of tumor-suppressor genes contributes heavily to oncogenesis. The mutation of TP53 has been well-studied and recognized as a major factor in the development of tumors. Yet other means of p53 inactivation has not been well-elucidated. We previously identified a hypermethylated gene ZDHHC1 that suppresses tumor growth when the expression was restored, but the specific mechanism was yet to be found. The protein product of ZDHHC1 is an S-palmitoyltransferase and we have identified p53 as a substrate for ZDHHC1-mediated palmitoylation, specifically at the C135, C176, and C275 residues. The novel form of post-translational modification of p53 is required for the nuclear translocation of the tumor suppressor. p53 recruited DNMT3A to ZDHHC1 promoter and is responsible for the hypermethylation of ZDHHC1. The epigenetic feedback loop formed by ZDHHC1 and p53 sheds light on the inactivation of p53 without the presence of genetic mutations.

Downregulation of the ubiquitin ligase KBTBD8 prevented epithelial ovarian cancer progression

OBJECTIVES

Kelch repeat and BTB domain-containing protein 8, KBTBD8, has been identified as a female fertility factor. However, there have been no reports on the role of KBTBD8 in the progression of epithelial ovarian cancer, EOC. Our study aimed to address this issue.

METHODS

We first examine KBTBD8 expression in EOC tissues and cells. Next, we performed RNA sequencing to reveal the overall mechanism. Then we investigated the roles of KBTBD8 in the proliferation, migration, and health status of cultured EOC cells. Finally, we employed tumor xenograft models to evaluate the role of KBTBD8 in vivo.

RESULTS

First, KBTBD8 level was significantly higher in EOC tissues and cells. Next, comparative RNA sequencing identified more tumorigenesis-related genes that KBTBD8 might regulate. Then we found that KBTBD8 knockdown significantly decreased EOC cell proliferation, migration, and the activities of multiple tumorigenesis-related kinases. Finally, KBTBD8 knockdown significantly diminished ovarian tumor formation in vivo.

CONCLUSION

Proper KBTBD8 level is essential for the healthy growth of ovarian somatic cells, such as ovarian epithelial cells. Excessive KBTBD8 might be a significant impetus for EOC progression. KBTBD8 reduction greatly inhibits EOC proliferation and migration.

DNA methylation downregulated ZDHHC1 suppresses tumor growth by altering cellular metabolism and inducing oxidative/ER stress-mediated apoptosis and pyroptosis

Cancer progression is an intricate biological process profiled by not only unscheduled proliferation, but also altered metabolism mechanisms. In this article, we introduced a novel tumor suppressor gene (TSG), Zinc Finger DHHC-Type Containing 1 (ZDHHC1, also known as ZNF377), frequently silenced due to epigenetic modification among various cancers, which exerts significant anti-tumor effects through metabolic regulation. Methods: Quantitative reversed-transcription PCR (qRT-PCR), reverse transcription PCR (RT-PCR) and Western blot were employed to demonstrate transcriptional and protein levels of targeted regulators. Methylation of ZDHHC1 promoter was detected by bisulfite genomic sequencing (BGS) and methylation specific PCR (MSP). Proteomics were analyzed by isobaric tags for relative and absolute quantitation (iTRAQ) and gas chromatography-mass spectrometry (GC-MS) were utilized for metabolomics analysis. Cellular functions were examined via corresponding approaches. Nude mice were used for xenograft tumor models. Indirect immunofluorescence staining was utilized to obtain precise location and expression of target proteins. Oxidative and ER stress indicators were detected using specific kits. Results: We found that ZDHHC1 expression was frequently silenced in multiple tumor cells and specimens due to methylation. Restoration of ZDHHC1 expression can curb cancer cell progression via stimulating apoptosis and cell cycle arrest, repressing metastasis, and reversing EMT transition and cell stemness. ZDHHC1's salient anti-tumor abilities were recognized in vivo as well. Metabolomic and proteomic analyses predicted inhibitory role of ZDHHC1 in glucose metabolism pathways in a CYGB-dependent manner, and in pentose phosphate pathway (PPP), which was validated by examining altered key factors. Moreover, we unraveled that ZDHHC1 dedicates to the increment of oxidative stress and endoplasmic reticulum (ER) stress to promote pyroptosis for anticancer purposes. Conclusion: Our study for the first time indicates ZDHHC1 is a potential tumor-suppressor frequently silenced due to promoter methylation, capable of negatively regulating metabolisms of tumor cells while stimulating oxidative stress and ER stress to expedite cell death through induction of pyroptosis and apoptosis, which can be exploited for development of new cancer prevention and therapies.

BTB/POZ zinc finger protein ZBTB16 inhibits breast cancer proliferation and metastasis through upregulating ZBTB28 and antagonizing BCL6/ZBTB27

Background

Breast cancer remains in urgent need of reliable diagnostic and prognostic markers. Zinc finger and BTB/POZ domain-containing family proteins (ZBTBs) are important transcription factors functioning as oncogenes or tumor suppressors. The role and regulation of ZBTB16 in breast cancer remain to be established.

Methods

Reverse-transcription PCR and methylation-specific PCR were applied to detect expression and methylation of ZBTB16 in breast cancer cell lines and tissues. The effects of ZBTB16 in breast cancer cells were examined via cell viability, CCK8, Transwell, colony formation, and flow cytometric assays. Xenografts and immunohistochemistry analyses were conducted to determine the effects of ZBTB16 on tumorigenesis in vivo. The specific mechanisms of ZBTB16 were further investigated using Western blot, qRT-PCR, luciferase assay, and co-IP.

Results

ZBTB16 was frequently downregulated in breast cancer cell lines in correlation with its promoter CpG methylation status. Restoration of ZBTB16 expression led to induction of G2/M phase arrest and apoptosis, inhibition of migration and invasion, reversal of EMT, and suppression of cell proliferation, both in vitro and in vivo. Furthermore, ectopically expressed ZBTB16 formed heterodimers with ZBTB28 or BCL6/ZBTB27 and exerted tumor suppressor effects through upregulation of ZBTB28 and antagonistic activity on BCL6.

Conclusions

Low expression of ZBTB16 is associated with its promoter hypermethylation and restoration of ZBTB16 inhibits tumorigenesis. ZBTB16 functions as a tumor suppressor through upregulating ZBTB28 and antagonizing BCL6. Our findings also support the possibility of ZBTB16 being a prognostic biomarker for breast cancer.