A novel TOX3-WDR5-ABCG2 signaling axis regulates the progression of colorectal cancer by accelerating stem-like traits and chemoresistance.

The eradication of cancer stem cells (CSCs) with drug resistance confers the probability of local tumor control after chemotherapy or targeted therapy. As the main drug resistance marker, ABCG2 is also critical for colorectal cancer (CRC) evolution, in particular cancer stem-like traits expansion. Hitherto, the knowledge about the expression regulation of ABCG2, in particular its upstream transcriptional regulatory mechanisms, remains limited in cancer, including CRC. Here, ABCG2 was found to be markedly up-regulated in CRC CSCs (cCSCs) expansion and chemo-resistant CRC tissues and closely associated with CRC recurrence. Mechanistically, TOX3 was identified as a specific transcriptional factor to drive ABCG2 expression and subsequent cCSCs expansion and chemoresistance by binding to -261 to -141 segments of the ABCG2 promoter region. Moreover, we found that TOX3 recruited WDR5 to promote tri-methylation of H3K4 at the ABCG2 promoter in cCSCs, which further confers stem-like traits and chemoresistance to CRC by co-regulating the transcription of ABCG2. In line with this observation, TOX3, WDR5, and ABCG2 showed abnormal activation in chemo-resistant tumor tissues of in situ CRC mouse model and clinical investigation further demonstrated the comprehensive assessment of TOX3, WDR5, and ABCG2 could be a more efficient strategy for survival prediction of CRC patients with recurrence or metastasis. Thus, our study found that TOX3-WDR5/ABCG2 signaling axis plays a critical role in regulating CRC stem-like traits and chemoresistance, and a combination of chemotherapy with WDR5 inhibitors may induce synthetic lethality in ABCG2-deregulated tumors.

MED27 plays a tumor-promoting role in breast cancer progression by targeting KLF4.

The mediator complex usually cooperates with transcription factors to be involved in RNA polymerase II-mediated gene transcription. As one component of this complex, MED27 has been reported in our previous studies to promote thyroid cancer and melanoma progression. However, the precise function of MED27 in breast cancer development remains poorly understood. Here, we found that MED27 was more highly expressed in breast cancer samples than in normal tissues, especially in triple-negative breast cancer, and its expression level was elevated with the increase in pathological stage. MED27 knockdown in triple-negative breast cancer cells inhibited cancer cell metastasis and stemness maintenance, which was accompanied by downregulation of the expression of EMT- and stem traits-associated proteins, and vice versa in non-triple-negative breast cancer. Furthermore, MED27 knockdown sensitized breast cancer cells to epirubicin treatment by inducing cellular apoptosis and reducing tumorsphere-forming ability. Based on RNA-seq, we identified KLF4 as the possible downstream target of MED27. KLF4 overexpression reversed the MED27 silencing-mediated arrest of cellular metastasis and stemness maintenance capacity in breast cancer in vitro and in vivo. Mechanistically, MED27 transcriptionally regulated KLF4 by binding to its promoter region at positions -156 to +177. Collectively, our study not only demonstrated the tumor-promoting role of MED27 in breast cancer progression by transcriptionally targeting KLF4, but also suggested the possibility of developing the MED27/KLF4 signaling axis as a potential therapeutic target in breast cancer.

BPTF inhibition antagonizes colorectal cancer progression by transcriptionally inactivating Cdc25A.

As the largest subunit of the nuclear remodeling factor complex, Bromodomain PHD Finger Transcription Factor (BPTF) has been reported to be involved in tumorigenesis and development in several cancers. However, to date, its functions and related molecular mechanisms in colorectal cancer (CRC) are still poorly defined and deserve to be revealed. In this study, we uncovered that, under the expression regulation of c-Myc, BPTF promoted CRC progression by targeting Cdc25A. BPTF was found to be highly expressed in CRC and promoted the proliferation and metastasis of CRC cells through BPTF specific siRNAs, shRNAs or inhibitors. Based on RNA-seq, combined with DNA-pulldown, ChIP and luciferase reporter assay, we proved that, by binding to -178/+107 region within Cdc25A promoter, BPTF transcriptionally activated Cdc25A, thus accelerating the cell cycle process of CRC cells. Meanwhile, BPTF itself was found to be transcriptionally regulated by c-Myc. Moreover, BPTF knockdown or inactivation was verified to sensitize CRC cells to chemotherapeutics, 5-Fluorouracil (5FU) and Oxaliplatin (Oxa), c-Myc inhibitor and cell cycle inhibitor not just at the cellular level in vitro, but in subcutaneous xenografts or AOM/DSS-induced in situ models of CRC in mice, while Cdc25A overexpression partially reversed BPTF silencing-caused tumor growth inhibition. Clinically, BPTF, c-Myc and Cdc25A were highly expressed in CRC tissues simultaneously, the expression of any two of the three was positively correlated, and their expressions were highly relevant to tumor differentiation, TNM staging and poor prognosis of CRC patients. Thus, our study indicated that the targeted inhibition of BPTF alone, or together with chemotherapy and/or cell cycle-targeted therapy, might act as a promising new strategy for CRC treatment, while c-Myc/BPTF/Cdc25A signaling axis is expected to be developed as an associated set of candidate biomarkers for CRC diagnosis and prognosis prediction.

TRIP4 transcriptionally activates DDIT4 and subsequent mTOR signaling to promote glioma progression.

In spite of significant advances in the understanding of glioma biology and pathology, survival remains poor. Therefore, it is still of great significance to further explore the key factors involved in tumorigenesis and development in glioma and find potential new therapeutic targets. Here, we show that thyroid hormone receptor interactor 4 (TRIP4) is highly expressed in glioma cells and tissues. Patients of glioma with high expression of TRIP4 possess poor overall survival. Knockdown of TRIP4 inhibited tumor cell proliferation, metastasis, and apoptosis suppression, whereas overexpression of TRIP4 displays the opposite effects. Further research showed that TRIP4 promoted glioma progression through regulating DDIT4 expression and subsequent activation of mTOR signaling. DDIT4 overexpression restored the inhibition of tumor growth by TRIP4 knockdown in vitro and in vivo. Consistently, mTOR activity inhibition reversed TRIP4 overexpression-mediated tumor promotion in vitro and in vivo. Moreover, molecular mechanism exploration demonstrates that TRIP4 functions as a specific transcriptional activator to anchor at the promoter region of DDIT4 gene (-196 to -11) to regulate its transcription and such regulation was affected by HIF1α. Clinically, TRIP4 expression is positively correlated with DDIT4 expression in glioma samples based on tissue microarray analysis and both of their high expression predicts the malignancy of the disease. Altogether, our findings identify TRIP4 as a critical promoter of glioma progression by targeting DDIT4 and mTOR signaling successively and suggest that TRIP4-DDIT4 axis has potential to be a novel therapeutic target in glioma treatment.

SPT6 recruits SND1 to co-activate human telomerase reverse transcriptase to promote colon cancer progression.

Human telomerase reverse transcriptase (hTERT) plays an extremely important role in cancer initiation and development, including colorectal cancer (CRC). However, the precise upstream regulatory mechanisms of hTERT in different cancer types remain poorly understood. Here, we uncovered the candidate transcriptional factor of hTERT in CRC and explored its role and the corresponding molecular mechanisms in regulating hTERT expression and CRC survival with an aim of developing mechanism-based combinational targeting therapy. The possible binding proteins at the hTERT promoter were uncovered using pull-down/mass spectrometry analysis. The regulation of SPT6 on hTERT expression and CRC survival was evaluated in human CRC cell lines and mouse models. Mechanistic studies focusing on the synergy between SPT6 and staphylococcal nuclease and Tudor domain containing 1 (SND1) in controlling hTERT expression and CRC progression were conducted also in the above two levels. The expression correlation and clinical significance of SPT6, SND1, and hTERT were investigated in tumor tissues from murine models and patients with CRC in situ. SPT6 was identified as a possible transcriptional factor to bind to the hTERT promoter. SPT6 knockdown decreased the activity of hTERT promoter, downregulated the protein expression level of hTERT, suppressed proliferation, invasion, and stem-like properties, promoted apoptosis induction, and enhanced chemotherapeutic drug sensitivity in vitro. SPT6 silencing also led to the delay of tumor growth and metastasis in mice carrying xenografts of human-derived colon cancer cells. Mechanistically, SND1 interacted with SPT6 to co-control hTERT expression and CRC cell proliferation, stemness, and growth in vitro and in vivo. SPT6, SND1, and hTERT were highly expressed simultaneously in CRC tissues, both from the murine model and patients with CRC in situ, and pairwise expression among these three factors showed a significant positive correlation. In brief, our research demonstrated that SPT6 synergized with SND1 to promote CRC development by targeting hTERT and put forward that inhibiting the SPT6-SND1-hTERT axis may create a therapeutic vulnerability in CRC.

YBX1 Enhances Metastasis and Stemness by Transcriptionally Regulating MUC1 in Lung Adenocarcinoma.

Abnormal expression of the transcription factor Y-box-binding protein-1 (YBX1) is associated with the proliferation, migration, aggressiveness, and stem-like properties of various cancers. These characteristics contribute to the tumorigenesis and metastasis of cancer. We found that the expression levels of Mucin-1 (MUC1) and YBX1 were positively correlated in lung adenocarcinoma cells and lung adenocarcinoma tissue. Our retrospective cohort study of 176 lung adenocarcinoma patients after surgery showed that low expression of both YBX1 and MUC1 was an independent predictor of the prognosis and recurrence of lung adenocarcinoma. In lung adenocarcinoma cells, the silencing/overexpression of YBX1 caused a simultaneous change in MUC1, and MUC1 overexpression partially reversed the decreased tumor cell migration, aggressiveness, and stemness caused by YBX1 silencing. Moreover, chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays proved that MUC1 was the downstream target of YBX1 and that YBX1 bound to the -1480~-1476 position in the promoter region of MUC1 to regulate its transcription. Furthermore, in mouse xenograft models and a lung cancer metastasis model, MUC1, which is downstream of YBX1, partially reversed the decreased number and size of tumors caused by YBX1 silencing. In conclusion, our findings indicated a novel mechanism by which YBX1 promotes the stemness and metastasis of lung adenocarcinoma by targeting MUC1 and provided a combination approach for diagnosis different from traditional single tumor biomarkers to predict patient prognosis and provide clinical treatment targets.

Melatonin increases the chemosensitivity of diffuse large B-cell lymphoma cells to epirubicin by inhibiting P-glycoprotein expression via the NF-κB pathway.

BACKGROUND: Epirubicin is a first-line chemotherapeutic drug for the clinical treatment of diffuse large B cell lymphoma (DLBCL), but the overexpression of multidrug resistance (MDR) transporter proteins, especially P-glycoprotein (P-gp), renders epirubicin ineffective. Some studies reveal the potential role of melatonin in chemotherapeutic synergy and MDR. METHODS: The cell viability and apoptosis were determined by CCK-8 assay and acridine orange/ethidium bromide (AO/EB) fluorescence staining assay. Immunofluorescence and immunohistochemical staining were used to detect the expression of P-gp in DLBCL cells and tissues. Rhodamine-123 accumulation assay was used to evaluate the pump function of P-gp. The possible mechanisms of melatonin sensitize DLBCL cells to epirubicin were explored by western blotting, cytochrome C release, and pulldown assay. RESULTS: Melatonin significantly enhanced the epirubicin-induced cell proliferation suppression, epirubicin-induced apoptosis, and reduced the IC50 value of epirubicin. Further, melatonin synergized with epirubicin to promote the activation of the mitochondria-mediated apoptosis pathway and increased the accumulation of epirubicin in DLBCL cells by inhibiting the expression and function of P-gp. Immunohistochemical staining studies revealed that P-gp expression was positively correlated with P65 expression. Epirubicin was subsequently discovered to upregulate the expression of P-gp by activating the NF-κB pathway in the DLBCL cells. Melatonin reduced the amount of P65 protein in the nucleus and abrogated the ability of P65 to bind to the ABCB1 promoter, decisively suppressing P-gp expression. CONCLUSIONS: Our results demonstrated that melatonin inactivates the NF-κB pathway and downregulates the expression of P-gp, ultimately sensitizing DLBCL cells to the epirubicin that suppresses their growth.

CRSP8 promotes thyroid cancer progression by antagonizing IKKα-induced cell differentiation.

CRSP8 plays an important role in recruiting mediators to genes through direct interaction with various DNA-bound transactivators. In this study, we uncovered the unique function of CRSP8 in suppressing thyroid cancer differentiation and promoting thyroid cancer progression via targeting IKKα signaling. CRSP8 was highly expressed in human thyroid cancer cells and tissues, especially in anaplastic thyroid cancer (ATC). Knockdown of CRSP8 suppressed cell growth, migration, invasion, stemness, and induced apoptosis and differentiation in ATC cells, while its overexpression displayed opposite effects in differentiated thyroid cancer (DTC) cells. Mechanistically, CRSP8 downregulated IKKα expression by binding to the IKKα promoter region (-257 to -143) to negatively regulate its transcription. Knockdown or overexpression of IKKα significantly reversed the expression changes of the differentiation and EMT-related markers and cell growth changes mediated by CRSP8 knockdown or overexpression in ATC or DTC cells. The in vivo study also validated that CRSP8 knockdown inhibited the growth of thyroid cancer by upregulating IKKα signaling in a mouse model of human ATC. Furthermore, we found that CRSP8 regulated the sensitivity of thyroid cancer cells to chemotherapeutics, including cisplatin and epirubicin. Collectively, our results demonstrated that CRSP8 functioned as a modulator of IKKα signaling and a suppressor of thyroid cancer differentiation, suggesting a potential therapeutic strategy for ATC by targeting CRSP8/IKKα pathway.

Targeting HMGB3/hTERT axis for radioresistance in cervical cancer.

BACKGROUND: Radiotherapy is regarded as a milestone for the cure of cervical cancer. However, clinical outcome heavily be hindered by radioresistance. So, exploring the underlying mechanism of radioresistance, and find potential target, well deserve fully emphasis. METHODS: In this study, we developed two novel radiation resistance cervical cancer cell lines, which could mimic clinical radioresistance. In order to find new potential targets, RNA-Seq, database analysis, streptavidin-agarose and LC/MS were used. Pull-down, luciferase and rescue assays were conducted to explore the regulatory mechanisms. To further evaluate the correlation between therapeutic responses and HMGB3/hTERT expression, 172 cervical cancer patients were recruited. RESULTS: Knockdown of HMGB3 significantly inhibit the DNA damage repair and induced more γH2AX foci, leading to enhanced chemo- and radio-sensitivity in vitro and in vivo, whereas HMGB3 overexpression has the opposite effects. HMGB3 promotes cell growth and radioresistance by transcriptionally up-regulating hTERT via the specifical binding of HMGB3 at the hTERT promoter region from - 902 to - 321. HMGB3 knockdown-mediated radiosensitization could be reversed by the overexpressed hTERT in both cervical cancer cell lines and xenograft tumor mouse model. Furthermore, clinical data from 172 cervical cancer patients proved that there was a positive correlation between HMGB3 and hTERT expression, and high expression of HMGB3/hTERT predicted poor response to radiotherapy, worse TNM stages and shorter survival time. CONCLUSION: Here, we have identified HMGB3/hTERT signaling axis as a new target for cervical cancer radioresistance. Our results provide new insights into the mechanism of cervical cancer radioresistance and indicate that targeting the HMGB3/hTERT signaling axis may benefit cervical cancer patients.

Importin 13 promotes NSCLC progression by mediating RFPL3 nuclear translocation and hTERT expression upregulation.

Our previous studies have reported that RFPL3 protein exerts its unique function as a transcriptional factor of hTERT promoter after being transported into the lung cancer cell nucleus. However, the detailed mechanism by which RFPL3 undergoes nuclear transport has not been reported yet. Here, we identified RFPL3 as a potential import cargo for IPO13, which was found to be overexpressed in NSCLC cells and tissues. IPO13 interacted with RFPL3 in lung cancer cells, and the knockdown of IPO13 led to the cytoplasmic accumulation of RFPL3, the decreased anchoring of RFPL3 at hTERT promoter, and the downregulation of hTERT expression. Moreover, IPO13 silencing suppressed tumor growth in vitro and in vivo. IHC analysis confirmed the positive correlation between the expression levels of IPO13 and hTERT in the tumor tissues from patients with lung cancer. Furthermore, the mechanistic study revealed that IPO13 recognized RFPL3 via a functional nuclear localization signal (NLS), which is located in the B30.2 domain at the C-terminal region of RFPL3. Of note, the presence of EGFR mutations was significantly related to the increased IPO13 expression. The EGFR-TKI Osimertinib downregulated IPO13 expression level in NSCLC cell lines with EGFR mutations, but not in EGFR wild-type ones. In summary, our data suggest that inhibition of IPO13 transport activity itself might be an alternative and potential therapeutic strategy for NSCLC.

PD-L1 promotes tumor growth and progression by activating WIP and ß-catenin signaling pathways and predicts poor prognosis in lung cancer.

PD-L1 is overexpressed in tumor cells and contributes to cancer immunoevasion. However, the role of the tumor cell-intrinsic PD-L1 in cancers remains unknown. Here we show that PD-L1 regulates lung cancer growth and progression by targeting the WIP and ß-catenin signaling. Overexpression of PD-L1 promotes tumor cell growth, migration and invasion in lung cancer cells, whereas PD-L1 knockdown has the opposite effects. We have also identified WIP as a new downstream target of PD-L1 in lung cancer. PD-L1 positively modulates the expression of WIP. Knockdown of WIP also inhibits cell viability and colony formation, whereas PD-L1 overexpression can reverse this inhibition effects. In addition, PD-L1 can upregulate ß-catenin by inhibiting its degradation through PI3K/Akt signaling pathway. Moreover, we show that in lung cancer cells ß-catenin can bind to the WIP promoter and activate its transcription, which can be promoted by PD-L1 overexpression. The in vivo experiments in a human lung cancer mouse model have also confirmed the PD-L1-mediated promotion of tumor growth and progression through activating the WIP and ß-catenin pathways. Furthermore, we demonstrate that PD-L1 expression is positively correlated with WIP in tumor tissues of human adenocarcinoma patients and the high expression of PD-L1 and WIP predicts poor prognosis. Collectively, our results provide new insights into understanding the pro-tumorigenic role of PD-L1 and its regulatory mechanism on WIP in lung cancer, and suggest that the PD-L1/Akt/ß-catenin/WIP signaling axis may be a potential therapeutic target for lung cancers.

YBX1 mediates autophagy by targeting p110ß and decreasing the sensitivity to cisplatin in NSCLC.

Y-box binding protein 1 (YBX1) is involved in the development of multiple types of tumors. However, the relationship between YBX1 and autophagy in non-small cell lung cancer (NSCLC) remains unclear. In this study, we analyzed the expression and clinical significance of YBX1 and markers of autophagy (LC3I/II) in NSCLC and examined their roles in regulating sensitivity to cisplatin in NSCLC. The retrospective analysis of patients with NSCLC indicated that YBX1 was positively correlated with autophagy. Increased levels of YBX1 or autophagy also observed in NSCLC cells compared with those in 16HBE cells. Compared to the controls, the knockdown of YBX1 expression suppressed autophagy, increased drug sensitivity and promoted apoptosis in response to cisplatin in NSCLC cells by targeting the p110ß promoter and inhibiting p110ß/Vps34/beclin1 signaling pathways. We also demonstrated in an in vivo study that the overexpressed YBX1 effectively increased NSCLC growth and progression and decreased the sensitivity to cisplatin by inducing autophagy in a xenograft tumor model, and these effects were concomitant with the increasing of p110ß and beclin1 expression. Collectively, these results show that YBX1 plays an essential role in autophagy in NSCLC.

α1,6-Fucosyltransferase (FUT8) regulates the cancer-promoting capacity of cancer-associated fibroblasts (CAFs) by modifying EGFR core fucosylation (CF) in non-small cell lung cancer (NSCLC).

Cancer-associated fibroblasts (CAFs) are the main cancer-promoting component in the tumor microenvironment (TME) of non-small cell lung cancer (NSCLC). α1,6-Fucosyltransferase (FUT8), the key enzyme catalyzing core α1,6-fucosylation (CF), plays a promoting role in multiple malignancies. In the current study, we investigated the function of FUT8 in CAFs and elucidated the mechanism through which FUT8 regulates the cancer-promoting capacity of CAFs in NSCLC. A bioinformatics analysis was performed to reveal the relationship between FUT8 and CAFs. Resected specimens from NSCLC patients were analyzed to assess the expression of FUT8 in CAFs. Primary CAFs and normal lung fibroblasts (NLFs) were extracted from NSCLC patient specimens and were co-cultured with NSCLC cell lines in a novel 3D-printed non-contact co-culture device. An In vivo CAF/NSCLC co-injection tumorigenesis assay was performed using nude mice to study the function of FUT8/CF in TME formation. The current study revealed that FUT8-mediated CF in CAFs plays a positive role in the cancer-promoting capacity of these cells. FUT8 overexpression was observed in CAFs isolated from some lung adenocarcinoma cases. Further investigation showed that FUT8/CF in CAFs promoted the formation of an invasive and malignant TME in vivo and in vitro, and the resulting NSCLC cells exhibited faster proliferation and increased invasiveness. EGFR signaling exerts a catalytic effect on the cancer-promoting capacity of CAFs and is regulated by the CF modification of the EGFR protein.

Aspirin enhances the sensitivity of colon cancer cells to cisplatin by abrogating the binding of NF-κB to the COX-2 promoter.

Cisplatin is one of the most potent chemotherapeutic agents for the treatment of colon cancer. Nevertheless, the unavoidability of the notable toxicity and the development of the acquired resistance severely restricted its clinical application. Aspirin and some other non-steroidal anti-inflammatory drugs have been used to prevent colon tumorigenesis as chemopreventive agents. Here, we explored the possibility of aspirin as an adjuvant drug to boost the anti-cancer effect of cisplatin for colon cancer. We found that aspirin significantly enhanced the cisplatin-mediated inhibitions of cell proliferation, migration and invasion and the induction of apoptosis in colon cancer cells. The combined treatment of aspirin and cisplatin suppressed the expression of the anti-apoptotic protein Bcl-2 and the EMT-related proteins, up-regulated the levels of the cleaved PARP and Bax, and blocked the PI3K/AKT and RAF-MEK-ERK signaling pathway. In addition, we demonstrated that the enhanced effect of aspirin on the cisplatin-induced inhibition of tumor cell growth was also mediated through the suppression of the binding activity of NF-κB to the COX-2 promoter. The combination of aspirin and cisplatin effectively attenuated the translocation of NF-κB p65/p50 from the cytoplasm to the nucleus, and abrogated the binding of NF-κB p65/p50 to the COX-2 promoter, thereby down-regulating COX-2 expression and PGE2 synthesis. Moreover, the in vivo study also verified the enhanced anti-tumor activity of such combined therapy in colon cancer by targeting the NF-κB/COX-2 signaling. Our results provided new insights into understanding the molecular mechanisms of aspirin in sensitizing cisplatin-mediated chemotherapeutic effect in colon cancer and indicated a great potential of this combined therapy for cancer treatment.

Cleavage and polyadenylation specific factor 4 promotes colon cancer progression by transcriptionally activating hTERT.

CPSF4 was identified as a crucial tumorigenic factor in lung cancer development. However, its precise function and the underlying molecular mechanisms in colon cancer progression remain completely unknown. Here, we demonstrate CPSF4 was highly expressed in human colon cancer cells and tissues. Its knockdown inhibited colorectal cancer progression in vitro, including cell proliferation, migration, invasion and stemness maintenance. In contrast, the ectopic overexpression of CPSF4 had the opposite effects in vitro and in vivo. Further mechanistic studies demonstrated that CPSF4 facilitated colorectal tumorigenesis and development partially through transcriptionally regulating hTERT expression by cooperating with NF-kB1 and co-anchoring at hTERT promoter -321 to -234 fragment. In addition, clinical samples analysis indicated that CPSF4 expression was positively correlated with hTERT, and the simultaneously high expression of CPSF4 and hTERT predicted poor patient outcome. Overall, our findings established CPSF4 as a pro-tumorigenic factor in colorectal cancer progression, and suggested that targeting CPSF4-hTERT axis may represent a promising therapeutic strategy in colon cancer treatment.

TRIP4 promotes tumor growth and metastasis and regulates radiosensitivity of cervical cancer by activating MAPK, PI3K/AKT, and hTERT signaling.

Thyroid hormone receptor interactor 4 (TRIP4), a subunit of the tetrameric nuclear activating signal co-integrator 1 (ASC-1) complex, exerts pro-tumorigenic effects. The role for TRIP4 in the regulation of cervical cancer growth and radiation resistance is presently unknown. In this study, TRIP4 was found to be highly expressed in cervical cancer cells and tumor tissues. Knockdown of TRIP4 significantly suppressed cervical cancer cell proliferation and epithelial-mesenchymal transition (EMT), accompanied by inactivation of PI3K/AKT and MAPK/ERK signaling. TRIP4 was also found to target hTERT signaling by regulating its binding to the hTERT promoter. Moreover, the knockdown of TRIP4 increased cell sensitivity to radiation, concomitant with downregulation of Rad51 and p-H2AX. We also demonstrated in an in vivo study that the knockdown of TRIP4 effectively suppressed cervical cancer growth and progression in a xenograft tumor model, and these effects were concomitant with the downregulation of p-AKT, p-ERK, p-MEK1/2, MMP-9 and hTERT expression. Immunohistochemical analysis of tumor tissue microarrays showed that TRIP4 overexpression predicted poor prognosis in patients with cervical cancer. Collectively, these results show that TRIP4 plays an essential role in cervical cancer growth and survival.

Melatonin synergizes BRAF-targeting agent vemurafenib in melanoma treatment by inhibiting iNOS/hTERT signaling and cancer-stem cell traits.

BACKGROUND: As the selective inhibitor of BRAF kinase, vemurafenib exhibits effective antitumor activities in patients with V600 BRAF mutant melanomas. However, acquired drug resistance invariably develops after its initial treatment. METHODS: Immunohistochemical staining was performed to detect the expression of iNOS and hTERT, p-p65, Epcam, CD44, PCNA in mice with melanoma xenografts. The proliferation and migration of melanoma cells were detected by MTT, tumorsphere culture, cell cycle, cell apoptosis, AO/EB assay and colony formation, transwell assay and scratch assay in vitro, and tumor growth differences were observed in xenograft nude mice. Changes in the expression of key molecules in the iNOS/hTERT signaling pathways were detected by western blot. Nucleus-cytoplasm separation, and immunofluorescence analyses were conducted to explore the location of p50/p65 in melanoma cell lines. Flow cytometry assay were performed to determine the expression of CD44. Pull down assay and ChIP assay were performed to detect the binding ability of p65 at iNOS and hTERT promoters. Additionally, hTERT promoter-driven luciferase plasmids were transfected in to melanoma cells with indicated treatment to determine luciferase activity of hTERT. RESULTS: Melatonin significantly and synergistically enhanced vemurafenib-mediated inhibitions of proliferation, colony formation, migration and invasion and promoted vemurafenib-induced apoptosis, cell cycle arresting and stemness weakening in melanoma cells. Further mechanism study revealed that melatonin enhanced the antitumor effect of vemurafenib by abrogating nucleus translocation of NF-κB p50/p65 and their binding at iNOS and hTERT promoters, thereby suppressing the expression of iNOS and hTERT. The elevated anti-tumor capacity of vemurafenib upon co-treatment with melatonin was also evaluated and confirmed in mice with melanoma xenografts. CONCLUSIONS: Collectively, our results demonstrate melatonin synergizes the antitumor effect of vemurafenib in human melanoma by inhibiting cell proliferation and cancer-stem cell traits via targeting NF-κB/iNOS/hTERT signaling pathway, and suggest the potential of melatonin in antagonizing the toxicity of vemurafenib and augmenting its sensitivities in melanoma treatment.

BPTF cooperates with p50 NF-κB to promote COX-2 expression and tumor cell growth in lung cancer.

Cyclooxygenase-2 (COX-2) is overexpressed in most human cancers, but its precise regulatory mechanism in cancer cells remains unclear. The aims of this study are to discover and identify the new regulatory factors which bind to the COX-2 promoter and regulate COX-2 expression and cancer cell growth, and to elucidate the mechanisms of action of these factors in lung cancer. In this study, the COX-2 promoter-binding protein BPTF (bromodomain PHD finger transcription factor) was detected, identified and verified by biotin-streptavidin-agarose pulldown, mass spectrum analysis and chromatin immunoprecipitation (ChIP) in lung cancer cells, respectively. The expressions of COX-2 and BPTF in lung cancer cell lines, mouse tumor tissues and human clinical samples were detected by RT-PCR, Western blot and immunohistochemistry assays. The interaction of BPTF with NF-kB was analyzed by immunoprecipitation and confocal immunofluorescence assays. We discovered and identified BPTF as a new COX-2 promoter-binding protein in human lung cancer cells. Knockdown of BPTF inhibited COX-2 promoter activity and COX-2 expression in lung cancer cells in vitro and in vivo. We also found that BPTF functioned as a transcriptional regulator through its interaction with the p50 subunit of NF-kB. Knockdown of BPTF abrogated the binding of p50 to the COX-2 promoter, while the inhibition of p50 activity abolished the decreased trend of COX-2 expression and lung cancer cell proliferation caused by BPTF silencing. Moreover, we showed that the expressions of BPTF and COX-2 in tumor tissues of lung cancer patients were positively correlated, and high co-expression of BPTF and COX-2 predicted poor prognosis in lung cancer patients. Collectively, our results indicated that BPTF cooperated with p50 NF-κB to regulate COX-2 expression and lung cancer growth, suggesting that the BPTF/p50/COX-2 axis could be a potential therapeutic target for lung cancer.

BPTF promotes hepatocellular carcinoma growth by modulating hTERT signaling and cancer stem cell traits.

Bromodomain PHD finger transcription factor (BPTF), a core subunit of nucleosome-remodeling factor (NURF) complex, plays an important role in chromatin remodeling. However, its precise function and molecular mechanism involved in hepatocellular carcinoma (HCC) growth are still poorly defined. Here, we demonstrated the tumor-promoting role of BPTF in HCC progression. BPTF was highly expressed in HCC cells and tumor tissues of HCC patients compared with normal liver cells and tissues. Knockdown of BPTF inhibited cell proliferation, colony formation and stem cell-like traits in HCC cells. In addition, BPTF knockdown effectively sensitized the anti-tumor effect of chemotherapeutic drugs and induced more apoptosis in HCC cells. Consistently, knockdown of BPTF in a xenograft mouse model also suppressed tumor growth and metastasis accompanied by the suppression of cancer stem cells (CSC)-related protein markers. Moreover, the mechanism study showed that the tumor-promoting role of BPTF in HCC was realized by transcriptionally regulating the expression of human telomerase reverse transcriptase (hTERT). Furthermore, we found that HCC patients with high BPTF expression displayed high hTERT expression, and high BPTF or hTERT expression level was positively correlated with advanced malignancy and poor prognosis in HCC patients. Collectively, our results demonstrate that BPTF promotes HCC growth by targeting hTERT and suggest that the BPTF-hTERT axis maybe a novel and potential therapeutic target in HCC.