Proline-rich 11 (PRR11) drives F-actin assembly by recruiting the actin-related protein 2/3 complex in human non-small cell lung carcinoma.

The actin cytoskeleton is extremely dynamic and supports diverse cellular functions in many physiological and pathological processes, including tumorigenesis. However, the mechanisms that regulate the actin-related protein 2/3 (ARP2/3) complex and thereby promote actin polymerization and organization in cancer cells are not well-understood. We previously implicated the proline-rich 11 (PRR11) protein in lung cancer development. In this study, using immunofluorescence staining, actin polymerization assays, and siRNA-mediated gene silencing, we uncovered that cytoplasmic PRR11 is involved in F-actin polymerization and organization. We found that dysregulation of PRR11 expression results in F-actin rearrangement and nuclear instability in non-small cell lung cancer cells. Results from molecular mechanistic experiments indicated that PRR11 associates with and recruits the ARP2/3 complex, facilitates F-actin polymerization, and thereby disrupts the F-actin cytoskeleton, leading to abnormal nuclear lamina assembly and chromatin reorganization. Inhibition of the ARP2/3 complex activity abolished irregular F-actin polymerization, lamina assembly, and chromatin reorganization due to PRR11 overexpression. Notably, experiments with truncated PRR11 variants revealed that PRR11 regulates F-actin through different regions. We found that deletion of either the N or C terminus of PRR11 abrogates its effects on F-actin polymerization and nuclear instability and that deletion of amino acid residues 100-184 or 100-200 strongly induces an F-actin structure called the actin comet tail, not observed with WT PRR11. Our findings indicate that cytoplasmic PRR11 plays an essential role in regulating F-actin assembly and nuclear stability by recruiting the ARP2/3 complex in human non-small cell lung carcinoma cells.

Identification and characterization of the promoter of cancer-related gene LOXL2.

Lysyl oxidase like 2, LOXL2, as a member of the lysyl oxidase (LOX) family, has been shown to function similarly to LOX in the extracellular matrix (ECM) by promoting crosslinking of collagen and elastin. LOXL2 is also engaged to transcription regulation, cell signaling transduction and cell adhesion regulation. It has been reported that LOXL2 is highly expressed in several types of tumors and promotes cell proliferation and migration in various cancer cells. However, the regulatory mechanism of LOXL2 expression remains largely unknown. To further investigate its transcriptional regulatory mechanism, LOXL2 promoter region has been cloned and identified in the present study. Chromatin state analysis revealed that LOXL2 gene locus contained an active promoter near its first exon. We then constructed five different LOXL2 gene promoter luciferase reporter constructs covering 1.7 kb upstream of LOXL2 gene transcription initiation site. Series luciferase reporter assay demonstrated that all the five constructs showed notable promoter activity, and LOXL2 core promoter was located in a region of 185 bp near the transcription initiation site. Transcriptional factor binding analysis indicated that, LOXL2 promoter lacked classical TATA box, but contained putative binding sites for classic transcriptional factors such as Sp1 and NF-κB. Ectopic overexpression of Sp1 significantly enhanced LOXL2 promoter activity as well as its endogenous expression in cells. In contrast, mithramycin A (a selective Sp1 inhibitor) treatment repressed LOXL2 promoter as well as its endogenous transcription. Site directed mutagenesis assay further confirmed that the Sp1 binding sites were essential for proximal prompter activity of LOXL2 gene. Chromatin immunoprecipitation (ChIP) assay revealed that Sp1 bound LOXL2 promoter in vivo. Of note, the expression of Sp1 and LOXL2 are positively correlated, and the higher expression of LOXL2 is associated with poor prognosis in colorectal cancer, strongly suggesting the implication of Sp1-mediated LOXL2 transactivation in the pathogenesis of colorectal cancer.

Loss of NFBD1/MDC1 disrupts homologous recombination repair and sensitizes nasopharyngeal carcinoma cells to PARP inhibitors.

BACKGROUND: Nasopharyngeal carcinoma (NPC), a highly invasive tumor, exhibits a distinctive racial and geographic distribution. As options of agents for effective combination chemoradiotherapy for advanced NPC are limited, novel therapeutic approaches are desperately needed. Here the potential of silencing NFBD1 in combination with PARP inhibition as a novel therapeutic strategy for NPC was investigated. METHODS: To investigate the function of NFBD1, we created NFBD1-depleted NPC cell lines via lentivirus mediated shRNA, and the colony formation, MTS assay, comet assay and apoptosis analysis were used to evaluate the sensitivity of NFBD1 knockdown on PARP inhibition. The signaling change was assessed by western blot, Immunofluorescence and flow cytometry. Furthermore, Xenografts model was used to evaluate the role of silencing NFBD1 in combination with PARP inhibition. RESULTS: We find that silencing NFBD1 in combination with PARP inhibition significantly inhibits the cell proliferation and cell cycle checkpoint activity, and increases the apoptosis and DNA damage. Mechanistic studies reveal that NFBD1 loss blocks olaparib-induced homologous recombination repair by decreasing the formation of BRCA1, BRCA2 and RAD51 foci. Furthermore, the xenograft tumor model demonstrated significantly increases sensitivity towards PARP inhibition under NFBD1 deficiency. CONCLUSIONS: We show that NFBD1 depletion may possess sensitizing effects of PARP inhibitor, and consequently offers novel therapeutic options for a significant subset of patients.

Impact of RUNX2 on drug-resistant human pancreatic cancer cells with p53 mutations.

BACKGROUND: Despite the remarkable advances in the early diagnosis and treatment, overall 5-year survival rate of patients with pancreatic cancer is less than 10%. Gemcitabine (GEM), a cytidine nucleoside analogue and ribonucleotide reductase inhibitor, is a primary option for patients with advanced pancreatic cancer; however, its clinical efficacy is extremely limited. This unfavorable clinical outcome of pancreatic cancer patients is at least in part attributable to their poor response to anti-cancer drugs such as GEM. Thus, it is urgent to understand the precise molecular basis behind the drug-resistant property of pancreatic cancer and also to develop a novel strategy to overcome this deadly disease. REVIEW: Accumulating evidence strongly suggests that p53 mutations contribute to the acquisition and/or maintenance of drug-resistant property of pancreatic cancer. Indeed, certain p53 mutants render pancreatic cancer cells much more resistant to GEM, implying that p53 mutation is one of the critical determinants of GEM sensitivity. Intriguingly, runt-related transcription factor 2 (RUNX2) is expressed at higher level in numerous human cancers such as pancreatic cancer and osteosarcoma, indicating that, in addition to its pro-osteogenic role, RUNX2 has a pro-oncogenic potential. Moreover, a growing body of evidence implies that a variety of miRNAs suppress malignant phenotypes of pancreatic cancer cells including drug resistance through the down-regulation of RUNX2. Recently, we have found for the first time that forced depletion of RUNX2 significantly increases GEM sensitivity of p53-null as well as p53-mutated pancreatic cancer cells through the stimulation of p53 family TAp63/TAp73-dependent cell death pathway. CONCLUSIONS: Together, it is likely that RUNX2 is one of the promising molecular targets for the treatment of the patients with pancreatic cancer regardless of their p53 status. In this review article, we will discuss how to overcome the serious drug-resistant phenotype of pancreatic cancer.

B-Myb Mediates Proliferation and Migration of Non-Small-Cell Lung Cancer via Suppressing IGFBP3.

B-Myb has been shown to play an important oncogenic role in several types of human cancers, including non-small-cell lung cancer (NSCLC). We previously found that B-Myb is aberrantly upregulated in NSCLC, and overexpression of B-Myb can significantly promote NSCLC cell growth and motility. In the present study, we have further investigated the therapeutic potential of B-Myb in NSCLC. Kaplan⁻Meier and Cox proportional hazards analysis indicated that high expression of B-Myb is significantly associated with poor prognosis in NSCLC patients. A loss-of-function study demonstrated that depletion of B-Myb resulted in significant inhibition of cell growth and delayed cell cycle progression in NSCLC cells. Notably, B-Myb depletion also decreased NSCLC cell migration and invasion ability as well as colony-forming ability. Moreover, an in vivo study demonstrated that B-Myb depletion caused significant inhibition of tumor growth in a NSCLC xenograft nude mouse model. A molecular mechanistic study by RNA-seq analysis revealed that B-Myb depletion led to deregulation of various downstream genes, including insulin-like growth factor binding protein 3 (IGFBP3). Overexpression of IGFBP3 suppressed the B-Myb-induced proliferation and migration, whereas knockdown of IGFBP3 significantly rescued the inhibited cell proliferation and motility caused by B-Myb siRNA (small interfering RNA). Expression and luciferase reporter assays revealed that B-Myb could directly suppress the expression of IGFBP3. Taken together, our results suggest that B-Myb functions as a tumor-promoting gene via suppressing IGFBP3 and could serve as a novel therapeutic target in NSCLC.

The PRR11-SKA2 Bidirectional Transcription Unit Is Negatively Regulated by p53 through NF-Y in Lung Cancer Cells.

We previously identified proline-rich protein 11 (PRR11) as a novel cancer-related gene that is implicated in the regulation of cell cycle and tumorigenesis. Our recent study demonstrated that PRR11 and its adjacent gene, kinetochore associated 2 (SKA2), constitute a classic head-to-head gene pair that is coordinately regulated by nuclear factor Y (NF-Y). In the present study, we further show that the PRR11-SKA2 bidirectional transcription unit is an indirect target of the tumor suppressor p53. A luciferase reporter assay revealed that overexpression of wild type p53, but not mutant p53, significantly represses the basal activity and NF-Y mediated transactivation of the PRR11-SKA2 bidirectional promoter. Deletion and mutation analysis of the PRR11-SKA2 promoter revealed that p53-mediated PRR11-SKA2 repression is dependent on the presence of functional NF-Y binding sites. Furthermore, a co-immunoprecipitation assay revealed that p53 associates with NF-Y in lung cancer cells, and a chromatin immunoprecipitation assay showed that p53 represses PRR11-SKA2 transcription by reducing the binding amount of NF-Y in the PRR11-SKA2 promoter region. Consistently, the ability of p53 to downregulate PRR11-SKA2 transcription was significantly attenuated upon siRNA-mediated depletion of nuclear factor Y subunit beta (NF-YB). Notably, lung cancer patients with lower expression of either PRR11 or SKA2 along with wild type p53 exhibited the best overall survival compared with others with p53 mutation and/or higher expression of either PRR11 or SKA2. Taken together, our results demonstrate that p53 negatively regulates the expression of the PRR11-SKA2 bidirectional transcription unit through NF-Y, suggesting that the inability to repress the PRR11-SKA2 bidirectional transcription unit after loss of p53 might contribute to tumorigenesis.

B-Myb Is Up-Regulated and Promotes Cell Growth and Motility in Non-Small Cell Lung Cancer.

B-Myb is a transcription factor that is overexpressed and plays an oncogenic role in several types of human cancers. However, its potential implication in lung cancer remains elusive. In the present study, we have for the first time investigated the expression profile of B-Myb and its functional impact in lung cancer. Expression analysis by quantificational real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry demonstrated that B-Myb expression is aberrantly overexpressed in non-small cell lung cancer (NSCLC), and positively correlated with pathologic grade and clinical stage of NSCLC. A gain-of-function study revealed that overexpression of B-Myb significantly increases lung cancer cell growth, colony formation, migration, and invasion. Conversely, a loss-of-function study showed that knockdown of B-Myb decreases cell growth, migration, and invasion. B-Myb overexpression also promoted tumor growth in vivo in a NSCLC xenograft nude mouse model. A molecular mechanistic study by RNA-sequencing (RNA-seq) analysis showed that B-Myb overexpression causes up-regulation of various downstream genes (e.g., COL11A1, COL6A1, FN1, MMP2, NID1, FLT4, INSR, and CCNA1) and activation of multiple critical pathways (e.g., extracellular signal-regulated kinases (ERK) and phosphorylated-protein kinase B (Akt) signaling pathways) involved in cell proliferation, tumorigenesis, and metastasis. Collectively, our results indicate a tumor-promoting role for B-Myb in NSCLC and thus imply its potential as a target for the diagnosis and/or treatment of NSCLC.

The gene pair PRR11 and SKA2 shares a NF-Y-regulated bidirectional promoter and contributes to lung cancer development.

Head-to-head gene pairs represent a unique feature of gene organization in eukaryotes, accounting for >10% of genes in the human genome. Identification and functional analysis of such gene pairs is only in its infancy. Recently, we identified PRR11 as a novel cancer-related gene that is implicated in cell cycle and lung cancer. Here we demonstrate that PRR11 is oriented in a head-to-head configuration with its neighboring gene, SKA2. 5'-RACE assay revealed that the intergenic spacer region between the two genes is <500 bp. Serial luciferase reporter assays demonstrated that a minimal 80-bp intergenic region functions as a core bidirectional promoter to drive basal transcription in both the PRR11 and SKA2 orientations. EMSA and ChIP assays demonstrated that NF-Y binds to and directly transactivates the PRR11-SKA2 bidirectional promoter. SiRNA-mediated NF-Y depletion significantly downregulated PRR11 and SKA2 expression. Expression of both PRR11 and SKA2 was significantly upregulated in lung cancer. Expression of the two genes was highly correlated with each other and with NF-Y expression. Remarkably, high expression of both PRR11 and SKA2 was associated with poorer prognosis in lung cancer patients compared with high expression of one gene or low expression of both genes. Knockdown of PRR11 and/or SKA2 remarkably reduced cell proliferation, migration, and invasion in lung cancer cells. Thus, the PRR11-SKA2 bidirectional transcription unit, which is a novel direct target of NF-Y, is essential for the accelerated proliferation and motility of lung cancer cells and may represent a potential target in the diagnosis and/or treatment of human lung cancer.

Knockdown of NFBD1/MDC1 enhances chemosensitivity to cisplatin or 5-fluorouracil in nasopharyngeal carcinoma CNE1 cells.

Nasopharyngeal carcinoma (NPC) is a rare but highly invasive cancer that is prevalent among people of southern Chinese ancestry in southern China and Southeast Asia. Radiotherapy and cisplatin (CDDP)-based chemotherapy are the main treatment options. Unfortunately, disease response to concurrent chemoradiotherapy varies among patients with NPC, and many cases are resistant to CDDP and radiotherapy. NFBD1 functions in cell cycle checkpoint activation and DNA repair following DNA damage. In this study, we identified the NFBD1 as a tractable molecular target to chemosensitize NPC cells. NFBD1 expression in NPC CNE1 cell lines was depleted using lentivirus-mediated short hairpin RNA, and the elevated sensitivity of these NFBD1-inhibited NPC cells to therapeutic reagent CDDP and 5-fluorouracil (5-FU) was evaluated using MTS assays. Flow cytometry analysis also showed that NFBD1 knockdown led to an obvious induction of apoptosis in CDDP- or 5-FU-treated CNE1 cells. Furthermore, we implicated the involvement of NFBD1 in Rad51 and DNA-PKcs foci formation following CDDP or 5-FU chemotherapy. In conclusion, NFBD1 knockdown improves the chemosensitivity of NPC cells by inhibiting cell growth and promoting apoptosis through the impairment of DNA damage repair, suggesting NFBD1 as a novel therapeutic target for NPC.

Identification and analysis of the promoter region of the human HAS3 gene.

Hyaluronan (HA) is a key component of the vertebrate extracellular matrix that is synthesized at the plasma membrane by the hyaluronan synthases including HAS1, HAS2 and HAS3. The expression and regulation of HAS1-3 are implicated in numerous physiological and pathological processes. The promoters of human HAS1 and HAS2 genes have been identified previously whereas HAS3 promoter remains unclear. In the present study, we have for the first time identified and characterized the human HAS3 gene promoter region. 5' RACE assay revealed two novel transcriptional variants of HAS3 gene with distinct transcription start sites. Progressive deletion analysis of the 5'-flanking region of HAS3 gene demonstrated that HAS3 proximal promoter is mainly restricted to a 450-bp region (i.e. -761 to -305 bp upstream of the major HAS3 transcription start site), whereas its core promoter is located to a minimal 129-bp region (i.e. -433 to -305 bp upstream of the major HAS3 transcription start site). Transcriptional factor binding analysis indicated that HAS3 gene promoter lacks of canonical TATA box, but contains classical GC box as well as other putative binding sites for transcriptional factors such as C/EBP and NFκB. In addition, site-directed mutagenesis assay demonstrated that the proximal Sp1 binding site is essential for the robust proximal promoter activity of HAS3 gene whereas the core MTE (core promoter motif ten elements) motif is required for the basic core promoter activity of HAS3 gene. Our present study should facilitate further studies on the mechanism regulating the expression of this important gene.

PRR11 regulates late-S to G2/M phase progression and induces premature chromatin condensation (PCC).

Recently, we have demonstrated that proline-rich protein 11 (PRR11) is a novel tumor-related gene product likely implicated in the regulation of cell cycle progression as well as lung cancer development. However, its precise role in cell cycle progression remains unclear. In the present study, we have further investigated the expression pattern and functional implication of PRR11 during cell cycle in detail in human lung carcinoma-derived H1299 cells. According to our immunofluorescence study, PRR11 was expressed largely in cytoplasm, the amount of PRR11 started to increase in the late S phase, and was retained until just before mitotic telophase. Consistent with those observations, siRNA-mediated knockdown of PRR11 caused a significant cell cycle arrest in the late S phase. Intriguingly, the treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. Moreover, knockdown of PRR11 also resulted in a remarkable retardation of G2/M progression, and PRR11-knockdown cells subsequently underwent G2 phase cell cycle arrest accompanied by obvious mitotic defects such as multipolar spindles and multiple nuclei. In addition, forced expression of PRR11 promoted the premature Chromatin condensation (PCC), and then proliferation of PRR11-expressing cells was massively attenuated and induced apoptosis. Taken together, our current observations strongly suggest that PRR11, which is strictly regulated during cell cycle progression, plays a pivotal role in the regulation of accurate cell cycle progression through the late S phase to mitosis.

The overexpression of MCPH1 inhibits cell growth through regulating cell cycle-related proteins and activating cytochrome c-caspase 3 signaling in cervical cancer.

MCPH1, initially identified as an hTERT repressor, has recently been implicated in mediating DNA damage response and maintaining chromosome integrity. This study is to investigate its potential role in the onset of cervical cancer. In the study, decreased expression of MCPH1 was observed in 19 of 31 cases (61.3%) at mRNA level and 44 of 63 cases (69.8%) at protein level of cervical tumor tissues compared with the paired nontumor tissues. Reduced MCPH1 protein expression was significantly associated with high-tumor grade (1 vs. 3 P = 0.013; 2 vs. 3 P = 0.047). In addition to inhibit SiHa cell migration and invasion, the overexpression of MCPH1 inhibited cervical cancer cells growth through inducing S phase arrest and mitochondrial apoptosis. Further analysis demonstrated cyclinA2/CDK2, CDC25C-cyclinB/CDC2, and p53/p21 pathways were involved in the MCPH1 overexpression-induced S phase arrest. Moreover, the overexpression of MCPH1 activated mitochondrial apoptosis through regulating several apoptosis-related proteins such as p53, Bcl-2, Bax, cytochrome c, caspase-3, and PARP-1. Our findings indicate that downregulated MCPH1 correlates with tumor progression in cervical cancer, and MCPH1 has an important role in regulating cell growth through regulating the cell cycle and apoptosis. Thus, it may be a crucial tumor suppressor gene and a novel candidate therapeutic target for cervical cancer.

Gene expression profiling analysis reveals that DLG3 is down-regulated in glioblastoma.

Glioblastoma multiforme (GBM) is the most malignant glioma. In the current study, 149 astrocytoma gene expression datasets were classified by prediction analysis of microarray. Strikingly, disks large homolog 3 (DLG3), a membrane-associated guanylate kinase-family gene, had the highest score in the GBM subset. DLG3 mRNA expression is significantly down-regulated in GBM relative to normal tissue and grade II or grade III astrocytoma according to the results of real-time polymerase chain reaction, and its protein expression shows an obvious difference by immunohistochemistry. Further assays show that DLG3 over-expression induces mitotic cell cycle arrest and apoptosis, and it inhibits proliferation and migration. However, DLG3 over-expression has almost no affect on invasion. The DLG3 protein expression in human brain GBM tissue and its effects on GBM cell invasion were not expected. Our data suggest that DLG3 is down-regulated in this cancer type. To our knowledge, this is the first report to clearly demonstrate the possible involvement of DLG3 in GBM.

Association between urinary phthalates and phthalate metabolites and cancer risk: A systematic review and meta-analysis.

Phthalates, widely utilized in industrial products, are classified as endocrine-disrupting chemicals (EDCs). Although certain phthalate and their metabolites have been implicated in cancer development, the reported findings have exhibited inconsistencies. Therefore, we conducted the comprehensive literature search to assess the association between phthalate and their metabolites and cancer risk by identifying original studies measuring phthalates or their metabolites and reporting their correlation with cancer until July 4, 2023. The Odds Ratios (ORs) and corresponding 95% confidence intervals (CIs) were extracted and analyzed to estimate the risk. Pooled data from eleven studies, including 3101 cancer patients and 6858 controls, were analyzed using a fixed- or random-effects model based on heterogeneity tests. When comparing extreme categories of different phthalates and their metabolites, we observed a significant association between urinary phthalates and phthalate metabolites (MEHHP, MECPP, DBP and MBzP) and cancer risk. The findings of our meta-analysis reinforce the existing evidence that urinary phthalates and phthalate metabolites is strongly associated with cancer development. Further investigations are warranted to elucidate the underlying mechanisms of this association. These results may offer novel insights into cancer development.

DEPDC1B is a Novel Direct Target of B-Myb and Contributes to Malignant Progression and Immune Infiltration in Lung Adenocarcinoma.

BACKGROUND: Lung cancer is the primary cause of cancer-related deaths, with one of the highest incidence and mortality rates of all malignant tumors. Dysregulated expression of DEPDC1B has been reported to occur in various tumor types. However, the functional implications of this alteration in lung adenocarcinoma (LUAD) and the underlying molecular mechanism remains unclear. In this study, we investigated the role and clinical significance of DEPDC1B in LUAD. METHODS: The expression of DEPDC1B in LUAD and its relationship with prognosis were systematically evaluated in several publically available datasets. The effects of DEPDC1B knockdown on the proliferation and motility of LUAD cells were assessed using the JULI Stage Real-time Cell History Recorder, while the effect of knockdown on the cell cycle was studied by flow cytometry. Furthermore, RNA-Sequencing (RNA-Seq) analysis was conducted to identify the downstream target genes and pathways regulated by DEPDC1B. Correlations between the expression of DEPDC1B and immune cell infiltration, immunotherapy resistance, and chemoresistance were also examined. Additionally, molecular biological methods were used to explore the regulatory mechanism of B-Myb on DEPDC1B expression. RESULTS: DEPDC1B was found to be upregulated in LUAD patients and this was associated with poor clinical outcomes. Knockdown of DEPDC1B inhibited cell growth, migration and motility, as well as cell cycle progression. Knockdown also resulted in the down-regulation of several downstream genes, including NID1, FN1, and EGFR, as well as the inactivation of multiple critical pathways, such as the ERK and PI3K-AKT pathways. Analysis of the tumor immuno-environment in LUAD revealed that high DEPDC1B expression was associated with an abundance of activated CD4+ memory T cells, M0 macrophages, M1 macrophages, and CD8+ T cells. Moreover, these tumors responded poorly to immunotherapy. Analysis of chemo-drug sensitivity showed that LUADs with high DEPDC1B expression were more responsive to frontline chemotherapeutic drugs such as Vinorelbine, Cisplatin, and Etoposide. Additionally, mechanistic investigations revealed that DEPDC1B is a direct target gene of B-Myb, and that its knockdown attenuated the proliferation and motility effects of B-Myb. CONCLUSIONS: In summary, our findings indicate that DEPDC1B is a critical regulator during the malignant progression of LUAD. DEPDC1B could therefore be a promising prognostic marker and therapeutic target in LUAD diagnosis and treatment.

KIF2C is a critical regulator for malignant progression of head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is a significant cause of mortality, while the underlying mechanism remains unclear. Our studies have revealed that KIF2C plays a crucial role in tumor proliferation and metastasis in HNSCC. The results demonstrate that KIF2C is highly expressed at both the mRNA and protein levels and is closely associated with lymph node metastasis. The gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses indicate that the differentially expressed genes are enriched in processes or pathways related to cell adhesion and cell mitosis in HNSCC. Moreover, the established protein-protein interaction network identifies KIF2C as a potential hub gene in HNSCC. Knockdown of KIF2C has been demonstrated to significantly reduce cell migration and invasion ability, leading to cell cycle arrest, a high proportion of abnormal cell apoptosis, and cell chromosome division mismatches in the HNSCC cell line. Downstream genes such as PDGFA, EGFR, TP63, SNAI2, KRT5, and KRT14 were found to be down-regulated, and multiple critical pathways, including mTOR, ERK, and PI3K-AKT pathways, were inactivated as a result of KIF2C knockdown. These findings provide strong evidence for the crucial role of KIF2C in HNSCC and suggest that targeting KIF2C may be a promising therapeutic strategy for this disease. Knockdown of KIF2C has been shown to significantly inhibit tumor proliferation in nude mice, demonstrating the potential therapeutic role of KIF2C in HNSCC treatment.

rRNA-Derived Small RNA rsRNA-28S Regulates the Chemoresistance of Prostate Cancer Cells by Targeting PTGIS.

BACKGROUND: rRNA-derived small RNAs (rsRNAs) represent a novel class of small non-coding RNAs (sncRNAs), produced by the specific cleavage of rRNAs; however, their roles in tumor development are unclear. In the present study, we explored the effect of a kind of rsRNA-28S, which originates from 28S rRNA, on the chemoresistance of prostate cancer cells and the mechanisms underlying its effect. METHODS: Quantitative reverse transcription PCR (RT-PCR) was performed to quantify rsRNA-28S levels in serum samples taken from prostate cancer patients. DU-145R cells, which are resistant to both paclitaxel and docetaxel, were generated from parental DU-145 cells. Northern blot was conducted to detect cellular rsRNA-28S levels following drug treatments. To verify the effect of rsRNAs-28S on chemoresistance, antisense oligonucleotides were utilized to block rsRNA-28S functions, and a series of assays were further performed, such as cell viability, cell proliferation, colony formation and tumor sphere formation. The target gene of rsRNA-28S was explored using dual-luciferase reporter gene assay. RESULTS: The rsRNA-28S level was reduced in the serum samples of patients who received chemotherapy compared to that of patients who did not. Furthermore, the rsRNA-28S level was remarkably declined in DU-145R cells, and drug treatments decreased the levels of rsRNA-28S in DU-145 and DU-145R cells. Moreover, rsRNA-28S inhibition enhanced the chemoresistance of prostate cancer cells as well as their cancer stem cell characteristics. Mechanistically, the prostaglandin I2 synthase (PTGIS) gene transcript was verified as a target of rsRNA-28S, as rsRNA-28S inhibited the translation of PTGIS mRNA by directly binding the 3' untranslated region of PTGIS mRNA. rsRNA-28S inhibition was also found to increase PTGIS abundance, and PTGIS overexpression significantly enhanced prostate cancer cell chemoresistance. CONCLUSIONS: Our findings indicate that rsRNA-28S attenuates prostate cancer cell chemoresistance by downregulating its target gene PTGIS. This study not only greatly contributes to systematic identification and functional elucidation of chemoresistance relevant rsRNAs, but also promotes rsRNA-included combinatorial therapeutic regimens for cancer.

Cell cycle dysregulation with overexpression of KIF2C/MCAK is a critical event in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a common malignant carcinoma of the head and neck, and the biological mechanisms underlying the pathogenesis of NPC remain not fully understood. In the present study, we systematically analyzed four independent NPC transcriptomic datasets and focused on identifying the critical molecular networks and novel key hub genes implicated in NPC. We found totally 170 common overlapping differentially expressed genes (DEGs) in the four NPC datasets. GO and KEGG pathway analysis revealed that cell cycle dysregulation is a critical event in NPC. Protein-protein interaction (PPI) network analysis identified a 15 hub-gene core network with overexpressed kinesin family member 2C (KIF2C) as a central regulator. Loss-of-function study demonstrated that knockdown of KIF2C significantly inhibited cell growth and cell motility, and delayed cell cycle progression, accompanied with dramatic mitotic defects in spindle formation in NPC cells. RNA-seq analysis revealed that KIF2C knockdown led to deregulation of various downstream genes. KIF2C could also regulate the AKT/mTOR pathways, and enhance paclitaxel sensitivity in NPC cells. Taken together, our results suggest that cell cycle dysregulation is a critical event during NPC pathogenesis and KIF2C is a novel key mitotic hub gene with therapeutic potential in NPC.

SKA2-mediated transcriptional downregulation of the key enzyme of CoQ10 biosynthesis PDSS2 in lung cancer cells.

Lung cancer is the leading cause of cancer-associated mortality worldwide. SKA2 is a novel cancer-associated gene that plays critical roles in both cell cycle and tumorigenesis including lung cancer. However, the molecular mechanisms underlying its implication in lung cancer remains elusive. In this study, we first analyzed the gene expression profiling after SKA2 knockdown, and identified several candidate downstream target genes of SKA2, including PDSS2, the first key enzyme in CoQ10 biosynthesis pathway. Further experiments verified that SKA2 remarkably repressed PDSS2 gene expression at both mRNA and protein levels. Luciferase reporter assay showed that SKA2 repressed PDSS2 promoter activity through its Sp1-binding sites. Co-immunoprecipitation assay demonstrated that SKA2 associated with Sp1. Functional analysis revealed that PDSS2 remarkably suppressed lung cancer cell growth and motility. Furthermore, SKA2-induced malignant features can be also significantly attenuated by PDSS2 overexpression. However, CoQ10 treatment showed no obvious effects on lung cancer cell growth and motility. Of note, PDSS2 mutants with no catalytic activity exhibited comparable inhibitory effects on the malignant features of lung cancer cells and could also abrogate SKA2-promoted malignant phenotypes in lung cancer cells, highly suggesting a non-enzymatic tumor-suppressing activity of PDSS2 in lung cancer cells. The levels of PDSS2 expression were significantly decreased in lung cancer samples, and lung cancer patients with high expression of SKA2 and low expression of PDSS2 displayed remarkable poor prognosis. Collectively, our results demonstrated that PDSS2 is a novel downstream target gene of SKA2 in lung cancer cells, and the SKA2-PDSS2 transcriptional regulatory axis functionally contributes to human lung cancer cell malignant phenotypes and prognosis.

NFBD1/MDC1 is a protein of oncogenic potential in human cervical cancer.

A large nuclear protein of 2089 amino acids, NFBD1/MDC1 has recently been implicated in tumorigenesis and tumor growth. In this study, we investigated its expression in cervical cancers and explored its function using gene knockdown approaches. We report here that NFBD1 expression is substantial increased in 24 of 39 cases (61.5%) of cervical cancer tissues at the mRNA level and in 35 of 60 cases (58.3%) at the protein level compared with the case matched normal tissues. Tumors with higher grade of malignancy tend to have higher levels of NFBD1 expression. By infecting cells with retroviruses expressing NFBD1 shRNA, we successfully knocked down NFBD1 expression in cervical cancer cell lines HeLa, SiHa, and CaSki. NFBD1 knockdown cells display significant growth inhibition, cell cycle arrest, higher apoptotic rate, and enhanced sensitivity to adriamycin. Furthermore, NFBD1 knockdown also inhibits the growth of HeLa cells in nude mice. Western blot analyses further revealed that NFBD1 knockdown induced Bax, Puma, and Noxa while down-regulating Bcl-2; it also up-regulated cytochrome C and activated caspases 3 and 9. Therefore, the function of NFBD1 may be involved in the CDC25C-CyclinB1/CDC2 pathway at the G2/M checkpoint, and the cytochrome C/caspase 3 apoptotic pathway. Since expression of NFBD1 seems to be related to the oncogenic potential of cervical cancer, and suppression of its expression can inhibit cancer cell growth both in vitro and in vivo, NFBD1 may be a potential therapeutic target in human cervical cancer.