Exosomal circPVT1 promotes angiogenesis in laryngeal cancer by activating the Rap1b-VEGFR2 signaling pathway.

Laryngeal cancer (LC) is the second most common head and neck cancer and has a decreasing 5-year survival rate worldwide. Circular RNAs regulate cancer development in diverse ways based on their distinct biogenesis mechanisms and expansive regulatory roles. However, currently, there is little research on how exosomal circular RNAs are involved in the development of laryngeal cancer. Here, we demonstrated that circPVT1, a circular RNA derived from the well-studied long noncoding RNA PVT1, is correlated with disease progression in LC and promotes angiogenesis both in vivo and in vitro. Mechanistically, circPVT1 is loaded into LC cell-secreted exosomes and taken up by vascular epithelium cells. By sponging miR-30c-5p, exosomal circPVT1 promotes Rap1b expression, which dramatically enhances VEGFR2 and PI3K/AKT pathway activation, ultimately resulting in the induction of angiogenesis. Furthermore, our xenograft models demonstrated that the combination of shRNA-circPVT1 and cetuximab showed high efficacy in inhibiting tumor growth and angiogenesis. Collectively, these findings uncover a novel mechanism of exosomal circular RNA-mediated angiogenesis modulation and provide a preclinical rationale for testing this analogous combination in patients with LC.

Single-cell RNA sequencing reveals pro-invasive cancer-associated fibroblasts in hypopharyngeal squamous cell carcinoma.

BACKGROUND: Hypopharyngeal squamous cell carcinoma (HPSCC) has the worst prognosis among all head-and-neck cancers, and treatment options are limited. Tumor microenvironment (TME) analysis can help identify new therapeutic targets and combined treatment strategies. METHODS: Six primary HPSCC tissues and two adjacent normal mucosae from six treatment-naïve patients with HPSCC were analyzed using scRNA-seq. Cell types were curated in detail, ecosystemic landscapes were mapped, and cell-cell interactions were inferred. Key results were validated with The Cancer Genome Atlas and cell biology experiments. RESULTS: Malignant HPSCC epithelial cells showed significant intratumor heterogeneity. Different subtypes exhibited distinct histological features, biological behaviors, and spatial localization, all affecting treatment selection and prognosis. Extracellular matrix cancer-associated fibroblasts (mCAFs) expressing fibroblast activation protein were the dominant CAFs in HPSCC tumors. mCAFs, constituting an aggressive CAF subset, promoted tumor cell invasion, activated endothelial cells to trigger angiogenesis, and synergized with SPP1+ tumor associated macrophages to induce tumor progression, ultimately decreasing the overall survival of patients with HPSCC. Moreover, the LAMP3+ dendritic cell subset was identified in HPSCC and formed an immunosuppressive TME by recruiting Tregs and suppressing CD8+ T cell function. CONCLUSIONS: mCAFs, acting as the communication center of the HPSCC TME, enhance the invasion ability of HPSCC cells, mobilizing surrounding cells to construct a tumor-favorable microenvironment. Inhibiting mCAF activation offers a new anti-HPSCC therapeutic strategy. Video Abstract.

Exosomal PD-L1 derived from head and neck squamous cell carcinoma promotes immune evasion by activating the positive feedback loop of activated regulatory T cell-M2 macrophage.

The positive feedback loop of activated regulatory T cells (aTregs) and M2 macrophages (M2) play a vital role in promoting the tumor immunosuppressive microenvironment of head and neck squamous cell carcinoma (HNSCC). However, the key factors regulating the positive feedback loop remain unclear. Herein, we investigated the effect of PD-L1 carried on exosomes derived from tumor cells (TEXs) on the aTreg-M2 positive feedback loop, as well as their role in mediating immunosuppression. In our study, TEXs with or without PD-L1 (TEX-PD-L1 or TEX-PD-L1KO) were treated with CD4+CD25- T cells and M0 macrophages, and the effect on the differentiation of aTregs, M2 and the aTreg-M2 positive feedback loop was assessed. TEXs carried more PD-L1 than tumor cells and not only promoted the differentiation of aTregs and M2, but also, most importantly, enhanced the positive feedback loop of aTreg-M2, which inhibited the proliferation of CD4+CD25- T cells and in turn led to tumor immune escape. Moreover, in vivo study showed that TEX-PD-L1KO could inhibit tumor growth and significantly improve the antitumor efficacy in both the peripheral and tumor microenvironments. Collectively this study revealed the role and mechanism of TEX-PD-L1 in negative immune regulation, and targeting TEX-PD-L1 may be a new idea and strategy for immunotherapy of HNSCC.

Upfront Surgery Versus Definitive Radiotherapy: Competing Risk Analyses in Early Stage Oropharyngeal Cancer.

OBJECTIVE: To compare the survival outcomes of early-stage oropharyngeal cancer (OPC) patients treated with upfront surgery versus definitive radiotherapy (RT). STUDY DESIGN: Retrospective observational study. SETTING: Publicly available database. METHODS: A total of 1877 patients with T1-2N0-1M0 OPC were retrieved from the Surveillance, Epidemiology, and End Results database. Primary endpoints were cancer-specific and noncancer mortalities, which were estimated using cumulative incidence function and compared by Gray's test. Univariate and multivariate Fine-Gray subdistribution hazard models were used to estimate the effects of treatment modality on mortality. Subgroup analyses were performed in propensity-score-matched cohorts. All the analyses were conducted separately in human papillomavirus (HPV)-negative and HPV-positive cohorts. RESULTS: In the HPV-negative cohort, definitive RT was independently associated with increased risk of cancer-specific mortality (adjusted subdistribution hazard ratio [SHR], 2.29; 95% confidence interval [CI], 1.42-3.68; p = .001) and noncancer mortality (adjusted SHR, 2.74; 95% CI, 1.50-5.02; p = .001). In the HPV-positive cohort, definitive RT and upfront surgery could achieve similar cancer-specific and noncancer survival outcomes. CONCLUSION: Upfront surgery is associated with lower cancer-specific and noncancer mortality in HPV-negative early-stage OPC patients. However, in the setting of HPV-positive early-stage OPC with better prognosis, the 2 treatment modalities have similar efficacy in terms of cancer-specific and noncancer survival outcomes. In the future, carefully designed prospective clinical trials are needed to confirm our findings.

Risk Factors and Characteristics of the Recurrence of Juvenile Nasopharyngeal Angiofibroma: A 22-Year Experience With 123 Cases at a Tertiary Center.

OBJECTIVES: Despite the efficacy of surgical treatments, the high rate of recurrence in juvenile nasopharyngeal angiofibroma (JNA) after surgery remains an unresolved problem. The present study comprehensively analyzed the risk factors and characteristics of JNA recurrence, providing clinical guidance for reducing recurrence. METHODS: A total of 123 patients who underwent surgery for JNA between 1997 and 2019 at a single hospital were analyzed retrospectively. Univariate and multivariate analyses were used to assess the clinical risk factors for the recurrence of JNA. The relapse-free survival and annual cumulative recurrence rates were analyzed for subgroups defined according to clinical parameters. RESULTS: After screening, 78 of the 123 patients were included in the present study. The main risk factors associated with JNA recurrence included the year of diagnosis, tumor size, sphenoid bone invasion, Radkowski stage, surgical approach, and intraoperative bleeding. Importantly, the surgical approach and sphenoid bone invasion were independent prognostic factors affecting recurrence. Patients who underwent endoscopic surgery without sphenoid bone invasion exhibited longer relapse-free survival. In the present study, the overall cumulative recurrence rate of JNA was 38.7%, and recurrence occurred mainly in the first year after the initial surgery. CONCLUSION: Endoscopic surgery achieved better relapse-free survival in JNA patients, and patients with sphenoid bone invasion should be carefully explored to avoid residual JNA. The recurrence rate of JNA differed among subgroups defined based on clinical parameters and was highest in the first year after surgery. Computed tomography or magnetic resonance imaging, along with close follow-up, should be performed strictly within 1 year after the primary operation.

The NOP14 nucleolar protein suppresses the function and stemness of melanoma stem-like cells through Wnt/beta-catenin signaling inactivation.

Cancer stem cells (CSCs) are closely related to tumor occurrence, development, metastasis, drug resistance, and recurrence. The role of CSCs in melanoma is poorly understood. Our previous studies suggested that the NOP14 nucleolar protein (NOP14) is involved in melanoma pathogenesis regulation. Importantly, NOP14 overexpression inhibits the Wnt/beta (ß)-catenin signaling pathway, an important mechanism regulating CSCs stemness. Therefore, in this study, we aimed to explore the role of NOP14 in the stemness and function of CSCs in melanoma in vitro. CD133, a stem cell marker, was used to identify melanoma stem-like cells (SLCs). NOP14 overexpression subsequently decreased the proportion of CD133+ SLCs, impaired the colony-forming capabilities, and downregulated the expression of Nanog, SOX2, and OCT4 stem cell markers in A375 and A875 cells, suggesting that NOP14 suppresses the stemness of melanoma SLCs. NOP14 overexpression suppressed the migration, invasion, and angiogenesis-inducing ability of A375-SLCs and A875-SLCs. NOP14 overexpression also inactivated Wnt/ß-catenin signaling in melanoma CD133+ SLCs. The Wnt signaling activator BML-284 alleviated the effect of NOP14 overexpression on the stemness and function of melanoma CSCs. In conclusion, NOP14 suppresses the stemness and function of melanoma SLCs by inactivating Wnt/ß-catenin signaling. Thus, NOP14 is a novel target for CSC treatment in melanoma.Abbreviations: CSCs, cancer stem cells; SLCs, stem-like cells; NOP14, NOP14 nucleolar protein; SCID, severe combined immunodeficiency; ß-catenin, beta-catenin; lv-NOP14, lentivirals expressing NOP14; PBS, phosphate buffer saline; HUVECs, human umbilical vein endothelial cells.

A novel comprehensive immune-related gene signature as a promising survival predictor for the patients with head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC), the most frequent subtype of head and neck cancer, continues to have a poor prognosis with no improvement. The TNM stage is not satisfactory for individualized prognostic assessment and it does not predict response to therapy. In the present study, we downloaded the gene expression profiles from TCGA database to establish a training set and GEO database for a validation set. In the training set, we developed an 10 immune-related genes signature which had superior predictive value compared with TNM stage. A nomogram including clinical characteristics was also constructed for accurate prediction. Furthermore, it was determined that our prognostic signature might act as an independent factor for predicting the survival of HNSCC patients. As for the immune microenvironment, our results showed higher immune checkpoint expression (CLTA-4 and PD-1) in low-risk group which might reflect a positive immunotherapy response. Thus, our signature not only provided a promising biomarker for survival prediction, but might be evaluated as an indicator for personalized immunotherapy in patients with HNSCC.

A Selectable Biomarker in Hair Follicle Cycles - Cathepsins: A Preliminary Study in Murine.

BACKGROUND/OBJECTIVE: Hair cycle is regulated by many biological factors. Cathepsins are involved in various physiological processes in human skin. Here, we investigated the cathepsin expression and distribution changes in follicular growth cycles for better understanding the hair cycles and to explore new intervention measures. METHODS: The 24 mice (C57BL/6, female, 7-week old) were selected and removed the back hair via rosin/paraffin method. At Day 8, Day 20, and Day 25, biopsy on post-plucking area was done. Immunohistochemical staining, Western blot, and Q-PCR were used to test the cathepsin B/D/L/E. RESULTS: In anagen, cathepsins (B, D, L, and E) were distributed in the hair follicle matrix, inner hair root sheath, and hair. In catagen, cathepsins were mainly observed in un-apoptosis inner root sheath and outer root sheath. Expression of cathepsins B-mRNA and L-mRNA was decreased from anagen and catagen to telogen. Cathepsin D-mRNA was increased in catagen and then decreased in telogen. Cathepsin E-mRNA was decreased in catagen and slightly increased in telogen. CONCLUSIONS: The distribution and expression of cathepsins B, D, L, and E in hair follicle changed with hair growth process which indicated that cathepsins might act as selectable biomarkers of hair cycle in different stages.

The survival benefit of lymph node dissection in resected T1-2, cN0 supraglottic cancer: A population-based propensity score matching analysis.

BACKGROUND: The survival benefit of clinically negative cervical lymph nodes (cN0) in patients with T1-2 supraglottic cancer (SC) remains unclear. This study aimed to comprehensively evaluate the prognostic value of lymph node dissection (LND) in patients with T1-2, cN0 SC. METHODS: We included 1036 confirmed T1-2, cN0 SC patients with clinicopathological characteristics between 2004 and 2015, based on the Surveillance, Epidemiology, and End Results program (SEER) database. The association between LND and overall survival (OS) was investigated by the Kaplan-Meier method. RESULTS: Before propensity score matching (PSM), patients selected for LND had better OS, compared to patients did not receive LND (5-year OS: 62.6% vs 51.2%, respectively; p = 0.011). After PSM, the LND group also present significant improvement in prognosis (5-year OS: 64.3% vs 51.7%, respectively; p < 0.01). CONCLUSIONS: LND was significantly associated with a more favorable prognosis compared with non-LND in patients with T1-2, cN0 SC.

miR­18a­5p promotes melanoma cell proliferation and inhibits apoptosis and autophagy by targeting EPHA7 signaling.

Micro (mi)RNAs serve crucial roles in cancer development although little is known about their cellular mechanisms in the pathogenesis of melanoma. The present study explored the regulatory roles of miR­18a­5p in melanoma cell proliferation, apoptosis and autophagy, in addition to its target gene in melanoma cells. miRNA and ephrin receptor A7 (EPHA7) mRNA were analyzed by reverse transcription­quantitative PCR. Cell Counting Kit­8 and colony formation assays were performed to examine the cell proliferation rate. Hoechst staining and flow cytometry were performed to investigate cell apoptosis. Western blotting was used to estimate the abundance of proteins. Dual-luciferase reporter assay verified the binding of miRNA with target gene sequences. Melanoma tissues and cell lines exhibited markedly elevated miR­18a­5p expression. miR­18a­5p inhibitor inhibited proliferation rates, and triggered apoptosis and autophagy marker protein expression in WM266­4 and A375 cells. It also negatively regulated EPHA7 expression in WM266­4 and A375 cells by directly binding at the 3'­untranslated region of EPHA7. miR­18a­5p mimics reversed the EPHA7 overexpression­induced suppression of proliferation, and the EPHA7 overexpression­induced promotion of apoptosis and autophagy. miR­18a­5p triggered proliferation of melanoma cells and inhibited apoptosis and autophagy by directly targeting and inhibiting EPHA7 expression. Thus, the present study aided our understanding of miRNA­mediated melanoma pathogenesis.

EMG1 interacts with NOP14 to regulate the growth, migration, and invasion of melanoma cells via the Wnt/ß-catenin pathway.

BACKGROUND: The role of EMG1 in the progression of malignant melanoma remains unclear. METHODS: Expression levels of EMG1 in melanoma tissues from GEO and TCGA databases was analyzed. The role of EMG1 was determined by overexpression on cell growth, apoptosis, migration and invasion. Glutathione S-transferase (GST) pulldown and co-immunoprecipitation (CoIP) assays were applied to reveal the relationship of EMG1 and nucleolar complex protein 14 (NOP14). RESULTS: The expression level of EMG1 was downregulated in melanoma tissues in GSE7553 dataset and further decreased in tissues from metastasis patients from both GEE7553 and TCGA cohorts. Overexpression of EMG1 suppressed proliferation, promoted apoptosis, and inhibited migration and invasion in melanoma cells. EMG1 interacted with NOP14 and functioned together to regulate the growth, apoptosis, migration and invasion of cultured melanoma cells. Furthermore, simultaneous overexpression of EMG1 and NOP14 decreased the levels of WNT3a, ß-catenin, phosphorylated-GSK-3ß, and c-Myc. CONCLUSIONS: EMG1 and NOP14 inhibit melanoma cell proliferation, migration, and invasion by regulating the Wnt/ß-catenin signaling pathway.

Downregulation of miR-29c-3p is associated with a poor prognosis in patients with laryngeal squamous cell carcinoma.

BACKGROUND: Laryngeal squamous cell carcinoma (LSCC) is considered to be a common malignancy of the head and neck with poor prognosis for its late diagnosis, metastasis and recurrence. Growing evidence demonstrates that the dysregulation of miR-29c-3p (microRNA-29c-3p) plays an important role in various tumor processes. Our study investigates the expression of miR-29c-3p in LSCC and analyzes the correlation of its dysregulation with clinicopathologic parameters and prognosis. METHODS: The expression of hsa-miR-29c-3p in LSCC tissues and the adjacent normal laryngeal tissues was detected in 96 LSCC formalin-fixed paraffin-embedded tissues by quantitative real-time PCR (qRT-PCR). The SPSS statistical software package (17.0) was used to analyze the associations between miR-29c-3p expressions and various clinicopathological characteristics. The overall survival (OS) was analyzed by the Kaplan-Meier method and log-rank test, and we analyzed the independent factor of prognosis by Cox proportional hazard analysis. RESULTS: A downregulation of miR-29c-3p expression in LSCC was significantly correlated with smoking index, tumor size, tumor site, differentiation, T classification, TNM stage, and lymph node metastasis (P < 0.05), but there was no correlation with age and alcohol consumption (P > 0.05). In the multivariate survival analysis, low miR-29c-3p expression was associated with shorter overall survival (P < 0.05). Furthermore, miR-29c expression was an independent prognostic factor for laryngeal cancer patients. CONCLUSIONS: MiR-29c-3p has different expression levels at different stages of tumor progression, suggesting that miR-29c-3p may be a promising biomarker for evaluating the progression of LSCC and the prognosis of patients with LSCC. MiR-29c-3p can also be a novel molecular target for anti-laryngeal cancer therapy.

MicroRNA-329 upregulation impairs the HMGB2/ß-catenin pathway and regulates cell biological behaviors in melanoma.

Melanoma is responsible for the majority of deaths caused by skin cancer. Antitumor activity of microRNA-329 (miR-329) has been seen in several human cancers. In this study, we identify whether miR-329 serves as a candidate regulator in melanoma. Melanoma-related differentially expressed genes were screened with its potential molecular mechanism predicted. Melanoma tissues and pigmented nevus tissues were collected, where the levels of miR-329 and high-mobility group box 2 (HMGB2) were determined. To characterize the regulatory role of miR-329 on HMGB2 and the ß-catenin pathway in melanoma cell activities, miR-329 mimics, miR-329 inhibitors, and siRNA-HMGB2 were transfected into melanoma cells. Cell viability, migration, invasion, cell cycle, and apoptosis were assessed. miR-329 was predicted to influence melanoma by targeting HMGB2 via the ß-catenin pathway. High level of HMGB2 and low miR-329 expression were observed in melanoma tissues. HMGB2 was targeted and negatively regulated by miR-329. In melanoma cells transfected with miR-329 mimics or siRNA-HMGB2, cell proliferation, migration, and invasion were impeded, yet cell cycle arrest and apoptosis were promoted, corresponding to decreased levels of ß-catenin, cyclin D1, and vimentin and increased levels of GSK3ß and E-cadherin. Collectively, our results show that miR-329 can suppress the melanoma progression by downregulating HMGB2 via the ß-catenin pathway.

NOP14 inhibits melanoma proliferation and metastasis by regulating Wnt/ß-catenin signaling pathway

Malignant melanoma is an aggressive skin cancer with a high mortality rate. Nucleolar protein 14 (NOP14) has been implicated in cancer development. However, the role of NOP14 in malignant melanoma progression remains largely unclear. In this study, we observed that malignant melanoma tissue showed NOP14 down-regulation compared to melanocytic nevi tissues. Moreover, we observed that NOP14 expression was significantly associated with melanoma tumor thickness and lymph node metastasis. NOP14 overexpression in melanoma cells suppressed proliferation, caused G1 phase arrest, promoted apoptosis, and inhibited melanoma cell migration and invasion. Further investigations revealed that NOP14 overexpression reduced the expression levels of Wnt3a, β-catenin, and GSK-3β of the Wnt/β-catenin pathway. In summary, we demonstrated that NOP14 inhibited melanoma cell proliferation and metastasis by regulating the Wnt/β-catenin signaling pathway.

[miR-122-5p inhibits the proliferation of melanoma cells by targeting NOP14].

OBJECTIVE: To investigate the expression profile of miR-122-5p in melanoma tissues and the effect of miR-122-5p on the proliferation, cell cycle and apoptosis of human melanoma cell lines SK-MEL-110 and A375. METHODS: The expression profiles of miR-122-5p in melanoma and pigmented nevus tissues were detected using real-time fluorescence quantitative PCR (qRT-PCR). SK-MEL-110 and A375 cells transfected with miR-122-5p inhibitor or negative control inhibitor (NC) I were examined for miR-122- 5p expression using qRT-PCR and changes in cell proliferation, cell cycle and apoptosis using MTT assay or flow cytometry. NOP14 mRNA and protein expressions in the cells were detected using qRT- PCR and Western blotting, respectively. Luciferase reporter assay was used to confirm the identity of NOP14 as the direct target of miR-122-5p. RESULTS: The relative expression of miR-122-5p in human pigmented nevus tissues and melanoma tissues was 1.23±0.270 and 7.65 ± 1.37, respectively. The relative expression of miR-122-5p in SK-MEL-110 and A375 cells transfected with miR-122-5p inhibitor was 0.21 ± 0.08 and 0.17 ± 0.05, respectively. miR-122-5p inhibitor obviously inhibited the cell proliferation and increased the percentage of cells in G1 stage in both SK-MEL-110 and A-375 cells, but did not cause obvious changes in the apoptosis of the two cells. miR-122-5p inhibitor did not significantly affect the expression level of NOP14 mRNA, but obviously increased the expression level of NOP14 protein. Luciferase reporter assay revealed a significantly lower luciferase activity in cells co-transfected with miR-122-5p mimics and wild-type psi-CHECK2-3'UTR plasmid than in the cells cotransfected with NC and wild-type psi-CHECK2-3'UTR plasmid (0.21 ± 0.14 vs 0.56 ± 0.1, P < 0.01). CONCLUSIONS: miR-122-5p expression is upregulated in melanoma tissues, indicating its involvement in the development of melanoma. miR-122-5p inhibits the proliferation of SK-MEL-110 and A-375 cells possibly by affecting the cycle through NOP14.

NOP14 inhibits melanoma proliferation and metastasis by regulating Wnt/ß-catenin signaling pathway.

Malignant melanoma is an aggressive skin cancer with a high mortality rate. Nucleolar protein 14 (NOP14) has been implicated in cancer development. However, the role of NOP14 in malignant melanoma progression remains largely unclear. In this study, we observed that malignant melanoma tissue showed NOP14 down-regulation compared to melanocytic nevi tissues. Moreover, we observed that NOP14 expression was significantly associated with melanoma tumor thickness and lymph node metastasis. NOP14 overexpression in melanoma cells suppressed proliferation, caused G1 phase arrest, promoted apoptosis, and inhibited melanoma cell migration and invasion. Further investigations revealed that NOP14 overexpression reduced the expression levels of Wnt3a, ß-catenin, and GSK-3ß of the Wnt/ß-catenin pathway. In summary, we demonstrated that NOP14 inhibited melanoma cell proliferation and metastasis by regulating the Wnt/ß-catenin signaling pathway.

miR-99b suppresses IGF-1R expression and contributes to inhibition of cell proliferation in human epidermal keratinocytes.

Condyloma acuminatum (CA) is a condition caused by the highly contagious human papillomavirus (HPV), characterized by warts that undergo abnormal cell proliferation. One of the important regulators of cell proliferation is microRNAs (miRNAs). In this study, we aimed to investigate the expression profile of miR-99b in HPV positive CA samples and normal skin. We found significantly lower miR-99b levels in CA samples than in normal skin. Therefore, we investigated the role of miR-99b in regulating the proliferation of primary cultured human epidermal keratinocytes, and found that forced expression of miR-99b inhibited proliferation and induced G1-phase arrest. Based on conserved sequences in 3'UTR for miR-99b binding, we identified the insulin-like growth factor-1 receptor (IGF-1R) gene as a direct target for miR-99b. Further, we confirmed the binding site for miR-99b in the IGF-1R 3'UTR by mutation using a luciferase reporter assay that showed decrease in luciferase activity in the presence of miR-99b in the construct with the wild-type 3'UTR, but not in the construct with the mutant 3'UTR. Moreover, miR-99b over-expression could down-regulate IGF-1R expression, and could repress the PI3K-AKT signaling pathway. Lastly, over-expression of IGF-1R reversed the inhibitory effect of miR-99b on keratinocyte proliferation. Taken together, our results suggest that IGF-1R levels may be modulated by miR-99b in CA: downregulation of miR-99b with concomitant upregulation of its target gene IGF-1R may over-induce the PI3K-AKT signaling pathway, leading to deregulated cell proliferation in CA.

MicroRNA-328 inhibits proliferation of human melanoma cells by targeting TGFß2.

Some microRNAs (miRNAs) have been shown to act as oncogenes or tumor suppressor genes in human melanomas. miR-328 is upregulated in blood cells of melanoma patients compared to in healthy controls. This suggests a role for miR-328 in melanoma that warrants investigation. In this study, we demonstrated miR-328 levels to be dramatically decreased in human melanoma cell lines. Moreover, forced expression of miR-328 inhibited proliferation and induced G1-phase arrest of the SK-MEL-1 melanoma cell line. We identified TGFß2 as a direct target gene for miR-328 using a fluorescent reporter assay and western blotting. Levels of TGFß2 were dramatically increased in human melanoma cell lines and were inversely correlated with the miR-328 expression level. Our findings provide new insights into the mechanisms of human melanoma development, indicating that miR-328 has therapeutic potential for this disease.

Cdc48/p97 mediates UV-dependent turnover of RNA Pol II.

Cdc48/p97 is an essential ATPase whose role in targeting substrates to the ubiquitin-proteasome system (UPS) remains unclear. Existing models posit that Cdc48 acts upstream of UPS receptors. To address this hypothesis, we examined the association of ubiquitin (Ub) conjugates with 26S proteasomes. Unexpectedly, proteasomes isolated from cdc48 mutants contain high levels of Ub conjugates, and mass spectrometry identified numerous nonproteasomal proteins, including Rpb1, the largest subunit of RNA Pol II. UV-induced turnover of Rpb1 depends upon Cdc48-Ufd1-Npl4, Ubx4, and the uncharacterized adaptor Ubx5. Ubiquitinated Rpb1, proteasomes, and Cdc48 accumulate on chromatin in UV-treated wild-type cells, and the former two accumulate to higher levels in mutant cells, suggesting that degradation of Rpb1 is facilitated by Cdc48 at sites of stalled transcription. These data reveal an intimate coupling of function between proteasomes and Cdc48 that we suggest is necessary to sustain processive degradation of unstable subunits of some macromolecular protein complexes.

UBXD7 binds multiple ubiquitin ligases and implicates p97 in HIF1alpha turnover.

p97 is an ATP-dependent chaperone that plays an important role in endoplasmic reticulum-associated degradation but whose connections to turnover of soluble proteins remain sparse. Binding of p97 to substrates is mediated by cofactors that contain ubiquitin-binding domains. We employed "network proteomics" to show that p97 assembles with all of the 13 mammalian UBX-domain proteins. The UBX proteins that bind ubiquitin conjugates also interact with dozens of E3 ubiquitin ligases, only one of which had been previously linked to p97. In particular, UBXD7 links p97 to the ubiquitin ligase CUL2/VHL and its substrate hypoxia-inducible factor 1alpha (HIF1alpha). Depletion of p97 leads to accumulation of endogenous HIF1alpha and increased expression of a HIF1alpha target gene. The large number of ubiquitin ligases found associated with UBX proteins suggests that p97 plays a far broader role than previously anticipated in the global regulation of protein turnover.