Tissue Microarray Analysis of Cyclin D1 Gene Amplification and Gain in Colorectal Carcinomas

CHREBP suppresses gastric cancer progression via the cyclin D1-Rb-E2F1 pathway

Accumulating evidence has demonstrated that carbohydrate response element binding protein (CHREBP) has a crucial function in tumor pathology. In this study, we found CHREBP downregulation in gastric cancer (GC) tissues, and CHREBP was determined to be an independent diagnostic marker of GC. The downregulation of CHREBP promoted cell proliferation and inhibited apoptosis. Moreover, the level of cyclin D1 was significantly correlated with CHREBP expression in GC and paracancerous normal samples. In addition, CHREBP transcriptionally inhibited cyclin D1 expression in GC cells. Tumor suppressor activity of CHREBP could be affected by the upregulation of cyclin D1. In summary, CHREBP was found to be an independent diagnostic marker of GC and to influence GC growth and apoptosis via targeting the cyclin D1-Rb-E2F1 pathway.

Comprehensive Analysis of Cyclin Family Gene Expression in Colon Cancer

Colon cancer is a common malignancy of the digestive tract with high morbidity and mortality. There is an urgent need to identify effective biomarkers for the early diagnosis of colon cancer and to prolong patient survival. Cyclins are a family of proteins that directly participate in the cell cycle and are associated with many types of tumors, but the role and regulatory mechanism of most cyclin family members in colon cancer remain unclear. Here, we provide a systematic and comprehensive study of cyclin family gene expression and their potential roles in colon cancer. Pan-cancer analysis revealed that cyclin genes were most differentially expressed in colon adenocarcinoma. Among the four datasets of colon cancer from The Cancer Genome Atlas and the Gene Expression Omnibus, six cyclin genes (CCNA2, CCNB1, CCND1, CCNE1, CCNF, and CCNJL) were differentially expressed between normal and tumor tissues. Four of them (CCNA2, CCNB1, CCNE1, and CCNF) were notably elevated in the early TNM stages and significantly correlated with overall survival. Meanwhile, the expression of CCNA2 and CCNB1 was positively correlated with tumor-killing immune cells, such as CD8+ T cells.The copy numbers of CCNA2, CCNB1, CCND1, CCNE1, and CCNF was positively related to gene expression. The methylation levels of CCNB1 were lower in tumor tissues than in normal tissues and were negatively correlated with gene expression. The receiver operating characteristic curves indicated that the gene expression of 24 cyclins had higher predictive accuracy than the TNM stage. Pathway analysis showed that cyclin genes were tightly associated with apoptosis, the cell cycle, hormone ER, the RAS/MAPK pathway, mismatch repair, mTORC1 signaling, KRAS signaling, Akt, and TGFB in colon cancer. Weighted gene co-expression network analysis suggested that cyclin genes were closely linked to CDK1, BIRC5, PLK1, and BCL2L12. At the protein level, Cyclin A2 and Cyclin B1 were also expressed higher in colon adenocarcinoma tissues. In addition, cyclin genes were highly related to the drug sensitivity of some FDA-approved drugs, such as MEK and EGFR inhibitors, which might provide guidance for clinical treatment. In conclusion, cyclin genes are promising biomarkers for the diagnosis and prognosis of colon cancer.

PI3K p110α Blockade Enhances Anti-Tumor Efficacy of Abemaciclib in Human Colorectal Cancer Cells

Simple Summary

Colorectal cancer (CRC) is the third most common cancer and the second highest cause of cancer related mortality worldwide. Especially, the survival of advanced CRC patients who were failed to achieve durable remission after the anti-angiogenic and anti-epithelial growth factor receptor agents are still poor. The aim of our study was to investigate the anti-tumor activity of the CDK4/6 inhibitor, abemaciclib, as a single agent and to identify an optimal combination agent with abemaciclib in CRC cell lines. We confirmed that abemaciclib monotherapy showed anti-tumor activity and combination therapy with abemaciclib and BYL719 demonstrated synergistic effects in CRC cell lines. Moreover, our study suggested that PIK3CA mutation could be a predictive marker for efficacy of abemaciclib and BYL719 combination therapy. These findings provide novel insight into a possible therapeutic strategy for patients with relapsed and refractory CRC.

Abstract

Targeting cell cycle regulation in colorectal cancer has not been fully evaluated. We investigated the efficacy of the CDK4/6 inhibitor, abemaciclib, and confirmed a synergistic interaction for PI3K p110α and CDK dual inhibition in colorectal cancer cell lines. Caco-2 and SNU-C4 cell lines were selected to explore the mechanism of action for and resistance to abemaciclib. In vitro and in vivo models were used to validate the anti-tumor activity of abemaciclib monotherapy and BYL719 combination therapy. Abemaciclib monotherapy inhibited cell cycle progression and proliferation in Caco-2 and SNU-C4 cells. CDK2-mediated Rb phosphorylation and AKT phosphorylation appeared to be potential resistance mechanisms to abemaciclib monotherapy. Abemaciclib/BYL719 combination therapy demonstrated synergistic effects regardless of PIK3CA mutation status but showed greater efficacy in the PIK3CA mutated SNU-C4 cell line. Growth inhibition, cell cycle arrest, and migration inhibition were confirmed as mechanisms of action for this combination. In an SNU-C4 mouse xenograft model, abemaciclib/BYL719 combination resulted in tumor growth inhibition and apoptosis with tolerable toxicity. Dual blockade of PI3K p110α and CDK4/6 showed synergistic anti-tumor effects in vivo and in vitro in human colorectal cancer cell lines. This combination could be a promising candidate for the treatment of patients with advanced colorectal cancer.

Cyclin D degradation by E3 ligases in cancer progression and treatment

D cyclins include three isoforms: D1, D2, and D3. D cyclins heterodimerize with cyclin-dependent kinase 4/6 (CDK4/6) to form kinase complexes that can phosphorylate and inactivate Rb. Inactivation of Rb triggers the activation of E2F transcription factors, which in turn regulate the expression of genes whose products drive cell cycle progression. Because D-type cyclins function as mitogenic sensors that link growth factor signaling directly with G₁ phase progression, it is not surprising that D cyclin accumulation is dysregulated in a variety of human tumors. Elevated expression of D cyclins results from gene amplification, increased gene transcription and protein translation, decreased microRNA levels, and inefficiency or loss of ubiquitylation-mediated protein degradation. This review focuses on the clinicopathological importance of D cyclins, how dysregulation of Ubiquitin-Proteasome System (UPS) contributes to the overexpression of D cyclins, and the therapeutic potential through targeting D cyclin-related machinery in human tumors.

Cyclin-dependent kinase inhibitors and the treatment of gastrointestinal cancers

The cell cycle is a highly conserved and tightly regulated biological system that controls cellular proliferation and differentiation. The cell cycle regulatory proteins, which include the cyclins, the cyclin-dependent kinases (CDKs), and the CDK inhibitors, are critical for the proper temporal and spatial regulation of cellular proliferation. Conversely, alterations in cell cycle regulatory proteins, leading to the loss of normal cell-cycle control, are a hallmark of many cancers, including gastrointestinal cancers. Accordingly, overexpression of CDKs and cyclins and by contrast loss of CDK inhibitors, are all linked to gastrointestinal cancers and are often associated with less favorable prognoses and outcomes. Because of the importance that the cell cycle regulatory proteins play in tumorigenesis, currently there is a broad spectrum of cell-cycle inhibitors under development that, as a group, hold promise as effective cancer treatments. In support of this approach to cancer treatment, the growing availability of molecular diagnostics techniques may help in identifying patients who have driving abnormalities in the cell-cycle machinery and are thus more likely to respond to cell-cycle inhibitors. In this review, we discuss the prevalence of cell-cycle abnormalities in patients with gastrointestinal cancers and provide a preclinical and clinical overview of new agents that target cell-cycle abnormalities with a special emphasis on gastrointestinal cancers.

Hath1 inhibits proliferation of colon cancer cells probably through up-regulating expression of Muc2 and p27 and down-regulating expression of cyclin D1

Previous studies showed that Math1 homologous to human Hath1 can cause mouse goblet cells to differentiate. In this context it is important that the majority of colon cancers have few goblet cells. In the present study, the potential role of Hath1 in colon carcinogenesis was investigated. Sections of paraffin-embedded tissues were used to investigate the goblet cell population of normal colon mucosa, mucosa adjacent colon cancer and colon cancer samples from 48 patients. Hath1 and Muc2 expression in these samples were tested by immunohistochemistry, quantitative real-time reverse transcription -PCR and Western blotting. After the recombinant plasmid, pcDNA3.1(+)-Hath1 had been transfected into HT29 colon cancer cells, three clones were selected randomly to test the levels of Hath1 mRNA, Muc2 mRNA, Hath1, Muc2, cyclin D1 and p27 by quantitative real-time reverse transcription-PCR and Western blotting. Moreover, the proliferative ability of HT29 cells introduced with Hath1 was assessed by means of colony formation assay and xenografting. Expression of Hath1, Muc2, cyclin D1 and p27 in the xenograft tumors was also detected by Western blotting. No goblet cells were to be found in colon cancer and levels of Hath1 mRNA and Hath1, Muc2 mRNA and Muc2 were significantly down-regulated. Hath1 could decrease cyclin D1, increase p27 and Muc2 in HT29 cells and inhibit their proliferation. Hath1 may be an anti-oncogene in colon carcinogenesis.

Differential regulation of cyclin D1 expression by protein kinase C α and ϵ signaling in intestinal epithelial cells

Cellular accumulation of cyclin D1, a key regulator of cell proliferation and tumorigenesis, is subject to tight control. Our previous studies have identified PKCα as a negative regulator of cyclin D1 in the intestinal epithelium. However, treatment of non-transformed IEC-18 ileal crypt cells with PKC agonists has a biphasic effect on cyclin D1 expression. Initial PKCα-mediated down-regulation is followed by recovery and subsequent accumulation of the cyclin to levels markedly higher than those seen in untreated cells. Using protein overexpression strategies, siRNA, and pharmacological inhibitors, we now demonstrate that the recovery and hyperinduction of cyclin D1 reflect the combined effects of (a) loss of negative signals from PKCα due to agonist-induced PKCα down-regulation and (b) positive effects of PKCϵ. PKCϵ-mediated up-regulation of cyclin D1 requires sustained ERK stimulation and transcriptional activation of the proximal cyclin D1 (CCDN1) promoter, without apparent involvement of changes in protein stability or translation. PKCϵ also up-regulates cyclin D1 expression in colon cancer cells, through mechanisms that parallel those in IEC-18 cells. Although induction of cyclin D1 by PKCϵ is dependent on non-canonical NF-κB activation, the NF-κB site in the proximal promoter is not required. Instead, cyclin D1 promoter activity is regulated by a novel interaction between NF-κB and factors that associate with the cyclic AMP-response element adjacent to the NF-κB site. The differential effects of PKCα and PKCϵ on cyclin D1 accumulation are likely to contribute to the opposing tumor-suppressive and tumor-promoting activities of these PKC family members in the intestinal epithelium.

Cyclin D as a therapeutic target in cancer

Cyclin D1, and to a lesser extent the other D-type cyclins, is frequently deregulated in cancer and is a biomarker of cancer phenotype and disease progression. The ability of these cyclins to activate the cyclin-dependent kinases (CDKs) CDK4 and CDK6 is the most extensively documented mechanism for their oncogenic actions and provides an attractive therapeutic target. Is this an effective means of targeting the cyclin D oncogenes, and how might the patient subgroups that are most likely to benefit be identified?

Fluorescence in situ hybridization analysis with a tissue microarray: 'FISH and chips' analysis of pathology archives

Practicing pathologists expect major somatic genetic changes in cancers, because the morphological deviations in the cancers they diagnose are so great that the somatic genetic changes to direct these phenotypes of tumors are supposed to be correspondingly tremendous. Several lines of evidence, especially lines generated by high-throughput genomic sequencing and genome-wide analyses of cancer DNAs are verifying their preoccupations. This article reviews a comprehensive morphological approach to pathology archives that consists of fluorescence in situ hybridization with bacterial artificial chromosome (BAC) probes and screening with tissue microarrays to detect structural changes in chromosomes (copy number alterations and rearrangements) in specimens of human solid tumors. The potential of this approach in the attempt to provide individually tailored medical practice, especially in terms of cancer therapy, is discussed.

Nuclear factor-kappa B as a promising target for selenium chemoprevention in rat hepatocarcinogenesis

BACKGROUND AND AIMS

Selenium's molecular mechanism for cancer chemoprevention remains unknown. We aimed to study the gene expression of nuclear factor-kappaB (NF-kappaB), tumor growth factor-alpha (TGF-alpha) and cyclin D1 and the effects of sodium selenite using preventive and therapeutic approaches in chemically-induced hepatocarcinogenesis in rats.

METHODS

Rats were divided randomly into six groups: negative control, positive control (diethyl nitrosamine [DEN] + 2-acetylaminofluorene [2-AAF]), preventive group, preventive control (respective control for preventive group), therapeutic group and therapeutic control (respective control for therapeutic group). The relative gene expression of NF-kappaB, TGF-alpha and cyclin D1 in liver tissues were measured using real-time polymerase chain reaction.

RESULTS

The findings showed that the gene expression of NF-kappaB in the preventive group and its respective control was significantly lower (P < 0.05) when compared with both the negative and positive controls. However, the expression of NF-kappaB in the positive controls and therapeutic group was significantly higher (P < 0.05) when compared with the negative controls. The expression of TGF-alpha and cyclin D1 was insignificant in all groups.

CONCLUSION

The inhibition of the NF-kappaB pathway in the initiation phase of hepatocarcinogenesis could be a promising target for selenium chemoprevention. However, further studies are required.

Amplification of c-myc and cyclin D1 genes in primary and metastatic carcinomas of the liver

The c-myc and cyclin D1 genes are included among the oncogenes the amplifications of which have been detected in cancers of various organs. However, there have been few reports on the amplification of both these genes in primary and metastatic liver carcinomas. In the present study, c-myc and cyclin D1 gene amplification was examined in 76 primary and metastatic liver carcinomas using formalin-fixed paraffin-embedded tissue sections and a differential polymerase chain reaction procedure. c-myc and cyclin D1 gene amplification was detected in 15 (33%) and two (4%) of 46 hepatocellular carcinomas (HCC), one (10%) and 0 (0%) of 10 intrahepatic cholangiocarcinomas (ICC), one (33%) and 0 (0%) of three combined hepatocellular and cholangiocarcinomas (HCC + ICC), and nine (56%) and three (19%) of 16 metastatic lesions to the liver from colorectal adenocarcinoma (MCA), respectively. The incidence of c-myc amplification was significantly higher in MCA than in ICC (P = 0.023), and it tended to be higher in HCC than in ICC. These results indicate that the amplification of the c-myc proto-oncogene is not unusual in HCC and MCA, and its detection may have a useful diagnostic significance in differentiating ICC from MCA or HCC from ICC.

Tissue microarray analysis of EGFR gene amplification and gain in Bulgarian patients with colorectal cancer

Colorectal cancer is one of the most common neoplastic diseases and a leading cause of cancer-related deaths. Overexpression of epidermal growth factor receptor (EGFR) is commonly associated with this cancer. The aim of our study was to determine the frequency of epidermal growth factor receptor gene amplification and gain in a large number of colorectal carcinomas, arranged in a tissue microarray, in order to assess their role in colorectal cancer development. A tissue microarray of 498 patients with colorectal tumors was constructed, and 239 samples for EGFR copy number changes were successfully analyzed by fluorescence in situ hybridization. No amplification of EGFR was detected in our cohort of patients with colorectal tumors, and the EGFR gene was upregulated in only 2 tumors (0.84%). Therefore, the development of colon cancer in patients cannot be explained by copy number changes of the EGFR gene.

Up close and personal: molecular diagnostics in oncology

The almost overwhelming volume of information and new technological developments that has demanded so much of our scientific attention over the last decade will shortly revolutionize clinical diagnostics. Some of these developments are already affecting the working lives of scientists and clinicians alike, but will eventually require a greater understanding and acceptance from a much wider audience. Therefore it is important in our current scientific endeavor and commercial enthusiasm for molecular diagnostics that we maintain some awareness of the significant obstacles that must be overcome if we are to see an appropriate, timely and widespread adoption of molecular diagnostic testing in oncology. This article presents a brief commentary on the current state of the art in molecular diagnostics in oncology and how this relates to a more personalized approach to treatment.