Cell Cycle Regulatory Proteins P27 Research Articles

SUZ12 promotes the malignant behavior of gastric cancer cells by CDKs.

Zeste 12 Homolog (SUZ12), as a transcription factor, has been found to be highly expressed in a variety of tumors and promote tumor progression. We focus on revealing its role and mechanism in gastric cancer. Cellular level studies were conducted in mouse gastric cancer MFC cells by performing overexpression of SUZ12, overexpression of CDK6, and treatment with CDK6 inhibitor, respectively. Changes in cell viability, invasion, metastasis and colony formation were detected, and the expression variations of cell cycle regulatory proteins CDK6, P21, and Cyclin D were determined. During the animal experimentation, a mouse xenograft model was established. After transplantation of SUZ12-overexpressing MFC-SUZ12, the tumor growth was compared with that in MFC, and the tissue expressions of CDK-6, SUZ12, and Cyclin D were examined. Overexpression of SUZ12 could enhance the viability of MFC cells while upregulating their migration, invasion and colony formation abilities, which promoted the expression of CDK6, P21, and Cyclin D. CDK6 inhibitor, on the other hand, could suppress the effects of SUZ12 overexpression and weaken the cell viability and malignant behavior. Overexpression of CDK6 also promoted the MFC viability and malignant behavior. We found that SUZ12 exerted its effects by promoting the expression of downstream cyclin CDK6. At the animal level, the mice xenografted with SUZ12-overexpressing MFC cells exhibited larger tumor volumes, as well as elevated cyclin expression.SUZ12 promotes the proliferation and malignant behavior of gastric cancer cells by regulating the expression of downstream CDK6.

Panax ginseng Meyer cv. Silvatica phenolic acids protect DNA from oxidative damage by activating Nrf2 to protect HFF-1 cells from UVA-induced photoaging

Ethnopharmacological relevanceLong-wave ultraviolet A (UVA) causes skin aging by damaging the fine structures of the skin, such as elastic fibers and collagen fibers, through oxidation. Currently, the use of plant extracts to protect skin from photoaging is a popular method. Panax ginseng C.A. Meyer exerts commendable anti-photoaging and antioxidant effects. P. ginseng Meyer cv. Silvatica, also known as forest ginseng (FG), is a type of ginseng cultivated by artificially simulating the growth environment of wild ginseng aged >15 years. However, there are only a few reports on its anti-photoaging effect on the skin caused by UVA stimulation.AIM OF THE STUDY: To investigate whether isolated and extracted FG can inhibit skin photoaging as well as to explore its action mechanism. MethodsThe FG extract (FGE) was obtained from the supernatant of FG after water extraction and alcohol precipitation with the D101 resin. The composition and content of phenolic acids in FGE were determined by high-performance liquid chromatography (HPLC). The MTT assay was performed to detect cell viability. The ratio of SA-β-GAL-positive cells, CoL-I level, 8-OHdG concentration, MDA, GSH, GPx, SOD, and CAT activity were measured using relevant kits. Furthermore, cell cycle alterations and ROS accumulation were assessed by flow cytometry. The expressions of p53, p21, p16, and Keap1 protein were detected by Western blotting. The Nrf2 translocation was monitored by immunofluorescence staining. ResultsThe findings revealed that FGE significantly restored UVA injury-induced cell viability, reduced the proportion of SA-β-GAL-positive cells, and increased the level of CoL-I secretion in a dose-dependent manner, where the main ingredients were chlorogenic acid, protocatechuic acid, salicylic acid, p-hydroxybenzoic acid, vanillic acid, ferulic acid, and caffeic acid. Further studies indicated that this phenolic acid mixture (PAM) could alleviate UVA-induced HFF-1 cell cycle arrest and protect the DNA from oxidative damage caused by UVA stimulation. Moreover, the expressions of cell cycle regulatory proteins p53, p21, and p16 and the accumulation of ROS were inhibited, the translocation of Nrf2 into the nucleus was promoted, the expression of Keap1 protein was inhibited, the activity of intracellular antioxidant indicators GSH, GPx, SOD, and CAT was enhanced, and the expression of malondialdehyde (MDA) was inhibited. ConclusionsCollectively, our results demonstrated that FG phenolic acids protect DNA from oxidative damage by activating Nrf2 to safeguard the skin from photoaging induced by UVA stimulation.

Antitumor Potential of Sericite Treatment Mediated by Cell Cycle Arrest in Triple-Negative MDA-MB231 Breast Cancer Cells.

Breast cancer is the most common cancer and the leading cause of cancer-related mortality among females worldwide. Triple-negative breast cancer (TNBC) accounts for about 10–15% of all breast cancers and is usually more aggressive and has a poorer prognosis. Sericite has been known to have antitumor and immune-stimulatory effects. Although the chemopreventive potential of sericite has been demonstrated in other cancers, its molecular pathways in TNBC still require investigation. Thus, in the present study, the antitumor mechanism of sericite against MDA-MB231 breast cancer cells was examined in vitro and in an in vivo xenograft mouse model. Sericite treatment reduced cell proliferation and cell proliferation marker proliferating cell nuclear antigen (PCNA) in MDA-MB231 cells. It also decreased the total cell number and arrested cells in the G0/G1 phase of the cell cycle with an increase in the phosphorylation of P53 and upregulation of cell cycle regulatory proteins P21 and P16. In addition, sericite treatment also induced apoptosis signaling, which was evident by the upregulation of apoptotic protein markers cleaved caspases 3 and 9. A reduction in reactive oxygen species (ROS), NADPH oxidase 4 (NOX4), p22phox, and heat shock proteins (HSPs) was also observed. Similar results were obtained in vivo with significantly reduced tumor volume in sericite-administered mice. Collectively, these findings suggest that sericite has antitumor potential based on its property to induce cell cycle arrest and apoptotic cell death and therefore could serve as a potential therapeutic agent and crucial candidate in anticancer drug development for TNBC.

Expression of Cell-Cycle Regulatory Proteins pRb, Cyclin D1, and p53 Is Not Associated with Recurrence Rates of Equine Sarcoids.

Simple SummaryExpression of cell-cycle regulatory proteins pRB, Cyclin D1, and p53 is not associated with recurrence rates of equine sarcoids. Sarcoids are common tumors of equids, and since the pathogenesis and Bovine Papillomavirus (BPV) mechanism of tumorigenesis is not fully understood yet, we investigated the expression of cell cycle regulatory proteins pRB, Cyclin D1, and p53 to understand whether BPV and Human Papillomavirus (HPV) share similar mechanisms of action. The expression pattern of these proteins in a series of BPV-positive equine sarcoids is different from HPV-induced tumors. Moreover, their expression is not correlated with the recurrence or occurrence of sarcoids in new body sites.Sarcoids are among the most common tumors diagnosed in equids; their association with bovine papillomaviruses (BPV) infection has been widely reported, but the mechanism of carcinogenesis has not been fully elucidated. To verify whether BPV infection causes dysregulation of the pRb-Cyclin D1-p16CDKN2A-p53 pathway as reported for human papillomavirus (HPV), the study employed immunohistochemistry to test 55 equine sarcoid biopsies for the expression of pRb, Cyclin D1, and p53 cell cycle regulatory proteins and to evaluate the proliferative rate through Ki67. High Cyclin D1 and pRb expression were observed in 51% and 80% of cases, respectively, while low expression was observed in 49% and 20% of cases, respectively. Significantly higher Ki67 proliferation indexes were observed in fibroblastic, nodular, and mixed sarcoids compared to the occult and verrucous. High proliferation was significantly associated with high Cyclin D1 expression. In contrast with previous studies, p53 positivity was not observed in the cases examined in this study. Moreover, follow-up analysis revealed that fibroblastic, mixed sarcoids were associated with significantly higher local recurrence rates while the verrucous subtype was associated with higher rates of new sarcoid development at distant sites.

ISODEOXYELEPHANTOPIN (IDOE) RETARDS TUMOR CELL MIGRATION BY DOWNREGULATING MMP-2/9 EXPRESSION IN TRIPLE NEGATIVE BREAST CANCER

Introduction: Isodeoxyelephantopin (C19H20O6), plant-derived sesquiterpene, extracted from Elephantopus Scaber Linn., have tremendous contributions in inhibiting the proliferation and metastasis of cancer cells.
 Materials and Methods: The cell viability assay was shown to be procured half-maximal inhibitory concentration of isodeoxyelephantopin on the MDA-MB-231cell line. Apoptosis was screened by AO/ EB staining and it was confirmed by annexin V staining. The DNA damaging property of IDOE was examined by comet assay. The cell cycle arrest determined using flow cytometry analysis and the growth inhibition due to the modulation of cell cycle regulatory protein p53 were substantiated by RT PCR. Scratch wound migratory assay was done to evaluate the migratory effect of IDOE on the MDA-MB-231 cell line. RT-PCR analysis showed that expression of MMP-2/9 was inhibited by IDOE treatment.
 Result: Anti-proliferative and anti-migratory effect of IDOE was determined by cell cycle analysis and annexin v staining. Cells were arrested in the G2/M phase and it is due to the modulation of cell cycle regulatory protein p53. The mRNA level expression studies of matrix metalloproteinases, MMP-2/9 provide supporting data to prove the anti-migratory property.

LRSAM1 E3 ubiquitin ligase promotes proteasomal clearance of E6-AP protein

Numerous proteins participate and actively contribute to the various cellular mechanisms, where several of them are crucial for regular metabolism, including survival. Thus, to maintain optimal cellular physiology, cells govern protein quality control functions with the assistance of comprehensive actions of molecular chaperones, the ubiquitin-proteasome system, and autophagy. In the ubiquitin-proteasome pathway, few quality control E3 ubiquitin ligases actively participate against misfolded protein aggregation generated via stress conditions. But how these quality control E3s active expression levels returned to basal levels when cells achieved re-establishment of proteostasis is still poorly understood. Our current study demonstrated that LRSAM1 E3 ubiquitin ligase promotes the proteasomal degradation of quality control E3 ubiquitin ligase E6-AP. We have observed the co-localization and recruitment of LRSAM1 with E6-AP protein and noticed that LRSAM1 induces the endogenous turnover of E6-AP. Partial depletion of LRSAM1 elevates the levels of E6-AP and affects overall cell cycle regulatory proteins (p53 and p27) expression, including the rate of cellular proliferation. The current finding also provides an excellent opportunity to better understand the basis of the E6-AP associated pathomechanism of Angelman Syndrome disorder. Additionally, this study touches upon the novel potential molecular strategy to regulate the levels of one quality control E3 ubiquitin ligase with another E3 ubiquitin ligase and restore proteostasis and provide a possible therapeutic approach against abnormal protein aggregation diseases.

AMPK Activity Contributes to G2 Arrest and DNA Damage Decrease via p53/p21 Pathways in Oxidatively Damaged Mouse Zygotes.

In zygotes, the capacity of G2/M checkpoint and DNA repair mechanisms to respond to DNA damage varies depending on different external stressors. In our previous studies, we found that mild oxidative stress induced a G2/M phase delay in mouse zygotes fertilized in vitro, due to the activation of the spindle assembly checkpoint. However, it is unclear whether the G2/M phase delay involves G2 arrest, triggered by activation of the G2/M checkpoint, and whether AMPK, a highly conserved cellular energy sensor, is involved in G2 arrest and DNA damage repair in mouse zygotes. Here, we found that mouse zygotes treated with 0.03 mM H2O2 at 7 h post-insemination (G1 phase), went into G2 arrest in the first cleavage. Furthermore, phosphorylated H2AX, a specific DNA damage and repair marker, can be detected since the early S phase. We also observed that oxidative stress induced phosphorylation and activation of AMPK. Oxidative stress-activated AMPK first localized in the cytoplasm of the mouse zygotes in the late G1 phase and then translocated to the nucleus from the early S phase. Overall, most of the activated AMPK accumulated in the nuclei of mouse zygotes arrested in the G2 phase. Inhibition of AMPK activity with Compound C and SBI-0206965 abolished oxidative stress-induced G2 arrest, increased the activity of CDK1, and decreased the induction of cell cycle regulatory proteins p53 and p21. Moreover, bypassing G2 arrest after AMPK inhibition aggravated oxidative stress-induced DNA damage at M phase, increased the apoptotic rate of blastocysts, and reduced the formation rate of 4-cell embryos and blastocysts. Our results suggest the G2/M checkpoint and DNA repair mechanisms are operative in coping with mild oxidative stress-induced DNA damage. Further, AMPK activation plays a vital role in the regulation of the oxidative stress-induced G2 arrest through the inhibition of CDK1 activity via p53/p21 pathways, thereby facilitating the repair of DNA damage and the development and survival of oxidative stress-damaged embryos. Our study provides insights into the molecular mechanisms underlying oxidative-stress induced embryonic developmental arrest, which is crucial for the development of novel strategies to ensure viable embryo generation.

Anti-prostate cancer activity of a nanoformulation of the spleen tyrosine kinase (SYK) inhibitor C61.

Patients with advanced or metastatic castration-resistant prostate cancer have a dismal prognosis and are therefore in urgent need for therapeutic innovations. Spleen tyrosine kinase has emerged as a new molecular target for castration-resistant prostate cancer. This study was done to test the cytotoxicity of the lead nanoformulation of a potent spleen tyrosine kinase inhibitor, C61-LNP, against the human prostatic carcinoma cell line, PC-3. PC-3 cells were treated with various concentrations of C61-LNP either alone or in combination with cisplatin (CDDP) for 24, 48 and 72 hours. The cell viability was evaluated by MTS assay. Cellular expression levels of various regulatory proteins in treated PC-3 cells were evaluated by Western blot analyses. C61-LNP exhibited dose-dependent cytotoxicity against PC-3 cells. C61-LNP, as well as C61-LNP + CDDP treatments, caused pro-apoptotic proteomic changes including an increase in cleaved fragments of caspases-3 and -9 consistent with caspase activation as well as an improvement in the anti-apoptotic Bcl2 and Bax levels. The combination of C61-LNP and CDDP changed in alterations of the cell cycle regulatory proteins p53, p21, p27, cyclin D1 and cyclin E levels. C61-LNP exhibited cytotoxicity against the castration-resistant prostate cancer cell line PC3. It also caused alterations in expression levels of regulatory proteins involved in apoptosis and cell cycle regulation and these effects were not abrogated by the standard chemotherapy drug CDDP. We are planning to further develop C61-LNP as a selective spleen tyrosine kinase inhibitor as part of a multi-modality treatment strategy for advanced/metastatic castration-resistant prostate cancer.

Antiangiogenic and antitumoral activity of LQFM126 prototype against B16F10 melanoma cells

Inhibition of mouse double minute 2 homolog (MDM2)-p53 interaction and reactivation of p53 signaling have been explored as effective anticancer therapeutic strategy. The potent and specific antitumor activity shown by Nutlins, first class of MDM2-p53 inhibitors discovered, has made these compounds potential antitumor candidates. To this end, we synthesized Nutlin-1 and Nutlin-2 analogs through molecular simplification and selected the compound with the most efficient antitumoral activity. Cytotoxicity of Nutlin-2 analog LQFM126 on B16F10 melanoma cells induced intense cytoplasmic vacuolization, reduction of cell size, chromatin condensation, cytoplasmic degeneration and nuclear fragmentation. LQFM126 antiproliferative effects mediated cell cycle retention in G0/G1 phase and increased the levels of cell cycle regulatory proteins p21 and p27. This Nutlin analog increased mitochondrial membrane potential, activated caspase-8, -9 and -3/7 and reduced VEGF levels in B16F10 cells. Therefore, LQFM126 promoted alterations suggestive of apoptosis, G0/G1 cell cycle arrest and suppression of angiogenesis through modulation of VEGF expression in B16F10 cells. Additionally, LQFM126 was classified as UN GHS category 4 (LD50 > 300–2000 mg/kg), suggesting it has low acute systemic toxicity. LQFM126 can be a promising prototype for anticancer therapy.

Punicalagin promotes the apoptosis in human cervical cancer (ME-180) cells through mitochondrial pathway and by inhibiting the NF-kB signaling pathway

Increasing attention of plant derived therapeutic agents against cancer, investigating the anti-proliferative efficiency of plant derived chemicals have achieved increasing momentum for the design of anticancer drug. Punicalagin, dietary phytochemical altered the various cell signal transduction pathways associated with cell apoptosis and proliferation. This investigation was intended to examine the efficiency of punicalagin lying on cell viability so as to examine the molecular based punicalagin mechanism stimulated apoptosis via exploring the expression of Bcl-2 family proteins, and caspases also the cell cycle regulatory proteins p53 and NF-κB signaling in human cervical cancer cells. We also analyzed the morphological characteristic changes through mitochondrial membrane depolarization, reactive oxygen species (ROS) generation, TUNEL assay, AO/EtBr analysis in cervical cancer cells. Our findings demonstrated that punicalagin repressed the viability of cervical cancer cells in a dosereliant mode via stimulating mitochondrial mediated apoptosis. Moreover, our this study demonstrated that punicalagin blocked cervical cancer cell proliferation and stimulated cell apoptosis by suppressing NF-kappa B activity. Hence our study suggested that punicalagin exhibits opposing actions on NF-kappa B signaling networks to block cancer cell progression acts as a classical candidate for anticancer drug designing.

Impaired expression of cell-cycle regulatory proteins in seborrheic keratosis

to investigate the expression of the cell-cycle regulatory proteins p53 and p16 and the cell proliferation marker Ki-67 in SK. The investigation used intraoperative SK material obtained from 130 patients. Tumors were removed from UV-exposed parts of the body in 63 (48%) patients and from the places that were more often closed in 67 (51.5%). An immunohistochemical (IHC) study was performed using monoclonal antibodies to p53, p16, and Ki-67. A positive reaction with monoclonal antibodies to p53 was recorded in 66 (50.7%) SK samples. In 92.1% of cases, the expression of p53 was found in SK located at the sites that were most exposed to UV radiation (p=0.00001). A positive reaction with monoclonal antibodies to p16 was observed in all SK cases as cytoplasmic staining of more than 50% of the tumor cells: a strong staining in 63 SK samples (overexpression) and a weak staining in 67 SK ones. The level of p16 expression correlated with age (R=0.21; p=0.019) and SK location at the sites exposed to increased insolation (R=0.35; p=0.000038). Overexpressions of p53 and p16 were significantly more commonly recorded in irritated SK. The tumor proliferative activity by the level of Ki-67 expression was low (3.0 to 11.3%). The largest number (8.5±4.8%) of proliferating cells was recorded in irritated SK (p=0.0000001). The found disorders in the expression of cell-cycle regulatory proteins in SK are suggestive of tumor suppressor activation and keratinocyte senescence. There may be malignant tumor transformation in irritated SK in terms of the significant increase in the expression of p53, p16 in the presence of high cell proliferative activity.

Fisetin, via CKIP-1/REGγ, limits oxidized LDL-induced lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells

To test the hypothesis that the flavonoid compound, fisetin, protects macrophages from lipid accumulation and senescence through regulation of casein kinase 2-interacting protein-1 (CKIP-1)/REGγ (11S regulatory particles, 28 kDa proteasome activator, proteasome activator subunit 3) signaling. RAW264.7 macrophage cells were exposed to 100 μg/ml oxidized low-density lipoprotein (ox-LDL) with or without 20 μg/ml fisetin for 24 h. Cell viability was detected by CCK-8 after 1 h. Intracellular lipid accumulation was measured using Oil Red O staining. Total cholesterol (TC) and free cholesterol (FC) contents were measured using assay kits, and cell senescence was inferred by β-gal staining. Protein expression levels of CKIP-1, REGγ, organic cation transporter 1 (Oct-1), lectin-like oxidized LDL receptor-1 (LOX-1), tumor suppressor protein p53 (p53), cell cycle regulatory protein p21 (p21), and multiple tumor suppressor-1 (p16) were detected by immunofluorescence and confirmed by Western blot. Stimulating RAW264.7 macrophage cells with 100 μg/ml ox-LDL for 24 h induced the formation of foam cells, increased intracellular lipid accumulation, increased TC and FC content, and promoted cell senescence. Furthermore, cells induced with 100 μg/ml ox-LDL for 24 h showed decreased CKIP-1 and REGγ protein, while the expressions of Oct-1, LOX-1, p53, p21 and p16 were increased. In contrast, treatment with 20 μg/ml fisetin reversed 100 μg/ml ox-LDL effects to increase cell viability, and decrease β-gal staining, intracellular lipid levels and TC and FC levels. These beneficial effects were associated with increased CKIP-1 and REGγ and decreased Oct-1, LOX-1, p53, p21, and p16 protein expression. Results indicated that fisetin limited ox-LDL-mediated lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells. The mechanism underlying these effects may involve regulation of CKIP-1/REGγ signaling.

Arnicolide D exerts anti-melanoma effects and inhibits the NF-κB pathway

BackgroundMelanoma is a lethal cancer. NF-κB has been validated as a molecular target for melanoma treatment. Current therapies for melanoma have limitations. Novel targeted therapeutics are needed. Arnicolide D (Ar-D), a sesquiterpene lactone isolated from the dried whole plant of Centipeda minima (L.) A. Br. et Aschers., has been reported to inhibit NF-κB activity in colorectal cancer cells. PurposeTo investigate the anti-melanoma effects of Ar-D in vitro and in vivo; and to determine whether Ar-D inhibits the NF-κB pathway in melanoma cells. MethodsA B16F10 allograft mouse model and two melanoma cell lines (A375 and B16F10) were used to investigate the anti-melanoma effects of Ar-D in vivo and in vitro. Dacarbazine was used as a positive control. Cell viability was assessed by MTT and crystal violet staining assays. Cell cycle arrest and apoptosis were analyzed by flow cytometry. Protein levels were determined by Immunoblotting. ResultsIn vivo assays showed that the average tumor weight in Ar-D-treated group (4 mg/kg, i.p, 15 days) was reduced by 53.7%, when compared with the control group. In vitro studies demonstrated that Ar-D reduced cell viability, induced G2/M cell cycle arrest and apoptosis, elevated levels of cell cycle regulatory proteins p53 and p21, and lowered levels of G2/M checkpoint proteins Cdc2 and Cyclin B1 in melanoma cells. Mechanistically, Ar-D inhibited the activity of IKKα/β, the degradation of IκBα, and the phosphorylation and expression of NF-κB p65 in melanoma cells. ConclusionAr-D has anti-melanoma effects, and inhibition of the IKK/IκBα/NF-κB p65 pathway is involved in the effects.

UCHL1 loss alters the cell-cycle in metastatic pancreatic neuroendocrine tumors.

Loss of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) expression by CpG promoter hypermethylation is associated with metastasis in gastroenteropancreatic neuroendocrine tumors; however, the mechanism of how UCHL1 loss contributes to metastatic potential remains unclear. In this study, we first confirmed that loss of UCHL1 expression on immunohistochemistry was significantly associated with metastatic tumors in a translational pancreatic neuroendocrine tumor (PNET) cohort, with a sensitivity and specificity of 78% and 89%, respectively. To study the mechanism driving this aggressive phenotype, BON and QGP-1 metastatic PNET cell lines, which do not produce UCHL1, were stably transfected to re-express UCHL1. In vitro assays, RNA-sequencing, and reverse-phase protein array (RPPA) analyses were performed comparing empty-vector negative controls and UCHL1-expressing cell lines. UCHL1 re-expression is associated with lower anchorage-independent colony growth in BON cells, lower colony formation in QGP cells, and a higher percentage of cells in the G0/G1 cell-cycle phase in BON and QGP cells. On RPPA proteomic analysis, there was an upregulation of cell-cycle regulatory proteins CHK2 (1.2 fold change, p=0.004) and P21 (1.2 fold change, p=0.023) in BON cells expressing UCHL1; western blot confirmed upregulation of phosphorylated CHK2 and P21. There were no transcriptomic differences detected on RNA-Sequencing between empty-vector negative controls and UCHL1-expressing cell lines. In conclusion, UCHL1 loss correlates with metastatic potential in PNETs and its re-expression induces a less aggressive phenotype in vitro, in part by inducing cell-cycle arrest through post-translational regulation of phosphorylated CHK2. UCHL1 re-expression should be considered as a functional biomarker in detecting PNETs capable of metastasis.

Function of cell-cycle regulators in predicting silent pituitary adenoma progression following surgical resection.

The present study investigated the use of cell-cycle regulators for predicting the progression of silent pituitary adenoma (SPA) following surgical resection, via immunohistochemical analysis of tumor samples obtained by surgical resection. The medical records of patients diagnosed with SPA between January 2000 and December 2013 in the Samsung Changwon Hospital, Sungkyunkwan University School of Medicine (Changwon, South Korea) were reviewed. Immunohistochemical staining was performed on sections of the archived, paraffin-embedded tissues obtained by surgery, with all tissues stained for cell-cycle regulatory proteins p16, p15, p21, cyclin-dependent kinase (CDK)4, CDK6, retinoblastoma protein (pRb) and cyclin D1, as well as E3 ubiquitin-protein ligase mib1 (MIB-1) antigen and p53. The primary end-point was to investigate the expression of cell-cycle regulatory proteins in SPA. The secondary end-point was to estimate the progression-free survival of patients with SPA following surgical resection and to identify its association with the expression of cell-cycle regulatory proteins. Of the 127 SPA samples, 44 (34.6%) were from patients with progression during a mean follow-up period of 62.4 months (range, 24.2–118.9 months). Immunohistochemical overexpression was identified in 61 samples (48.0%) for p16, 38 samples (29.9%) for p15, 19 samples (15.0%) for p21, 49 samples (38.6%) for CDK4, 17 samples (13.4%) for CDK6, 57 samples (44.9%) for pRb and in 65 samples (51.2%) for cyclin D1. Multivariate analysis revealed that null cell adenoma [95% confidence interval (CI), 0.276–0.808], somatotroph SPAs (95% CI, 1.296–3.121), corticotroph SPAs (95% CI, 1.811–4.078), pluripotent SPAs (95% CI, 2.264–5.194), decreased expression of p16 (95% CI, 2.724–5.588), overexpression of pRb (95% CI, 2.557–5.333), cyclin D1 (95% CI, 1.894–4.122) and MIB-1 (95% CI, 1.561–4.133), increased mitotic index (95% CI, 1.228–4.079), increased p53 expression (95% CI, 1.307–4.065) and invasion into the cavernous sinus (95% CI, 3.842–7.502) predicted SPA progression following resection. The results of the present study suggested that specific cell-cycle regulators, including p16, cyclin D1 and pRb, were associated with SPA progression.

Luteolin inhibits cell proliferation and induces cell apoptosis via down-regulation of mitochondrial membrane potential in esophageal carcinoma cells EC1 and KYSE450.

In current study, we investigated the anti-tumor effect of luteolin in human ESCC cell lines in vitro and in vivo and tried to explore the potential mechanisms. Results from flow cytometry showed that luteolin could induce apoptosis and caspase-3 activation and induce cell cycle arrest at G2/M phase in a dose- and time-dependent manner in EC1 and KYSE450 cells. JC-1 test results showed that membrane potential of mitochondria after luteolin treatment was down-regulated and this was an indicator for intrinsic apoptosis. Western Blot results showed the expression of cell cycle regulatory protein p21 and p53 increased and three apoptosis related proteins that participate in mitochondrial apoptotic pathway, namely, Bim, CYT-c and cPARP, also increased in luteolin treated cells compared with control groups. We further confirmed that luteolin could significantly inhibit the growth of ESCC tumors in xenograft mouse models and no evidence of systemic toxicity was observed. Our results suggest that luteolin can induce cell apoptosis and cell cycle arrest in G2/M phase through mitochondrial pathway in EC1 and KYSE450 cell lines and proper utilization of luteolin might be a practical approach in ESCC chemotherapy.

MPTH-07. ROLE OF CELL-CYCLE REGULATORS IN PREDICTING PROGRESSION OF SILENT PITUITARY ADENOMA AFTER SURGICAL RESECTION

This study investigated the use of cell-cycle regulators for predicting progression of silent pituitary adenoma (SPA) after surgical resection via immunohistochemical analysis of tumor samples obtained by surgical resection. We reviewed the medical records of patients diagnosed with SPA from January 2000 to December 2013 in our institute. Immunohistochemical staining was performed on sections of the archived, paraffin-embedded tissues obtained by surgery; cell-cycle regulatory proteins p16, p15, p21, CDK 4 and 6, pRB protein, and cyclin D1; MIB-1 antigen; and p53. The primary end-point was to investigate the expression of cell-cycle regulatory proteins in SPA. The secondary end-point was to estimate the progression-free survival of SPA after surgical resection and find out its association with the expression of cell-cycle regulatory protein. Of the 127 SPA samples, 44 (34.6%) were from patients with progression during a mean follow-up period of 62.4 months (range 24.2–118.9 months). Immunohistochemistry (IHC) was reactive in 61 samples (48.0%) for p16, in 38 samples (29.9%) for p15, in 19 samples (15.0%) for p21, in 49 samples (38.6%) for CDK4, in 17 samples (13.4%) for CDK6, in 57 samples (44.9%) for pRB protein, and in 65 samples (51.2%) for cyclin D1. Multivariate analysis using a Cox proportional hazard regression model showed that null cell adenoma (95% confidence interval [CI] 0.276–0.808); somatotroph SPAs (95% CI, 1.296–3.121); corticotroph SPAs (95% CI 1.811–4.078); pluripotent SPAs (95% CI 2.264–5.194); immunohistochemical normostaining for p16 (95% CI 2.724–5.588); immunohistochemical overstaining for pRB protein (95% CI 2.557–5.333), cyclin D1 (95% CI 1.894–4.122), or MIB-1 (95% CI 1.561–4.133); mitotic index (95% CI 1.228-4.079); p53 (95% CI 1.307-4.065); and invasion into the cavernous sinus (95% CI 3.842–7.502) predicted SPA progression after surgical resection. Our study suggested that specific cell-cycle regulators were associated with SPA progression.

Abstract 3038: Investigating novel targeted therapies for double hit diffuse large B-cell lymphoma (DH-DLBCL)

Abstract Background: Molecular studies divide DLBCL into three subtypes with distinct pathogenesis and clinical outcomes: activated B-cell (ABC), germinal center B-cell (GCB) and primary mediastinal lymphoma (PML). Florescence in situ hybridization (FISH) studies identified another subgroup of DLBCL, classified as DH-DLBCL, with a poor clinical outcome harboring concurrent gene rearrangements of the c-MYC, BCL2 and/or BCL6 proto-oncogenes, resulting in the over-expression of c-Myc, Bcl2 and Bcl6 proteins. Previously, our retrospective review from single institution series revealed that 30 out of 611 DLBCL patients had aberrations in c-MYC and BCL2 or BCL6 by FISH. These patients exhibited inferior response rates (RR) to rituximab-based chemotherapy, and a shorter progression-free survival (PFS)/overall survival (OS), suggesting that newer therapies are in dire need. DH-DLBCL is characterized by de-regulation of apoptosis and cell cycle progression, resulting in rapid cellular proliferation and resistance to apoptotic stimuli. In ABC-DLBCL, anti-apoptotic factor MCL-1 is implicated in poor prognosis leading to resistance to standard chemotherapy. C-MYC transcriptionally upregulates Mcl1. Translocation of c-MYC in DH-DLBCL may contribute to the aggressive phenotype and chemotherapy resistance via the MCL-1 pathway. We hypothesize that dual inhibition of both anti-apoptotic proteins BCL2 and MCL1 is an effective strategy in inducing lymphoma cell death in DH-DLBCL. Materials & Methods: At the pre-clinical level, we studied 3 novel therapeutic agents targeting BCL2 (ABT-199), c-MYC (JQ-1), and various cell cycle regulatory proteins (p21) and other BCL2 family members affecting ABT-199 activity (irreversible proteasome inhibitor carfilzomib(CFZ)) using DH lymphoma (DHL) cell lines (Val, DOHH-2, ROS-50). DHL cell lines were exposed to ABT-199 (0-10 uM), JQ-1 (0-100 uM) and carfilzomib (CFZ) (0-50 nM) at 24, 48 and 72 hours. Changes in cell viability were evaluated using Presto Blue assay. Subsequently, DHL cells were exposed to doublet combinations of ABT-199, JQ-1 and CFZ for 48 hours. Coefficient of synergy was calculated using CalcuSyn. Results: In vitro, ABT199, JQ-1, and CFZ induced cell death in a dose- and time-dependent manner. Significant synergistic activity was observed by combining ABT199 with CFZ and to a lesser degree with JQ-1. Conclusion: ABT199 exhibited strong synergistic activity with CFZ. Dual targeting of BCL2 and c-MYC pathways results in synergistic activity in DHL cell lines. Of interest, this pharmacological interaction could be related to the effects of proteasome inhibition on MCL1 and p21 levels in lymphoma cells, further enhancing the activity of ABT199. Using combination therapy to inhibit c-MYC and the proteasome and in turn decreasing MCL1 will render ABT-199 more effective and be a more potent combination in causing apoptosis and lymphoma cell death. Further pre-clinical work is ongoing. Citation Format: Priyank P. Patel, Alison Zeccola, Juan Gu, Cory Mavis, Sheila N. J. Sait, Vishala Neppalli, Francisco J. Hernandez-Ilizaliturri. Investigating novel targeted therapies for double hit diffuse large B-cell lymphoma (DH-DLBCL). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3038.

The role of cell cycle regulatory protein p53 in Follicular neoplasms of thyroid with hurthle cells

<p class="abstract"><strong><span lang="EN-US">Background:</span></strong><span lang="EN-US"> The disease biology of Follicular neoplasms of thyroid with hurthle cells is poorly understood. Very few studies in literature have addressed the role of p53 in these neoplasms. The aim of the present study is to analyze the histomorphological features of Follicular neoplasms with hurthle cell change and to evaluate the role of p53 in their tumor biology.</span></p><p class="abstract"><strong><span lang="EN-US">Methods:</span></strong>32 cases of Follicular neoplasms of thyroid with focal and pure hurthle cell change over a period of 2.5 years were studied histologically and immunohistochemically using p53 antibody (Biogenex). They included 20 follicular adenomas with focal hurthle cells, 10 pure hurthle cell adenomas and 2 hurthle cell carcinomas.</p><p class="abstract"><strong><span lang="EN-US">Results:</span></strong><span lang="EN-US"> All cases showed nuclear p53 positivity in hurthle cells. Muller-Hocker et al criteria was used for frequency scoring. Out of the 32 cases, 12 cases of pure hurthle cells showed score 3, Remaining 20 cases of follicular adenomas with focal hurthle cell change showed score 3 in cases with >50% hurthle cells, score 2 in cases with 20-40% hurthle cells and score 0 in cases with <10% hurthle cells.</span></p><p class="abstract"><strong><span lang="EN-US">Conclusions:</span></strong>The study showed a good correlation of p53 protein expression with tumor progression and aggressiveness. Hence this indicates that molecular alterations in p53 pathway play a role in tumor biology in Follicular neoplasms of thyroid with hurthle cell change.</p>

HIV-1 Infection Dysregulates Cell Cycle Regulatory Protein p21 in CD4+ T Cells Through miR-20a and miR-106b Regulation.

Both CD4+ T lymphocytes and macrophages are the major targets of human immunodeficiency virus type 1 (HIV-1); however, they respond differently to HIV-1 infection. We hypothesized that HIV-1 infection alters gene expression in CD4+ T cells and monocyte-derived macrophages (MDMs) in a cell specific manner and microRNAs (miRNAs) in part play a role in cell-specific gene expression. Results indicate that 183 and 31 genes were differentially regulated in HIV-1 infected CD4+ T cells and MDMs, respectively, compared to their mock-infected counterparts. Among the differentially expressed genes, cell cycle regulatory gene, p21 (CDKN1A) was upregulated in virus infected CD4+ T cells both at the mRNA and protein level in CD4+ T cells, whereas no consistent change was observed in MDMs. Productively infected CD4+ T cells express higher amount of p21 compared to bystander cells. In determining the mechanism(s) of cell type specific regulation of p21, we found that the miRNAs miR-106b and miR-20a that target p21 were specifically downregulated in HIV-1 infected CD4+ T cells. Overexpression of these two miRNAs reduced p21 expression significantly in HIV-1 infected CD4+ T cells. These findings provide a potential mechanism, by which, HIV-1 could exploit host cellular machineries to regulate selective gene expression in target cells. J. Cell. Biochem. 117: 1902-1912, 2016. © 2016 Wiley Periodicals, Inc.