Casticin Attenuates Stemness in Cervical Cancer Stem-Like Cells by Regulating Activity and Expression of DNMT1.

OBJECTIVE: To explore whether casticin (CAS) suppresses stemness in cancer stem-like cells (CSLCs) obtained from human cervical cancer (CCSLCs) and the underlying mechanism. METHODS: Spheres from HeLa and CaSki cells were used as CCSLCs. DNA methyltransferase 1 (DNMT1) activity and mRNA levels, self-renewal capability (Nanog and Sox2), and cancer stem cell markers (CD133 and CD44), were detected by a colorimetric DNMT activity/inhibition assay kit, quantitative real-time reverse transcription-polymerase chain reaction, sphere and colony formation assays, and immunoblot, respectively. Knockdown and overexpression of DNMT1 by transfection with shRNA and cDNA, respectively, were performed to explore the mechanism for action of CAS (0, 10, 30, and 100 nmol/L). RESULTS: DNMT1 activity was increased in CCSLCs compared with HeLa and CaSki cells (P<0.05). In addition, HeLa-derived CCSLCs transfected with DNMT1 shRNA showed reduced sphere and colony formation abilities, and lower CD133, CD44, Nanog and Sox2 protein expressions (P<0.05). Conversely, overexpression of DNMT1 in HeLa cells exhibited the oppositive effects. Furthermore, CAS significantly reduced DNMT1 activity and transcription levels as well as stemness in HeLa-derived CCSLCs (P<0.05). Interestingly, DNMT1 knockdown enhanced the inhibitory effect of CAS on stemness. As expected, DNMT1 overexpression reversed the inhibitory effect of CAS on stemness in HeLa cells. CONCLUSION: CAS effectively inhibits stemness in CCSLCs through suppression of DNMT1 activation, suggesting that CAS acts as a promising preventive and therapeutic candidate in cervical cancer.

Detection of a novel panel of 24 genes with high frequencies of mutation in gastric cancer based on next-generation sequencing.

BACKGROUND: Gastric cancer is a leading cause of cancer-related mortality worldwide. Many somatic mutations have been identified based on next-generation sequencing; they likely play a vital role in cancer treatment selection. However, next-generation sequencing has not been widely used to diagnose and treat gastric cancer in the clinic. AIM: To test the mutant gene frequency as a guide for molecular diagnosis and personalized therapy in gastric cancer by use of next-generation sequencing. METHODS: We constructed a panel of 24 mutant genes to detect somatic nucleotide variations and copy number variations based on a next-generation sequencing technique. Our custom panel included high-mutation frequency cancer driver and tumour suppressor genes. Mutated genes were also analyzed using the cBioPortal database. The clinical annotation of important variant mutation sites was evaluated in the ClinVar database. We searched for candidate drugs for targeted therapy and immunotherapy from the OncoKB database. RESULTS: In our study, the top 16 frequently mutated genes were TP53(58%), ERBB2(28%), BRCA2 (23%), NF1 (19%), PIK3CA (14%), ATR (14%), MSH2 (12%), FBXW7 (12%), BMPR1A (12%), ERBB3 (11%), ATM (9%), FGFR2 (8%), MET (8%), PTEN (6%), CHD4 (6%), and KRAS (5%). TP53 is a commonly mutated gene in gastric cancer and has a similar frequency to that in the cBioPortal database. 33 gastric cancer patients (51.6%) with microsatellite stability and eight patients (12.5%) with microsatellite instability-high were investigated. Enrichment analyses demonstrated that high-frequency mutated genes had transmembrane receptor protein kinase activity. We discovered that BRCA2, PIK3CA, and FGFR2 gene mutations represent promising biomarkers in gastric cancer. CONCLUSION: We developed a powerful panel of 24 genes with high frequencies of mutation that could detect common somatic mutations. The observed mutations provide potential targets for the clinical treatment of gastric cancer.

ß-Boswellic Acid Suppresses Breast Precancerous Lesions via GLUT1 Targeting-Mediated Glycolysis Inhibition and AMPK Pathway Activation.

Breast carcinoma is a multistep progressive disease. Precancerous prevention seems to be crucial. ß-Boswellic acid (ß-BA), the main component of the folk medicine Boswellia serrata (B. serrata), has been reported to be effective in various diseases including tumors. In this work, we demonstrated that ß-BA could inhibit breast precancerous lesions in rat disease models. Consistently, ß-BA could suppress proliferation and induce apoptosis on MCF-10AT without significantly influencing MCF-10A. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that ß-BA may interfere with the metabolic pathway. Metabolism-related assays showed that ß-BA suppressed glycolysis and reduced ATP production, which then activated the AMPK pathway and inhibited the mTOR pathway to limit MCF-10AT proliferation. Further molecular docking analysis suggested that GLUT1 might be the target of ß-BA. Forced expression of GLUT1 could rescue the glycolysis suppression and survival limitation induced by ß-BA on MCF-10AT. Taken together, ß-BA could relieve precancerous lesions in vivo and in vitro through GLUT1 targeting-induced glycolysis suppression and AMPK/mTOR pathway alterations. Here, we offered a molecular basis for ß-BA to be developed as a promising drug candidate for the prevention of breast precancerous lesions.

Retraction: 8-bromo-7-methoxychrysin targets NF-κB and FoxM1 to inhibit lung cancer stem cells induced by pro-inflammatory factors.

[This retracts the article DOI: 10.7150/jca.30143.].

Genistein inhibits lung cancer cell stem-like characteristics by modulating MnSOD and FoxM1 expression.

Manganese superoxide dismutase (MnSOD) promotes invasive and migratory activities by upregulating Forkhead box protein M1 (FoxM1) expression. The present study investigated whether modulation of MnSOD and FoxM1 expression was responsible for the antitumor effects of genistein on cancer stem-like cells (CSLCs) derived from non-small cell lung cancer cells (NSCLCs). Spheroids prepared from H460 or A549 cells were defined as lung cancer stem-like cells (LCSLCs) and were treated with genistein. The Cell Counting Kit-8 assay was performed to assess human lung fibroblast IMR-90 cell proliferation, as well as NSCLC H460 and A549 cell proliferation following treatment with genistein. MnSOD, FoxM1, cluster of differentiation (CD)133, CD44, BMI1 proto-oncogene, polycomb ring finger (Bmi1) and Nanog homeobox (Nanog) protein expression levels were examined via western blotting. The sphere formation assay was conducted to evaluate LCSLC self-renewal potential, and LSCLC migratory and invasive activities were analyzed using the wound healing and Transwell invasion assays, respectively. Knockdown and overexpression of MnSOD and FOXM1 via short hairpin-RNA or cDNA transfection were performed. The results indicated that genistein (80 and 100 µM) suppressed H460 and A549 cell viability compared with IMR-90 cells. Sub-cytotoxic concentrations of genistein (20 and 40 µM) inhibited sphere formation activity and decreased the protein expression levels of CD133, CD44, Bmi1 and Nanog in LCSLCs compared with the control group. Genistein also suppressed the migratory and invasive activities of LCSLCs compared with the control group. MnSOD and FoxM1 overexpression antagonized the effects of genistein (40 µM), whereas MnSOD and FoxM1 knockdown enhanced the inhibitory effects of genistein (20 µM) on CSLC characteristics of LCSLCs. Overall, the results suggested that genistein suppressed lung cancer cell CSLC characteristics by modulating MnSOD and FoxM1 expression levels.

Modulation of MnSOD and FoxM1 Is Involved in Invasion and EMT Suppression by Isovitexin in Hepatocellular Carcinoma Cells.

BACKGROUND: Manganese superoxide dismutase (MnSOD) induces FoxM1 expression, subsequently contributing to migration in several cancer cells. Isovitexin (ISOV) was recently found to downregulate MnSOD and FoxM1, decreasing stemness in hepatocellular carcinoma (HCC) stem-like cells (HCSLCs). The current study aimed to determine whether inhibition of migration, invasion and EMT in HCSLCs by ISOV results from MnSOD/FoxM1 signaling blockade and subsequent Twist1, Slug, ZEB1 and MMP-2 downregulation. MATERIALS AND METHODS: We examined the migratory and invasive capabilities and EMT phenotype in HCC cells and their HCSLCs, respectively, by wound-healing assay, transwell invasion assay and Western blot after treatment with non-cytotoxic concentrations of ISOV, and explored the mechanism by which ISOV affects migration, invasion and EMT by MnSOD or FoxM1 knockdown and/or overexpression in HCSLCs or HCC cells. RESULTS: The results showed that ISOV not only downregulated MnSOD and FoxM1 but also suppressed the migratory and invasive capabilities and reversed the EMT phenotype in HCSLCs, which was reflected by elevated E-cadherin protein amounts, and reduced N-cadherin, Twist1, Slug, ZEB1 and MMP-2 protein levels. The suppressive effects of ISOV on the migratory and invasive capabilities and EMT phenotype could be potentiated by MnSOD or FoxM1 knockdown in HCSLCs, and attenuated by MnSOD or FoxM1 overexpression in HCC cells. Importantly, FoxM1 overexpression reversed MnSOD knockdown combined with ISOV suppression on the migratory and invasive capabilities and EMT phenotype in HCSLCs, while having little effects on MnSOD expression. CONCLUSION: Collectively, the above findings demonstrated that ISOV suppresses migration, invasion and EMT in HCSLCs by blocking MnSOD/FoxM1 signaling subsequently inhibiting the expression of EMT-related transcription factors and MMP-2.

The DNMT1/miR-34a/FOXM1 Axis Contributes to Stemness of Liver Cancer Cells.

BACKGROUND: Whether DNA methyltransferase 1 (DNMT1)/miR-34a/FoxM1 signaling promotes the stemness of liver cancer stem cells (LCSCs) remains unclear. This study aimed to assess whether methylation-based silencing of miR-34a by DNMT1 contributes to stemness features via FoxM1 upregulation in LCSCs. METHODS: The CD133+ subgroup of MHCC97H cells sorted by MACS was used as LCSCs. DNMT1, BMI1, SOX2, and OCT4 mRNA levels, and miR-34a amounts were determined by qRT-PCR. DNMT1, CD44, and FoxM1 proteins were analyzed by immunoblot. Sphere and colony formation abilities were detected by respective assays. CD133+ cell percentages were assessed by flow cytometry. In vivo oncogenicity was evaluated using a tumor xenograft model in mice. The effects of DNMT1/miR-34a signaling on the stemness of LCSCs were examined by knockdown or overexpression of DNMT1 and/or transfection of miR-34a mimic or inhibitor using lentivirus-delivery systems. FoxM1 association with miR-34a was detected by a reporter assay. RESULTS: We here showed that LCSCs exhibited elevated DNMT1 activity and expression, lower miR-34a expression with higher promoter methylation, and stronger stemness, compared with the parental liver cancer cells. DNMT1 knockdown repressed DNMT1, increased miR-34a amounts by promoter demethylation, and reduced stemness in LCSCs, whereas DNMT1 overexpression had the opposite effects in liver cancer cells. Transfection with miR-34a mimic repressed the stemness of LCSCs, while miR-34a inhibitor significantly downregulated miR-34a and enhanced stemness, without affecting DNMT1 in liver cancer cells. MiR-34a mimic rescued the effects of DNMT1 overexpression on the stemness of LCSCs, without affecting DNMT1 expression. Finally, FOXM1 was identified as a direct target by miR-34a in LCSCs. CONCLUSIONS: We revealed that aberrant activation of DNMT1 causes miR-34a promoter methylation and suppression, leading to FoxM1 upregulation by disinhibition and promotion of LCSC stemness. These findings suggest that blockage of DNMT1/miR-34a-mediated FOXM1 upregulation might suppress liver cancer by targeting LCSCs.

Isovitexin Inhibits Stemness and Induces Apoptosis in Hepatocellular Carcinoma SK-Hep-1 Spheroids by Upregulating miR-34a Expression.

BACKGROUND: We previously demonstrated that isovitexin (apigenin-6-C-glucoside, ISOV) suppressed the stemness of human Hepatocellular Carcinoma (HCC) cells. However, the mechanism of its action remains to be deciphered. OBJECTIVE: The current study was to examine whether ISOV regulates the miR-34a expression and hence suppresses the stemness of HCC SK-Hep-1 cells. METHODS: After identification of the stemness, apoptosis resistance and decreased miR-34a expression of spheres from SK-Hep-1 cells (SK-SC), we utilized transfection of a miR-34a mimic or inhibitor to investigate the effects of ISOV on miR-34a, Bcl-2, Bax and Mcl-1 expression in order to understand the mechanism underlying ISOV-mediated repression of stemness and promotion of apoptosis. RESULTS: Our results demonstrated that SK-SC displayed higher stemness and resistance to apoptosis, as well as reduced miR-34a levels compared to SK-Hep-1 cells. ISOV suppressed sphere and colony formation, and decreased CD44+ cell populations. In addition, ABCG2, ALDH1, and NANOG mRNA levels were decreased, while there was a concomitant increase in miR-34a levels. With regards to apoptosis-related proteins, ISOV increased Bax protein levels, and reduced Bcl-2 and Mcl-1 protein levels in SK-SC. Importantly, there was a cooperative effect when miR-34a was overexpressed in the presence of ISOV in SK-SC, and down-regulation of miR-34a attenuated the effects of ISOV in SK-Hep-1 cells. CONCLUSION: We suggest that ISOV-mediated miR-34a upregulation induces apoptosis and suppresses the stemness of SK-SC. Our data indicate that ISOV exhibits therapeutic potential for the treatment of HCC.

Casticin inhibits stemness of hepatocellular carcinoma cells via disrupting the reciprocal negative regulation between DNMT1 and miR-148a-3p.

Casticin (CAS) is a polymethyl flavonoid from Fructus viticis and has multiple pharmacological activities, including anticancer. However, whether the molecular mechanism underlying CAS represses stemness characteristics in hepatocellular carcinoma (HCC) cells involves intervention in the reciprocal negative regulation between DNA methyltransferase 1 (DNMT1) and miR-148a-3p has not yet been reported. In this study, the effect of CAS on stemness characteristics of HCC cells and its mechanism were investigated. Results showed that CAS selectively reduced the viabilities of HCC cells but not L02 cells, as determined by CCK-8 assay. Importantly, the sub-cytotoxic concentrations of CAS could inhibit the stemness characteristics in HCC cells, as demonstrated by the expression of stemness biomarkers (CD44, EpCAM, Bmi1, Nanog, and Oct4), sphere forming assay, RT-qPCR, and Western blotting. In addition, CAS repressed DNMT1 activity and expression and increased miR-148a-3p. The effect of CAS on stemness characteristics was abolished by stable DNMT1 overexpression. MiR-148a-3p overexpression enhanced the reduction of CAS on stemness characteristics. DNMT1 overexpression promoted miR-148a-3p promoter hypermethylation as detected by methylation-specific PCR (MSP), which repressed its expression. Conversely, miR-148a-3p repressed DNMT1 expression by specific site binding to 3'-UTR of DNMT1 mRNA, as determined by luciferase assay. Moreover, the combination of CAS and agomir-148a-3p had robust effects on tumor suppression as compared to the sole activity of either molecule in nude mouse xenograft experiments in vivo. The findings suggested that CAS could inhibit stemness characteristics in HCC cells by interruption of the reciprocal negative regulation between DNMT1 and miR-148a-3p.

8-bromo-7-methoxychrysin targets NF-κB and FoxM1 to inhibit lung cancer stem cells induced by pro-inflammatory factors.

We have previously reported that 8-bromo-7-methoxychrysin (BrMC), a novel synthetic derivative of chrysin, was demonstrated anti-tumor activities against several human cancers, including lung cancer. Interaction between inflammation and cancer stem cell are recently increasingly recognized in tumorigenesis and progression. The purpose of this study was to investigate whether BrMC inhibits lung cancer stemness of H460 cells induced by inflammatory factors (TGF-ß combined with TNF-α) and its potential mechanism. Our results showed that BrMC inhibited lung cancer stemness, as validated by enhanced self-renewal ability, higher in vitro tumorigenicity, and increased expression of CD133, CD44, Bmi1 and Oct4 in H460 cells administered TNF-α after prolonged induction by TGF-ß, in a concentration-dependent manner. Both NF-κB inhibition by SN50 and FoxM1 suppression by thiostrepton (THI) prompted the inhibition of BrMC on lung CSCs. Conversely, overexpression of NF-κBp65 significantly antagonized the above effects of BrMC. Meanwhile, overexpression of FoxM1 also significantly compromised BrMC function on suppression of FoxM1 and NF-κBp65 as well as stemness of lung CSCs. Our results suggest that activation of NF-κB and FoxM1 by cytokines facilitate the acquisition CSCs phenotype, and compromise the chemical inhibition, which may represent an effective therapeutic target for treatment of human lung cancer. Moreover, BrMC may be a potential promising candidate for targeting NF-κB/ FoxM1 to prevent the tumorigenesis under inflammatory microenvironment.

Isovitexin reduces carcinogenicity and stemness in hepatic carcinoma stem-like cells by modulating MnSOD and FoxM1.

BACKGROUND: Manganese superoxide dismutase (MnSOD) upregulating FoxM1 have previously been demonstrated promoting lung cancer stemness. Isovitexin exhibits antitumor activities in various cancers. This study aimed to assess whether isovitexin inhibits hepatic carcinoma stem-like cells (HCSLCs) features via regulating MnSOD and FoxM1 expression. METHODS: Second-generation spheres from the hepatic carcinoma cell lines, respectively, were used as HCSLCs. Protein amounts of MnSOD, FoxM1 and stemness-associated markers (CD133, CD44, ALDH1, Bmi1, Nanog and Oct4) were determined by immunoblotting. In vitro carcinogenicity was evaluated by sphere- and colony-formation assays. The effects of isovitexin on HCSLC carcinogenicity and stemness were examined in vitro and in xenograft models. An adenoviral delivery system was employed to manipulate MnSOD and/or FoxM1. Luciferase reporter assay was performed to verify isovitexin downregulated FoxM1 by inhibiting MnSOD-mediated effects of E2F1 and/or Sp1 on activation of FoxM1 promoter. RESULTS: FoxM1 upregulation by MnSOD contributed to carcinogenicity and stemness, with increased sphere- and colony-formation capabilities, upregulated stemness-associated markers and CD133+ subpopulation as well as elevated oncogenicity in vivo in HCSLCs compared with hepatic carcinoma cells. Isovitexin substantially decreased sphere and colony formation rates, and stemness-associated markers in cultured HCSLCs by suppressing MnSOD and FoxM1 expression. Importantly, isovitexin significantly inhibited tumor growth of in nude mice bearing HCSLCs and reduced CD133 protein expression of xenograft in nude mice. MnSOD or FoxM1 knockdown enhanced the effects of isovitexin suppression on carcinogenicity and stemness in HCSLC. MnSOD or FoxM1 overexpression attenuated the effects of isovitexin. Additionally, isovitexin and MnSOD knockdown could inhibit FoxM1 reporter activity via a decreased binding of E2F1 and/or Sp1 onto FoxM1 promoter. FoxM1 overexpression reversed the effects of isovitexin combined with MnSOD knockdown, without affecting MnSOD expression. Moreover, MnSOD knockdown plus thiostrepton, a FoxM1 specific inhibitor, cooperated with isovitexin to repress xenograft tumor growth and downregulate MnSOD and FoxM1 in nude mice bearing HCSLCs from MHCC97H cells. CONCLUSIONS: Isovitexin inhibits carcinogenicity and stemness in HCSLCs by downregulating FoxM1via inhibition of MnSOD.

Genistein inhibits stemness of SKOV3 cells induced by macrophages co-cultured with ovarian cancer stem-like cells through IL-8/STAT3 axis.

BACKGROUND: Recent studies showed that macrophages co-cultured with ovarian cancer stem-like cells (OCSLCs) induced SKOV3 cell stemness via IL-8/STAT3 signaling. Genistein (GEN) demonstrates chemopreventive activity in inflammation-associated cancers. The present study aimed to examine whether and if GEN inhibits the stemness of SKOV3 and OVCA-3R cells induced by co-culture of THP-1 macrophages and SKOV3-derived OCSLCs. METHODS: The co-culture was treated with or without different concentrations (10, 20, and 40 µmol/L) of GEN for 24 h. Depletion or addition of IL-8 in Co-CM and knockdown or overexpression of STAT3 in THP-1 macrophages was performed to demonstrate the possible associated mechanisms. The combined effects of GEN and STAT3 knockdown were examined with the nude mouse modle by co-injection of SKOV3-derived OCSLCs with THP-1 macrophages. RESULTS: Our results showed that GEN down-regulated CD163 and p-STAT3 expression of THP-1 macrophage, decreased the levels of IL-10, increased the levels of IL-12 and nitric oxide (NO) in the conditioned medium, and reduced the clonogenic and sphere-forming capacities and the expression of CD133 and CD44 in SKOV3 cells induced by co-culture of THP-1 macrophages and OCSLCs in a dose-dependent manner. Moreover, depletion or addition of IL-8 enhanced or attenuated the effect of GEN. Additionally, knockdown or overepression of STAT3 in THP-1 macrophages potentiated or attenuated the inhibitory effects of GEN. Importantly, STAT3 overexpression retrieved the effects of IL-8 combined with GEN depletion on M2 polarization of THP-1 macrophages and stemness of SKOV3 cells induced by co-culture. The combination of GEN and STAT3 knockdown cooperatively inhibited the growth of tumors co-inoculated with OCSLCs/THP-1 macrophages in nude mice in vivo through blocking IL-8/STAT3 signaling. CONCLUSIONS: In summary, our findings suggested that GEN can inhibit the increased M2 polarization of macrophages and stemness of ovarian cancer cells by co-culture of macrophages with OCSLCs through disrupting IL-8/STAT3 signaling axis. This assisted GEN to be as a potential chemotherapeutic agent in human ovarian cancer.

NF-κB/Twist axis is involved in chysin inhibition of ovarian cancer stem cell features induced by co-treatment of TNF-α and TGF-ß.

Chrysin (ChR) inhibits various cancer cells and possesses anti-inflammatory activities. NF-kB has been shown to regulate the expression of genes involved in epithelial-mesenchymal transformation (EMT) by upregulation of TWIST1. This study aimed to assess whether ChR can inhibit EMT phenotype and cancer stem-like cell (CSLC) features in ovarian cancer cells co-treated with TNF-α and TGF-ß. Here, OVCAR-3 cells were co-treated with TNF-α and TGF-ß in the presence or absence of ChR. Then, the expression levels of E-cadherin, N-cadherin, CD133, CD44, NF-κBp65, and TWIST1 were analyzed by western blotting. Wound healing and tumor sphere formation assays were performed to assess the migration and sphere-forming capabilities of cells, respectively. Overexpression and/or knockdown of NF-κBp65 and/or TWIST1 were used to explore the molecular mechanisms. We showed that ChR inhibited EMT and CSLC properties in ovarian cancer cells administered TNF-α after prolonged TGF-ß treatment, in a dose-dependent manner. Also, knockdown of NF-κBp65 and ChR cooperatively enhanced the inhibition of NF-κBp65 and TWIST1 expression, EMT phenotype, and CSLC properties. Conversely, overexpression of NF-κBp65 antagonized the above-mentioned activities of ChR. Furthermore, TWIST1 silencing or overexpression did not affect the ChR treatment effect on NF-κBp65 levels, but it reduced or enhanced EMT and CSLC properties. In conclusion, ChR can inhibit a proinflammatory cytokine to induce EMT and CSLC characteristics in OVCAR-3 cells, which may be involved in blocking the NF-κB/Twist axis.