Transcriptional positive cofactor 4 promotes breast cancer proliferation and metastasis through c-Myc mediated Warburg effect

PC4 promotes bladder cancer progression and stemness by directly interacting with Sp1 to transcriptionally activate the Wnt5a/β-catenin pathway

Bladder cancer is a common malignancy with a poor prognosis worldwide. Positive cofactor 4 (PC4) is widely reported to promote malignant phenotypes in various tumors. Nonetheless, the biological function and mechanism of PC4 in bladder cancer remain unclear. Here, for the first time, we report that PC4 is elevated in bladder cancer and is associated with patient survival. Moreover, PC4 deficiency obviously inhibited bladder cancer cell proliferation and metastasis by reducing the expression of genes related to cancer stemness (CD44, CD47, KLF4 and c-Myc). Through RNA-seq and experimental verification, we found that activation of the Wnt5a/β-catenin pathway is involved in the malignant function of PC4. Mechanistically, PC4 directly interacts with Sp1 to promote Wnt5a transcription. Thus, our study furthers our understanding of the role of PC4 in cancer stemness regulation and provides a promising strategy for bladder cancer therapy.

PC4-mediated Ku complex PARylation facilitates NHEJ-dependent DNA damage repair

Radiotherapy is one of the mainstay treatments for hepatocellular carcinoma (HCC). However, a substantial number of patients with HCC develop radioresistance and eventually suffer from tumor progression or relapse, which is a major impediment to the use of radiotherapy. Therefore, elucidating the mechanisms underlying radioresistance and identifying novel therapeutic targets to improve patient prognosis are important in HCC management. In this study, using in vitro and in vivo models, laser microirradiation and live cell imaging methods, and coimmunoprecipitation assays, we report that a DNA repair enhancer, human positive cofactor 4 (PC4), promotes nonhomologous end joining-based DNA repair and renders HCC cells resistant to radiation. Mechanistically, PC4 interacts with poly (ADP-ribose) polymerase 1 and directs Ku complex PARylation, resulting in the successful recruitment of the Ku complex to damaged chromatin and increasing the efficiency of nonhomologous end joining repair. Clinically, PC4 is highly expressed in tumor tissues and is correlated with poor prognosis in patients with HCC. Taken together, our data suggest that PC4 is a DNA repair driver that can be targeted to radiosensitize HCC cells.

SEC-seq: association of molecular signatures with antibody secretion in thousands of single human plasma cells

The secreted products of cells drive many functions in vivo; however, methods to link this functional information to surface markers and transcriptomes have been lacking. By accumulating secretions close to secreting cells held within cavity-containing hydrogel nanovials, we demonstrate workflows to analyze the amount of IgG secreted from single human B cells and link this information to surface markers and transcriptomes from the same cells. Measurements using flow cytometry and imaging flow cytometry corroborate the association between IgG secretion and CD38/CD138. By using oligonucleotide-labeled antibodies we find that upregulation of pathways for protein localization to the endoplasmic reticulum and mitochondrial oxidative phosphorylation are most associated with high IgG secretion, and uncover surrogate plasma cell surface markers (e.g., CD59) defined by the ability to secrete IgG. Altogether, this method links quantity of secretion with single-cell sequencing (SEC-seq) and enables researchers to fully explore the links between genome and function, laying the foundation for discoveries in immunology, stem cell biology, and beyond.

Targeting positive cofactor 4 induces autophagic cell death in MYC-expressing diffuse large B-cell lymphoma

MYC-expressing diffuse large B-cell lymphoma (DLBCL) is one of the refractory lymphomas. Currently, the pathogenesis of MYC-expressing DLBCL is still unclear, and there is a lack of effective therapy. We characterized positive cofactor 4 (PC4) as an upstream regulator of c-Myc, and PC4 is overexpressed in DLBCL and is closely related to clinical staging, prognosis, and c-Myc expression. Furthermore, our in vivo and in vitro studies revealed that PC4 knockdown can induce autophagic cell death and enhance the therapeutic effect of doxorubicin in MYC-expressing DLBCL. Inhibition of c-Myc-mediated aerobic glycolysis and activation of the AMPK/mTOR signaling pathway are responsible for the autophagic cell death induced by PC4 knockdown in MYC-expressing DLBCL. Using dual-luciferase reporter assay and electrophoretic mobility shift assay assays, we also found that PC4 exerts its oncogenic functions by directly binding to c-Myc promoters. To sum up, our study provides novel insights into the functions and mechanisms of PC4 in MYC-expressing DLBCL and suggests that PC4 may be a promising therapeutic target for MYC-expressing DLBCL.

The Catalytic Subunit of Schizosaccharomyces pombe CK2 (Cka1) Negatively Regulates RNA Polymerase II Transcription through Phosphorylation of Positive Cofactor 4 (PC4)

Positive cofactor 4 (PC4) is a transcriptional coactivator that plays important roles in transcription and DNA replication. In mammals, PC4 is phosphorylated by CK2, and this event downregulates its RNA polymerase II (RNAPII) coactivator function. This work describes the effect of fission yeast PC4 phosphorylation on RNAPII transcription in a cell extract, which closely resembles the cellular context. We found that fission yeast PC4 is strongly phosphorylated by the catalytic subunit of CK2 (Cka1), while the regulatory subunit (Ckb1) downregulates the PC4 phosphorylation. The addition of Cka1 to an in vitro transcription assay can diminish the basal transcription from the Ad-MLP promoter; however, the addition of recombinant fission yeast PC4 or Ckb1 can stimulate the basal transcription in a cell extract. Fission yeast PC4 is phosphorylated in a domain which has consensus phosphorylation sites for CK2, and two serine residues were identified as critical for CK2 phosphorylation. Mutation of one of the serine residues in PC4 does not completely abolish the phosphorylation; however, when the two serine residues are mutated, CK2 is no longer able to phosphorylate PC4. The mutant which is not phosphorylated is able to stimulate transcription even though it is previously phosphorylated by Cka1, while the wild type and the point mutant are inactivated by Cka1 phosphorylation, and they cannot stimulate transcription by RNAPII in cell extracts. Those results demonstrate that CK2 can regulate the coactivator function of fission yeast PC4 and suggests that this event could be important in vivo as well.

Reversing the HDAC-inhibitor mediated metabolic escape in MYCN-amplified neuroblastoma

In MYCN-amplified neuroblastoma (NB), we noticed that the single compound treatment with the HDAC inhibitor vorinostat led to a reprogramming of the glycolytic pathway in these cells. This reprogramming was upregulation of fatty acid oxidation (FAO) and oxidative phosphorylation (OXPHOS), allowing the cells to generate ATP, albeit at a reduced rate. This behavior was dependent on reduced levels of MYCN and a corresponding increase in the levels of PPARD transcription factors. By integrating metabolic and functional studies in NB cells and mouse xenografts, we demonstrate a compensatory upregulation of FAO/OXPHOS metabolism that promotes resistance to HDAC inhibitors. From the additional compounds that could reverse this metabolic reprogramming, the mTORC1 inhibitor sirolimus was selected. Besides both a block of glycolysis and OXPHOS, the HDAC/mTORC1 inhibitor combination produced significantly higher levels of reactive oxygen species (ROS) in the treated cells and in xenograft tumor samples, also a consequence of increased glycolytic block. The lead compounds were also tested for changes in the message levels of the glycolytic enzymes and their pathway activity, and HK2 and GPI glycolytic enzymes were most affected at their RNA message level. This combination was seen with no overall toxicity in treated mice in terms of weight loss or liver/kidney function.

Receptor for activated C kinase 1 promotes cervical cancer lymph node metastasis via the glycolysis‑dependent AKT/mTOR signaling

Cervical cancer (CC), an aggressive form of squamous cell carcinoma, is characterized by early-stage lymph node metastasis and an extremely poor prognosis. The authors have previously demonstrated that patients with CC have aberrant glycolysis. The upregulation of receptor for activated C kinase 1 (RACK1) is associated with CC lymph node metastasis (LNM). However, its role in mediating aerobic glycolysis in CC LNM remains unclear. In the present study, ¹H nuclear magnetic resonance analysis revealed a significant association between RACK1 expression and the glycolysis/gluconeogenesis pathway. Additionally, RACK1 knockdown inhibited aerobic glycolysis and lymphangiogenesis in vitro and suppressed CC LNM in vivo. Furthermore, protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling was identified as a critical RACK1-regulated pathway that increased lymphangiogenesis in CC. Co-immunoprecipitation, immunofluorescence and western blot analysis revealed that RACK1 activated AKT/mTOR signaling by interacting with insulin-like growth factor 1 receptor (IGF1R). POU class 2 homeobox 2 (POU2F2) bound to the RACK1 promoter and regulated its transcription, thereby functionally contributing to glycolysis and lymphangiogenesis in CC. Of note, the admin-istration of 2-deoxy-D-glucose, which attenuates glycolysis, inhibited RACK1-induced lymphangiogenesis in CC. The correlations between RACK1, IGF1R, POU2F2 and hexokinase 2 were further confirmed in CC tissues. Thus, RACK1 plays a crucial role in CC tumor LNM by regulating glycolysis via IGF1R/AKT/mTOR signaling. Thus, the targeting of the POU2F2/RACK1/IGF1R/AKT/mTOR signaling pathway may provide a novel treatment strategy for CC.

The Human Positive Cofactor 4 is a Promising Chemotherapeutic Target in Lung Adenocarcinoma

Reduced sensitivity to chemotherapeutic drugs is almost inevitable in lung adenocarcinoma patients. Thus, understanding the relevant mechanisms is urgent. Positive cofactor 4 (PC4) was at first revealed to be a coactivator of basal transcription. Previous research has shown that PC4 participates in various cellular processes in normal and malignant cells. However, it is still unknown whether PC4 participates in altering the lung adenocarcinoma cell sensitivity to chemotherapy, and the relevant mechanisms remain to be explained. In this study, we discovered that PC4 was overexpressed in cisplatin-resistant lung adenocarcinoma cells. PC4 decreased cisplatin's cytotoxic effects on lung adenocarcinoma in vivo and in vitro. Furthermore, PC4 positively correlated with SOX9 in multiple cancers. PC4 was an upstream regulator of SOX9 in lung adenocarcinoma. Furthermore, PC4 mediated lung adenocarcinoma cell sensitivity to the HIF-PH inhibitor DMOG and the mTOR inhibitor rapamycin, and PC4 mediated the synergistic effect of DMOG and cisplatin. Finally, PC4 destabilized HIF-1α upon cisplatin treatment. Our research showed that PC4 participates in mediating lung adenocarcinoma cell sensitivity to multiple drugs. Mechanistically, PC4 governs multiple downstream pathways associated with chemotherapy resistance, including the SOX9 and HIF-1α pathways. Thus, PC4 is a promising chemotherapeutic target in lung adenocarcinoma.

Melatonin inhibits proliferation, migration, and invasion by inducing ROS-mediated apoptosis via suppression of the PI3K/Akt/mTOR signaling pathway in gallbladder cancer cells

BACKGROUND

Melatonin is an indolic compound mainly secreted by the pineal gland and plays a vital role in the regulation of circadian rhythms and cancer therapy. However, the effects of melatonin in gallbladder cancer (GBC) and the related mechanism remain unknown.

METHODS

In this study, the antitumor activity of melatonin on gallbladder cancer was explored both in vitro and in vivo. After treatment with different concentrations of melatonin, the cell viability, migration, and invasion of gallbladder cancer cells (NOZ and GBC-SD cells) were evaluated by CCK-8 assay, wound healing, and Transwell assay.

RESULTS

The results showed that melatonin inhibited growth, migration, and invasion of gallbladder cancer cells. Subsequently, the assays suggested that melatonin significantly induced apoptosis in gallbladder cancer cells and altered the expression of the apoptotic proteins, including Bax, Bcl-2, cytochrome C, cleaved caspase-3, and PARP. Besides, the intracellular reactive oxygen species (ROS) was found to be upregulated after melatonin treatment in gallbladder cancer cells. Melatonin was found to suppress the PI3K/Akt/mTOR signaling pathway in a time-dependent manner by inhibiting the phosphorylation of PI3K, Akt, and mTOR. Treatment with N-acetyl-L-cysteine (NAC) or 740 Y-P remarkably attenuated the antitumor effects of melatonin in NOZ and GBC-SD cells. Finally, melatonin suppressed the growth of GBC-SD cells in an athymic nude mice xenograft model in vivo.

CONCLUSIONS

Our study revealed that melatonin could induce apoptosis by suppressing the PI3K/Akt/mTOR signaling pathway. Therefore, melatonin might serve as a potential therapeutic drug in the future treatment of gallbladder cancer.

Integrative Transcriptome-Wide Analyses Uncover Novel Risk-Associated MicroRNAs in Hormone-Dependent Cancers

Background

Hormone-dependent cancers (HDC) are among the leading causes of death worldwide among both men and women. Some of the established risk factors of HDC include unhealthy lifestyles, environmental factors, and genetic influences. Numerous studies have been conducted to understand gene-cancer associations. Transcriptome-wide association studies (TWAS) integrate data from genome-wide association studies (GWAS) and gene expression (expression quantitative trait loci - eQTL) to yield meaningful information on biological pathways associated with complex traits/diseases. Recently, TWAS have enabled the identification of novel associations between HDC risk and protein-coding genes.

Methods

In the present study, we performed a TWAS analysis using the summary data-based Mendelian randomization (SMR)-heterogeneity in dependent instruments (HEIDI) method to identify microRNAs (miRNAs), a group of non-coding RNAs (ncRNAs) associated with HDC risk. We obtained eQTL and GWAS summary statistics from the ncRNA-eQTL database and the National Human Genome Research Institute-European Bioinformatics Institute (NHGRI-EBI) GWAS Catalog.

Results

We identified 13 TWAS-significant miRNAs at cis regions (±1 Mb) associated with HDC risk (two, five, one, two, and three miRNAs for prostate, breast, ovarian, colorectal, and endometrial cancers, respectively). Among them, eight novel miRNAs were recognized in HDC risk. Eight protein-coding genes targeted by TWAS-identified miRNAs (SIRT1, SOX4, RUNX2, FOXA1, ABL2, SUB1, HNRNPH1, and WAC) are associated with HDC functions and signaling pathways.

Conclusion

Overall, identifying risk-associated miRNAs across a group of related cancers may help to understand cancer biology and provide novel insights into cancer genetic mechanisms. This customized approach can be applied to identify significant miRNAs in any trait/disease of interest.

RING-finger protein 6 enhances c-Myc-mediated Warburg effect by promoting MAD1 degradation to facilitate pancreatic cancer metastasis

Aerobic glycolysis (the Warburg effect) promotes tumor metastasis; hence, drugs targeting its regulators are being developed. c-Myc, a critical transcription factor that regulates the Warburg effect, is involved in the tumorigenesis of many cancers, including pancreatic cancer (PC). However, the upstream regulating mechanisms of c-Myc in PC are unclear. Herein, we reported that E3 ubiquitin ligase RING-finger protein 6 (RNF6) was upregulated in PC tissues, and an elevated RNF6 level was closely associated with metastasis and poor prognosis in patients with PC. In functional experiments, RNF6 over-expression accelerated the metastatic ability of PC cells, whereas RNF6 knockdown impaired PC cell motility and invasiveness along with metastasis in an orthotopic mouse model. Furthermore, we found that RNF6 promoted PC cell metastasis by enhancing c-Myc-mediated aerobic glycolysis. Mechanistically, RNF6 increased the expression level of c-Myc by catalyzing the ubiquitination of Max-dimerization protein-1 (MAD1), a cellular antagonist of c-Myc. Lastly, RNF6 promoted the degradation of MAD1 via the ubiquitin-proteasome pathway, and this reduction in the MAD1 levels enabled c-Myc to promote the Warburg effect in PC. Our results demonstrate that RNF6 may be a novel biomarker in PC carcinogenesis, thereby indicating that targeting the RNF6/MAD1/c-Myc axis is a potential strategy for PC therapy.

Knockdown of PC4 increases chemosensitivity of Oxaliplatin in triple negative breast cancer by suppressing mTOR pathway

As a multifunctional nuclear protein, the human positive cofactor 4 (PC4) is highly expressed in various tumors including breast cancer and has potential roles in cancer development and progression. However, the functional signatures and molecular mechanisms of PC4 in triple negative breast cancer (TNBC) progression and chemotherapeutic response are still unknown. In this study, we found that PC4 is significantly upregulated in TNBC cells compared with non-TNBC cells, implying its potential role in TNBC. Then, in vivo and in vitro studies revealed that knockdown of PC4 increased chemosensitivity of Oxaliplation (Oxa) in TNBC by suppressing mTOR pathway. Therefore, our findings demonstrated the signatures and molecular mechanisms of PC4 in TNBC chemotherapeutic response, and indicated that PC4 might be a promising therapeutic target for TNBC.

UBE2T promotes proliferation, invasion and glycolysis of breast cancer cells by regualting the PI3K/AKT signaling pathway

PURPOSE

Breast cancer (BCa) is one of the most common gynecological malignancies. Ubiquitin-coupled enzyme E2T (UBE2T) has been demonstrated to play crucial roles in various tumors.

METHODS

UBE2T levels were detected using quantitative real time PCR and western blot. CCK-8 and colony formation assays were used to evaluate cell proliferation. A xenograft model was used to evaluate the effects of UBE2T on tumor growth in mice, and immunohistochemistry (IHC) assay was performed to detect the expression of UBE2T and Ki-67. Transwell assay was performed to determine cell migration and invasion. The ATP level, glucose consumption and lactate production were measured using the corresponding commercial kits. Western blot assay was used to detect the levels of epithelial-mesenchymal transformation (EMT), glycolytic and the PI3K/AKT pathway related proteins regulated by UBE2T.

RESULTS

Upregulation of UBE2T expression in human BCa tissues was found in human clinical BCa tissues and The Cancer Genome Atlas (TCGA) dataset. The expression of UBE2T was confirmed to be up-regulated in BCa cells compared to normal breast epithelial cell line (MCF-10A). Overexpression of UBE2T promoted proliferation, migration, invasion and glycolysis in BCa cells, while UBE2T knockdown showed the opposite results. Moreover, UBE2T knockdown suppressed tumor growth in mice. Further mechanism analysis shows that UBE2T participated in the regulation of BCa progression through affecting the PI3K/AKT signaling pathway.

CONCLUSION

UBE2T promoted proliferation, invasion and glycolysis through modulating PI3K/AKT signaling pathway in BCa, implying that UBE2T may provide a promising therapeutic target for the therapy of BCa.

Human Positive Coactivator 4 Affects the Progression and Prognosis of Pancreatic Ductal Adenocarcinoma via the mTOR/P70s6k Signaling Pathway

Introduction

Pancreatic cancer is one of the deadliest cancers in the world, and pancreatic ductal adenocarcinoma (PDAC) accounts for 90% of all cases. Human positive coactivator 4 (PC4) is a transcriptional coactivator that has been associated with the development and progression of several tumors. However, no studies investigated the potential role of PC4 in PDAC.

Methods

We investigated PC4 expression in 81 PDAC tissue samples using immunohistochemistry and studied the impact of PC4 expression and the molecular mechanisms of this altered expression on PDAC tumorigenesis and proliferation both in vitro and in vivo.

Results

PC4 overexpression was correlated with a poor outcome in PDAC patients. The RNAi-mediated knockdown of PC4 expression in CFPAC-1 and AsPC-1 cell lines reduced cell proliferation and tumor growth. The loss of PC4 in PDAC inhibits cell growth by inducing cell cycle arrest at the G1/S transition and suppressing the mTOR/p70s6k pathway.

Discussion/Conclusion

Our findings reveal for the first time that PC4 exerts oncogenic functions by activating mTOR/p70s6k signaling pathway-mediated cell proliferation, implying that PC4 is a promising therapeutic target for PDAC.

Coffee decoction enhances tamoxifen proapoptotic activity on MCF-7 cells

The consumption of coffee has been suggested to effectively enhance the therapeutic effects of tamoxifen against breast cancer; however, the underlying molecular mechanisms remain unclear. We herein attempted to clarify how coffee decoction exerts anti-cancer effects in cooperation with tamoxifen using the estrogen receptor α (ERα)-positive breast cancer cell line, MCF-7. The results obtained showed that coffee decoction down-regulated the expression of ERα, which was attributed to caffeine inhibiting its transcription. Coffee decoction cooperated with tamoxifen to induce cell-cycle arrest and apoptotic cell death, which may have been mediated by decreases in cyclin D1 expression and the activation of p53 tumor suppressor. The inclusion of caffeine in coffee decoction was essential, but not sufficient, to induce cell-cycle arrest and apoptotic cell death, suggesting the requirement of unknown compound(s) in coffee decoction to decrease cyclin D1 expression and activate apoptotic signaling cascades including p53. The activation of p53 through the cooperative effects of these unidentified component(s), caffeine, and tamoxifen appeared to be due to the suppression of the ERK and Akt pathways. Although the mechanisms by which the suppression of these pathways induces p53-mediated apoptotic cell death remain unclear, the combination of decaffeinated coffee, caffeine, and tamoxifen also caused cell-cycle arrest and apoptotic cell death, suggesting that unknown compound(s) present in decaffeinated coffee cooperate with caffeine and tamoxifen.

JARID1B promotes colorectal cancer proliferation and Wnt/β-catenin signaling via decreasing CDX2 level

BACKGROUND

Jumonji AT-rich interactive domain 1B(JARID1B) has been shown to be upregulated in many human cancers and plays a critical role in the development of cancers cells. Nevertheless, its functional role in colorectal cancer (CRC) progression is not fully understood.

METHODS

Herein, JARID1B expression levels were detected in clinical CRC samples by western blotting and qRT-PCR. DLD-1 cells with JARID1B knockdown or overexpression by stably transfected plasmids were used in vitro and in vivo study. Colony formation, 5-ethynyl-20-deoxyuridine (EdU) and Real Time Cellular Analysis (RTCA) assays were used to detect cell proliferation and growth. Transcriptome and CHIP assays were used to examine the molecular biology changes and molecular interaction in these cells. Nude mice was utilized to study the correlation of JARID1B and tumor growth in vivo.

RESULTS

Here, we first observed that JARID1B was significantly upregulated in CRC tissue compared to adjacent normal tissues. In CRC patients, JARID1B high expression was positively relation with poor overall survival. Multivariate analyses revealed that high JARID1B expression was an independent predictive marker for the poor prognosis of CRC. In addition, we found that JARID1B promoted CRC cells proliferation by Wnt/β-catenin signaling pathway. Further studies demonstrated CDX2 as a downstream target of JARID1B, and our data demonstrated that CDX2 is crucial for JARID1B -mediated Wnt/β-catenin signaling pathway. Mechanistically, we demonstrated that JARID1B regulated CDX2 expression through demethylation of H3K4me3.

CONCLUSIONS

CDX2 inhibited by JARID1B-derived H3K4me3 methylation promoted cells proliferation of CRC via Wnt/β-catenin signaling pathway. Therefore, our studies provided a novel insight into the role of JARID1B in CRC cells proliferation and potential new molecular target for treating CRC. Video abstract.

circ_BICD2 acts as a ceRNA to promote tumor progression and Warburg effect in oral squamous cell carcinoma by sponging miR-107 to enhance HK2

Numerous studies have proved that the Warburg effect serves a vital role involved in regulating the progression of malignant tumors. Previous studies confirmed that circRNAs act as a novel biomarker for diagnostic and therapeutic in various tumors. However, the functional role and mechanism of circ_BICD2 for the regulation of tumor growth and metastasis in oral squamous cell carcinoma (OSCC) via mediating the Warburg effect are largely unknown. In this study, we found that circ_BICD2 was upregulated in OSCC tumor tissues and cell lines. Inhibition of circ_BICD2 significantly decreased glycolysis, cell proliferation, migration and invasion of OSCC. Moreover, dual-luciferase reporter assay confirmed that circ_BICD2 directly targeted miR-107, as well as a targeted binding between miR-107 and HK2. Mechanistically, upregulation of miR-107 by circ_BICD2-silenced inhibited tumor growth by downregulating the HK2-mediated Warburg effect in OSCC. In conclusion, our findings suggested that circ_BICD2-deficient exerted anti-tumorigenesis and anti-glycolysis in OSCC by sponging miR-107 to downregulate HK2 expression, which provided a new potential therapeutic biomarker for OSCC clinical treatment.

SALL4 promotes gastric cancer progression via hexokinase II mediated glycolysis

Background

The stem cell factor SALL4 is reactivated in human cancers. SALL4 plays diverse roles in tumor growth, metastasis, and drug resistance, but its role in tumor metabolism has not been well characterized.

Methods

The glycolytic levels of gastric cancer cells were detected by glucose uptake, lactate production, lactate dehydrogenase activity, ATP level, and hexokinase activity. QRT-PCR and western blot were used to detect the changes in the expression of glycolytic genes and proteins. The downstream target genes of SALL4 were identified by microarray. The regulation of hexokinase II (HK-2) by SALL4 was analyzed by luciferase reporter assay and chromatin immunoprecipitation assay. Transwell migration assay, matrigel invasion assay, cell counting assay and colony formation assay were used to study the roles of HK-2 regulation by SALL4 in gastric cancer cells in vitro. The effects of SALL4 on glycolysis and gastric cancer progression in vivo were determined by subcutaneous xenograft and peritoneal metastasis tumor models in nude mice.

Results

SALL4 knockdown inhibited glucose uptake, lactate production, lactate dehydrogenase activity, ATP level and hexokinase activity in gastric cancer cells, and decreased the expression of glycolytic genes and proteins. Microarray analysis showed that SALL4 knockdown affected glycolysis-related pathway. The regulation of HK-2 gene expression by SALL4 was confirmed by luciferase reporter assay and chromatin immunoprecipitation assay. HK-2 knockdown abrogated the promotion of glycolysis by SALL4 in gastric cancer cells, indicating that HK-2 acts as a downstream effector of SALL4. Moreover, HK-2 knockdown reversed the promoting role of SALL4 in gastric cancer cell proliferation, migration and invasion, suggesting that SALL4 drives gastric cancer progression by upregulating HK-2.

Conclusions

SALL4 promotes gastric cancer progression through HK-2-mediated glycolysis, which reveals a new mechanism for the oncogenic roles of SALL4 in cancer.

PC4 serves as a negative regulator of skin wound healing in mice

Background

Human positive cofactor 4 (PC4) was initially characterized as a multifunctional transcriptional cofactor, but its role in skin wound healing is still unclear. The purpose of this study was to explore the role of PC4 in skin wound healing through PC4 knock-in mouse model.

Methods

A PC4 knock-in mouse model (PC4^+/+) with a dorsal full-thickness wound was used to investigate the biological functions of PC4 in skin wound healing. Quantitative PCR, Western blot analysis and immunohistochemistry were performed to evaluate the expression of PC4; Sirius red staining and immunofluorescence were performed to explore the change of collagen deposition and angiogenesis. Proliferation and apoptosis were detected using Ki67 staining and TUNEL assay. Primary dermal fibroblasts were isolated from mouse skin to perform cell scratch experiments, cck-8 assay and colony formation assay.

Results

The PC4^+/+ mice were fertile and did not display overt abnormalities but showed an obvious delay in cutaneous healing of dorsal skin. Histological staining showed insufficient re-epithelialization, decreased angiogenesis and collagen deposition, increased apoptosis and decreased cell proliferation in PC4^+/+ skin. Our data also showed decreased migration rate and proliferation ability in cultured primary fibroblasts from PC4^+/+ mice in vitro.

Conclusions

This study suggests that PC4 might serve as a negative regulator of skin wound healing in mice.

CD38 is involved in cell energy metabolism via activating the PI3K/AKT/mTOR signaling pathway in cervical cancer cells

In contrast to normal cells, cancer cells typically undergo metabolic reprogramming. Studies have shown that oncogenes play an important role in this metabolic reprogramming. CD38 is a multifunctional transmembrane protein that is expressed abnormally in a variety of tumor types. To investigate the effect and possible mechanism of CD38 in cervical cancer cells and to provide a new therapeutic target for the treatment of cervical cancer, the present study identified that CD38 is involved in regulating cell metabolism in cervical cancer cells. Liquid chromatography‑tandem mass spectrometry and bioinformatic analyses revealed that differentially abundant proteins in CD38‑overexpressed cervical cancer cells (CaSki‑CD38 and HeLa‑CD38) are predominantly involved in glycolytic pathways, oxidative phosphorylation and the NAD/NADH metabolic process. Further experiments using an ATP test kit and lactate test kit revealed that CD38 promotes glucose consumption, increases lactate accumulation and increases ATP production. In addition, CD38 increases the phosphorylation of phosphatidylserine/threonine kinase (AKT), mechanistic target of rapamycin (mTOR) and phosphatidylinositol‑4,5‑bisphosphate 3‑kinase (PI3K), which play a key role in tumor metabolism. Furthermore, it was found that the energy metabolism of cervical cancer cells was inhibited following treatment with the mTOR inhibitor rapamycin. In conclusion, the results of the present study suggested that CD38 regulates the metabolism of cervical cancer cells by regulating the PI3K/AKT/mTOR pathway, which may be a candidate target for the treatment of cervical cancer.

Resibufogenin suppresses tumor growth and Warburg effect through regulating miR-143-3p/HK2 axis in breast cancer

Increasing evidence confirmed that the Warburg effect plays an important role involved in the progression of malignant tumors. Resibufogenin (RES) has been proved to have a therapeutic effect in multiple malignant tumors. However, the mechanism of whether RES exerted an antitumor effect on breast cancer through regulating the Warburg effect is largely unknown. The effect of RES on glycolysis was determined by glucose consumption, lactate production, ATP generation, extracellular acidification rate and oxygen consumption rate in breast cancer cells. The total RNA and protein levels were respectively measured by RT-qPCR and western blot. Cell proliferation and apoptosis were examined using the CCK-8 assay, colony formation assay, and flow cytometry, respectively. The interaction between miR-143-3p and HK2 was verified by dual-luciferase reporter gene assay. We also evaluated the influence of RES on the tumor growth and Warburg effect in vivo. RES treatment significantly decreased glycolysis, cell proliferation and induced apoptosis of both MDA-MB-453 and MCF-7 cells. Simultaneously, the expression of HK2 was decreased in breast cancer cells treated with RES, which was positively associated with tumor size and glycolysis. Moreover, HK2 was a direct target gene of miR-143-3p. Mechanistically, upregulation of miR-143-3p by RES treatment inhibited tumor growth by downregulating HK2-mediated Warburg effect in breast cancer. Our findings suggested that RES exerted anti-tumorigenesis and anti-glycolysis activities in breast cancer through upregulating the inhibitory effect of miR-143-3p on HK2 expression, which provided a new potential strategy for breast cancer clinical treatment.

VPS33B suppresses lung adenocarcinoma metastasis and chemoresistance to cisplatin

The presence of VPS33B in tumors has rarely been reported. Downregulated VPS33B protein expression is an unfavorable factor that promotes the pathogenesis of lung adenocarcinoma (LUAD). Overexpressed VPS33B was shown to reduce the migration, invasion, metastasis, and chemoresistance of LUAD cells to cisplatin (DDP) in vivo and in vitro. Mechanistic analyses have indicated that VPS33B first suppresses epidermal growth factor receptor (EGFR) Ras/ERK signaling, which further reduces the expression of the oncogenic factor c-Myc. Downregulated c-Myc expression reduces the rate at which it binds the p53 promoter and weakens its transcription inhibition; therefore, decreased c-Myc stimulates p53 expression, leading to decreased epithelial-to-mesenchymal transition (EMT) signal. NESG1 has been shown to be an unfavorable indicator of non-small-cell lung cancer (NSCLC). Here, NESG1 was identified as an interactive protein of VPS33B. In addition, NESG1 was found to exhibit mutual stimulation with VPS33B via reduced RAS/ERK/c-Jun-mediated transcription repression. Knockdown of NESG1 activated EGFR/Ras/ERK/c-Myc signaling and further downregulated p53 expression, which thus activated EMT signaling and promoted LUAD migration and invasion. Finally, we observed that nicotine suppressed VPS33B expression by inducing PI3K/AKT/c-Jun-mediated transcription suppression. Our study demonstrates that VPS33B as a tumor suppressor is significantly involved in the pathogenesis of LUAD.

Chromatin protein PC4 is downregulated in breast cancer to promote disease progression: Implications of miR-29a

The human transcriptional coactivator PC4 has numerous roles to play in the cell. Other than its transcriptional coactivation function, it facilitates chromatin organization, DNA damage repair, viral DNA replication, etc. Although it was found to be an essential protein in vivo, the importance of this multifunctional protein in the regulation of different cellular pathways has not been investigated in details, particularly in oncogenesis. In this study, PC4 downregulation was observed in a significant proportion of mammary tissues obtained from Breast cancer patient samples as well as in a subset of highly invasive and metastatic Breast cancer patient-derived cell lines. We have identified a miRNA, miR-29a which potentially reduce the expression of PC4 both in RNA and protein level. This miR-29a was found to be indeed overexpressed in a substantial number of Breast cancer patient samples and cell lines as well, suggesting one of the key mechanisms of PC4 downregulation. Stable Knockdown of PC4 in MCF7 cells induced its migratory as well as invasive properties. Furthermore, in an orthotopic breast cancer mice model system; we have shown that reduced expression of PC4 enhances the tumorigenic potential substantially. Absence of PC4 led to the upregulation of several genes involved in Epithelial to Mesenchymal Transition (EMT), indicating the possible mechanism of uniform tumour progression in the orthotropic mice. Collectively these data establish the role of PC4 in tumour suppression.

HIF1α/miR-520a-3p/AKT1/mTOR Feedback Promotes The Proliferation And Glycolysis Of Gastric Cancer Cells

Purpose

Various microRNAs are involved in the development of gastric cancer (GC). This study investigated the role and mechanism of miR-520a-3p in GC.

Method

Quantitative real-time fluorescence PCR (qRT-PCR) was applied to measure the expression level of miR-520a-3p in GC tissues and cell lines. The chi-squared test was employed to evaluate the relationship between the expression level of miR-520a-30p and clinical traits. The cell count kit-8 assay was used to detect the effect of miR-520a-3p on GC cell proliferation, while its effect on glycolysis was determined using the glucose assumption, lactate, and ATP production assay. The effect of miR-520a-3p on tumor growth in vivo was examined using a xenograft model. The relationship between miR-520a-30p and AKT1/mTOR/HIF1α pathway in normoxia and hypoxia was investigated using bioinformatics analysis, dual-luciferase reporter assay, qRT-PCR and Western blotting.

Results

The expression of miR-520a-3p was decreased in GC tissues and cell lines. The expression level of miR-520a-3p was negatively associated with various malignant biological properties in patients. Overexpression/inhibition of miR-520a-3p decreased/promoted cell proliferation and glycolysis in vitro. Overexpression of miR-520a-3p inhibited tumor growth in vivo. AKT1 is the functional target of MiR-520a-3p, which was decreased in miR-520a-3p-overexpressing cells. In addition, overexpression of miR-520a-3p decreased the protein level of AKT1, mTOR, HIF1α, and target genes of HIF1α such as Glut1 and VEGF. Restoration of the expression of AKT1 can decrease the inhibitory effect of miR-520a-3p on the AKT1/mTOR/HIF1α pathway, as well as cell proliferation and glycolysis. Furthermore, the level of miR-520a-3p was decreased, while that of AKT1 was increased under hypoxia. Notably, inhibition of HIF1α or overexpression of miR-520a-3p suppressed these effects.

Conclusion

Our study provided the first evidence for the existence of HIF1α/miR-520a-3p/AKT1/mTOR feedback, which promotes the proliferation and glycolysis of GC cells, highlighting a potential novel target for treatment.

Hypermethylated KLF9 Is An Independent Prognostic Factor For Favorable Outcome In Breast Cancer

Background and objective

Breast cancer (BC) is the most lethal human malignancy and is the leading cause of cancer-associated death in women worldwide. Krüppel-like factor 9 (KLF9) belongs to a family of transcriptional regulators and its role in BC has not been fully investigated.

Method

Data mining was used to analyze BC data from The Cancer Genome Atlas (TCGA) database, which was downloaded using the UCSC Xena browser. The differential expression and methylation level of KLF9 was analyzed in patients with BC and corresponding normal controls enrolled from our hospital. Besides, the correlation of KLF9 methylation and prognosis was explored, and gene set enrichment analysis (GSEA) was conducted to identify the potential signaling pathway of KLF9 involved.

Results

Both TCGA and BC tissues indicated hypermethylation of the KLF9 promoter region in patients with BC compared with normal controls, which might account for the dysregulation of KLF9 in patients with BC. Besides, hypermethylation of KLF9 was detected in patients with estrogen or progesterone receptor-positive and non-triple-negative disease. Further, hypermethylation of KLF9 was demonstrated to be a potential independent biomarker in obtaining favorable outcomes in BC. By GSEA, tumor-associated biological processes and signaling pathway were identified, which indicated that KLF9 might play a vital role in the carcinogenesis of BC.

Conclusion

KFL9 plays an important role in the carcinogenesis of BC through the multiple tumor-associated signaling pathway. The hypermethylation of KLF9 resulted in its reduced expression in BC, while the hypermethylation of KLF9 has potential in the prediction of favorable outcomes in BC.