Project description:Analysis of genes regulated by cisplatin exposure, using non-tumourigenic keratinocytes to filter out genes regulated following cisplatin exposure that are unlikely to be involved in tumourigenesis. Results identify genes that may be important in mediating an increase in tumourigenic potential in cisplatin-resistant HNSCC cells.
Project description:Cisplatin resistance is one of the main causes of treatment failure and death of head and neck squamous cell carcinoma (HNSCC). In order to better understand the mechanism of cisplatin resistance and formulate effective treatment strategies, we identified differentially expressed genes related to cisplatin resistance by RNA sequencing, RT-PCR and immunoblotting. CREB5 was selected as the most significantly up-regulated gene in cisplatin resistant cells. Gain- and loss-of-function experiments were performed to detect the effect of CREB5 on cisplatin resistance and mitochondrial apoptosis in HNSCC. Chromatin immunoprecipitation (ChIP) assay, dual-luciferase reporter assay, and immunoblotting experiments were performed to explore the underlying mechanisms of CREB5.
Project description:Protein phosphorylation, a widely occurring and significant post-translational modification, is integral to various biological processes. We previously utilized a protein affinity probe to identify genes damaged by cisplatin, revealing that it inflicts substantial damage on protein kinase and protein phosphatase genes. In this study, we investigated cisplatin-induced alterations in the proteome and global phosphoproteome of A549 cells. Employing Fe-IMAC beads and tyrosine phosphorylation enrichment antibodies, we identified 6944 protein groups and 18,274 phosphorylation sites on 4,915 proteins across three biological replicates of both cisplatin-treated A549 cells and control cells. Among these, 730 tyrosine phosphorylation sites were identified—marking the most substantial discovery of such sites in A549 cells following cisplatin treatment. Bioinformatics analysis indicated that the proteins exhibiting significant phosphorylation level changes, which are predominantly involved in RNA processing, modification, transcription, translation, and the spliceosome. This suggests that cisplatin-induced damage to protein kinases and phosphatases may disrupt the normal function of these proteins, consequently impairing DNA replication, RNA translation, and shearing, ultimately culminating in tumor cell death. Moreover, we cross-referenced our proteomic data with our previously obtained cisplatin-damaged genes, observing that the majority of down-regulated proteins derived from cisplatin-induced gene damage.
Project description:In order to improve therapy for head and neck squamous cell carcinoma (HNSCC), biomarkers associated with local and/or distant tumor relapses and cancer drug resistance are urgently needed. This study identified a potential biomarker, BAG-1 (Bcl-2 associated athanogene-1), that is implicated in HNSCC insensitive to cisplatin and tumor progression. Advanced HNSCC cells revealed resistant to cisplatin accompanied by increased expression of BAG-1 protein. siRNA knockdown of BAG-1 expression resulted in significant improvement of HNSCC sensitivity to cisplatin. BAG-1 expression enhanced stability of BCL-xL and conferred cisplatin resistant to the HNSCC cells. In addition, high levels of expression of phospho AKT, BAG-1, and BCL- xL were observed in advanced HNSCC compared to in that of primary HNSCC. Conclusion: Increased expression of BAG-1 was associated with cisplatin resistance and tumor progression in HNSCC patients and warrants further validation in larger independent studies. Over expression of BAG-1 may be a biomarker for cisplatin resistance in patients with primary or recurrent HNSCCs and targeting BAG-1 could be helpful in overcoming cisplatin resistance.
Project description:Background: Oropharynx squamous cell carcinoma (OPSCC) is a subtype of HNSCC, arising from the base of tongue, lingual tonsil, tonsil, oropharynx, pharynx. The majority of OPSCC positive for HPV infection is associated with better prognosis, but a fraction of them, similarly to HPV-negative ones, is resistant to therapy and has poor prognosis. A deep molecular study of OPSCC is mandatory to identify either prognostic markers or targets for therapy, in particular in patients with worse prognosis. Methods: 14 HPV-positive and 15 HPV-negative Italian OPSCC (n=29) with complete clinical information and follow-up of more than 5 years were molecularly characterized by gene expression profiling and compared to three cohorts of OPSCC extracted from public HNSCC datasets. AKR1C3 emerged as robust marker overexpressed in HPV-negative OPSCC and in HPV-positive lesions with worse prognosis. Fadu and Cal-27 OPSCC cell lines were treated with AKR1C3 inhibitors, alone or in combination with Cisplatin. Results: Gene set enrichment analysis revealed that up-regulated genes in HPV-positive samples are involved in immune system, muscle related processes, response to stimuli, actin organization, tissue development and adhesion, while down-regulated genes participated in glutathione derivative biosynthetic and xenobiotic metabolic processes, hypoxia and oxidative stress. AKR1C3, coding for an enzyme involved in chemio-radioresistance, is in the top10 genes with higher upregulation in HPV-negative samples. Pre-treatment with a selective AKR1C3 inhibitor potentiated the effect of Cisplatin in cells with higher basal level of the enzyme. Conclusions: We identified a druggable target, AKR1C3, associated with survival in subgroups of OPSCC patients either positive or negative for HPV infection and to resistance to chemo-radiotherapy in HNSCC. Pretreatment of OPSCC cell lines expressing this enzyme with a selective AKR1C3 inhibitor is able to enhance Cisplatin efficacy.
Project description:Treatment-related DNA hypermethylation may play a role in creating drug resistant phenotypes by inactivating genes that are required for cytotoxicity, but there have been no genome-wide studies to systematically investigate methylation of individual genes following exposure to chemotherapy. We used microarrays and a pharmacologic unmasking protocol in isogenic cisplatin-sensitive and -resistant cell lines to identify genes that were down-regulated in cisplatin-resistant cells and could be re-activated by the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (5-Aza-dC). We identified several hundred genes that were down-regulated in each resistant cell line. Of these, 30 genes were common to > 2 cell lines, and/or reported to be down-regulated in previous studies. siRNA knockdown of two candidate genes increased cell viability with cisplatin treatment in sensitive parental cell lines
Project description:Cisplatin resistance is a major therapeutic challenge in advanced head and neck squamous cell carcinoma (HNSCC). Here, we aimed to investigate the key signaling pathway for cisplatin resistance in HNSCC cells. HNSCC cell lines that were sensitive (HN4 and HN30) or resistant (HN4/DDP and HN30/DDP) to cisplatin were used for this study. Moreover, the cisplatin-resistant human melanoma cell lines (A375/DDP) and human lung cancer cell lines (A549/DDP) have also been established. To identify the role of proteins in the acquisition of cisplatin resistance, we analyzed the abnormally expressed protein via protein mass spectrometry methods (isobaric tags for relative and absolute quantitation, iTRAQ) in cisplatin-sensitive and cisplatin-resistant cancer cells, and found that VN1R5 was highly expressed in cisplatin-resistant cells. Long noncoding RNA lnc-POP1-1 upregulated by VN1R5. To deeply investigate the mechanism by which lnc-POP1-1 affects cisplatin resistance in HNSCC cells, we used RNA pull-down assays followed by mass spectrometry to explore the putative RNA-binding proteins (RBPs) interacting with lnc-POP1-1.
Project description:The bromodomain and extraterminal family members are epigenetic readers and transcriptional coactivators which are critically involved in various biological processes including tumorigenesis. BRD4 has been increasingly appreciated as a key oncogene and promising anticancer target. Here, we sought to characterize the expression of BRD4 and its tumorigenic roles as well as therapeutic targeting in HNSCC. Expression of BRD4 mRNA and protein was determined by bioinformatics interrogation of public available databases, primary HNSCC samples and 4NQO-induced HNSCC animal model. The tumorigenic roles of BRD4 in HNSCC were evaluated by genetic and pharmacological approach in vitro and in vivo. Therapeutic efficiency of BRD4 targeting by JQ1 was assessed in three preclinical models including xenograft model, 4NQO-induced model and patients-derived xenograft model. Gene candidates responsible for therapeutic effects of JQ1 were identified by transcriptional profiling in HNSCC cells after JQ1 exposure. Significant upregulation of BRD4 was found in primary HNSCC samples and 4NQO-induced HNSCC model. Its overexpression associated with aggressive clinicopathological features and inferior overall and disease-free survival. BRD4 depletion by genetic silencing or pharmacological inhibition impaired cell proliferation, migration and invasion and reduced tumor growth and metastasis in vivo. Transcriptional profiling of HNSCC cells following JQ1 exposure identified hundreds of genes which might mediated its antitumor effects and enriched in cancer-relevant pathways. A novel prognostic risk score derived from JQ1-regualted genes was developed to stratify patients into subgroups with favorable or inferior prognosis. Our findings reveal that BRD4 serves as a novel oncogene driving cancer progression and a robust prognostic biomarker in HNSCC. Therapeutic targeting of BRD4 represents a potent and promising strategy against HNSCC.
Project description:Treatment-related DNA hypermethylation may play a role in creating drug resistant phenotypes by inactivating genes that are required for cytotoxicity, but there have been no genome-wide studies to systematically investigate methylation of individual genes following exposure to chemotherapy. We used microarrays and a pharmacologic unmasking protocol in isogenic cisplatin-sensitive and -resistant cell lines to identify genes that were down-regulated in cisplatin-resistant cells and could be re-activated by the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (5-Aza-dC). We identified several hundred genes that were down-regulated in each resistant cell line. Of these, 30 genes were common to > 2 cell lines, and/or reported to be down-regulated in previous studies. siRNA knockdown of two candidate genes increased cell viability with cisplatin treatment in sensitive parental cell lines Cisplatin-sensitive and -resistant SCC cells and KB and KB cisplatin-resistant clones (n=2) were split to low density and treated with freshly prepared 5 microM 5-Aza-dC dissolved in 50% acetic acid/50% PBS or were mock treated with the same volume of vehicle in the media for 5 days. Subsequently, RNA was extracted and hybridized on Affymetrix U133A microarrays. Signal intensity and statistical significance was established for each transcript, and a 2-fold decrease in signal in each paired sensitive/resistant cell line in combination with 1.5-fold increase after 5Aza-dC treatment was used to identify candidate genes.
Project description:Recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) has a poor prognosis with less than 1-year median survival. Platinum-based chemotherapy (cisplatin or carboplatin) remains the first-line treatment for HNSCC. The cancer stem cell (CSC) hypothesis postulates that tumors are maintained by a self-renewing CSC population that is also capable of differentiating into non-self renewing cell populations that constitute the bulk of the tumor. A small population of CSCs exists within HNSCC that are relatively resistant to chemotherapy and clinically predicted to mediate tumor recurrence. These CSCs are identified by high cell-surface expression of CD44 and high intracellular activity of aldehyde dehydrogenase (ALDH) and termed ALDHhighCD44high. We investigated the molecular pathways active in ALDHhighCD44high cells, which remain poorly studied. Additionally, we performed a molecular examination of cisplatin-resistant ALDHhighCD44high cells, which has not been reported. Two HNSCC cell lines, UM-SCC-1 and UM-SCC-22b, were utilized in this study. For microarray analysis, UM-SCC-22b cells were treated for 5 days in vitro with 2uM cisplatin and analyzed by flow cytometry, sorted and submitted for microarray analysis of ALDHhighCD44high and ALDHlowCD44low cells from untreated and cisplatin treated cells. Four separate flow cytometry experiments were performed using Affymetrix Human Gene ST 2.1 microarrays. Microarray data was analyzed using R/Bioconductor. Files were preprocessed by Robust Multiarray Average (RMA) with background substraction, quantile normalization, and median polish (oligo package). Data was fitted with robust probe level linear models to all the probesets (oligo package). Experiment and processing batch differences were accounted for using 'ComBat' within the SVA package. Differentially expressed genes were identified using univariate comparisons after fitting data to a linear model (limma package). Initial statistics were determined using an empirical Bayesian model. Multiple testing comparisons were adjusted using Benjamini and Hochberg (aka FDR). Probes with an adjusted p-value <0.05 were considered statistically significant. Unsupervised hierarchical clustering with complete linkage and Euclidean distance was performed on only statistically significant probes. In four separate experiments, the head and neck squamous cell carcinoma cell line UM-SCC-22b were cultured for 5 days with or without 2uM (micromolar) cisplatin in 6-well plates. Media was replaced every other day. Control and cisplatin treated cells were trypsinized, procesed, and stained for CD44 cell-surface expression and intracellular aldehyde dehydrogenase (ALDH) activity to identify cancer stem cells (ALDH+CD44+). CSCs and non-CSCs (ALDH-CD44-) were collected by flow cytometry from both groups. Total RNA was collected from each fraction (ALDH+CD44+, ALDH-CD44-), treatment (control, cisplatin), and experiment (#1-4). A total of 16 samples were analyzed. One set of 4 (experiment #4) were analyzed on a Human Gene ST 2.1 strip and the rest on a Human Gene ST 2.1 plate. Differential gene expression was determined with R/Bioconductor with Robust Multiarray Average (RMA) and fitting the data to linear models (limma). Experimental and processing batch effects were accounted for using ComBat. Four sets of univariate comparisons were made: 1) Cisplatin ALDH+CD44+ vs Control ALDH+CD44+; 2) Control ALDH+CD44+ vs Control ALDH-CD44-; 3) Cisplatin ALDH+CD44+ vs Cisplatin ALDH-CD44-; 4) Cisplatin ALDH-CD44- vs Control ALDH-CD44-. Multiple testing comparisons were adjusted using Benjamini and Hochberg (aka FDR). Probes with an adjusted p-value <0.05 were considered statistically significant.