Patient-derived castration-resistant prostate cancer model revealed CTBP2 upregulation mediated by OCT1 and androgen receptor.

BACKGROUND: Prostate cancer is dependent on androgen receptor (AR) signaling, and androgen deprivation therapy (ADT) has proven effective in targeting prostate cancer. However, castration-resistant prostate cancer (CRPC) eventually emerges. AR signaling inhibitors (ARSI) have been also used, but resistance to these agents develops due to genetic AR alterations and epigenetic dysregulation. METHODS: In this study, we investigated the role of OCT1, a member of the OCT family, in an AR-positive CRPC patient-derived xenograft established from a patient with resistance to ARSI and chemotherapy. We conducted a genome-wide analysis chromatin immunoprecipitation followed by sequencing and bioinformatic analyses using public database. RESULTS: Genome-wide analysis of OCT1 target genes in PDX 201.1 A revealed distinct OCT1 binding sites compared to treatment-naïve cells. Bioinformatic analyses revealed that OCT1-regulated genes were associated with cell migration and immune system regulation. In particular, C-terminal Binding Protein 2 (CTBP2), an OCT1/AR target gene, was correlated with poor prognosis and immunosuppressive effects in the tumor microenvironment. Metascape revealed that CTBP2 knockdown affects genes related to the immune response to bacteria. Furthermore, TISIDB analysis suggested the relationship between CTBP2 expression and immune cell infiltration in prostate cancer, suggesting that it may contribute to immune evasion in CRPC. CONCLUSIONS: Our findings shed light on the genome-wide network of OCT1 and AR in AR-positive CRPC and highlight the potential role of CTBP2 in immune response and tumor progression. Targeting CTBP2 may represent a promising therapeutic approach for aggressive AR-positive CRPC. Further validation will be required to explore novel therapeutic strategies for CRPC management.

Diallyl disulfide induces DNA damage and growth inhibition in colorectal cancer cells by promoting POU2F1 ubiquitination.

Previous studies have demonstrated that diallyl disulfide (DADS) exhibits potent anti-tumor activity. However, the pharmacological actions of DADS in inhibiting the growth of colorectal cancer (CRC) cells have not been clarified. Herein, we show that DADS treatment impairs the activation of the pentose phosphate pathway (PPP) to decrease PRPP (5-phosphate ribose-1-pyrophosphate) production, enhancing DNA damage and cell apoptosis, and inhibiting the growth of CRC cells. Mechanistically, DADS treatment promoted POU2F1 K48-linked ubiquitination and degradation by attenuating the PI3K/AKT signaling to up-regulate TRIM21 expression in CRC cells. Evidently, TRIM21 interacted with POU2F1, and induced the K272 ubiquitination of POU2F1. The effects of DADS on the enhanced K272 ubiquitination of POU2F1, the PPP flux, PRPP production, DNA damage and cell apoptosis as well as the growth of CRC tumors in vivo were significantly mitigated by TRIM21 silencing or activating the PI3K signaling in CRC cells. Conversely, the effects of DADS were enhanced by TRIM21 over-expression or inhibiting the PI3K/AKT signaling in CRC cells. Collectively, our findings reveal a novel mechanism by which DADS suppresses the growth of CRC by promoting POU2F1 ubiquitination, and may aid in design of novel therapeutic intervention of CRC.

Transcriptional Coactivator BOB1 (OBF1, OCA-B) Modulates the Specificity of DNA Recognition by the POU-Domain Factors OCT1 and OCT2 in a Monomeric Configuration.

BOB1, a mammalian lymphocyte-specific transcriptional coactivator of the transcription factors OCT1 and OCT2 (OCT1/2), plays important roles in normal immune responses, autoimmunity, and hematologic malignancies. The issue of a DNA sequence preference change imposed by BOB1 was raised more than two decades ago but remains unresolved. In this paper, using the EMSA-SELEX-Seq approach, we have reassessed the intrinsic ability of BOB1 to modulate the specificity of DNA recognition by OCT1 and OCT2. Our results have reaffirmed previous conclusions regarding BOB1 selectivity towards the dimer configuration of OCT1/2. However, they suggest that the monomeric configuration of these factors, assembled on the classical octamer ATGCAAAT and related motifs, are the primary targets of BOB1. Our data further specify the DNA sequence preference imposed by BOB1 and predict the probability of ternary complex formation. These results provide an additional insight into the action of BOB1-an essential immune regulator and a promising molecular target for the treatment of autoimmune diseases and hematologic malignancies.

LncRNA AC026401.3 interacts with OCT1 to intensify sorafenib and lenvatinib resistance by activating E2F2 signaling in hepatocellular carcinoma.

Multitargeted kinase inhibitors (MKIs) including sorafenib and lenvatinib, are applied for first-line treatment for inoperable hepatocellular carcinoma (HCC) patients, but the therapeutic effect is limited because of drug resistance. Therefore, we sought potential biomarkers to indicate sorafenib and lenvatinib resistance in HCC. In this article, we report a novel long non-coding RNA (lncRNA), AC026401.3, in promoting sorafenib and lenvatinib resistance of HCC cells. AC026401.3 is upregulated in HCC tissues and is positively relevant to HCC patients with large tumor size, cancer recurrence, advanced TNM stage, and poor prognosis. AC026401.3 knockdown or knockout enhances the sensitivity of HCC cells to sorafenib and lenvatinib, respectively. Moreover, AC026401.3 upregulates the expression of the transcription factor E2F2. Mechanistically, AC026401.3 interacts with OCT1 and promotes the recruitment of OCT1 to the promoter region of E2F2, intensifying sorafenib and lenvatinib resistance in HCC by activating the transcription of E2F2. In conclusion, our results reveal that lncRNA AC026401.3 is a risk factor for HCC patients by enhancing sorafenib and lenvatinib resistance of HCC cells, and targeting the AC026401.3-OCT1-E2F2 signaling axis would be a promising strategy for HCC therapeutics.

Free Cholesterol Affects the Function and Localization of Human Na+/Taurocholate Cotransporting Polypeptide (NTCP) and Organic Cation Transporter 1 (OCT1).

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are associated with obesity. They are accompanied by increased levels of free cholesterol in the liver. Most free cholesterol resides within the plasma membrane. We assessed the impact of adding or removing free cholesterol on the function and localization of two hepatocellular uptake transporters: the Na+/taurocholate cotransporting polypeptide (NTCP) and the organic cation transporter 1 (OCT1). We used a cholesterol-MCD complex (cholesterol) to add cholesterol and methyl-ß-cyclodextrin (MCD) to remove cholesterol. Our results demonstrate that adding cholesterol decreases NTCP capacity from 132 ± 20 to 69 ± 37 µL/mg/min and OCT1 capacity from 209 ± 66 to 125 ± 26 µL/mg/min. Removing cholesterol increased NTCP and OCT1 capacity to 224 ± 65 and 279 ± 20 µL/mg/min, respectively. In addition, adding cholesterol increased the localization of NTCP within lipid rafts, while adding or removing cholesterol increased OCT1 localization in lipid rafts. These results demonstrate that increased cholesterol levels can impair NTCP and OCT1 function, suggesting that the free cholesterol content of the liver can alter bile acid and drug uptake into the liver. This could explain the increased plasma bile acid levels in NAFLD and NASH patients and potentially lead to altered drug disposition.

[Reduced Expression of the Tissue-Specific Oct-IL Isoform Exerts an Antitumor Effect on Namalwa Burkitt's Lymphoma Cells].

Increased expression levels of the Oct-1 transcription factor is considered to be one of the key markers of poor cancer prognosis. In addition to the ubiquitous Oct-1A isoform, which is found in all cells, there also exists a tissue-specific Oct-1L isoform, which is expressed in hematopoietic cells. Oct-1L increases cell resistance to different stresses and also regulates the expression of genes controlling differentiation of hematopoietic and immune system cells. The tissue-specific Oct-1L isoform levels are significantly increased in the B-cell lymphoblastoma Namalwa and Raji lines and the T-cell lymphoblastoma Jurkat line compared to normal B and T cells. Apparently, aberrant Oct-1L overexpression not only enhances stress resistance but also leads to the disruption of developmental pathways in the cells promoting their malignant transformation. We report here that targeted suppression of the tissue-specific Oct-1L isoform expression reduces the proliferation rate of Namalwa B-lymphoblastic Burkitt's lymphoma cells, significantly increases cell death rate under hypoxic conditions, and makes cells more sensitive to chemotherapeutic agents such as docetaxel and doxorubicin. These results indicate that targeted therapy aimed at the suppression of the Oct-1 isoforms with increased expression levels in tumor cells rather than the total Oct-1, thus avoiding the traumatic effects of total Oct-1 knockdown, may be promising. Selective suppression of Oct-1 isoforms is a promising strategy in the treatment of lymphoid tumors and may contribute to mitigating the disease course and increasing survival rates in cancer patients.

SOX12 Promotes Thyroid Cancer Cell Proliferation and Invasion by Regulating the Expression of POU2F1 and POU3F1.

PURPOSE: SOX12 is overexpressed in many cancers, and we aimed to explore the biological function and mechanism of SOX12 in thyroid cancer. MATERIALS AND METHODS: We first analyzed the expression of SOX12 in thyroid cancer using data in The Cancer Genome Atlas. Immunohistochemistry and qRT-PCR were performed to identify SOX12 expression in thyroid cancer tissue and cells. Thyroid cancer cells were transfected with small interfering RNA targeting SOX12, and cellular functional experiments, including CCK8, wound healing, and Transwell assays, were performed. Protein expression was examined by Western blot analysis. A xenograft model was developed to evaluate the effect of SOX12 on tumor growth in vivo. RESULTS: SOX12 expression was increased in thyroid cancer tissue and cells. SOX12 promoted cell proliferation, migration, and invasion and accelerated tumor growth in vivo. The expression of PCNA, Cyclin D1, E-cadherin, Snail, MMP-2, and MMP-9 was affected by SOX12 knockdown. Bioinformatic analysis showed that SOX12 could interact with the POU family. SOX12 knockdown inhibited the expression of POU2F1, POU2F2, POU3F1 and POU3F2, and SOX12 expression showed a positive correlation with POU2F1, POU3F1, and POU3F2 expression in clinical data. POU2F1 and POU3F1 were able to reverse the effect of SOX12 knockdown on thyroid cancer cells. CONCLUSION: SOX12 affects the progression of thyroid cancer by regulating epithelial-mesenchymal transition and interacting with POU2F1 and POU3F1, which may be novel targets for thyroid cancer molecular therapy.

5-Azacytidine Suppresses the Expression of Tissue-Specific Oct-1 Isoform in Namalwa Burkitt's Lymphoma Cell Culture.

Overexpression of the transcription factor POU2F1 (Oct-1) increases the malignant potential of the tumor and determines the unfavorable prognosis for both solid and hematological cases of the disease in human carcinogenesis. The Oct-1 level determines the rate of development of the disease in acute myelodysplastic leukemia (AML), and a decrease in its expression significantly delays the development of leukemia in mice; however, a complete knockout of Oct-1 leads to the death of the animals. POU2F1 (Oct-1) is expressed as several isoforms transcribed from alternative promoters. They include both ubiquitous and tissue-specific isoforms. It was shown that in Burkitt's lymphoma Namalwa cells 5-azacytidine specifically suppresses the expression of the tissue-specific isoform Oct-1L mRNA (level of Oct-1L is abnormally increased in these cells), while not causing changes in the amount of the ubiquitous isoform Oct-1A mRNA. These results show that it is possible to selectively reduce the transcription level of the Oct-1L isoform aberrantly expressed in human tumor cells.

The interaction between long non-coding RNA LINC01564 and POU2F1 promotes the proliferation and metastasis of gastric cancer.

BACKGROUND: An increasing number of studies have demonstrated that long non-coding RNAs (lncRNAs) serve as key regulators in tumor development and progression. However, only a few lncRNAs have been functionally characterized in gastric cancer (GC). METHODS: Bioinformatics analysis was conducted to find lncRNAs that are associated with GC metastasis. RNA FISH, RIP, and RNA pull down assays were used to study the complementary binding of LINC01564 complementary to the 3'UTR of transcription factor POU2F1. The transcription activation of LINC01564 by POU2F1 as a transcription factor was examined by ChIP assay. In vitro assays such as MTT, cell invasion assay, and clonogenic assay were conducted to examined the impacts of LINC01564 and POU2F1 on GC cell proliferation and invasion. Experiments in vivo were performed to access the impacts of LINC01564 and POU2F1 on GC metastasis. RESULTS: The results showed that LINC01564 complementary bound to the 3'UTR of POU2F1 to form an RNA duplex, whereby stabilizing POU2F1 mRNA and increasing the enrichment in cells. The level of LINC01564 was also increased by POU2F1 through transcription activation. In vitro assays showed that LINC01564 promoted the proliferation, invasion and migration of GC cells through increasing POU2F1. In vivo experiments indicate the promotion of GC proliferation and metastasis by the interaction between LINC01564 and POU2F1. CONCLUSION: Taken together, our results indicate that the interaction between LINC01564 and POU2F1 promotes the proliferation, migration and invasion of GC cells.

OCT1-target neural gene PFN2 promotes tumor growth in androgen receptor-negative prostate cancer.

Androgen and androgen receptor (AR) targeted therapies are the main treatment for most prostate cancer (PC) patients. Although AR signaling inhibitors are effective, tumors can evade this treatment by transforming to an AR-negative PC via lineage plasticity. OCT1 is a transcription factor interacting with the AR to enhance signaling pathways involved in PC progression, but its role in the emergence of the AR-negative PC is unknown. We performed chromatin immunoprecipitation sequencing (ChIP-seq) in patient-derived castration-resistant AR-negative PC cells to identify genes that are regulated by OCT1. Interestingly, a group of genes associated with neural precursor cell proliferation was significantly enriched. Then, we focused on neural genes STNB1 and PFN2 as OCT1-targets among them. Immunohistochemistry revealed that both STNB1 and PFN2 are highly expressed in human AR-negative PC tissues. Knockdown of SNTB1 and PFN2 by siRNAs significantly inhibited migration of AR-negative PC cells. Notably, knockdown of PFN2 showed a marked inhibitory effect on tumor growth in vivo. Thus, we identified OCT1-target genes in AR-negative PC using a patient-derived model, clinicopathologial analysis and an animal model.

Characterization of the promoter of the human farnesyltransferase beta subunit and the impact of the transcription factor OCT-1 on its expression.

Farnesyltransferase (FTase) enables about 100 proteins to interact with cellular membranes by catalyzing the posttranslational addition of a farnesyl group. Farnesylated proteins provide important functions and inhibitors against the ß-subunit of the heterodimer of FTase are intensively studied in clinical and preclinical trials. However, very little is known about the transcriptional regulation of the ß-subunit. The examined promoter region of the human FTase ß-subunit gene (FNTB) showed significant basal promoter activity in HEK-293 and in HeLa cells. We were able to locate the core promoter at -165 to -74. Ten potential binding sites of the transcription factor OCT-1 were detected. Three could be confirmed using EMSA super shift experiments. OCT-1 overexpression and knockdown confirmed it as an important regulator of FNTB expression. Our results provide a basis for further research on FNTB/OCT-1 regulation, its inhibitors and diseases influenced by both such as colon carcinoma or diabetes mellitus.

Hypoxia-inducible lncRNA MIR210HG interacting with OCT1 is involved in glioblastoma multiforme malignancy.

An insufficient oxygen supply within the intratumoral environment, also known as hypoxia, induces glioblastoma multiforme (GBM) invasion, stemness, and temozolomide (TMZ) drug resistance. Long noncoding (lnc)RNAs have been reported to be involved in hypoxia and GBM progression. However, their roles in hypoxic GBM malignancy are still unclear. We investigated the mechanisms of hypoxia-mediated lncRNAs in regulating GBM processes. Using The Cancer Genome Atlas (TCGA) and data mining, hypoxia-correlated lncRNAs were identified. A hypoxia-upregulated lncRNA, MIR210HG, locating in nuclear regions, predicted poor prognoses of patients and modulated hypoxia-promoted glioma stemness, TMZ resistance, and invasion. Depletion of hypoxic MIR210HG suppressed GBM and patient-derived cell growth and increased TMZ sensitivity in vitro and vivo. Using RNA sequencing and gene set enrichment analysis (GSEA), MIR210HG-upregulated genes significantly belonged to the targets of octamer transcription factor 1 (OCT1) transcription factor. The direct interaction between OCT1 and MIR210HG was also validated. Two well-established worse prognostic factors of GBM, insulin-like growth factor-binding protein 2 (IGFBP2) and fibroblast growth factor receptor 1 (FGFR1), were identified as downstream targets of OCT1 through MIR210HG mediation in hypoxia. Consequently, the lncRNA MIR210HG is upregulated by hypoxia and interacts with OCT1 for modulating hypoxic GBM, leading to poor prognoses. These findings might provide a better understanding in functions of hypoxia/MIR210HG signaling for regulating GBM malignancy.

Positive feedback loop of lncRNA FAM201A/miR­146a­5p/POU2F1 regulates IL­1ß­induced chondrocyte injury in vitro.

Numerous studies have previously demonstrated that long non­coding RNAs (lncRNAs) serve an important regulatory role in osteoarthritis (OA). In particular, the lncRNA family with sequence similarity 201 member A (FAM201A) was previously found to be downregulated in necrotic femoral head samples. However, the role of FAM201A in IL­1ß­induced chondrocyte injury remains unclear. It was hypothesized that FAM201A may exert a protective effect on IL­1ß­induced chondrocyte injury in OA by sponging microRNAs (miRNAs/miRs). The purpose of the present study was to explore the role and molecular mechanism of FAM201A in IL­1ß­induced chondrocyte injury. A model of OA was established by stimulation C­28/I2 cell with IL­1ß in vitro. The expression levels of FAM201A following IL­1ß­induced chondrocyte injury were detected via reverse transcription­quantitative PCR. Luciferase reporter assay was used to assess the possible associations among FAM201A, miR­146a­5p and POU class 2 homeobox 1 (POU2F1). Chromatin immunoprecipitation assay was performed to analyze the interaction between POU2F1 and miR­146a­5p. ELISA, TUNEL and western blotting were performed to measure the level of inflammation, lactate dehydrogenase release, apoptosis and the expression of apoptosis­related proteins (Bcl­2, Bax, cleaved caspase 3 and cleaved caspase 9), respectively. The expression levels of FAM201A were found to be downregulated following IL­1ß­induced chondrocyte injury. Overexpression of FAM201A exerted a protective effect against IL­1ß­induced chondrocyte injury. In addition, FAM201A could upregulate the expression levels of POU2F1 by sponging miR­146a­5p. Further experiments revealed that POU2F1 could bind to the promoter region of FAM201A and subsequently regulate the expression levels of POU2F1, indicating a role for the FAM201A/miR­146a­5p/POU2F1 positive feedback loop in IL­1ß­induced chondrocyte injury. The present study revealed the protective effects of the FAM201A/miR­146a­5p/POU2F1 positive feedback loop on IL­1ß­induced chondrocyte injury and provided a potential therapeutic target for OA.

No significant influence of OCT1 genotypes on the pharmacokinetics of morphine in adult surgical patients.

We investigated the impact of genetic variants in OCT1 (SLC22A1) on morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) pharmacokinetics in adult patients scheduled for major surgery. Blood samples were taken before and 5, 10, 15, 30, 45, 60 and 90 min after a bolus of morphine (0.15 mg/kg). Patients were genotyped for the genetic variants (rs12208357, rs34059508, rs72552763 and rs34130495) in OCT1. Eighty-six patients completed the trial. The mean difference (95% confidence interval) for dose adjusted morphine, M3G and M6G AUC was 0.9 (-0.7-2.4), -5.9 (-11.8 to -0.03) and -1.1 (-2.5-0.4) h/L*10-6 , respectively, in patients with two reduced function alleles compared to patients with no reduced function alleles in OCT1. Accordingly, the (AUCM3G/Dose )/(AUCmorphine/Dose ) and (AUCM6G/Dose )/(AUCmorphine/Dose ) ratio was reduced, -1.8 (-3.2 to -0.4) and -0.4 (-0.7 to -0.03), respectively, when comparing the same groups. OCT1 variants had no influence on the experience of pain, adverse events or the number of PCA doses used. In conclusion, genetic variants in OCT1 had a small and clinically unimportant impact on the exposure of morphine after intravenous administration. Our results do not support pre-emptive genotyping for OCT1 prior to morphine administration in patients scheduled for major surgery.

OCT1 Is a Poor Prognostic Factor for Breast Cancer Patients and Promotes Cell Proliferation via Inducing NCAPH.

Octamer transcription factor 1 (OCT1) is a transcriptional factor reported to be a poor prognostic factor in various cancers. However, the clinical value of OCT1 in breast cancer is not fully understood. In the present study, an immunohistochemical study of OCT1 protein was performed using estrogen receptor (ER)-positive breast cancer tissues from 108 patients. Positive OCT1 immunoreactivity (IR) was associated with the shorter disease-free survival (DFS) of patients (p = 0.019). Knockdown of OCT1 inhibited cell proliferation in MCF-7 breast cancer cells as well as its derivative long-term estrogen-deprived (LTED) cells. On the other hand, the overexpression of OCT1 promoted cell proliferation in MCF-7 cells. Using microarray analysis, we identified the non-structural maintenance of chromosomes condensin I complex subunit H (NCAPH) as a novel OCT1-taget gene in MCF-7 cells. Immunohistochemical analysis showed that NCAPH IR was significantly positively associated with OCT1 IR (p < 0.001) and that positive NCAPH IR was significantly related to the poor DFS rate of patients (p = 0.041). The knockdown of NCAPH inhibited cell proliferation in MCF-7 and LTED cells. These results demonstrate that OCT1 and its target gene NCAPH are poor prognostic factors and potential therapeutic targets for patients with ER-positive breast cancer.

Primate-specific stress-induced transcription factor POU2F1Z protects human neuronal cells from stress.

The emergence of new primate-specific genes is an essential factor in human and primate brain development and functioning. POU2F1/Oct-1 is a transcription regulator in higher eukaryotes which is involved in the regulation of development, differentiation, stress response, and other processes. We have demonstrated that the Tigger2 transposon insertion into the POU2F1 gene which occurred in the primate lineage led to the formation of an additional exon (designated the Z-exon). Z-exon-containing primate-specific Oct-1Z transcript includes a short upstream ORF (uORF) located at its 5'-end and the main ORF encoding the Oct-1Z protein isoform (Pou2F1 isoform 3, P14859-3), which differs from other Oct-1 isoforms by its N-terminal peptide. The Oct-1Z-encoding transcript is expressed mainly in human brain cortex. Under normal conditions, the translation of the ORF coding for the Oct-1Z isoform is repressed by uORF. Under various stress conditions, uORF enables a strong increase in the translation of the Oct-1Z-encoding ORF. Increased Oct-1Z expression levels in differentiating human neuroblasts activate genes controlling stress response, neural cell differentiation, brain formation, and organogenesis. We have shown that the Oct-1Z isoform of the POU2F1/Oct-1 transcription factor is an example of a primate-specific genomic element contributing to brain development and cellular stress defense.

Impact of Camellia japonica Bee Pollen Polyphenols on Hyperuricemia and Gut Microbiota in Potassium Oxonate-Induced Mice.

Camellia japonica bee pollen is one of the major types of bee pollen in China and exhibits antioxidant and anti-inflammatory activities. The aims of our study were to evaluate the effects and the possible mechanism of Camellia japonica bee pollen polyphenols on the treatment of hyperuricemia induced by potassium oxonate (PO). The results showed that Camellia japonica bee pollen ethyl acetate extract (CPE-E) owned abundant phenolic compounds and strong antioxidant capabilities. Administration with CPE-E for two weeks greatly reduced serum uric acid and improved renal function. It inhibited liver xanthine oxidase (XOD) activity and regulated the expression of urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), organic anion transporter 1 (OAT1), organic cation transporter 1 (OCT1) and ATP-binding cassette superfamily gmember 2 (ABCG2) in kidneys. Moreover, CPE-E suppressed the activation of the toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-κB (TLR4/MyD88/NF-κB) signaling pathway and nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome in PO-treated mice, and related inflammatory cytokines were reduced. CPE-E also modulated gut microbiota structure, showing that the abundance of Lactobacillus and Clostridiaceae increased in hyperuicemic mice. This study was conducted to explore the protective effect of CPE-E on hyperuricemia and provide new thoughts for the exploitation of Camellia japonica bee pollen.

NPR3, transcriptionally regulated by POU2F1, inhibits osteosarcoma cell growth through blocking the PI3K/AKT pathway.

Natriuretic peptide receptor 3 (NPR3), mediates natriuretic peptides degradation, was reported to act as a tumor suppressor or promoter in some types of cancer. Previous studies showed that NPR3 was significantly decreased in osteosarcoma (OS) samples. However, the function and potential regulatory mechanism of NPR3 in OS development are unknown. By analyzing the protein expression of NPR3 in OS cell lines (n = 5) and human osteoblast cell line hFOB 1.19, we found that NPR3 expression was also significantly decreased in OS cells. The loss/gain-of-function analysis indicated that NPR3 overexpression observably decreased OS cell viability, arrested cell cycle, and induced apoptosis. However, NPR3 knockdown further enhanced the malignant phenotype of OS cells. Furthermore, NPR3 downregulation activated the PI3K/AKT pathway in OS cells, and the effects of NPR3 silencing on cell proliferation were reversed by the blockade of PI3K/AKT pathway. Of note, dual-luciferase reported assay and site-directed mutagenesis assay indicated that transcription factor POU domain class 2 transcription factor 1 (POU2F1) was proved to suppress NPR3 promoter activity by mainly binding to the -900 to -800 bp region of NPR3 promoter. Moreover, NPR3 overexpression inversed the promotion effect of POU2F1 on cell proliferation. In vivo experiments confirmed that NPR3 overexpression suppressed the growth of xenograft tumors. Taken together, the present study demonstrates that NPR3 may serve as a novel tumor suppressive factor through blocking the PI3K/AKT pathway and transcriptionally regulated by POU2F1.

Novel inhibitor of OCT1 enhances the sensitivity of human esophageal squamous cell carcinoma cells to antitumor agents.

Esophageal squamous cell carcinoma (ESCC) is one of the most fatal malignancies of the digestive system, and shows an especially high incidence in some regions of China. Octamer transcription factors are a family of transcription factors whose DNA-binding domain is a POU domain. OCT transcription factors (OCT-TFs) mediate maintenance of the pluripotency of embryonic stem cells. We measured expression of OCT-TFs in ESCC clinical specimens. Among the OCTs tested, OCT1 showed the highest expression in ESCC tissues. Using molecular docking, we discovered a small-molecule inhibitor, which we named "novel inhibitor of OCT1" (NIO-1), for OCT1. Treatment with NIO-1 inhibited recruitment of OCT1 to the promoter region of its downstream genes and, consequently, repressed OCT1 activation. Treatment with NIO-1 enhanced the susceptibility of ESCC cells to chemotherapeutic agents. Therefore, OCT1 may be a valuable target for ESCC treatment, and NIO-1 could be a promising therapeutic agent.

Octamer transcription factor-1 induces the Warburg effect via up-regulation of hexokinase 2 in non-small cell lung cancer.

Reprogramming of energy metabolism is a hallmark of cancer which is prevalent worldwide. Octamer transcription factor-1 (OCT1) is a well-known transcription factor. However, the role of OCT1 in metabolism remodeling has not been well defined. In the present study, we found that OCT1 was up-regulated in non-small cell lung cancer (NSCLC) and correlated with poor patient survival. Further data identified that OCT1 increased glycolysis flux, promoting proliferation in lung cancer cells. Mechanistically, OCT1 facilitated the aerobic glycolysis and cell proliferation via up-regulation of hexokinase 2 (HK2), a crucial enzyme of the Warburg effect. Hence, our findings indicate that, in NSCLC, high levels of OCT1 contribute to the Warburg effect through up-regulation of HK2, linking up the OCT1/HK2 axis and cancer progression, which provide a potential biomarker and therapeutic target for NSCLC treatment.