MicroRNA-186 targets SKP2 to induce p27(Kip1)-mediated pituitary tumor cell cycle deregulation and modulate cell proliferation

Pituitary tumors are usually benign but can occasionally exhibit hormonal and proliferative behaviors. Dysregulation of the G1/S restriction point largely contributes to the over-proliferation of pituitary tumor cells. F-box protein S-phase kinase-interacting protein-2 (SKP2) reportedly targets and inhibits the expression of p27(Kip1), a well-known negative regulator of G1 cell cycle progression. In this study, SKP2 expression was found to be upregulated while p27(Kip1) expression was determined to be downregulated in rat and human pituitary tumor cells. Furthermore, SKP2 knockdown induced upregulation of p27(Kip1) and cell growth inhibition in rat and human pituitary tumor cells, while SKP2overexpression elicited opposite effects on p27(Kip1) expression and cell growth. The expression of microRNA-186 (miR-186) was reported to be reduced in pituitary tumors. Online tools predicted SKP2 to be a direct downstream target of miR-186, which was further confirmed by luciferase reporter gene assays. Moreover, miR-186 could modulate the cell proliferation and p27(Kip1)-mediated cell cycle alternation of rat and human pituitary tumor cells through SKP2. As further confirmation of these findings, miR-186 and p27(Kip1) expression were downregulated, while SKP2 expression was upregulated in human pituitary tumor tissue samples; thus, SKP2 expression negatively correlated with miR-186 and p27(Kip1) expression. In contrast, miR-186 expression positively associated with p27(Kip1) expression. Taken together, we discovered a novel mechanism by which miR-186/SKP2 axis modulates pituitary tumor cell proliferation through p27(Kip1)-mediated cell cycle alternation.

Different influence of simvastatin on p27 protein expressions of vascular smooth muscle cells and endo-thelial cells in rats / 心血管康复医学杂志

Objective:To observe influence of simvastatin on p 27 protein (cyclin‐dependent kinase inhibitor ) expres‐sions of vascular smooth muscle cells (SMC) and endothelial cells (EC) in rats for screening new generation coating drugs of eluting stents .Methods :Primary aortic SMC and EC of rat were isolated and cultured by methods of adher‐ent and enzymatic digestion respectively .Which were inoculated on fibronectin -coated culture plates .α smooth muscle actin immunofluorescence staining was used to identify SMC ,and von Willebrand factor (vWF) immunofluo‐rescence staining was used to identify EC .SMC and EC were cultured for 24h with different concentrations of simv‐astatin (0.01 ,0.1 ,1 and 10 μmol/L) ,then Western blot was used to measure p27 protein expression .Results:Compared with blank control group ,0.01μmol/L simvastatin had no significant influence on p 27 protein expression of SMC ,but 0.1 ,1 and 10 μmol/L simvastatin significantly raised p27 protein expression of SMC [ (0.53 ± 0.08) vs .(0.86 ± 0.05) ,(1.20 ± 0.05) ,(1.60 ± 0.04)] , P 0.05 ,indicating that simvastatin only dose‐de‐pendently promoted p27 protein expression of SMC .Conclusion:Simvastatin dose -dependently promotes p27 pro‐tein expression of vascular smooth muscle cells without affecting p 27 protein expression of endothelial cells .So local application of simvastatin may inhibit restenosis and promote reendothelialization of injured vessels .

Do Helper T Cell Subtypes in Lymphocytic Thyroiditis Play a Role in the Antitumor Effect?

BACKGROUND: Papillary thyroid carcinoma (PTC) is frequently accompanied by lymphocytic thyroiditis (LT). Some reports claim that Hashimoto's thyroiditis (the clinical form of LT) enhances the likelihood of PTC; however, others suggest that LT has antitumor activity. This study was aimed to find out the relationship between the patterns of helper T cell (Th) cytokines in thyroid tissue of PTC with or without LT and the clinicopathological manifestation of PTC. METHODS: Fresh surgical samples of PTC with (13 cases) or without (10 cases) LT were used. The prognostic parameters (tumor size, extra-thyroidal extension of PTC, and lymph node metastasis) were analyzed. The mRNA levels of two subtypes of Th cytokines, Th1 (tumor necrosis factor α [TNF-α], interferon γ [IFN-γ ], and interleukin [IL] 2) and Th2 (IL-4 and IL-10), were analyzed. Because most PTC cases were microcarcinomas and recent cases without clinical follow-up, negative or faint p27 immunoreactivity was used as a surrogate marker for lymph node metastasis. RESULTS: PTC with LT cases showed significantly higher expression of TNF-α (p = .043), IFN-γ (p < .010), IL-4 (p = .015) than those without LT cases. Although the data were not statistically significant, all analyzed cytokines (except for IL-4) were highly expressed in the cases with higher expression of p27 surrogate marker. CONCLUSIONS: These results indicate that mixed Th1 (TNF-α, IFN-γ , and IL-2) and Th2 (IL-10) immunity might play a role in the antitumor effect in terms of lymph node metastasis.

The Relevance of Women's Diseases, Jun Activation-domain Binding Protein 1 (JAB1) and p27(kip1)

The Jun activation-domain binding protein 1 (Jab1) recognize a potential coactivator of activator protein 1 (AP-1) such as c-fos, c-jun transcription factor and the fifth subunit of the COP9 signalosome complex. Also, Jab1 activate the c-jun gene resulted cell proliferation. Not only a powerful tumor suppressor but also regulator of apoptosis negative cdk inhibitor p27(kip1) are involved in the cell cycle. This is Jab1 and p27(kip1) interact with each other, Jab1 accelerate p27(kip1) from nuclear to cytoplasm through ubiquitin/proteasome pathway. However, information about the relationship between Jab1 and p27(kip1) is not known much. Taken together, the results of this study identify function and structure of Jab1 and p27(kip1) were described in a recent article on the basis of relevant. Besides Jab1 and p27(kip1) will organize the relationship between the disease and women.

Role of p21 and p27 in carcinogenesis and drug resistance / 国际外科学杂志

Human cancers arise from an imbalance of cell growth and cell death.Critical factors that control the balance are those regulate the cell cycle.Several molecular effectors have been identified to be able to regulate specific phases of the cell cycle,including cyclins,cyclin-dependent kinases (CDKs) and CDK inhibitors.Notably,deficiency of two G1-checkpoint CDK inhibitors-p21 (CDKN1A) and p27 (CDKN1B)-has been implicated to be correlated with initiation or progression of many human malignancies or cancer cells drug-resistance.However,contradict reports also suggested that p21 and p27 could promote tumor progression.Here,we summarized the historic and recent studies on these two CDK inhibitors,including their identification as well as their roles in carcinogenesis and drug resistance.

p27 Loss Is Associated with Poor Prognosis in Gastroenteropancreatic Neuroendocrine Tumors / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) represent a heterogeneous disease group originating from the neuroendocrine cells. Identification of prognostic markers, related to neuroendocrine tissue-selective tumorigenesis, is necessary to find therapeutic targets. MATERIALS AND METHODS: A total of 327 patients with GEP-NETs were included in this study; there were 49 gastric, 29 duodenal, 49 pancreatic, 12 hepatobiliary, 33 appendiceal, 5 proximal colon, and 150 distal colon cases. We performed immunostaining with the tissue microarray method for menin, p27, and p18. RESULTS: We observed negative staining for menin, p27, and p18 in 34%, 21%, and 56% of GEP-NETs, respectively. The loss of p27, but not menin, was positively correlated with the grade of Ki-67. Menin-/p27-, menin-/p27+, menin+/p27-, and menin+/p27+ phenotype groups included 13%, 22%, 8%, and 57% of patients, respectively. A dichotomized comparison showed that menin- or p27- tumors were significantly associated with foregut and midgut localizations, high World Health Organization (WHO) grade, lymph node metastasis, and more advanced stage as compared to menin+/p27+ patients. Kaplan-Meier analysis for the overall survival showed that p27 loss was significantly associated with decreased survival. Multivariate analysis showed that p27 loss is an independent factor for poor overall survival. CONCLUSION: Our results revealed that the loss of p27 is associated with poor prognosis and the menin-p27 pathway is important in the tumorigenesis of GEP-NETs.

Análise do gene CDKN1B/p27kip1 em pacientes com neoplasia endócrina múltipla tipo 2 / CDKN1B/p27kip1 gene analysis in patients with multiple endolcrine neopasia type 2 (MEN2)

INTRODUÇÃO: Na Neoplasia Endócrina Múltipla tipo 2 (NEM2), o desenvolvimento do Carcinoma Medular de Tireoide (CMT), Feocromocitoma (FEO) e Hiperparatireoidismo primário (HPT) está associado à mutações germinativas ativadoras no proto-oncogene RET. Casos de CMT esporádico podem apresentar mutações somáticas no RET (~40%). A variabilidade fenotípica observada em casos de CMT e FEO familiais associados à NEM2 indica o envolvimento de eventos genéticos adicionais que seriam responsáveis pelas diferenças clínicas observadas nos indivíduos afetados (idade de desenvolvimento, progressão e agressividade do tumor). Outras alterações genéticas no RET como duplas mutações, SNPs e haplótipos específicos podem influenciar na susceptibilidade, agressividade e modulação do fenótipo NEM2. Entretanto, os estudos de outros genes envolvidos no processo da tumorigênese NEM2 ainda estão em andamento. Recentemente foi mostrado que RET ativado controla a expressão de proteínas inibidoras do ciclo celular (p18 e p27). Mutações germinativas no gene p27 foram recentemente associadas à susceptibilidade de tumores neuroendócrinos e estão associadas à síndrome NEM4 (Neoplasia endócrina múltipla tipo 4). Mutações somáticas, inativadoras de p27, são raramente encontradas em vários tipos de tumores. Entretanto, diversos estudos documentaram que a redução na expressão e a sublocalização citoplamática de p27 são controladas por alterações pós-transducionais e/ou epigenéticas. OBJETIVOS: o estudo teve como objetivos avaliar a participação de genes, recentemente associados ao RET ativado, em tumores de pacientes com NEM2 e também verificar se polimorfismos no gene p27 estariam atuando como moduladores de fenótipo em uma grande família com NEM2. CASUÍTICA: foram analisadas 66 amostras tumorais advindas de 36 pacientes com diagnóstico clínico e genético de NEM2 e 28 indivíduos pertencentes a uma grande família com NEM2A-CMTF e mutação C620R no gene RET. MÉTODOS:...

INTRODUCTION: In Multiple Endocrine Neoplasia type 2 (MEN2) the development of medullary thyroid carcinoma (MTC), pheochromocytoma (PHEO) and primary hyperparathyroidism (HPT) are associated with activating germline mutations in RET proto-oncogene. Cases of sporadic MTC may have somatic RET mutations (~ 40%). The phenotypic variability observed in cases with familial MTC/MEN2 and PHEO/MEN2 indicates the probable involvement of additional genetic events that could be responsible for the clinical differences observed in the affected individuals (age development, progression and aggressiveness of the tumor). Other genetic alterations such as RET double mutations, SNPs and specific haplotypes may influence susceptibility, aggressiveness and MEN2 phenotype modulation. However, studies of other genes involved in the tumorigenesis of MEN2 are still in progress. Recently, it was shown that the activated RET controls the expression of cell cycle inhibitory proteins (p18 and p27). Germline mutations in the p27 gene have recently been associated with the susceptibility to neuroendocrine tumors and are associated with the MEN4 syndrome (Multiple endocrine neoplasia type 4). Somatic inactivating mutations p27 are rarely found in many types of tumors. However, several studies have documented that reduced expression and subcellular location of p27 is controlled by post-transductional changes and/or epigenetic factors. OBJECTIVES: This study aimed to evaluate the role of genes recently associated with RET activated in tumors from MEN2 patients and also check whether polymorphisms in the p27 gene would be acting as modulators of phenotype in a large MEN2 family. PATIENTS: We analyzed 66 tumor samples from 36 patients with clinical and genetic diagnosis of MEN2 and from 28 individuals belonging to a large family with FMTC/MEN2A and RET C620R mutation. METHODS: The analyses of somatic p27, p15, p18 and RET...

Expression of P27kip1 and Skp2 in basal cell carcinoma and its clinical pathological characters / 国际肿瘤学杂志

Objective To investigate the expression of Skp2 and P27kip1 and their relationship with the clinicopathologic characters in basal cell carcinoma(BCC). To explore their expression between with the types of BCC of skin, especially in morpheaform BCC group. Methods Immunohistochemical SP technique was used to examine the expression of Skp2 and P27kip1 in 50 cases of BCC and 30 cases of normal tissues of skin.The expression level was analyzed combined with clinicopathological features of age, sex and types of tumor.Results Skp2 positive products located in cytoplasm or nucleus. P27kip1 positive products located in nucleus.The high expression of Skp2 and the low expression of P27kip1 were observed in BCC, there was statistical significance between the tumor group and the control group (P ＜ 0. 05 ) . The expression of Skp2 and P27kip1 were correlated with clinical types of BCC ( P ＜ 0. 05 ), while which were not correlated with age and sex ( P ＞0.05 ). In BCC tissue, Skp2 expression was negatively correlated with P27kip1 ( - 0.624; P ＜ 0.05), there was no correlated with each other in morpheaform BCC group ( P ＞ 0. 05 ). Conclusion The expression of Skp2 and P27kip1 in BCC are significant differences to normal skin tissues, and they are correlated with each other.They may play an important role in carcinogenesis and the development of BCC, and also make targets to treat it. Compared to nodular and superficial BCC group, the expression of Skp2 are higher in morpheaform BCC group, and the expression of P27kip1 is lower. They may play an important role in the types of the BCC and useful factors to predict the types of the tumor, also determine surgical margin for BCC cases.

Low-dose interferon-γ influences differentiation of oligodendrocyte precursor cell through P27kip1 / 中华围产医学杂志

Objective To expore the mechanism of low-dose interfone-γ(IFN-γ) influences on differentiation of oligodendrocyte precursor cell. Methods The cerebral cortex samples were obtained from one day old SD rats to form mixed single cell suspensions. After culturing in full medium for 7 to 10 days, succession and differential velocity adherent technique were performed to acquire oligodendrocyte precursor cell and cultured in serum-free medium. IFN-γ, AG490 and Fludarabine were added during the culture of oligodendrocyte precursor cell and reverse transcription-polymerase chain reaction, Western blot and flow cytometry were performed to evaluate the expression of intracellular P27kip1 and its influence on the differentiation of oligodendrocyte precursor cell. Results (1)The expression of P27kip1 mRNA and protein was lower in IFN-γ group than in control group (t=85. 535, P<0. 05;t= 12. 481, P<0. 05), while the expression of P27kip1 mRNA and protein in IFN-γ+AG490 group and IFN-γ+Fludarabine group were both higher than those in IFN-γ group (P<0. 05). (2) The phosphorylation levels of JAK2/STAT1 in INF-γ group were higher than that in the other three groups (P<0. 05). (3) The percentage of myelin basic protein positive cells was (68. 42 ± 2. 53)% in IFN-γ group, lower than that in control group [(88.21 ± 1.97)%](t=10.682, P < 0.05). Myelin basic protein positive cells in IFN-γ + AG490 group were (57. 63 ±2. 75) %, lower than those in the IFN-γ group. The same figure in IFN-γ+Fludarabine group were (79. 53±4. 15)% , higher than those in IFN-γ group (t = 3.957, P<0.05). Conclusions Low-dose IFN-γ can regulate the expression of intracellular P27kip1 through JAK2/STAT1 signal transduction pathway and Fludarabine may participate in this process and improve the differentiation and maturation of oligodendrocyte precursor cell.

Prospect for research on cyclin E and p27 in breast cancer / 国际肿瘤学杂志

Deregulation of cell cycle is one of important mechanisms leading to breast cancer. It has been revealed that cyclin E and p27 are the most important regulatory factor for cell cycle control and a better marker for evaluating prognosis of breast cancer compared to other biological markers.

Estudo de p27, p21, p16 em epitélio escamoso normal, papiloma escamoso e carcinoma de células escamosas da cavidade oral / Comparative analysis of the immunohistochemistry expression of p27, p21WAF/Cip1, and p16INK4a in oral normal epithelium, squamous papilloma and squamous cell carcinoma

INTRODUÇÃO E OBJETIVO: O tipo de câncer oral mais frequente é o carcinoma de células escamosas, que corresponde a 95 por cento dos casos(9). O papiloma escamoso oral é uma neoplasia benigna normalmente associada à infecção pelo papilomavírus humano (HPV)(21). A análise da literatura mostra alterações nos genes reguladores do ciclo celular p27, p21WAF/Cip1 e p16INK4a, porém sem uma definição de seus papéis na carcinogênese oral. O objetivo foi caracterizar imuno-histoquimicamente p27, p21WAF/Cip1 e p16NK4a em epitélio escamoso normal, papilomas escamosos e carcinomas de células escamosas da cavidade oral. MÉTODOS: Imuno-histoquímica para p27, p21WAF/Cip1 e p16NK4a em 32 casos de epitélio escamoso normal, 30 casos de papiloma escamoso e 34 de carcinoma de células escamosas da cavidade oral. RESULTADOS: p27: 97,06 por cento dos casos de carcinoma de células escamosas apresentaram imunopositividade focal. O grupo papiloma escamoso apresentou 33,33 por cento e o grupo controle, 18,75 por cento. p21WAF/Cip1: 100 por cento de imunopositividade focal tanto no grupo controle como no grupo carcinoma de células escamosas, e 90 por cento no grupo papiloma escamoso. p16INK4a: 100 por cento de imunopositividade focal para os grupos controle e papiloma escamoso, e 94 por cento para o grupo carcinoma de células escamosas. CONCLUSÃO: Imuno-histoquimicamente demonstrou-se diferença significativa para p27 quando feita comparação dos grupos controle e papiloma escamoso com o grupo carcinoma de células escamosas. O p21WAF/Cip1 não demonstrou poder de diferenciar os grupos analisados. O p16INK4a apresentou imunopositividade difusa em uma minoria dos casos do grupo carcinoma de células escamosas. O grupo papiloma escamoso se comportou de maneira similar ao grupo controle em relação aos três marcadores.

INTRODUCTION: The most frequent type of oral cancer is the squamous cell carcinoma, which corresponds to 95 percent of the cases(9).The oral squamous papilloma is a benign neoplasia, commonly associated with infections caused by the human papilloma virus(21). The analysis of medical literature shows changes in cell cycle regulatory genes (p27, p21WAF/Cip1 and p16INK4a), but does not define their roles in oral carcinogenesis. Objective: Characterize the immuno-histochemical expression of p27, p21WAF/Cip1 and p16INK4a in oral normal squamous epithelium, oral squamous papilloma and oral squamous cell carcinoma. METHODS: Immuno-histochemical evaluation of p27, p21WAF/Cip1 and p16INK4a in 32 samples of oral normal squamous epithelium, 30 of oral squamous papilloma and 34 of oral squamous cell carcinoma. RESULTS: 97.06 percent of the oral squamous cell carcinoma group, 33.33 percent of the squamous papilloma group and 18.75 percent of the control group showed focal immunopositivity for p27. 100 percent of both control and oral squamous cell carcinoma groups and 90 percent of the oral squamous papilloma group showed focal immunopositivity for p21WAF/Cip1. 100 percent of both control and oral squamous papilloma groups and 94 percent of the oral squamous cell carcinoma group showed focal immunopositivity for p16INK4a. CONCLUSIONS: The study revealed a statistically significant difference for p27 expression when comparing the control and oral squamous papilloma groups with the oral squamous cell carcinoma group. p21WAF/Cip1 did not prove to be useful to differentiate the groups. p16INK4a showed diffuse immunopositivity in a minority of the oral squamous cell carcinoma cases. The oral squamous papilloma group behaved similarly to the control group as to the three markers.

The function of p27(KIP1) during tumor development

Timely cell cycle regulation is conducted by sequential activation of a family of serine-threonine kinases called cycle dependent kinases (CDKs). Tight CDK regulation involves cyclin dependent kinase inhibitors (CKIs) which ensure the correct timing of CDK activation in different phases of the cell cycle. One CKI of importance is p27(KIP1). The regulation and cellular localization of p27(KIP1) can result in biologically contradicting roles when found in the nucleus or cytoplasm of both normal and tumor cells. The p27(KIP1) protein is mainly regulated by proteasomal degradation and its downregulation is often correlated with poor prognosis in several types of human cancers. The protein can also be functionally inactivated by cytoplasmic localization or by phosphorylation. The p27(KIP1) protein is an unconventional tumor suppressor because mutation of its gene is extremely rare in tumors, implying the normal function of the protein is deranged during tumor development. While the tumor suppressor function is mediated by p27(KIP1)'s inhibitory interactions with the cyclin/CDK complexes, its oncogenic function is cyclin/CDK independent, and in many cases correlates with cytoplasmic localization. Here we review the basic features and novel aspects of the p27(KIP1) protein, which displays genetically separable tumor suppressing and oncogenic functions.

Single nucleotide polymorphisms in cell cycle regulator p21 and p27 genes are associated with susceptibility to epithelial ovarian cancer / 中华妇产科杂志

Objective To investigate the association of single nucleotide polymorphisms(SNP)in p21and p27 genes with the risk of epithelial ovarian cancer(EOC).Methods Genotypes were analyzed by polymerase chain reaction-restrictive fragment length polymorphism(PCR-RFLP)method in 234 patients with EOC and 284 control women in China.Results (1)The frequencies of the p21 in healthy controls were 34.2%.49.6%and 16.2%,while the distribution of the C and T allele was 59.0%and 41.0%,respectively.The p21 C/C(28.2%),C/T(53.0%),T/T(18.8%)distribution in ovarian cancer patients was not significantly different from that in healthy controls(P＞0.05).There was no statistic difference in allele distribution between ovarian cancer patients and healthy controls(P＞0.05)either.The stratification analysis by tumor histological type did show that the genotype distribution in four types of ovarian cancer patients was significantly different from that in healthy controls(P=0.02).The C/C genotype was likely to reduce the risk of epithelial endometrial cancer.and the adjusted odds ratio was 0.56(95%CI:0.32-0.98).(2)The genotype frequencies of the p27 in healthy controls were 88.4%,10.9%and 0.7%.while the distribution of the V and G allele was 93.8%and 6.2%.respectively.The V/V(93.6%),V/G(5.1%)and G/G(1.3%)distribution in ovarian cancer patients was significantly different from that in healthy controls(P=0.04).There was no statistic difference in allele distributionbetween ovarian cancer patients and healthy controls(P＞0.05).Compared with the V/G and G/G genotypes,the V/V genotype increased the risk of EOC,the adjusted odds ratio was 1.92(95%CI:1.02-3.63).Conclusion The C/C genotype of p21 may reduce the risk of epithelial endometrial cancer,and the genotype of p27 V/V may be a potential risk factor for susceptibility to EOC.

Cyclin-Dependent Kinase Inhibitor p27(Kip1) Controls Growth and Cell Cycle Progression in Human Uterine Leiomyoma

The molecular mechanism of the cell-cycle machinery in uterine leiomyoma has not yet been fully elucidated. Among the various types of cell-cycle regulators, p27(Kip1)(p27) is considered to be a potent tumor suppressor. To provide further molecular basis for understanding the progression of uterine leiomyoma, our objective was to evaluate the expression level of p27 in normal myometrium and uterine leiomyoma tissue and its effect on cytogenic growth. Western blot analysis, real-time polymerase chain reaction (PCR) and immunohistochemical staining revealed that p27 protein and messenger RNA were down-regulated in uterine leiomyoma tissue and cultured cells compared to normal myometerium. Full-length human p27 cDNA was transferred using a replication-deficient recombinant adenoviral vector (Ad.p27) into uterine leiomyoma cells and evaluated the effect on cell proliferation. Transfection of Ad.p27 into uterine leiomyoma cells resulted in the induction of apoptosis, reduction in viability and proliferation of uterine leiomyoma cells. Our results suggest a new paradigm that down-regulated p27 protein expression is the possible underlying mechanism for the growth of uterine leiomyoma and over-expression of p27 induces cell death. This study provides better understanding of the control exerted by p27 in regulating growth and disease progression of uterine leiomyoma.

Expression and significance of PCNA and p27 in inverted papilloma of nasal cavities and paranasal sinuses / 中国耳鼻咽喉头颈外科

0.05). CONCLUSION The PCNA labeling index may reflect the proliferating condition of NIP, but does not have relationship with NIP recurrence. And the role of p27 in the development of NIP needs more investigation.

Heterogeneous nuclear ribonuclear protein C is increased in the celecoxib-induced growth inhibition of human oral squamous cell carcinoma

Celecoxib is a selective inhibitor of cyclooxygenase-2 (COX-2) that is a critical factor in carcinogenesis, but precise mechanism of its action remains to be elucidated. Here we evaluated the inhibitory effect of celecoxib on cell growth of human oral squamous cell carcinoma (OSCC) YD-10B, which was established to be used as in vitro OSCC model, and identified celecoxib-regulated protein by proteomics techniques. Celecoxib (IC50=37 micrometer) inhibited the growth of YD-10B cells with the decrease of COX-2 protein expression. Its inhibition could be linked in the arrest of G1 phase with increased levels of p(27)protein, a specific CDK inhibitor. Using proteomics, the 10- to 20-fold increase of heterogeneous nuclear ribonuclear protein C (hnRNP C), which has been suggested to be related with the translation of p(27)mRNA, was observed in celecoxib-treated YD-10B cells. In summary, celecoxib has a potential to induce the protein expression of hnRNP C and its increase subsequently induce the translation of p(27)mRNA, which trigger the inhibition of cell growth via p(27)-regulated cell cycle arrest in YD-10B cells. In addition, YD-10B cells could be useful to study the pathological mechanism of OSCC.

Bis induces growth inhibition and differentiation of HL-60 cells via up-regulation of p27

Bis (Bag-3, CAIR), a Bcl-2-interacting protein, promotes the anti-apoptotic activity of Bcl-2 and increased levels of Bis have been observed in several disease models. The involvement of Bcl-2 and some Bcl-2-binding proteins in differentiation has recently been reported. However, the relevance of Bis to cellular differentiation remains unknown. The findings herein show that Bis expression is up-regulated during the differentiation of HL-60 cells. To investigate the effect of Bis expression on differentiation, we established Bis-overexpressing HL-60 cells (HL-60-bis). HL-60-bis cells have a low nuclear: cytoplasmic ratio and indented nucleus in Wright- Giemsa staining, and an increased expression of CD11b in immunofluorescence study, indicating the promotion of differentiation. The overexpression of Bis also resulted in a retarded cell growth rate, accompanied by the accumulation of HL-60 cells at the G0/G1 phase of the cell cycle, which was sustained during the differentiation process. Western blot analysis revealed that the expression of p27, a representative inducer of cell cycle arrest at the G1 phase, was increased 2.5-fold in HL-60-bis cells compared to HL-60-neo cells. These results suggest that the Bis induced growth inhibition of HL-60 cells promotes G0/G1 phase arrest via up-regulation of p27, which seems to be a prerequisite for differentiation. Further studies will be required to define the exact roles of Bis on cellular differentiation more precisely.