Low Cyclin Research Articles

Breast cancer in young women and prognosis: How important are proliferation markers?

AimCompared to middle-aged women, young women with breast cancer have a higher risk of systemic disease. We studied expression of proliferation markers in relation to age and subtype and their association with long-term prognosis. MethodsDistant disease-free survival (DDFS) was studied in 504 women aged <40 years and 383 women aged ≥40 years from a population-based cohort. Information on patient characteristics, treatment and follow-up was collected from medical records. Tissue microarrays were produced for analysis of oestrogen receptor, progesterone receptor (PR), Her2, Ki-67 and cyclins. ResultsYoung women with luminal tumours had significantly higher expression of Ki-67 and cyclins. Proliferation markers were prognostic only within this subtype. Ki-67 was a prognostic indicator only in young women with luminal PR+ tumours. The optimal cut-off for Ki-67 varied by age. High expression of cyclin E1 conferred a better DDFS in women aged <40 years with luminal PR− tumours (hazard ratio [HR] 0.47 [0.24–0.92]). Age <40 years was an independent risk factor of DDFS exclusively in women with luminal B PR+ tumours (HR 2.35 [1.22–4.50]). Young women with luminal B PR− tumours expressing low cyclin E1 had a six-fold risk of distant disease compared with luminal A (HR 6.21 [2.17–17.6]). ConclusionsThe higher expression of proliferation markers in young women does not have a strong impact on prognosis. Ki-67 is only prognostic in the subgroup of young women with luminal PR+ tumours. The only cyclin adding prognostic value beyond subtype is cyclin E1. Age is an independent prognostic factor only in women with luminal B PR+ tumours.

TRAP1 controls cell cycle G2-M transition through the regulation of CDK1 and MAD2 expression/ubiquitination.

Regulation of tumour cell proliferation by molecular chaperones is still a complex issue. Here, the role of the HSP90 molecular chaperone TRAP1 in cell cycle regulation was investigated in a wide range of human breast, colorectal, and lung carcinoma cell lines, and tumour specimens. TRAP1 modulates the expression and/or the ubiquitination of key cell cycle regulators through a dual mechanism: (i) transcriptional regulation of CDK1, CYCLIN B1, and MAD2, as suggested by gene expression profiling of TRAP1-silenced breast carcinoma cells; and (ii) post-transcriptional quality control of CDK1 and MAD2, being the ubiquitination of these two proteins enhanced upon TRAP1 down-regulation. Mechanistically, TRAP1 quality control on CDK1 is crucial for its regulation of mitotic entry, since TRAP1 interacts with CDK1 and prevents CDK1 ubiquitination in cooperation with the proteasome regulatory particle TBP7, this representing the limiting factor in TRAP1 regulation of the G2-M transition. Indeed, TRAP1 silencing results in enhanced CDK1 ubiquitination, lack of nuclear translocation of CDK1/cyclin B1 complex, and increased MAD2 degradation, whereas CDK1 forced up-regulation partially rescues low cyclin B1 and MAD2 levels and G2-M transit in a TRAP1-poor background. Consistently, the CDK1 inhibitor RO-3306 is less active in a TRAP1-high background. Finally, a significant correlation was observed between TRAP1 and Ki67, CDK1 and/or MAD2 expression in breast, colorectal, and lung human tumour specimens. This study represents the first evidence that TRAP1 is relevant in the control of the complex machinery that governs cell cycle progression and mitotic entry and provides a strong rationale to regard TRAP1 as a biomarker to select tumours with deregulated cell cycle progression and thus likely poorly responsive to novel cell cycle inhibitors. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Abstract 5055: Multiplatform metabolomics analysis of growth arrest in pancreatic tumor xenografts

Abstract R,S-4-Methoxy-1-naphthylfenoterol, MNF, inhibits the G protein-coupled receptor GPR55. In this study, we determine the effect of MNF on human PANC-1 pancreatic tumor growth in mice and apply multiplatform metabolomics analysis to identify pathways associated with growth arrest. Methods: Female Balb/c nude mice, 6-8 weeks old, 18-20g, were inoculated subcutaneously with 5 x 106 PANC-1 cells. On Day 8, mice were placed in groups of 10 using random block design based upon tumor volume. Mice received daily ip injections of vehicle or 40mgxkg-1 MNF 5 days/week for 3 treatment cycles. Mice were monitored daily and tumor volumes measured at beginning and end of each dosing cycle. On Day 33, mice were euthanized, and plasma samples and tumors collected. Tumor tissue was homogenized, extracted and analyzed using liquid chromatography-QTOF-MS, capillary electrophoresis-TOF-MS and gas chromatography-EI-Q-MS. Differences between groups were evaluated by unpaired t-test or Mann−Whitney test with post hoc Benjamini-Hochberg correction. Statistical significance was set at P≤0.05. Compound identification was accomplished using online databases and in-house standards Results Tumor volume increased in vehicle-treated mice by ~700%, 142 ± 8 mm3 to 957 ± 79 mm3 and only ~250% in MNF-treated mice, 143 ± 8 mm3 to 259 ± 27 mm3. On Day 33, MNF was not detected in plasma but accumulated in tumor tissues, 43.9 ± 32.7 ng/g. Plasma L-lactate levels were reduced from 3.29 ± 0.66 mmol/L το 2.81 ± 0.60 mmol/L, P≤0.001. Differences in tumor tissue metabolome were observed with MNF compared to vehicle, which was reflected by significant, P≤0.05, changes in relative metabolite signals. MNF treatment was accompanied by the disruption of pyrimidine nucleotide biosynthesis at uridine 5'-monophosphate, UMP, and increased UMP degradation. Moreover, the +237% increase in ophthalmic acid and +95% increase in its precursor 2-aminobutyrate indicate higher oxidative stress and the +51% increase in 2-hydroxyproline suggest greater HFI-1α proteolysis upon MNF treatment. Conclusions These results are consistent with our previous observations in PANC-1 cells showing that GPR55 inhibition attenuates activation of the EGFR-MEK-ERK, Wnt-β-catenin and PI3K/AKT pathways resulting in lower cyclin D1 expression and halting the cell cycle in G1. The reduction in HIF-1α expression and glycolytic flux in MNF-treated PANC-1 cells is in line with the decline in L-lactate plasma levels in MNF-treated mice. The data from this study indicate that MNF may be useful in the treatment of pancreatic cancer. Citation Format: Irving W. Wainer, Danuta Dudzik, Michel Bernier, Coral Barbas. Multiplatform metabolomics analysis of growth arrest in pancreatic tumor xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5055. doi:10.1158/1538-7445.AM2017-5055

Cytoplasmic Cyclin E Predicts Recurrence in Patients with Breast Cancer.

Purpose: Low molecular weight cyclin E (LMW-E) detected by Western blot analysis predicts for reduced breast cancer survival; however, it is impractical for clinical use. LMW-E lacks a nuclear localization signal that leads to accumulation in the cytoplasm that can be detected by IHC. We tested the hypothesis that cytoplasmic staining of cyclin E can be used as a predictor of poor outcome in different subtypes of breast cancer using patient cohorts with distinct clinical and pathologic features.Experimental Design: We evaluated the subcellular localization of cyclin E in breast cancer specimens from 2,494 patients from 4 different cohorts: 303 from a prospective study and 2,191 from retrospective cohorts [NCI, MD Anderson Cancer Center (MDA), and the United Kingdom (UK)]. Median follow-up times were 8.0, 10.1, 13.5, and 5.7 years, respectively.Results: Subcellular localization of cyclin E on IHC was associated with full-length (nuclear) and low molecular weight isoforms (cytoplasmic) of cyclin E on Western blot analysis. In multivariable analysis, cytoplasmic cyclin E staining was associated with the greatest risk of recurrence compared with other prognostic factors across all subtypes in three (NCI, MDA, and UK) of the cohorts. In the MDA cohort, cytoplasmic cyclin E staining outperformed Ki67 and all other variables as prognostic factors.Conclusions: Cytoplasmic cyclin E identifies patients with the highest likelihood of recurrence consistently across different patient cohorts and subtypes. These patients may benefit from alternative therapies targeting the oncogenic isoforms of cyclin E. Clin Cancer Res; 23(12); 2991-3002. ©2016 AACR.

Mig-6 is down-regulated in HCC and inhibits the proliferation of HCC cells via the P-ERK/Cyclin D1 pathway

The ablation of Mig-6 has been shown to induce tumor formation in various tissues. However, the relationships between Mig-6 expression, clinical pathological factors, and prognosis have not been clarified in hepatocellular carcinoma (HCC), and the mechanism by which Mig-6 regulates the proliferation of HCC cells has not been reported. In this study, we investigated the clinical significance of the loss of Mig-6 expression in HCC and the mechanism underlying the inhibition of cell proliferation by Mig-6. The down-regulation of Mig-6 correlated significantly with large tumors, a more advanced BCLC stage, and a more advanced TNM stage, and low Mig-6 expression predicted significantly reduced survival. Low Mig-6 expression and high Cyclin D1 expression were independent predictors for survival. The overexpression of Mig-6 led to significant G1 arrest and growth inhibition in HCC cells, possibly through the inhibition P-ERK and Cyclin D1. These results indicate that Mig-6 expression is low in HCC, which predicts a poor prognosis. Mig-6 may regulate cell proliferation and the cell cycle through the P-ERK/Cyclin D1 pathway.

Autoimmune responses are dependent on the MAVS innate pathway due to its natural co-stimulating effect on B cell activation and maturation

Abstract There is evidence that autoimmune disease might be induced by deficient regulation of innate immune pathways that normally induce type I interferon in response to pathogen-derived nucleic acids. To investigate a potential role for nucleic acid sensing pathways with cytosolic localization and more ubiquitous expression, we tested the requirement for MAVS (dsRNA-sensing) or STING (dsDNA-sensing) in the lupus autoimmune disease developed by FcγRIIB-KO (R2−/−) mice. These experiments revealed that STING was mildly protective, while MAVS was an essential factor for autoimmune disease in R2−/− mice. We found that MAVS deficiency, but not type I IFN receptor deficiency, completely eliminated autoantibodies and autoimmune pathology in R2−/− mice. MAVS deficiency also eliminated spontaneous activation of B and T cells, germinal center formation and follicular helper T cell development. Using mixed bone marrow reconstitution experiments, we determined that MAVS was required for autoreactivity in a B cell intrinsic manner, with a profound effect on B cell survival in the germinal center. MAVS deficiency did not alter BCR-proximal signaling, but resulted in diminished long term proliferative capacity of B cells, with lower cyclin D2 and Bcl-xL expression 24 hours after anti-IgM stimulation. MAVS deficiency also resulted in B cell developmental defects, fewer total B cells but a skewing toward marginal zone and against the follicular B cell program. Overall MAVS seems to provide its costimulatory effect independent of type I IFN, by enhancing the activation of NFκB in situations where T cell help or other modes of costimulation are not present and most importantly, by providing survival stimulus for autoreactive B cells.

Disruption of Estrogen Receptor Alpha in Rats Results in Faster Initiation of Compensatory Regeneration Despite Higher Liver Injury After Carbon Tetrachloride Treatment.

Estrogen receptor alpha (ESR1) is 1 of the 2 intracellular receptors for estrogen and is expressed by hepatocytes in the liver. The role of ESR1 in the regulation of toxicant-induced liver injury and compensatory regeneration is not completely clear. We investigated the role of ESR1 in liver regeneration after carbon tetrachloride (CCl4)-induced liver injury using wild type (WT) and ESR1 knockout (ESR1-KO) rats. Adult female WT and ESR1-KO rats were treated with 1 mL/kg CCl4 and euthanized over a time course of 0 to 48 hours. Liver injury measured by serum alanine amino transaminase, and histopathological analysis showed significantly higher liver injury in ESR1-KO as compared to WT rats. Hematoxylin and eosin staining revealed 2-fold higher necrosis and significant inflammatory cell infiltration in ESR1-KO rats. Chloracetate esterase staining revealed higher neutrophil infiltration in ESR1-KO rat livers. Interestingly, proliferating cell nuclear antigen immunohistochemistry showed that in spite of 2-fold higher liver injury, the ESR1-KO rats had equal liver regeneration as compared to WT rats. Western blot analysis of cyclin D1 and phosphorylated Rb, proteins involved in the initiation of the cell cycle, was significantly higher at all time points in ESR1-KO rats. Further analysis revealed faster activation of canonical Wnt/β-catenin and NF-κB signaling in ESR1-KO rats characterized by higher activated β-catenin and phosphorylated p65 at 12 hours after CCl4 treatment. Taken together, these data indicate that ESR1-mediated signaling inhibits liver regeneration by downregulation of Wnt signaling resulting in lower cyclin D1 activation after chemical-induced liver injury.

BRAF V600E Mutant Colorectal Cancer Subtypes Based on Gene Expression.

Mutation of BRAF at the valine 600 residue occurs in approximately 10% of colorectal cancers, a group with particularly poor prognosis. The response of BRAF mutant colorectal cancer to recent targeted strategies such as anti-BRAF or combinations with MEK and EGFR inhibitors remains limited and highly heterogeneous within BRAF V600E cohorts. There is clearly an unmet need in understanding the biology of BRAF V600E colorectal cancers and potential subgroups within this population. In the biggest yet reported cohort of 218 BRAF V600E with gene expression data, we performed unsupervised clustering using non-negative matrix factorization to identify gene expression-based subgroups and characterized pathway activation. We found strong support for a split into two distinct groups, called BM1 and BM2. These subtypes are independent of MSI status, PI3K mutation, gender, and sidedness. Pathway analyses revealed that BM1 is characterized by KRAS/AKT pathway activation, mTOR/4EBP deregulation, and EMT whereas BM2 displays important deregulation of the cell cycle. Proteomics data validated these observations as BM1 is characterized by high phosphorylation levels of AKT and 4EBP1, and BM2 patients display high CDK1 and low cyclin D1 levels. We provide a global assessment of gene expression motifs that differentiate BRAF V600E subtypes from other colorectal cancers. We suggest that BRAF mutant patients should not be considered as having a unique biology and provide an in depth characterization of heterogeneous motifs that may be exploited for drug targeting. Clin Cancer Res; 23(1); 104-15. ©2016 AACR.

Cyclins A, B, E and p27 in Endometrial Endometrioid Adenocarcinoma

We have previously shown that cyclin A, B and E hold prognostic significance in endometrial endometrioid adenocarcinoma. The aim of this study was to investigate the impact of cyclin-dependent kinase inhibitor p27 on cancer-specific survival and other clinicopathological variables, as well as further analyze the relationship between p27 and cyclins A, B and E and their combined relation to prognosis in the disease. The study comprised of 211 patients surgically treated for endometrial endometrioid adenocarcinoma at the Oulu University Hospital between 1992 and 2000. Tissue samples were immunohistochemically stained for cyclins A, B and E, as well as p27. Clinicopathological data were retrospectively retrieved from the patients' records. In this study, universally low cyclin expression was found to be an independent, favorable prognostic factor in endometrial endometrioid adenocarcinoma. A strong correlation was found between cyclin A and cyclin B expression and weaker correlations between other cyclin and p27 pairs. Nuclear p27 expression correlated with stage and produced near-significant results in univariate survival analysis. Combining the expression level of different cyclins may be useful in determining the prognosis in endometrial cancer. Unfortunately, it remains unclear whether high p27 expression is a poor or a favorable prognostic factor. Further large-scale studies are required to assess the effects of cyclins and p27 in endometrial cancer.

P16 overexpression in high-grade neuroendocrine carcinomas of the head and neck: potential diagnostic pitfall with HPV-related carcinomas.

High-grade neuroendocrine carcinomas (HGNECs) of the head and neck have the morphological appearance of undifferentiated carcinomas and could be histologically similar to human papillomavirus (HPV)-associated non-keratinizing squamous cell carcinomas of the head and neck. The aim of the study is to characterize histologically, immunohistochemically, and virologically these unusual neoplasms. Nineteen HGNECs of the head and neck (1 oropharyngeal, 5 sinonasal, 7 of the larynx, and 6 of the parotid gland) were reviewed and analyzed with a immunohistochemical panel, with special emphasis on cell cycle proteins. The tumors were tested for HPV by in situ hybridization (GenPoint HPV, Dako) and PCR (SPF10-DEIA-LiPA25). Merkel cell polyomavirus was studied using the antibody CM2B4. Fifteen HGNEC were of small cell and 4 of large cell type. Most of the tumors (14/19, 73.7%), including all the pure small cell carcinomas, showed a strong and diffuse positive staining for p16. Eleven of them (78.5%) had Rb loss and a low or absent cyclin D1 expression. All cases were negative for HPV and polyomavirus. Most patients were smokers, diagnosed at advanced stages of the disease, and had a poor outcome, with a 5-year survival of 18%. In conclusion, HGNECs of the head and neck are infrequently related to HPV infection, but usually show strong, diffuse positive p16 immunostaining due to Rb pathway dysregulation. Awareness of this immunohistochemical pattern of expression may avoid a potential diagnostic pitfall with HPV-associated non-keratinizing squamous cell carcinomas, which have a better prognosis.

Cytoplasmic Cyclin E and Phospho–Cyclin-Dependent Kinase 2 Are Biomarkers of Aggressive Breast Cancer

Cyclin E and its co-activator, phospho-cyclin-dependent kinase 2 (p-CDK2), regulate G1 to S phase transition and their deregulation induces oncogenesis. Immunohistochemical assessments of these proteins in cancer have been reported but were based only on their nuclear expression. However, the oncogenic forms of cyclin E (low molecular weight cyclin E or LMW-E) in complex with CDK2 are preferentially mislocalized to the cytoplasm. Here, we used separate nuclear and cytoplasmic scoring systems for both cyclin E and p-CDK2 expression to demonstrate altered cellular accumulation of these proteins using immunohistochemical analysis. We examined the specificity of different cyclin E antibodies and evaluated their concordance between immunohistochemical and Western blot analyses in a panel of 14 breast cell lines. Nuclear versus cytoplasmic staining of cyclin E readily differentiated full-length from LMW-E, respectively. We also evaluated the expression of cyclin E and p-CDK2 in 1676 breast carcinoma patients by immunohistochemistry. Cytoplasmic cyclin E correlated strongly with cytoplasmic p-CDK2 (P<0.0001), high tumor grade, negative estrogen/progesterone receptor status, and human epidermal growth factor receptor 2 positivity (all P<0.0001). In multivariable analysis, cytoplasmic cyclin E plus phosphorylated CDK2 (as one variable) predicted breast cancer recurrence-free and overall survival. These results suggest that cytoplasmic cyclin E and p-CDK2 can be readily detected with immunohistochemistry andused as clinical biomarkers for aggressive breast cancer.

P53, Cyclin D1, p21 (WAF1) and Ki-67 (MIB1) Expression at Invasive Tumour Fronts of Oral Squamous Cell Carcinomas and Development of Local Recurrence.

Expression of p53, cyclin D1, p21 (WAF1) and Ki-67 (MIB1) was evaluated in oral squamous cell carcinoma (OSCC) to test whether levels of these markers at invasive tumour fronts (ITFs) could predict the development of local recurrence. Archived paraffin-embedded specimens from 51 patients with T1/T2 tumours were stained immunohistochemically and analysed quantitatively. Local recurrence-free survival was tested with Kaplan-Meier survival plots (log-rank test) using median values to define low and high expression groups and with a Cox's proportional hazards model in which the expression scores were entered as continuous variables. The assessment of expression of all markers was highly reliable, univariate analysis showing that patients with clear surgical margins, with low cyclin D1 and high p21 expression at the ITF had the best local recurrence-free survival. Multivariate analysis showed that these three parameters were independent prognostic factors but that neither p53 nor MIB1 expression were of prognostic value. Assessment of p53, cyclin D1, p21 (WAF1), and Ki-67 (MIB1) at the ITF could help to predict local recurrence in early stage oral squamous cell carcinoma cases.

Effect of Buyang Huanwu decoction and its simple prescription(Naojian tablet) on CDK4/Cyclin D1 expression of rats with cerebral ischemia

To evaluate the regulating effect of Buyang Huanwu decoction and its simple prescription (Naojian tablet) on CDK4/Cyclin D1 expression in hippocampus tissues of rats with cerebral ischemia, SD rats were divided into the sham-operation group, the model group, the Buyang Huanwu decoction group (ig, 3.15 g · kg⁻¹) and the simple prescription group (ig, 2.41 g · kg⁻¹). Each group was further divided into five subgroups based on time points after the administration, i. e. 1 d, 3 d, 7 d, 14 d and 28 d, respectively. CDK4/Cyclin D1 expressions of the group at different time points were examined by using immunohistochemistry and real-time qPCR. According to the results, the cerebral ischemia model group showed higher CDK4/Cyclin D1 expression than the sham-operation groups (P < 0.05), suggesting that the cell cycle signal pathway would be activated by the cerebral ischemic injury. Both Buyang Huanwu decoction and simple prescription groups showed significantly lower cyclin expression than the model group at 3 d, 7 d, 14 d, 28 d (P < 0.05), indicating both Buyang Huanwu decoction and its simple prescription could play the neuroprotective effect through the cell cycle signal pathway.

Defective Myb Function Ablates Cyclin E1 Expression and Perturbs Intestinal Carcinogenesis.

Cyclin E1 is essential for the reentry of quiescent cells into the cell cycle. When hypomorphic mutant Myb mice (Myb(Plt4)) were examined, it was noted that Cyclin E1 (Ccne1) expression was reduced. Furthermore, the induction of Ccne1 in recovering intestinal epithelia following radiation-induced damage was ablated in Myb-mutant mice. These data prompted us to investigate whether Myb directly regulated Ccne1 and to examine whether elevated Myb in colorectal cancer is responsible for Cyclin E1-driven tumor growth. Here, it was found that Myb/MYB and Ccne1/CCNE1 expressions were coupled in both mouse and human adenomas. In addition, the low molecular weight Cyclin E1 was the predominant form in intestinal crypts and adenomatous polyposis coli (Apc)-mutant adenomas. Chromatin immunoprecipitation (ChIP) analysis confirmed that Myb bound directly to the Ccne1 promoter and regulated its endogenous expression. In contrast, Myb(Plt4) served as a dominant-negative factor that inhibited wild-type Myb and this was not apparently compensated for by the transcription factor E2F1 in intestinal epithelial cells. Myb(Plt4/Plt4) mice died prematurely on an Apc(Min/) (+) background associated with hematopoietic defects, including a myelodysplasia; nevertheless, Apc(Min/) (+) mice were protected from intestinal tumorigenesis when crossed to Myb(Plt4/) (+) mice. Knockdown of CCNE1 transcript in murine colorectal cancer cells stabilized chromosome ploidy and decreased tumor formation. These data suggest that Cyclin E1 expression is Myb dependent in normal and transformed intestinal epithelial cells, consistent with a cell-cycle progression and chromosome instability role in cancer. This study demonstrates that Myb regulates Cyclin E1 expression in normal gastrointestinal tract epithelial cells and is required during intestinal tumorigenesis.

Abstract POSTER-TECH-1123: Advancing metformin as therapeutic for ovarian cancer: metabolomic profiling of mouse ovarian tumors identifies metformin-induced global metabolic changes

Abstract Background: Epidemiologic and preclinical studies indicate that use of metformin, a widely prescribed anti-diabetic drug, has protective effects in ovarian cancer (OvCa). One of the current challenges in the field is understanding which patients are most likely to benefit from metformin treatment. The aim of this study was to test the hypothesis that metformin would prevent OvCa progression in a mouse model and to identify metabolic changes induced in tumors by metformin. The long-term goal of these studies is to use the findings to inform the analysis of biospecimens in an ongoing prospective clinical trial of metformin in OvCa. Methods: To test the effect of metformin on ovarian tumorigenesis, HeyA8 xenograft mice were treated with metformin (250 mg/kg/day) or control. At the time of sacrifice, mean tumor weight was determined and tumors were stained by immunohistochemistry for Cyclin D1. Metabolomic analysis was performed on serum and tumor samples from mice treated with metformin and compared to mice treated with control. Here, after precipitation in 80% methanol and reconstitution in LC/MS grade water/HPLC grade acetonitrile samples were analyzed using a Q-Exactive Mass Spectrometer coupled to HILIC chromatography that was able to quantify over 300 polar metabolites and over 5000 molecular features in each sample. Results: The results indicate that in a mouse model metformin inhibits OvCa progression and induces global metabolic alterations. Metformin-treated mice had 68% lower mean tumor weight than controls (p=0.003). To understand how metformin inhibited tumor growth we stained tumors for Cyclin D1 to test whether metformin induced cell cycle arrest, a finding demonstrated in our prior studies (unpublished results). We found lower Cyclin D1 levels in tumors from metformin-treated mice than controls. Next, we measured the level of metformin in both the serum and tumors using mass-spectrometry. In serum, the results showed metformin levels in mice ranging from 1-5 nM; this was comparable to reports of serum levels of patients taking 1 gm of metformin daily. In tumors, there was trend toward smaller tumors having higher levels of metformin (Spearman, one-tailed R= -0.60, p=0.16). Finally, we used metabolomic profiling for a more global and unbiased assessment of metformin’s effect in OvCa. This analysis revealed two novel findings. First, an unbiased hierarchical clustering approach revealed metabolome profiles that could clearly predict the mice that had been treated with metformin. Second, global metabolic changes were noted in tumors from metformin treated mice. Metabolic pathways altered in metformin-treated mice included: alterations in glycolytic intermediates, induction of oxidative stress, decreased biosynthetic components of nucleotides, and changes in lipid metabolism. Conclusion: These findings of decreased tumor burden in metformin-treated mice add to the growing body of evidence supporting repurposing metformin as a metabolic therapeutic for OvCa. In addition, the metabolic changes in tumors induced by metformin indicate that it might be possible to establish a metabolomic signature in ovarian tumors that is predictive of metformin response. Citation Format: Iris L. Romero, Xiaojing Liu, Anirban K Mitra, Ernst Lengyel, Jason W. Locasale. Advancing metformin as therapeutic for ovarian cancer: metabolomic profiling of mouse ovarian tumors identifies metformin-induced global metabolic changes [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-TECH-1123.

Cyclin D1 Loss Distinguishes Prostatic Small-Cell Carcinoma from Most Prostatic Adenocarcinomas.

Small-cell neuroendocrine differentiation in prostatic carcinoma is an increasingly common resistance mechanism to potent androgen deprivation therapy (ADT), but can be difficult to identify morphologically. We investigated whether cyclin D1 and p16 expression can inform on Rb functional status and distinguish small-cell carcinoma from adenocarcinoma. We used gene expression data and immunohistochemistry to examine cyclin D1 and p16 levels in patient-derived xenografts (PDX), and prostatic small-cell carcinoma and adenocarcinoma specimens. Using PDX, we show proof-of-concept that a high ratio of p16 to cyclin D1 gene expression reflects underlying Rb functional loss and distinguishes morphologically identified small-cell carcinoma from prostatic adenocarcinoma in patient specimens (n = 13 and 9, respectively). At the protein level, cyclin D1, but not p16, was useful to distinguish small-cell carcinoma from adenocarcinoma. Overall, 88% (36/41) of small-cell carcinomas showed cyclin D1 loss by immunostaining compared with 2% (2/94) of Gleason score 7-10 primary adenocarcinomas at radical prostatectomy, 9% (4/44) of Gleason score 9-10 primary adenocarcinomas at needle biopsy, and 7% (8/115) of individual metastases from 39 patients at autopsy. Though rare adenocarcinomas showed cyclin D1 loss, many of these were associated with clinical features of small-cell carcinoma, and in a cohort of men treated with adjuvant ADT who developed metastasis, lower cyclin D1 gene expression was associated with more rapid onset of metastasis and death. Cyclin D1 loss identifies prostate tumors with small-cell differentiation and may identify a small subset of adenocarcinomas with poor prognosis. Clin Cancer Res; 21(24); 5619-29. ©2015 AACR.

Abstract 3772: Cyclin E as a prognostic marker and predictor of response to neoadjuvant chemotherapy and adjuvant hormonal therapy in patients with stage II-III breast cancer

Abstract Purpose: While we know that many cytotoxic chemotherapeutic agents act to modulate the cell cycle, the role of cyclin E as a predictive marker of response to chemotherapy is unknown. Given that the cell cycle is compromised in tumors that overexpress cyclin E, we hypothesized that cyclin E overexpression would predict decreased response to neoadjuvant chemotherapy and increased risk of relapse in the subset of patients with pathologic complete response (pCR). Experimental Design: 286 women with a diagnosis of clinical stage II-III invasive breast cancer that had received neoadjuvant chemotherapy with paclitaxel (or docetaxel) and FAC, FEC or AC followed by surgery were enrolled into this study. Histological sections from the pre- and post-therapy tissue sections of the patient samples were analyzed for cyclin E using immunohistochemistry (IHC). In breast cancers, high levels of cyclin E result in the expression of its low molecular weight isoforms (LMW-E) which are predominantly cytoplasmic due to the loss of the nuclear localization signal. LMW-E expression can be measured by cytoplasmic staining of cyclin E on IHC. The expression of cyclin E was correlated with response to treatment using multivariable logistic regression. Clinical-Pathological factors, disease-free (DFS), recurrence-free (RFS), and overall survival (OS) rates were also evaluated. Results: A complete pCR was obtained in 79 of 286 cases (31%). Patients with high pretreatment cytoplasmic cyclin E expression on IHC had a decreased pCR rate as compared to those patients with low cytoplasmic cyclin E levels (32.3% vs 67.7%). On multivariable logistic regression analysis, the strongest predictors of poor response to therapy (failure to attain pathologic complete response) were the cytoplasmic cyclin E expression and negative Her-2 status (p&amp;lt;0.0001, OR: 9.0 and p&amp;lt;0.0001, OR: 6.5 respectively). Patients with high cytoplasmic cyclin E expression were significantly correlated with poor DFS, RFS and OS in both pretreatment and posttreatment groups. Conclusions: Cytoplasmic cyclin E expression is a strong predictive factor for pCR in breast cancer patients treated with neoadjuvant anthracycline-based chemotherapy. Routine clinical assessment of cyclin E could be used to identify patients at high risk for poor response to neoadjuvant therapy or recurrence and stratified for more personalized therapy. Citation Format: Cansu Karakas, Ashleigh Francis, Min Yi, Aysegul Sahin, Khandan Keyomarsi, Kelly Hunt. Cyclin E as a prognostic marker and predictor of response to neoadjuvant chemotherapy and adjuvant hormonal therapy in patients with stage II-III breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3772. doi:10.1158/1538-7445.AM2015-3772

Cyclin b1 suppresses colorectal cancer invasion and metastasis by regulating e-cadherin.

Cyclin B1, a mitotic cyclin, has been implicated in malignances. However, its contribution to colorectal cancer invasion and metastasis are still not well understood. Here, we demonstrated that the invasion and metastasis of colorectal cancer is regulated by Cyclin B1. Overexpression of Cyclin B1 was observed in colorectal cancer tissues, but this elevated expression was negatively associated with lymph node metastasis, distant metastasis stage, and TNM stage. The Kaplan-Meier survival analysis proved that low Cyclin B1 expression was associated with poor overall survival of patients with colorectal cancer. Inhibition of Cyclin B1 in colorectal cancer cells enhanced the cell migration and invasion of three different colorectal cancer cell lines. In studying the possible mechanism by which Cyclin B1 suppresses colorectal cancer invasion and metastasis, we observed that suppression of Cyclin B1 decreased the expression of E-cadherin protein level. Our findings suggest that Cyclin B1 could suppress the invasion and metastasis of colorectal cancer cells through regulating E-cadherin expression, which enables the development of potential intervention strategies for colorectal cancer.

Nicotinamide impairs entry into and exit from meiosis I in mouse oocytes.

Following exit from meiosis I, mammalian oocytes immediately enter meiosis II without an intervening interphase, accompanied by rapid reassembly of a bipolar spindle that maintains condensed chromosomes in a metaphase configuration (metaphase II arrest). Here we study the effect of nicotinamide (NAM), a non-competitive pan-sirtuin inhibitor, during meiotic maturation in mouse oocytes. Sirtuins are a family of seven NAD+-dependent deacetylases (Sirt1-7), which are involved in multiple cellular processes and are emerging as important regulators in oocytes and embryos. We found that NAM significantly delayed entry into meiosis I associated with delayed accumulation of the Cdk1 co-activator, cyclin B1. GVBD was also inhibited by the Sirt2-specific inhibitor, AGK2, and in a very similar pattern to NAM, supporting the notion that as in somatic cells, NAM inhibits sirtuins in oocytes. NAM did not affect subsequent spindle assembly, chromosome alignment or the timing of first polar body extrusion (PBE). Unexpectedly, however, in the majority of oocytes with a polar body, chromatin was decondensed and a nuclear structure was present. An identical phenotype was observed when flavopiridol was used to induce Cdk1 inactivation during late meiosis I prior to PBE, but not if Cdk1 was inactivated after PBE when metaphase II arrest was already established, altogether indicating that NAM impaired establishment rather than maintenance of metaphase II arrest. During meiosis I exit in NAM-treated medium, we found that cyclin B1 levels were lower and inhibitory Cdk1 phosphorylation was increased compared with controls. Although activation of the anaphase-promoting complex-Cdc20 (APC-Cdc20) occurred on-time in NAM-treated oocytes, Cdc20 levels were higher in very late meiosis I, pointing to exaggerated APC-Cdc20-mediated proteolysis as a reason for lower cyclin B1 levels. Collectively, therefore, our data indicate that by disrupting Cdk1 regulation, NAM impairs entry into meiosis I and the establishment of metaphase II arrest.

Abstract P5-05-05: Low molecular weight cyclin E regulates response to aromatase inhibitors in post-menopausal breast cancer patients

Abstract Almost seventy percent of all breast cancer patients have estrogen receptor (ER) positive tumors requiring hormonal therapy. Aromatase inhibitors (AIs) are considered as the first line hormonal therapy for ER+ post-menopausal patients. However, resistance to these drugs remains a major challenge in clinic and the biology of such resistance is not clear. Previous studies have shown that cyclin E pathway, a key regulator in the G1 to S transition of cell cycle, is deregulated in breast cancer. Full-length cyclin E is abnormally cleaved into low molecular weight isoforms (LMW-E) that renders patients to poor survival. Here we hypothesize that cyclin E deregulation can confer resistance to AIs. To address this, we engineered aromatase overexpressing MCF7 cells to overexpress LMW-E under doxycycline inducible promoter. Full-length cyclin E, GFP and empty vector transfected cells were also generated and used as controls. Our results indicated that AIs inhibited proliferation by arresting the cells at G1 phase of the cell cycle. However, LMW-E expression significantly enhanced proliferation of the cells when treated with AIs. In addition, LMW-E bypassed G1 arrest following AI treatment. At the molecular level, AIs decreased CDK2, pCDK2, and Rb levels and attenuated Rb phosphorylation. However, these effects were completely rescued only when LMW-E was expressed. Moreover, using an in vitro kinase assay we indicated that AIs decreased CDK2 kinase activity while LMW-E expression reversed this effect by increasing CDK2 enzymatic activity. Taken together, these results suggest that LMW-E inactivates Rb protein as a tumor suppressor and renders the cells to bypass G1 checkpoint following AI treatment. In addition, this study provides early evidence that CDK2 inhibitors could be beneficial in combination with AIs for LMW-E expressing tumors. Currently we are investigating whether LMW-E can bypass the activity of AIs using inducible breast cancer cell line xenograft. We are also examining the correlation between cyclin E status and response to treatment in a cohort of patients who received AIs in the neo-adjuvant setting. Citation Format: Iman Doostan, Stacy L Moulder, Kelly K Hunt, Khandan Keyomarsi. Low molecular weight cyclin E regulates response to aromatase inhibitors in post-menopausal breast cancer patients [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-05-05.