Cytoplasmic P27 Expression Research Articles

TRIM25 enhances cell growth and cell survival by modulating p53 signals via interaction with G3BP2 in prostate cancer.

Prostate cancer growth is promoted by the gene regulatory action of androgen receptor (AR) and its downstream signals. The aberrant dysfunction of tumor suppressor p53 has an important role in the prognosis of cancer. We previously found that androgen treatments translocate p53 to the cytoplasm. The mechanism of this translocation depends on sumoylation of p53 by complex of SUMO E3 ligase RanBP2 with androgen-induced GTPase-activating protein-binding protein 2 (G3BP2). Here, we identified tripartite motif-containing protein 25 (TRIM25)/estrogen-responsive finger protein (Efp) as a novel interacting partner of G3BP2 protein complex. Then, we demonstrated that TRIM25 knockdown resulted in p53 downstream activation for cell cycle inhibition and apoptosis induction in LNCaP and 22Rv1 cells. In contrast, overexpression of TRIM25 promoted prostate cancer cell proliferation and inhibited apoptosis by docetaxel treatment in LNCaP cells. We observed that p53 activity was reduced by mechanism of G3BP2-mediated nuclear export in TRIM25-overexpressing prostate cancer cells. We also found TRIM25 is important for G3BP2/RanBP2-mediated p53 modification. Clinically, we newly demonstrated that TRIM25 is a prognostic factor for prostate cancer patients. Expression of TRIM25 is significantly associated with cytoplasmic p53 expression and G3BP2. Moreover, TRIM25 knockdown results in reduced tumor growth and increased p53 activity in the mouse xenograft model of prostate cancer. Thus, our findings show that overexpression of TRIM25 promoted prostate cancer cell proliferation and cell survival by modulating p53 nuclear export mechanism with G3BP2 interaction.

Investigation of cancer-associated fibroblasts and p62 expression in oral cancer before and after chemotherapy

PurposeThe aim of this study is to investigate the expression of the autophagy protein p62 in oral squamous cell carcinoma (OSCC) cells before and after chemotherapy. We also detected cancer-associated fibroblasts (CAFs) in these OSCC samples to explore the roles of p62 and CAFs in chemotherapy. Materials and methodsImmunohistochemistry was used to analyze the expression of p62 and α-SMA in 26 paired OSCC samples before and after chemotherapy. The relationships between clinicopathological features, clinical outcome and the expression of these proteins were analyzed. ResultsOur results indicated an increased stromal α-SMA expression after chemotherapy in OSCC samples. High p62 expression of OSCC cells closely correlated with stromal α-SMA expression after chemotherapy. Furthermore, the post-chemotherapy p62 expression was associated with the prognosis for OSCC patients. ConclusionThese results suggest that chemotherapy may increase CAFs in OSCC. High cytoplasmic p62 expression may serve as a poor prognostic marker for OSCC patients.

Comparative analysis of Nuclear and Cytoplasmic p21 Expression with p53 and cdk2 Expression in Canine Tumours

The present study was undertaken to evaluate the comparative expression of cell cycle regulators- p53, p21 and cdk2 in spontaneous canine tumours. Out of 46 cases diagnosed as tumour by histopathology, 19 were benign and 27 were malignant. Expression of p53, p21 and cdk2 was analyzed by employing immunohistochemical staining technique and their expression was detected in 84.62%, 69.23% and 69.23% cases, respectively. The percent expressions of p53, p21 and cdk2 showed variation among different histopathological types of tumours. Visceral/mucosal tumours exhibited higher expression of p53 when compared tocutaneous tumours. Expression of p21 was found to be 62.5% and 80% whereas cdk2 was 68.75% and 70% in skin and visceral/mucosal tumours, respectively. Analysis of individual cases for the expression and localization of these three biomarkers revealed seven different patterns. Out of 15 tumours which showed both p53 and p21 overexpression, 11 tumours showed cytoplasmic expression of p21 along with overexpression of cdk2, which indicated that cytoplasmic p21 was not able to perform its normal function of blocking the expression of cdk2. Overexpression of p53 along with cdk2 was observed in 5 cases where p21 expression was totally absent indicating overexpression of abnormal or mutated p53 which was not able to induce the expression of p21 leading to overexpression of cdk2. From present study it can be concluded that cytoplasmic or abnormal p21 expression is induced by either the abnormal/mutated p53 or any other pathway independent of p53.

Cytoplasmic Expression of P16 is Related to Low Infiltration of CD8+ T cell and Poor Prognosis in Digestive Neuroendocrine Carcinoma

Background and Aims: The aim of this study is to examine the predictive and prognostic value of cytoplasmic P16Ink4A (cP16) and poor infiltration of CD8+ T cell in primary digestive neuroendocrine carcinoma (dNEC). Methods: We retrospectively reviewed 86 cases of NEC and mixed NEC (all cases thereafter refer to NEC), which had primary sites in digestive system. Kaplan-Meier survival curves and log-rank test were used for the survival analysis. Bioinformatics analysis was performed to identify the P16-related pathways. Results: The expression frequency of P16 in dNEC and adjacent tissues was 81.4% and 19.3% respectively (p<0.0001). There was no difference in overall survival (OS) between dNEC patients with P16 positive or negative expression. However, there was a statistically lower OS in dNEC patients with cP16 expression than those without cP16 expression (p=0.050). In addition, cP16 expression was correlated with poor infiltration of intratumoral CD8+ T cells. Furthermore,we found that dNEC patients with two features of cP16 expression in tumor and poor infiltration of CD8+ T cells in intratumoral tissue showed more poor survival (p=0.0133) than patients with single feature alone respectively. Bioinformatics analysis suggested that EGR1 and HLA class I might be involved in the inhibitory effect of cP16 on intratumoral infiltrated T cells. Conclusions: Therefore, the cP16 and poor intratumoral infiltration of CD8+ T cells may serve as poor prognostic biomarkers in dNEC. CP16 expression is associated with decreased intratumoral infiltration of CD8+ T cells probably related to deregulation of EGR1/ HLA class I pathway.

Tumor-Secreted Exosomal miR-222 Promotes Tumor Progression via Regulating P27 Expression and Re-Localization in Pancreatic Cancer

Background/Aims: MicroRNAs (miRNAs) or exosomes have recently been shown to play vital regulatory or communication roles in cancer biology. However, the roles and mechanisms of exosomal miRNAs in pancreatic ductal adenocarcinoma (PDAC) remain unknown. We aimed to investigate the detailed roles and mechanisms of tumor-generated exosomal miRNAs in progression of PDAC. Methods: miR-222 was identified by miRNA microarray studies in exosomes of PDAC cells, and further analyzed in plasma exosomes of PDAC patients. The regulatory mechanisms of miR-222 were explored by qRT-PCR, WB, dual-luciferase assays and immunofluorescence or confocal analysis. Other biological assays include transwell, xenograft models and so on. Results: miR-222 is significantly high in tumor exosomes or highly invasive PDAC cells. miR-222 could directly regulate p27 to promote cell invasion and proliferation. miR-222 could also activate AKT by inhibiting PPP2R2A expression, thus inducing p27 phosphorylation and cytoplasmic p27 expression to promote cell survival, invasion and metastasis. Expressions of miR-222 and p27 were significantly inversely correlated, and cytoplasmic p27, instead of nuclear p27, was associated with tumor malignancy. miR-222 could be transmitted between PDAC cells via exosome communication, and the exosomal miR-222 communication is functional. Plasma exosomal miR-222 in PDAC patients was high and significantly correlated to tumor size and TNM stage, and was an independent risk factor for PDAC patient survival. Conclusion: Tumor-generated exosomes could promote invasion and proliferation of neighboring tumor cells via miR-222 transmission, the plasma exosomal miR-222 plays important roles and may be a useful prognostic maker in PDAC.

Dexamethasone-Induced Intrauterine Growth Restriction Is Associated With Altered Expressions of Metastasis Tumor Antigens and Cell Cycle Control Proteins in Rat Placentas.

Molecular mechanisms affecting placental formation in intrauterine growth-restricted (IUGR) pregnancies are not clearly understood. Since metastasis tumor antigens (MTAs) MTA1 and MTA2 promote cell proliferation and MTA3 suppresses it, we hypothesized that IUGR alters cell survival/cell death programs driven by placental MTAs. To induce IUGR, pregnant Sprague Dawley rats were given daily intraperitoneal injections of either saline or dexamethasone (0.4 mg/kg) starting from 14 days of gestation (dg) to either 19 dg or 21 dg. Gene and protein expressions of MTA1-3 in the placental basal and labyrinth zones were investigated by real-time polymerase chain reaction, Western blotting, and immunohistochemistry. We also explored the expressions of proliferating cell nuclear antigen (PCNA), caspase-3, p53, p21, and β-catenin. Dexamethasone-induced IUGR resulted in decreased expression of MTA1 in the nuclei of cells in the basal zone. The expression of p21 was increased and that of PCNA was reduced in both placental zones of IUGR rats. Cytoplasmic expression of MTA1 and p53 increased in the labyrinth zone of IUGR placentas in association with an increase in cell death as indicated by an increased caspase-3 expression. The labyrinth zone of IUGR placentas showed a significant reduction in MTA2-MTA3 gene expression and an increase in p53 protein levels. Total MTA3 level increased and β-catenin level decreased in the labyrinth zone of IUGR placentas associated with a reduction in cell proliferation. Taken together, these results strongly suggest that dexamethasone-induced IUGR is associated with changes in MTA expression, decreased cell proliferation, and increased cell death in placentas.

Association of MDM2 expression with shorter progression-free survival and overall survival in patients with advanced pancreatic cancer treated with gemcitabine-based chemotherapy.

This study evaluated the prognostic roles of murine double minute 2 (MDM2) and p53 in pancreatic cancer patients treated with gemcitabine-based chemotherapy. A total of 137 advanced or recurrent adenocarcinoma patients who were treated with gemcitabine-based palliative chemotherapy were reviewed, selected from 957 patients with pancreatic malignancy between 2008 and 2013 at our hospital. Immunohistochemical staining for MDM2 and p53 with formalin-fixed, paraffin-embedded tumor tissues was independently reviewed. Nuclear or cytoplasmic expression of MDM2 and p53 was found in tumor cells of 30 (21.9%) and 71 (51.8%) patients, respectively. Patients with MDM2 expression had shorter median overall survival (OS) (3.7 vs 5.8 mo; P = .048) and median progression-free survival (PFS) (1.5 vs 2.5 mo; P < .001); by contrast, p53 expression was not correlated with OS or PFS. In the multivariate analysis, MDM2 expression (hazard ratio = 1.731; P = .025) was an independent and unfavorable prognostic factor of OS. Additionally, MDM2 expression was significantly associated with progressive disease (PD) and death (P = .015) following first-line gemcitabine-based therapy. In advanced pancreatic cancer patients, MDM2 expression is associated with shorter OS and PFS after gemcitabine-based chemotherapy.

P16 expression in cutaneous squamous cell carcinoma of the head and neck is not associated with integration of high risk HPV DNA or prognosis

Head and neck cutaneous squamous cell carcinoma (HNcSCC) can present with cervical metastases without an obvious primary. Immunohistochemistry for p16 is established as a surrogate marker of human papillomavirus (HPV) in oropharyngeal cancer. p16 expression in HNcSCC needs to be elucidated to determine its utility in predicting the primary site. The aim of this study was to evaluate the rate of p16 expression in HNcSCC and its association with prognostic factors and survival. p16 immunohistochemistry was performed on 166 patients with high risk HNcSCC (2000-2013) following histopathology review. Chromogenic in situ hybridisation (CISH) for HPV was performed. Fifty-three (31.9%) cases showed strong, diffuse nuclear and cytoplasmic p16 expression including 14 (41%) non-metastatic and 39 (29.5%) metastatic tumours (p=0.21). HPV CISH was negative in all cases. p16 expression significantly increased with poorer differentiation (p=0.033), but was not associated with size (p=0.30), depth of invasion (p=0.94), lymphovascular invasion (p=0.31), perineural invasion (p=0.69), keratinisation (p=0.99), number of involved nodes (p=0.64), extranodal extension (p=0.59) or survival. Nearly 32% of HNcSCCs, particularly poorly differentiated HNcSCCs, show p16 expression. A primary HNcSCC should be considered in p16 positive neck node metastases in regions with high prevalence of HNcSCC. p16 expression is not associated with improved survival in HNcSCC.

Expression of Cell Cycle-related Proteins p16, p27 and Ki-67 Proliferating Marker in Laryngeal Squamous Cell Carcinomas and in Laryngeal Papillomas.

The deregulation of the cell cycle is crucial for the processes of carcinogenesis and tumor progression. The cell cycle is under the control of cyclin-dependent kinases (CDKs) and their inhibitors (CDKIs). Proteins p16 and p27 are CDKIs, and their altered expression has been noticed in many types of cancers. The aim of this study has been to compare the expression levels of these proteins in laryngeal papillomas and carcinomas in order to confirm their predictive value in cancer development. Eighty-three cases of laryngeal lesions were analyzed: cancers (51) and papillomas (32). Immunohistochemical (IHC) reactions were performed in order to detect the expression levels of p16, p27 and Ki-67. Immunofluorescence (IF) and western blot were performed on HEp-2 cell line. The expression of p16 and p27 was decreased in cancer cells in comparison to papillomas. Additionally, we observed cytoplasmic expression of p16 in cancers and lack of such expression in papillomas. The same pattern of expression of p16 was also detected by IF and western blot analysis in HEp-2 cell line. The expression of Ki-67 protein revealed no significant differences in the case of papilloma compared with cancer, however a significant correlation between tumor grade and the nuclear expression of Ki-67 was observed. There is a necessity in finding biomarkers, which would predict the risk level of malignant transformation. Our study has confirmed that altered expressions of the p16 and p27 proteins might be useful biomarkers in the progression of laryngeal squamous cell carcinomas (LSCC).

Hydroquinone-induced FOXP3-ADAM17-Lyn-Akt-p21 signaling axis promotes malignant progression of human leukemia U937 cells

Hydroquinone (1,4-benzenediol; HQ), a major marrow metabolite of the leukemogen benzene, has been proven to evoke benzene-related hematological disorders and myelotoxicity in vitro and in vivo. The goal of the present study was to explore the role of FOXP3 in HQ-induced malignant progression of U937 human leukemia cells. U937 cells were treated with 5μM HQ for 24h, and the cells were re-suspended in serum-containing medium without HQ for 2days. The same procedure was repeated three times, and the resulting U937/HQ cells were maintained in cultured medium containing 5μM HQ. Proliferation and colony formation of U937/HQ cells were notably higher than those of U937 cells. Ten-eleven translocation methylcytosine dioxygenase-mediated demethylation of the Treg-specific demethylated region in FOXP3 gene resulted in higher FOXP3 expression in U937/HQ cells than in U937 cells. FOXP3-induced miR-183 expression reduced β-TrCP mRNA stability and suppressed β-TrCP-mediated Sp1 degradation, leading to up-regulation of Sp1 expression in U937/HQ cells. Sp1 up-regulation further increased ADAM17 and Lyn expression, and ADAM17 up-regulation stimulated Lyn activation in U937/HQ cells. Moreover, U937/HQ cells showed higher Lyn-mediated Akt activation and cytoplasmic p21 expression than U937 cells did. Abolishment of Akt activation decreased cytoplasmic p21 expression in U937/HQ cells. Suppression of FOXP3, ADAM17, and Lyn expression, as well as Akt inactivation, repressed proliferation and clonogenicity of U937/HQ cells. Together with the finding that cytoplasmic p21 shows anti-apoptotic and oncogenic activities in cancer cells, the present data suggest a role of FOXP3/ADAM17/Lyn/Akt/p21 signaling axis in HQ-induced hematological disorders.

Alterations in PTEN, MDM2, TP53 and AR protein and gene expression are associated with canine prostate carcinogenesis

The PTEN, AR, MDM2 and p53 protein network plays a central role in the development of many human cancers, thus eliciting the development of targeted cancer therapeutics. Dogs spontaneously develop tumours, and they are considered a good model for comparative oncology initiatives. Due to the limited information on these proteins in canine tumours, this study aimed to investigate gene and protein alterations in PTEN, AR, MDM2 and p53 in canine prostate cancer (PC). Protein expression was evaluated by immunohistochemistry (15 normal, 22 proliferative inflammatory atrophy (PIA) and 19 PC samples) and Western blotting (2 normal prostate tissue, 2 BPH, 2 PIA samples and 2 PC samples) and gene expression by RT-qPCR (10 normal, 10 PIA and 15 PC samples) of formalin-fixed tissue. We identified nuclear and cytoplasmic expression of PTEN and p53 in all samples, with only nuclear staining found for MDM2 and AR. Our results revealed high expression of MDM2 in PC and PIA samples compared to normal samples, whereas PTEN, P53 and AR expression was down-regulated in PC compared to normal tissue. All tumour samples (n=19) showed loss of nuclear PTEN expression, and all cancer mimickers showed positive nuclear staining. Therefore, nuclear PTEN staining could be a good diagnostic marker for differentiating between malignant lesions and mimickers. Canine prostate carcinogenesis involves increased expression of MDM2 in association with decreased expression of PTEN, p53 and AR, such as occurs in hormone refractory PC in men. Thus, dogs may be an important model for studying advanced stage PC.

Why some tumours trigger neovascularisation and others don't: the story thus far.

BackgroundAngiogenesis is not essential for tumours to develop and expand, as cancer can also grow in a non-angiogenic fashion, but why this type of growth occurs is unknown. Surprisingly, our data from mRNA transcription profiling did not show any differences in the classical angiogenic pathways, but differences were observed in mitochondrial metabolic pathways, suggesting a key role for metabolic reprogramming. We then validated these results with mRNA profiling by investigating differential protein expression via immunohistochemistry in angiogenic and non-angiogenic non-small cell lung cancers (NSCLCs).MethodsImmunohistochemical staining for 35 angiogenesis- and hypoxia-related biomarkers were performed on a collection of 194 angiogenic and 73 non-angiogenic NSCLCs arranged on tissue microarrays. Sequencing of P53 was performed with frozen tissue samples of NSCLC.ResultsThe non-angiogenic tumours were distinguished from the angiogenic ones by having higher levels of proteins associated with ephrin pathways, mitochondria, cell biogenesis, and hypoxia-inducible factor 1 (HIF1) regulation by oxygen and transcription of HIF-controlled genes but lower levels of proteins involved in the stroma, cell–cell signaling and adhesion, integrins, and Delta-Notch and epidermal growth factor (EGF)-related signaling. However, proteins classically associated with angiogenesis were present in both types of tumours at very comparable levels. Cytoplasmic expression of P53 was strongly associated with non-angiogenic tumours. A pilot investigation showed that P53 mutations were observed in 32.0% of angiogenic cases but in 71.4% of non-angiogenic tumours.ConclusionsOur observations thus far indicate that both angiogenic and non-angiogenic tumours experience hypoxia/HIF and vascular endothelial growth factor (VEGF) pathway protein expression in a comparable fashion. However, angiogenesis does not ensue in the non-angiogenic tumours. Surprisingly, metabolic reprogramming seems to distinguish these two types of neoplastic growth. On the basis of these results, we raise the hypothesis that in some, but not in all cases, initial tissue remodeling and/or inflammation could be one of the secondary steps necessary to trigger angiogenesis. In the non-angiogenic tumours, in which neovascularisation fails to occur, HIF pathway activation could be the driving force toward metabolic reprogramming.Electronic supplementary materialThe online version of this article (doi:10.1186/s40880-016-0082-6) contains supplementary material, which is available to authorized users.

Prognostic significance of cytoplasmic p27 in oral squamous cell carcinoma.

p27 is a cell cycle-dependent kinase inhibitor whose presence in nucleus is associated with good prognosis. Recent studies propose that when localized to cytoplasm, it functions as an oncogene and confers a poorer prognosis. This study aimed at analysing the subcellular localization of p27 and its prognostic significance in oral squamous cell carcinomas (OSCCs). Immunohistochemistry for p27 was carried out on 60 cases of OSCC (30 cases each of those with lymph node metastasis [LN+ve SCC] and without lymph node metastasis [LN-ve SCC]) and 30 normal mucosa. The relationship between p27 localization and prognosis was analysed statistically. Nuclear immunopositivity was seen in 15%, 23%, 7% and 60%, while cytoplasmic immunopositivity was seen in 80%, 63%, 97% and 43% of all SCC, LN+ve OSCC, LN-ve SCC cases and normal mucosa, respectively. There was a significant inverse correlation between nuclear and cytoplasmic p27 immunopositivity (P = 0.001). Nodal status and tumour stage were the only two parameters that correlated with disease-free survival (DFS) in OSCC cases. However, in LN+ve SCC, a significantly shortened DFS was seen in cases with cytoplasmic p27 expression compared to those without (P = 0.02). Conversely, LN+ve SCC with nuclear p27 had longer DFS on comparison with those without (P = 0.04). To the best of our knowledge, this is the first study to analyse cytoplasmic localization of p27 in OSCC and correlate with prognosis. Cytoplasmic localization is associated with poor prognosis in OSCC with lymph node metastasis allowing the consideration of cytoplasmic p27 in predicting prognosis and targeted therapeutic approaches.

Association of cytoplasmic p27 expression with an unfavorable response to cisplatin-based chemotherapy and poor outcomes in non-small cell lung cancer.

Reduced nuclear p27 expression is associated with a poor outcome in various cancers, including non-small cell lung cancer (NSCLC). Cytoplasmic p27 expression was shown to be associated with an unfavorable response to chemotherapy and poor outcomes in some carcinomas, but it has not been well studied in NSCLC. Herein, p27 expression in 219 tumors surgically resected from NSCLC patients was evaluated by immunohistochemistry (IHC). The most common of p27 immunostaining in lung tumors was observed in the cytoplasm (N-/C+, 32%), followed by negative (N-/C-, 29%), nucleus (N+/C-, 24%), and nucleus plus cytoplasm (N+/C+, 15%). Kaplan-Meier and Cox regression models showed that p27 N-/C+ tumors exhibited the worst overall survival (OS) and relapse-free survival (RFS) among the four categories of tumors. Among 135 of 219 patients who received cisplatin-based chemotherapy, p27 N-/C+ tumors most commonly showed an unfavorable response to cisplatin-based chemotherapy, followed by p27 N-/C- tumors when p27 N+/C- tumors were used as a reference. IHC analysis for phosphorylated extracellular signal-regulated kinase (p-ERK) and Bcl-2 expression in the lung tumors was performed to test whether ERK activation could enhance p27 nuclear export and the expression of Bcl-2 to test whether ERK activation could enhance p27 nuclear export and Bcl-2 expression. The data showed that p-ERK expression was positively correlated with cytoplasmic p27 (N-/C+) and Bcl-2 expression in the lung tumors. Patients with high Bcl-2-expressing tumors treated with cisplatin-based chemotherapy showed unfavorable predictive values in a subset of this study population. Therefore, we suggest that cytoplasmic p27 (N-/C+) via ERK-activated Bcl-2 expression may predict an unfavorable response to cisplatin-based chemotherapy and poor outcomes in NSCLC.

HPV Infection, but Not EBV or HHV-8 Infection, Is Associated with Salivary Gland Tumours.

Benign and malignant salivary gland tumours are clinically heterogeneous and show different histology. Little is known about the role of human herpes virus 8 (HHV-8), Epstein-Barr virus (EBV), and human papillomavirus (HPV) infection in salivary gland neoplasms. We investigated the presence of the three viruses in formalin-fixed, paraffin-embedded tissue samples in a cohort of 200 different salivary gland tumours. We performed EBV-LMP-1 and HHV-8 and p16 immunohistochemistry, a specific chip based hybridization assay for detection and typing of HPV and a chromogenic in situ hybridization for EBV analysis. Only one case, a polymorphic low-grade carcinoma, showed HHV-8 expression and one lymphoepithelial carcinoma was infected by EBV. In 17 cases (9%) moderate or strong nuclear and cytoplasmic p16 expression was detected. The HPV type was investigated in all of these cases and additionally in 8 Warthin's tumours. In 19 cases HPV type 16 was detected, mostly in Warthin's tumour, adenoid cystic carcinoma, and adenocarcinoma NOS. We concluded that HHV-8 infection and EBV infection are not associated with salivary gland cancer, but HPV infection may play a role in these tumour entities.

Induction of α-phellandrene on autophagy in human liver tumor cells.

α-Phellandrene (α-PA) is a cyclic monoterpene. To investigate the induction of autophagy by α-PA and its mechanism, human liver tumor cells (J5) were incubated with α-PA and analyzed for cell viability and the molecular regulation of pre-autophagosome origination and autophagosome formation. According to the results, PI3K-I, mTOR, and Akt protein levels were decreased after α-PA treatment compared to those of the control group (p < 0.05). The phosphorylation of Bcl-2, and PI3K-III, LC3-II and Beclin-1 protein levels in J5 cells were increased after α-PA treatment (p < 0.05). In addition, α-PA up-regulated nuclear p53 and down-regulated cytoplasmic p53 expression in J5 cells. The NF-κB pathway was activated, as indicated by increase in cytosolic phosphorylated IκB, nuclear NF-κB levels, and the DNA-binding activity of NF-κB after α-PA treatment in J5 cells (p < 0.05). These results suggest that α-PA can induce J5 cell autophagy by regulating mTOR and LC-3II expression, p53 signaling, and NF-κB activation in J5 cells.

ARID5B Regulates Leukemia Sensitivity to Antimetabolites in Children with Acute Lymphoblastic Leukemia Via Effects on Cell Cycle Progression

▪Acute lymphoblastic leukemia (ALL) in children is a prototype of cancer that can be cured by chemotherapy alone. However, the molecular mechanisms for anti-leukemic drug sensitivity and genetic basis of inter-patient variability in treatment response are not fully understood. Taking a genome-wide approach, we recently identified genetic variants in the ARID5B gene that strongly predispose children to developing ALL and also a high risk of relapse following therapy (J Clin Oncol 2012 30:751, Nat Genet 2009 41:1001). To understand the mechanisms by which ARID5B is linked to treatment outcome in childhood ALL, we sought to 1) characterize ARID5B expression in different genetic subtypes of ALL, 2) determine the effects of ARID5B expression on cytotoxicity of chemotherapeutic agents commonly used in ALL therapy, and 3) describe molecular pathways linking ARID5B to anti-leukemic drug sensitivity. In 567 children with newly diagnosed ALL treated at St. Jude Children’s Research Hospital (GSE33315), ARID5B expression was highest in cases with hyperdiploid karyotype (>50 chromosomes) and lowest in T-cell ALL and cases with MLL rearrangements. This pattern was validated in an independent cohort of 106 children from the Dutch Childhood Oncology Group (GSE13351). In 59 patients treated on the Children’s Oncology Group (COG) CCG1961 trial, lower ARID5B expression was associated with higher rates of relapse (P=0.01, GSE7440). Importantly, when we compared matched newly-diagnosed vs. relapsed ALL blasts from a cohort of 60 patients enrolled in COG trials (GSE28460), ARID5B expression was further downregulated at disease recurrence (P=0.0009). shRNA-mediated ARID5B knockdown in 3 ALL cell lines (Nalm6, SEM, and UOCB-1) substantially increased resistance to antimetabolites (an average of 5.16 and 35.3-fold increase in IC50 for methotrexate [MTX] and 6-mercaptopurine [6MP], respectively), with minimal effects on glucocorticoids, vincristine, asparaginase, and daunorubicin. Because cytotoxic effects of MTX and 6MP are highly dependent on the rate of cell proliferation, we postulate that ARID5B directly influences cell cycle entry. In all 3 cell lines, ARID5B knockdown led to significant blockade at the G1/S checkpoint, increasing the percent of cells in G0/G1 phase. At the molecular level, downregulation of ARID5B resulted in higher levels of p21 and reduction in phosphorylated Rb, consistent with the retention at G0/G1 phase. ARID5B expression was restricted to nucleus but affected both nuclear and cytoplasmic p21 expression in a time-dependent fashion. Interestingly, there was a highly significant negative correlation between p21 expression and MTX- and 6MP-induced apoptosis in all 3 ALL cell lines. Taken together, we hypothesize that lower expression of ARID5B impairs ALL cell cycling by upregulating p21, contributing to resistance to MTX and 6MP and eventually leukemia relapse. Finally, we compared global gene expression in ARID5B knockdown vs. control ALL cells, and via the Connectivity Map analysis we identified histone deacetylase (HDAC) inhibitors as promising agents for overcoming ARID5B-related drug resistance. Indeed, ARID5B knockdown cells were significantly more sensitive to panobinostat than controls, suggesting HDAC inhibitors as potential therapeutic options for patients with ARID5B-deficient and drug resistant ALL. DisclosuresNo relevant conflicts of interest to declare.

Prognostic significance of p62/SQSTM1 subcellular localization and LC3B in oral squamous cell carcinoma

Background:Autophagy is a programmed cell survival mechanism that has a key role in both physiologic and pathologic conditions. The relationship between autophagy and cancer is complex because autophagy can act as either a tumour suppressor or as a tumour promoter. The role of autophagy in oral squamous cell carcinoma (OSCC) is controversial. Several studies have claimed that either a high or low expression of autophagy-related proteins was associated with poor prognosis of OSCCs. The aims of the study were to compare autophagy in OSCCs, verrucous hyperplasias, and normal oral mucosas, and to inspect the prognostic role of autophagy in OSCCs.Methods:We used the autophagosome marker, LC3B, and autophagy flux marker, p62/SQSTM1 (p62), by using immunohistochemistry, and examined p62 mRNA by RNA in situ hybridization, to evaluate autophagy in 195 OSCCs, 47 verrucous hyperplasias, and 37 normal oral mucosas. The prognostic roles of LC3B and p62 protein expressions in OSCCs were investigated.Results:We discovered that the normal oral mucosa exhibited limited LC3B punctae and weak cytoplasmic p62 staining, whereas the OSCCs exhibited a marked increase in LC3B punctae and cytoplasmic p62 expression. The expression pattern of LC3B and cytoplasmic p62 of the verrucous hyperplasias were between normal oral mucosas and OSCCs. The normal oral mucosas, verrucous hyperplasias, and OSCCs presented no differences in nuclear p62 expression and the p62 mRNA level. p62 mRNA expression was elevated in a minority of cases. High p62 mRNA expression was associated with high p62 protein expression in the cytoplasm. Increased LC3B punctae, high cytoplasmic p62, and low nuclear p62 expressions in OSCCs were associated with aggressive clinicopathologic features and unfavourable prognosis. In addition, low nuclear p62 expression was an independent prognostic factor for overall and disease-specific survival rates. Furthermore, we disclosed that high cytoplasmic p62 expression accompanied with either a low or high LC3B expression, which indicated autophagy impairment under basal or activated autophagic activity, was associated with aggressive behaviour in advanced OSCCs.Conclusions:We suggested that autophagy was altered during cancer initiation and progression. Autophagy impairment contributed to cancer progression in advanced OSCCs.

Cyclin-dependent kinase inhibitors, p16 and p27, demonstrate different expression patterns in thymoma and thymic carcinoma.

The role of cell cycle inhibitors in tumorigenesis has been proven in various neoplasms; however, their roles in thymic tumors are still unclear. We examined the expression of cell cycle inhibitors such as those of the Cip/Kip family (p21, p27, and p57) and the INK-4/ARF family (p16 and p14) in thymoma and thymic carcinoma. Samples from 41 thymoma and 14 thymic carcinoma patients, and 34 normal thymic tissue samples were prepared for the study. Immunohistochemical analysis using antibodies to p21, p27, p57, p16, and p14 was carried out, and the positivity for these inhibitors in each group was estimated in terms of their subcellular location and percentage of cells showing positive staining. Nuclear p27 showed a stepwise decrease (p < 0.0001), and the cytoplasmic p27 showed a stepwise increase (p < 0.0001) in expression level with the increase in malignancy. p16 in both the nucleus and cytoplasm showed a stepwise increase (p < 0.0001) in expression level with the increase in malignancy. However, as for p21, p57, and p14, there was almost no nuclear or cytoplasmic expression in each group. Our findings suggest that low nuclear and high cytoplasmic p27 expression levels, and high nuclear and cytoplasmic p16 expression levels may correlate with the increase in thymic malignancy.

The opposite prognostic significance of nuclear and cytoplasmic p21 expression in resectable gastric cancer patients

Protein p21(Cip1/Waf1) is a cyclin-dependent kinase inhibitor, which plays important roles in cell cycle arrest, senescence, and apoptosis. Interestingly, the nuclear and cytoplasmic p21 executes various functions in the cell. In this study, we investigated the prognostic impact of subcellular p21 expression in gastric cancer (GC). Expressions of subcellular p21 was assessed by immunohistochemistry using a tissue microarray in a training cohort and it went into a second testing cohort and finally to a validating cohort. Prognostic and predictive role of subcellular p21 expression status was evaluated. We also studied the roles of subcellular p21 in GC cell migration and invasion. Nuclear and cytoplasmic p21 protein levels were significantly reduced and increased in GC lesions compared with adjacent non-cancerous tissues, respectively. Low nuclear p21 or high cytoplasmic p21 expression significantly correlated with shorter overall survival (OS), as well as with clinicopathologic characteristics in patients. Multivariate regression analysis showed that low nuclear and high cytoplasmic p21 expression, separately and together, were independent negative markers of OS. Finally, we found that nuclear p21 inhibits but cytoplasmic p21 promotes cell migration and invasion abilities. These findings suggest that nuclear and cytoplasmic p21 protein expression in tumor are novel candidate prognostic markers in resectable human gastric carcinoma, and they exert distinct roles in cell migration and invasion.