High Levels Of Cyclin D1 Research Articles

OVEREXPRESSION OF CYCLIN D1 IN ORAL CANCER INCREASES TPF CHEMOTHERAPEUTIC DRUGS VIA ACTIVATING THE CASPASE-3 PATHWAY

Previous studies have indicated that induction chemotherapy can limit the possibility of early lesion eradication and lessen the severity of globally advanced tumors. This study aimed to ascertain if cyclin D1 expression in OSCC patients who were qualified for TPF induction chemotherapy might be regarded as a valid prognostic indicator for long-term outcomes. This study aimed to determine whether or not there was a connection between OSCC cell intervention and the production of cyclin D1 and chemosensitivity to TPF medicines through the apoptotic mechanism. The current work used immunohistochemistry to determine the expression of cyclin D1 in various tissues. To ascertain the survival rate of 232 people diagnosed with locally advanced oral squamous cell carcinoma (OSCC), the study utilized the log-rank test and Kaplan-Meier analysis. The participants in this historical clinical trial were observed for a mean duration of five years. Cytotoxicity assays were employed to assess the therapeutic effectiveness of TPF chemotherapy drugs. The activity of caspase-3 and PARP was evaluated in the HB96, CAL27, and HN30 cell lines following cyclin D1 inhibition, respectively. Long-term clinical outcomes were significantly better for patients with OSCC whose cancer cells expressed low amounts of cyclin D1 than those whose cells expressed high protein levels. Time to initial illness occurrence, time to initial local recurrence, time to mortality, and overall survival were among the metrics evaluated. The groups with low and high expression levels of cyclin D1 showed significantly different survival rates for disease-free survival, overall survival (OS), DMFS, local recurrence-free survival, and local recurrence-free survival (p0.001, 0.003, 0.004, and 0.001, respectively). Patients with cN2 oral squamous cell carcinoma (OSCC) with higher cyclin D1 expression had better distant metastasis-free survival (OS, P=0.024; DMFS, P=0.024) and overall survival (OS, P=0.024; DMFS, P=0.024) with TPF induction chemotherapy. However, patients with cN2 OSCC and low cyclin D1 expression did not show this survival advantage (P=0.024). Research has shown that oral squamous cell carcinoma (OSCC) is more sensitive to TPF-based chemotherapeutic drugs using caspase-3-mediated apoptosis that occurs when cyclin D1 expression rises. Based on these results, TPF induction chemotherapy may provide longer-term benefits than traditional treatment approaches for patients with cN2 OSCC and high cyclin D1 expression. Through a caspase-3-dependent mechanism, oral squamous cell carcinoma (OSCC) cell lines become more susceptible to TPF chemotherapeutic drugs when cyclin D1 is overexpressed.

Assessment of YME1L and mitofusin2 as a possible diagnostic and/or therapeutic target in hepatocellular carcinoma

Mitochondrial dynamics are a contraversal issue in hepatocellular carcinoma. The present study tries to illustrate the role of mitochondrial dynamics proteins (mitofusin-2 (Mfn2) and YME1L) in hepatocarcinogenesis. Five groups were used: the control group and three HCC groups (after 8, 16, and 24 weeks from DENA induction). The last group was treated with Sorafenib (SP) (10 mg/kg), via oral gavage for 4 weeks after cancer induction. This study revealed that Mfn-2 was downregulated and YME1l was overexpressed in different HCC groups. This dysregulation of mitochondrial dynamics proteins was associated with high hepatic levels of cyclin D1, MMP-9, and MDA and overexpression of ki67 as well as decreasing the hepatic expression of tissue inhibitor of matrix metalloproteinase-3 (Timp-3) and Bax. To confirm the possible role of Mfn2 and YME1L in HCC, we assessed the effect of sorafenib on these parameters and its related HCC characteristics. Sorafenib corrected the level of Mfn2 and YME1L and decreased tumor cell proliferation as well. We also elucidated that mitochondrial dynamics proteins (Mfn2 and YME1L) could be a good therapeutic target for HCC.

232 (PB-056) Poster - Co-expressing genes with TACSTD2 and interacting microRNAs in patients with recurrent luminal breast cancers

Background: Previous studies showed that high expression of the Trop-2 gene, TACSTD2, is associated with higher cyclin D1 levels, lymph node and distant organ metastases in breast cancer. It would be interesting to investigate the interacting microRNAs and co-expressing genes with TACSTD2 in recurrent luminal A breast tumors.

Overexpressed Cyclin D1 and CDK4 proteins are responsible for the resistance to CDK4/6 inhibitor in breast cancer that can be reversed by PI3K/mTOR inhibitors.

CDK4/6 inhibitors are the standard treatment in advanced HR+/HER2- breast cancer patients. Nevertheless, the resistance to CDK4/6 inhibitors is inevitable and the strategies to overcome resistance are of great interest. Here, we show that the palbociclib-resistant breast cancer cells expressed significantly higher levels of Cyclin D1 and CDK4 proteins because of upregulated protein synthesis. Silencing Cyclin D1 or CDK4 led to cell cycle arrest while silencing Cyclin E1 or CDK2 restored the sensitivity to palbociclib. Furthermore, PI3K/mTOR pathway was hyper-activated in palbociclib-resistant cells, leading to more phosphorylated 4E-BP1 and higher levels of Cyclin D1 and CDK4 translation. Targeting PI3K/mTOR pathway with a specific PI3Kα inhibitor (BYL719) or an mTOR inhibitor (everolimus) reduced the protein levels of Cyclin D1 and CDK4, and restored the sensitivity to palbociclib. The tumor samples expressed significantly higher levels of Cyclin D1, CDK4, p-AKT and p-4E-BP1 after progression on palbociclib treatment. In conclusion, our findings suggest that overexpressed Cyclin D1 and CDK4 proteins lead to the resistance to CDK4/6 inhibitor and PI3K/mTOR inhibitors are able to restore the sensitivity to CDK4/6 inhibitors, which provides the biomarker and rationale for the combinational use of CDK4/6 inhibitors and PI3K/mTOR inhibitors after CDK4/6 inhibitor resistance in breast cancer.

Abstract P2-04-01: Overexpressed cyclin D1 and CDK4 proteins are responsible for the resistance to CDK4/6 inhibitor in breast cancer that can be reversed by PI3K/mTOR inhibitors

Abstract CDK4/6 inhibitors are now the standard treatment in advanced HR+/HER2- breast cancer patients. Nevertheless, the resistance to CDK4/6 inhibitors is inevitable, limiting its use and efficacy. The mechanisms and the strategies to overcome resistance are of great interest. Here, we show that the palbociclib-resistant breast cancer cells express significantly higher levels of Cyclin D1 and CDK4 proteins because of upregulated protein synthesis. Silencing Cyclin D1 or CDK4 directly led to cell cycle arrest while silencing Cyclin E1 or CDK2 restored the sensitivity to palbociclib in palbociclib-resistant cells. Furthermore, PI3K/mTOR pathway was hyper-activated in palbociclib-resistant cells, leading to more phosphorylated 4E-BP1 and higher levels of Cyclin D1 and CDK4 translation. Targeting PI3K/mTOR pathway with a specific PI3Kα inhibitor (BYL719) or an mTOR inhibitor (everolimus) reduced the protein levels of Cyclin D1 and CDK4, and restored the sensitivity to palbociclib in resistant cells both in vitro and in vivo. The tumors from breast cancer patients who progressed after palbociclib treatment had significantly higher protein expression of Cyclin D1, CDK4, p-AKT and p-4E-BP1 than the paired samples before palbociclib treatment. In conclusion, our findings suggest that overexpressed Cyclin D1 and CDK4 proteins lead to the resistance to CDK4/6 inhibitor and PI3K/mTOR inhibitors are able to restore the sensitivity to CDK4/6 inhibitors, which provides the biomarker and rationale for the combinational use of CDK4/6 inhibitors and PI3K/mTOR inhibitors after CDK4/6 inhibitor resistance in breast cancer. Citation Format: Qiang Liu, Zijie Cai, Jingru Wang, Yudong Li, Lok Lam Wong. Overexpressed cyclin D1 and CDK4 proteins are responsible for the resistance to CDK4/6 inhibitor in breast cancer that can be reversed by PI3K/mTOR inhibitors [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-04-01.

Uveal Melanoma and Paraneoplastic Perivascular Dermal Melanocytic Proliferation in the Setting of Bilateral Diffuse Uveal Melanocytic Proliferation: The Potential Role of the Hepatocyte Growth Factor/c-Met Axis in Their Pathogenesis

Two patients, with non-small cell lung carcinoma treated with pembrolizumab, developed bilateral diffuse uveal melanocytic proliferation (BDUMP) with interesting histopathological features. The first patient developed a right ciliary body mass concurrently with BDUMP. The globe was enucleated. The ciliary body mass was a mitotically active epithelioid uveal melanoma, invading the trabecular meshwork and peripheral corneal stroma, with over 90% of the cells expressing Cyclin D1 protein. The melanoma showed no chromosome 3 or 8 changes. The background uvea showed diffuse, bland spindle cell melanocytic proliferation with much lower Cyclin D1 expression (around 10%). In the choroid, this population was punctuated by islands of pigmented epithelioid cells, some of which were necrotic. All these islands expressed a high level of Cyclin D1, and some islands expressed nuclear preferentially expressed antigen in melanoma (PRAME). The ciliary body mass, epithelioid cell islands, and the BDUMP all expressed c-Met (the receptor for hepatocyte growth factor [HGF]). The features were those of ciliary body melanoma and choroidal melanoma “tumorlets,” developing on a background of BDUMP. The second patient developed bilateral periocular skin pigmentation following a diagnosis of BDUMP, which when biopsied, showed dermal islands of paraneoplastic perivascular melanocytic cell proliferation. These cells also expressed c-Met protein. These observations implicate the HGF/c-Met axis in the pathogenesis of BDUMP, the uveal melanomas in the ciliary body and choroid in the first patient and the paraneoplastic dermal melanocytic proliferation in the second patient.

Abstract PD9-04: Identification of biomarkers associated with therapeutic resistance: Quantitative protein/phosphoprotein analysis of ~750 patients across 8 arms of the neoadjuvant I-SPY 2 TRIAL for high-risk early stage breast cancer

Abstract Background: The goal of I-SPY 2 is to rapidly test novel therapies in addition to standard of care in high-risk breast cancer patients. It has resulted in increasing response rates, where pCR rates in TNBC and HR-HER2+ subsets have reached ~60% and ~75%, respectively. Yet, there remains a sizeable subset of non-responders, especially among HR+ patients. Identification of ‘universal’ resistance mechanisms may guide rational selection of agents to improve these patient's outcomes. Thus, we analyzed reverse phase protein array (RPPA) based quantitative protein/phosphoprotein data across arms to assess whether there are common mechanisms rendering these cancers resistant to all agent classes tested to date. Methods: 736 patients (260 HR+HER2-, 252 TN, 142 HR+HER2-, and 82 HR-HER2+; over 8 arms: 194 Ctr, 105 neratinib (N), 63 veliparib/carboplatin (VC), 128 AMG386 (anti-ANG1/2), 87 MK2206 (anti-AKT), 43 TH/pertuzumab (P), 49 TDM1/P, and 67 pembrolizumab (Pembro)) with pCR and RPPA data at the pre-treatment time point were considered for this analysis. 141 RPPA endpoints representing key cancer pathways were assessed for association with pCR using logistic regression modeling, with HR, HER2 and treatment arm as covariates (likelihood ratio test; p<0.05). Analysis was also performed in HR/HER2 subsets and within treatment arms. Markers were analyzed individually; multiple comparison correction (Benjamini-Hochberg) was applied to p-values. Our analysis is exploratory, and does not adjust for other biomarkers outside this study. Results: Prior to FDR correction, high levels of Cyclin D1, a cell cycle protein implicated in estrogen-mediated DNA damage repair, associate with non-pCR in the population as a whole and within all subtypes except for the HR-HER2+ subset; an association that retains significance after FDR correction overall as well as in HER2- and HR+HER2- subsets. Within individual arms, high Cyclin D1 predicted non-response in VC, control, and AMG386; and trends toward association in Pembro and N. In addition, high quantitative ER and phospho-androgen receptor (pAR; S650) associate with non-pCR in the population as a whole and in the HR+HER2- subset. For both ER and pAR the strongest association with non-pCR was in the Pembro arm. Candidates for universal sensitivity signals include immune proteins JAK-STAT (pSTAT5 (Y694) and pSTAT1 (Y701)) overall; and pERBB2/pEGFR for HER2+ patients. Conclusions: High levels of Cyclin D1, but not other cell cycle proteins, predict non-response to chemo-/targeted-therapy across arms and subtypes, suggesting that agents specifically targeting Cyclin D1 may increase chemo-sensitivity. ER/phospho-AR as global resistance signals suggest inclusion of anti-AR agents in combination therapy, and the need for new endocrine-based approaches. Citation Format: Julia Wulfkuhle, Denise Wolf, Christina Yau, Lamorna Brown-Swigart, Rosa I Gallagher, Gillian Hirst, Laura Sit, Smita Asare, I-SPY 2 TRIAL Investigators, Nola Hylton, Angela DeMichele, Douglas Yee, Jo Chien, Hope Rugo, John Park, Kathy Albain, Rita Nanda, Debu Tripathy, Richard Schwab, Don Berry, Laura Esserman, Laura van t' Veer, Emanual Petricoin, III. Identification of biomarkers associated with therapeutic resistance: Quantitative protein/phosphoprotein analysis of ~750 patients across 8 arms of the neoadjuvant I-SPY 2 TRIAL for high-risk early stage breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD9-04.

3EZ, 20Ac-ingenol-induced Apoptosis in Chemoresistant Cancers With Cyclin D1 Accumulation.

The topoisomerase 1 catalytic inhibitor 3EZ, 20Ac-ingenol specifically induces apoptosis through the activation of ATR and the up-regulation of PTEN by enhancing the DNA damage response (DDR) in human B lymphoma (BALL-1) cells. The accumulation of cyclin D1 in cancer is known to be related to chemoresistance to DNA damage agents and nuclei of BALL-1 cells exhibit high levels of cyclin D1. However, 3EZ, 20Ac-ingenol effectively induced apoptosis of BALL-1 cells. Cell growth, protein levels, and apoptosis were determined by an MTT assay, immunoblotting and DNA fragmentation assay, respectively. 3EZ, 20Ac-ingenol strongly induced inhibition of cell proliferation and apoptosis in Jeko-1 and Panc-1 cell lines through the activation of tumor suppressor proteins and caspase 3. 3EZ, 20Ac-ingenol-induced apoptosis might occur in cells with cyclin D1 accumulation through enhancing DDR, regardless of the cancer cell type.

Significance of Targeting VEGFR-2 and Cyclin D1 in Luminal-A Breast Cancer.

The hormonal luminal-A is the most pre-dominant sub type of breast cancer (BC), and it is associated with a high level of cyclin D1 in Saudi patients. Tamoxifen is the golden therapy for hormonal BC, but resistance of cancer cells to tamoxifen contributes to the recurrence of BC due to many reasons, including high levels of AIB1 and cyclin D1. Overcoming drug resistance could be achieved by exploring alternative targetable therapeutic pathways and new drugs or combinations. The objective of this study was to determine the differentially enriched pathways in 12 samples of Saudi women diagnosed with luminal-A using the PamChip peptide microarray-based kinase activity profiling, and to compare the activity of HAA2020 and dinaciclib with tamoxifen in singles and combinations in the MCF7 luminal-A cell line. Our results of network and pathway analysis of the 12 samples highlighted the importance of VEGFR and CDKs in promoting luminal-A breast cancer. The activation of VEGF signaling via VEGFR-2 leads to activation of PI3K/AKT kinases and an increase of cell survival, and leads to activation of Hsp90, which induces the phosphorylation of FAK1, resulting in cytoskeleton remodeling. PLC-gamma 1 is also activated, leading to FAK-2 and PKC activation. Notably, the G1/S cell cycle phases and phosphorylation processes contribute to the top seven tumorigenesis processes in the 12 samples. Further, the MTT combination of HAA2020 and dinaciclib showed the best combination index (CI), was more clonogenic against MCF7 cells compared to the other combinations, and it also showed the best selectivity index (SI) in normal MRC5 cells. Interestingly, HAA2020 and dinaciclib showed a synergistic apoptotic and G1 cell cycle effect in MCF7 cells, which was supported by their synergistic CDK2, cyclin D1, and PCNA inhibition activities. Additionally, the combination showed VEGFR-2 and Hsp90 inhibition activities in MCF7 cells. The results show the significance of targeting VEGFR-2 and cyclin D1 in Saudi luminal-A breast cancer patients, and the effect of combining HAA2020 and dinaciclib on those targets in the MCF7 model. It also warrants further preclinical and in vivo investigations for the combination of HAA2020 and dinaciclib as a possible future second-line treatment for luminal-A breast cancers.

MiR-129-5p induces cell cycle arrest through modulating HOXC10/Cyclin D1 to inhibit gastric cancer progression.

MicroRNAs (miRNAs) play important roles in posttranscriptional regulation and may serve as targets for the diagnosis and treatment of cancers. Nevertheless, a comprehensive understanding of miRNAs profiles in gastric cancer progression is still lacking. Here, we report that miR-129-5p is downregulated in gastric cancer by analyzing TCGA database (n=41) and clinical tumor samples (n=60). MiR-129-5p transfection suppressed gastric cancer cell proliferation through inducing G1 phase arrest in vitro and inhibit xenograft tumor growth in vivo. MiR-129-5p directly targeted the 3' untranslated regions (3' UTR) of HOXC10 mRNA and downregulated its expression. Importantly, miR-129-5p could reverse the oncogenic effect induced by HOXC10. We systemically screened the downstream target of HOXC10 by ChIP sequencing, and found that HOXC10 could transcriptionally regulate the expression of Cyclin D1 and facilitate G1/S cell cycle transition. Notably, high levels of HOXC10 and Cyclin D1 were related with poor prognosis of gastric cancer patients (n=90). These findings reveal a novel role of miR-129-5p/HOXC10/Cyclin D1 axis in modulating cell cycle and gastric tumorigenesis, which might provide potential prognostic biomarkers and therapeutic targets for gastric cancer patients.

Enhanced expression of Cyclin D1 and C-myc, a prognostic factor and possible mechanism for recurrence of papillary thyroid carcinoma

A direct association has been shown between Cyclin D1 and C-myc gene expressions and the proliferation of human thyroid tumor cells. Our previous study showed that increased β catenin led to a reduction in disease-free probability in patients with papillary thyroid cancer. This study was designed to investigate Cyclin D1 and C-myc genes as targets for β catenin function in PTC and to determine the association between genes expression and staging, recurrence, metastasis, and disease-free survival of PTC. This study was conducted via a thorough investigation of available data from medical records as well as paraffin blocks of 77 out of 400 patients over a 10-year period. Cyclin D1 and C-myc gene expression levels were measured using real-time polymerase chain reaction (RT-PCR) and the Kaplan-Meier method was used to evaluate disease-free survival. Higher levels of Cyclin D1 and C-myc gene expressions were observed in patients with recurrence by 8.5 (P = 0.004) and 19.5 (p = 0.0001) folds, respectively. A significant positive correlation was found between Cyclin D1 expression and the cumulative dose of radioactive iodine received by patients (r = −0.2, p value = 0.03). The ten-year survival rate in the patients included in this study was 98.25% while disease-free survival was 48.1%. Higher Cyclin D1 and C-myc gene expression levels were observed in patients with recurrence/distant metastasis. Inversely, lower expression of Cyclin D1 and C-myc genes were associated with better survival of patients (SD, 0.142-0.052) (Mantel-Cox test, P = 0.002). The enhancement of Cyclin D1 and C-myc gene expression may be a potential mechanism for recurrence and aggressiveness of PTC.

Development of prediction models for lymph node metastasis in endometrioid endometrial carcinoma

BackgroundIn endometrioid endometrial cancer (EEC), current clinical algorithms do not accurately predict patients with lymph node metastasis (LNM), leading to both under- and over-treatment. We aimed to develop models that integrate protein data with clinical information to identify patients requiring more aggressive surgery, including lymphadenectomy.MethodsProtein expression profiles were generated for 399 patients using reverse-phase protein array. Three generalised linear models were built on proteins and clinical information (model 1), also with magnetic resonance imaging included (model 2), and on proteins only (model 3), using a training set, and tested in independent sets. Gene expression data from the tumours were used for confirmatory testing.ResultsLNM was predicted with area under the curve 0.72–0.89 and cyclin D1; fibronectin and grade were identified as important markers. High levels of fibronectin and cyclin D1 were associated with poor survival (p = 0.018), and with markers of tumour aggressiveness. Upregulation of both FN1 and CCND1 messenger RNA was related to cancer invasion and mesenchymal phenotype.ConclusionsWe demonstrate that data-driven prediction models, adding protein markers to clinical information, have potential to significantly improve preoperative identification of patients with LNM in EEC.

Mouse fibroblast growth factor 9 N143T mutation leads to wide chondrogenic condensation of long bones

Long bones of the appendicular skeleton are formed through endochondral ossification. Endochondral bone formation initiates with mesenchymal condensation, followed by the formation of a cartilage template which is replaced by bone. Fibroblast growth factor 9 (FGF9) regulates bone development. Fgf9-/- mice exhibit disproportionate shortening of proximal skeletal elements. Fgf9 missense mutations in mice and humans induce joint synostosis. Thus, FGF9 is critical for regulating bone length and joint formation. Conversely, mechanisms regulating bone width remain unclear. Here, we showed that the homozygous elbow knee synostosis (Eks) mutant mice harboring N143T mutation in Fgf9 have wide long bones at birth. We investigated the cellular and molecular mechanisms underlying the widened prospective humerus in Fgf9Eks/Eks embryos. Increased and expanded FGF signaling in concert with wider expression domain of Fgf receptor 3 (Fgfr3) during chondrogenic condensation of the humerus led to widened cartilage, which resulted in the formation of wider prospective humeri in neonatal Fgf9Eks/Eks mice. Increased and expanded FGF signaling during chondrogenic condensation led to increased density of chondrocytes of the humeri accompanied by increased proliferation of chondrocytes which express inappropriately higher levels of cyclin D1 in Fgf9Eks/Eks embryos. The results suggest that FGF9 regulates the width of prospective long bones by controlling the width of chondrogenic condensation.

Immunohistochemical evaluation of Ki-67, Cyclin D1 and β-catenin expression in the subtypes of triple negative breast cancer

Aim. To evaluate the expression levels of Ki-67 and cyclin D1 and β-catenin in the subtypes of triple negative breast cancer. Methods. The study was conducted on the surgical material from 60 patients of clinical stage 2A (T1N1M0 or T2N0M0) who were treated at the Rostov Research Institute of Oncology from 2012 to 2015. For immunohistochemistry, antibodies to estrogen and progesterone receptors, cytokeratins 5/6, Ki-67, cyclin D1, β-catenin, HER2/neu and EGFR proteins were used. Results. Triple negative breast cancer with the signs of basal epithelium was found to have a significantly higher expression level of Ki-67 compared to non-basal-like one. In some part of triple negative breast cancer samples overexpression of cyclin D1 was observed. The high level of cyclin D1 in the basal-like subtype was less common than in the subtypes without the signs of basal epithelium, but its average value was significantly higher. In triple negative cancer with cyclin D1 overexpression, the loss of β-catenin on the cell membrane and its abnormal accumulation in the cytoplasm was significantly more frequent. β-catenin translocation into the cell nucleus was observed only in basal-like triple negative cancer, and 2 times more often in case of cyclin D1 overexpression. Conclusion. In triple negative breast cancer tumors with overexpression of cyclin D1 and abnormal expression of β-catenin are observed in some cases; these biomarkers can be considered as potential therapeutic targets for this group of tumors.

Dependency of Cholangiocarcinoma on Cyclin D–Dependent Kinase Activity

Cholangiocarcinoma (CCA) is a bile duct cancer with a very poor prognosis. Currently, there is no effective pharmacological treatment available for it. We showed that CCA ubiquitously relies on cyclin-dependent kinases 4 and 6 (CDK4/6) activity to proliferate. Primary CCA tissues express high levels of cyclin D1 and the specific marker of CDK4/6 activity, phospho-RB Ser780. Treatment of a 15-CCA cell line collection by pharmacological CDK4/6 inhibitors leads to reduced numbers of cells in the S-phase and senescence in most of the CCA cell lines. We found that expression of retinoblastoma protein (pRB) is required for activity of the CDK4/6 inhibitor, and that loss of pRB conferred CDK4/6 inhibitor-drug resistance. We also identified that sensitivity of CCA to CDK4/6 inhibition is associated with the activated KRAS signature. Effectiveness of CDK4/6 inhibition for CCA was confirmed in the three-dimensional spheroid-, xenograft-, and patient-derived xenograft models. Last, we identified a list of genes whose expressions can be used to predict response to the CDK4/6 inhibitor. Conclusion: We investigated a ubiquitous dependency of CCA on CDK4/6 activity and the universal response to CDK4/6 inhibition. We propose that the CDK4/6-pRB pathway is a suitable therapeutic target for CCA treatment.

Ki-67 and Cyclin D1 in subtypes of triple-negative breast cancer with different androgen profiles.

e12552 Background: The purpose of the study was to analyze Ki-67 and Cyclin D1 expression in subtypes of triple negative breast cancer (TNBC) with different androgen profiles. Methods: Tissues of 60 patients with verified TNBC (T1N1M0/T2N0M0, ER-/PR-/Her2-) were studied. Immunohistochemical staining was performed with antibodies to androgen receptors (AR), CK5/6, Ki-67, Cyclin D1, and EGFR. Basal-like (BL) subtype was identified when > 25% cells were CK5/6+ and/or EGFR+ (any staining). Tumors with ≥10% positively stained cells were considered AR+. Parametric statistical methods were used. Significance of the difference between the two means was assessed by the Student's t-test. Results: BL TNBC showed significantly higher Ki-67 expression (81.9±3.1%), compared to other subtypes (70.8±3.1%), p < 0.05. A number of TNBC samples demonstrated Cyclin D1 overexpression ( > 30% stained cells) with no correlation with Ki-67 expression (r = 0.12). High Cyclin D1 levels were less common in BL TNBC (32.4% tumors), compared to other subtypes (43.5% tumors), but its average values were significantly higher (89.9±4.7% vs. 66.5±6.6%, p < 0.05). AR+ tumors were observed in 11 cases (18.3%). Levels of Ki-67 were similar in TNBC with different AR profiles. The percentage of BL tumors was similar in AR+ and AR- cancers (63.6% and 61.3%, respectively). Expression of Cyclin D1 was more frequent in AR+ TNBC (45.5%), vs. 34.7% in АR-. Average levels of Cyclin D1 were significantly higher in AR+ tumors (51.8±13.7%), vs. AR- (31.6±5.1%). Conclusions: TNBC differs in the Cyclin D1 leves; some tumors show its overexpression. Inhibition of cyclin-dependent kinases blocks the cell cycle, which may be useful in the TNBC treatment, which currently has no targets for therapy.

Thyroid Hormone Promotes β-Catenin Activation and Cell Proliferation in Colorectal Cancer.

Thyroid hormone status has long been implicated in cancer development. Here we investigated the role of thyroxine (T4) in colorectal cancer cell lines HCT 116 (APC wild type) and HT-29 (APC mutant), as well as the primary cultures of cancer cells derived from patients. Cell proliferation was evaluated with standard assay and proliferation marker expression. β-Catenin activation was examined according to nuclear β-catenin accumulation and β-catenin target gene expression. The results showed that T4 increased colorectal cancer cell proliferation while cell number and viability were elevated by T4 in both established cell lines and primary cells. Moreover, the transcriptions of proliferative genes PCNA, CCND1, and c-Myc were enhanced by T4 in the primary cells. T4 induced nuclear β-catenin accumulation, as well as high cyclin D1 and c-Myc levels compared to the untreated cells. In addition, the β-catenin-directed transactivation of CCND1 and c-Myc promoters was also upregulated by T4. CTNNB1 transcription was raised by T4 in HCT 116, but not in HT-29, while the boosted β-catenin levels were observed in both. Lastly, the T4-mediated gene expression could be averted by the knockdown of β-catenin. These results suggested that T4 promotes β-catenin activation and cell proliferation in colorectal cancer, indicating that an applicable therapeutic strategy should be considered.

Expression of Cyclin D1 protein in residual tumor after neoadjuvant chemotherapy for breast cancer.

Hormone receptor (HR)-positive breast cancer (BC) shows a poor response to neoadjuvant chemotherapy (NACT). New treatment targets like the Cyclin D1-CDK4/CDK6 complex are promising adjuvant/post-neoadjuvant therapeutic strategies. Evaluating Cyclin D1 overexpression in residual tumor could recognize those patients that benefit most from such post-neoadjuvant treatment. In this study, we determined Cyclin D1 expression in residual BC after NACT. Secondary aims were to correlate Cyclin D1 expression levels with clinicopathological parameters and to assess its prognostic value after NACT. We retrospectively assessed the nuclear expression of Cyclin D1 on tissue microarrays with residual tumor from 284 patients treated in the neoadjuvant GeparTrio (n=186) and GeparQuattro (n=98) trials. Evaluation was performed with a standardized immunoreactive score (IRS) after selecting a cut-off value. A high expression level (IRS≥6) of Cyclin D1 was found in 37.3% of the assessed specimens. An increased Cyclin D1 expression was observed in HR-positive tumors, compared to HR-negative tumors (p=0.02). Low Cyclin D1 levels correlated with clinical tumor stage 1-3 (p=0.03). Among patients with HR-positive/Her2-negative tumors and high Cyclin D1 expression, a better disease-free survival (DFS) was graphically suggested, but not significant (p=0.21). Our study demonstrates a measurable nuclear expression of Cyclin D1 in post-neoadjuvant residual tumor tissue of HR-positive BC. Cyclin D1 expression was not prognostic for DFS after NACT. Our results and defined cut-off suggest that the marker can be used to stratify tumors according to protein expression levels. Based on this, a prospective evaluation is currently performed in the ongoing Penelope-B trial.

Cytoplasmic cyclin D1 controls the migration and invasiveness of mantle lymphoma cells

Mantle cell lymphoma (MCL) is a hematologic neoplasm characterised by the t(11;14)(q13;q32) translocation leading to aberrant cyclin D1 expression. The cell functions of cyclin D1 depend on its partners and/or subcellular distribution, resulting in different oncogenic properties. We observed the accumulation of cyclin D1 in the cytoplasm of a subset of MCL cell lines and primary cells. In primary cells, this cytoplasmic distribution was correlated with a more frequent blastoid phenotype. We performed immunoprecipitation assays and mass spectrometry on enriched cytosolic fractions from two cell lines. The cyclin D1 interactome was found to include several factors involved in adhesion, migration and invasion. We found that the accumulation of cyclin D1 in the cytoplasm was associated with higher levels of migration and invasiveness. We also showed that MCL cells with high cytoplasmic levels of cyclin D1 engrafted more rapidly into the bone marrow, spleen, and brain in immunodeficient mice. Both migration and invasion processes, both in vivo and in vitro, were counteracted by the exportin 1 inhibitor KPT-330, which retains cyclin D1 in the nucleus. Our data reveal a role of cytoplasmic cyclin D1 in the control of MCL cell migration and invasion, and as a true operator of MCL pathogenesis.

CDK4/6 Inhibition in Breast Cancer: Mechanisms of Response and Treatment Failure.

To describe the role of D-type cyclins and CDKs 4 and 6 in breast cancer, and to discuss potential biomarkers for sensitivity or resistance to CDK4/6 inhibitors. A small number of preclinical and clinical studies have explored potential mechanisms of CDK4/6 inhibitor response and resistance in breast cancer. Putative markers of response include ER-positivity, luminal patterns of gene expression, high cyclin D1 levels, and low p16 levels. Possible resistance mechanisms include loss of Rb function, overexpression/amplification of cyclin E, and CDK6 amplification. Most these remain speculative and have not been validated in clinical specimens. If early successes with CDK4/6 inhibitors are to be capitalized upon, it is critical that our understanding of CDK4/6 biology in breast cancer extends beyond its current rudimentary state. Only then we will be able to develop rational therapeutic combinations that further enhance the efficacy of these agents.