Cyclin D1 expression in gliomas

[Gemistocytic astrocytomas]

Gemistocytic astrocytomas (GA) are a variant of diffuse astrocytomas GII (WHO, 2016). Like all diffuse astrocytomas, GA recur with time, which is often accompanied by malignant degeneretion into the anaplastic astrocytoma GIII or to the secondary glioblastoma GIV. However, the progression-free survival and overall survival in patients with GA is less than in patients with diffuse astrocytomas. Given that this group of patients, according to the WHO classification (2016), is classified as GII, patients with GA usually do not receive comprehensive treatment. We have conducted a thorough analysis of research on this problem for the period from 1956 to 2017. Differences in the histological pattern, immunohistochemical and molecular-genetic profiles, survival of patients with GA and diffuse astrocytomas GII are shown there. A clinical case of a patient with transformation of a diffuse astrocytoma in GA (GIII) and then into a secondary glioblastoma is presented.

Impact of 9p deletion and p16, Cyclin D1, and Myc hyperexpression on the outcome of anaplastic oligodendrogliomas

Objective

To study the presence of 9p deletion and p16, cyclin D1 and Myc expression and their respective diagnostic and prognostic interest in oligodendrogliomas.

Methods

We analyzed a retrospective series of 40 consecutive anaplastic oligodendrogliomas (OIII) from a single institution and compared them to a control series of 10 low grade oligodendrogliomas (OII). Automated FISH analysis of chromosome 9p status and immunohistochemistry for p16, cyclin D1 and Myc was performed for all cases and correlated with clinical and histological data, event free survival (EFS) and overall survival (OS).

Results

Chromosome 9p deletion was observed in 55% of OIII (22/40) but not in OII. Deletion was highly correlated to EFS (median = 29 versus 53 months, p<0.0001) and OS (median = 48 versus 83 months, p<0.0001) in both the total cohort and the OIII population. In 9p non-deleted oligodendrogliomas, p16 hyperexpression correlated with a shorter OS (p = 0.02 in OII and p = 0.0001 in OIII) whereas lack of p16 expression was correlated to a shorter EFS and OS in 9p deleted OIII (p = 0.001 and p = 0.0002 respectively). Expression of Cyclin D1 was significantly higher in OIII (median expression 45% versus 14% for OII, p = 0.0006) and was correlated with MIB-1 expression (p<0.0001), vascular proliferation (p = 0.002), tumor necrosis (p = 0.04) and a shorter EFS in the total cohort (p = 0.05). Hyperexpression of Myc was correlated to grade (median expression 27% in OII versus 35% in OIII, p = 0.03), and to a shorter EFS in 9p non-deleted OIII (p = 0.01).

Conclusion

Chromosome 9p deletion identifies a subset of OIII with significantly worse prognosis. The combination of 9p status and p16 expression level identifies two distinct OIII populations with divergent prognosis. Hyperexpression of Bcl1 and Myc appears highly linked to anaplasia but the prognostic value is unclear and should be investigated further.

The novel agent phospho-glycerol-ibuprofen-amide (MDC-330) inhibits glioblastoma growth in mice: an effect mediated by cyclin D1

Given that glioblastoma multiforme (GBM) is associated with poor prognosis, new agents are urgently needed. We developed phospho-glycerol-ibuprofen-amide (PGIA), a novel ibuprofen derivative, and evaluated its safety and efficacy in preclinical models of GBM, and its mechanism of action using human GBM cells and animal tumor models. Furthermore, we explored whether formulating PGIA in polymeric nanoparticles could enhance its levels in the brain. PGIA was 3.7- to 5.1-fold more potent than ibuprofen in suppressing the growth of human GBM cell lines. PGIA 0.75× IC50 inhibited cell proliferation by 91 and 87% in human LN-229 and U87-MG GBM cells, respectively, and induced strong G1/S arrest.In vivo, compared with control, PGIA reduced U118-MG and U87-MG xenograft growth by 77 and 56%, respectively (P< 0.05), and was >2-fold more efficacious than ibuprofen. Normal human astrocytes were resistant to PGIA, indicating selectivity. Mechanistically, PGIA reduced cyclin D1 levels in a time- and concentration-dependent manner in GBM cells and in xenografts. PGIA induced cyclin D1 degradation via the proteasome pathway and induced dephosphorylation of GSK3β, which was required for cyclin D1 turnover. Furthermore, cyclin D1 overexpression rescued GBM cells from the cell growth inhibition by PGIA. Moreover, the formulation of PGIA in poly-(L)-lactic acid poly(ethylene glycol) polymeric nanoparticles improved its pharmacokinetics in mice, delivering PGIA to the brain. PGIA displays strong efficacy against GBM, crosses the blood-brain barrier when properly formulated, reaching the target tissue, and establishes cyclin D1 as an important molecular target. Thus, PGIA merits further evaluation as a potential therapeutic option for GBM.

The role of NF-κB in the pathogenesis of glioma

Activation of NF-κB affects multiple aspects of cancer biology including cell survival and resistance to treatment. Glioblastoma (GBM) is the most common primary malignant tumor of the brain in adults and is resistant to treatment. Recent studies have reported that NF-κB activation in GBM is widespread and have elucidated the underlying regulatory mechanisms. EGFR gene amplification and mutation are among the key genetic alterations in GBM, and aberrant EGFR signaling is a key activator of NF-κB in GBM. In this review we discuss the evidence for activation of NF-κB in GBM and the key signaling pathways involved. Substantial evidence suggests a role for NF-κB in the pathogenesis of GBM and its resistance to treatment, indicating that NF-κB pathways may be useful targets for treatment.

Characterization of fenofibrate-mediated anti-proliferative pro-apoptotic effects on high-grade gliomas and anti-invasive effects on glioma stem cells

Glioblastoma is the most common, and at the same time, most aggressive type of high-grade glioma (HGG). The prognosis of glioblastoma patients treated with standard therapy including surgery, temozolomide and radiation therapy remains poor. Peroxisome proliferator-activated receptor-α (PPARα) agonists are in widespread clinical use for the treatment of hyperlipidemia. Recent evidence has suggested a potential role in various cancers including glioblastoma. In this study, we characterized the effects of PPARα agonist, fenofibrate, directly on HGG cells and glioma stem cells (GSC). Fenofibrate exhibited dose-dependent p53-independent anti-proliferative effects on HGG starting at 25 μM and pro-apoptotic effects starting at 50 μM, suggesting that the anti-proliferative actions are present only at 25 μM. PPARα was expressed in all HGG cell lines. Inhibition of PPARα with specific inhibitor GW6471 did not affect either proliferation or apoptosis suggesting that these are PPARα-independent effects. Fenofibrate treatment of HGG cells robustly diminished the expression of key signaling pathways, including NF-κB and cyclin D1. Phosphorylation of Akt was also diminished, with no change in total Akt. Effects on apoptotic signaling molecules, Bax and Bcl-xL, had a trend towards pro-apoptotic effects. With respect to GSC, fenofibrate treatment at 25 μM significantly decreased invasion in association with a decrease in CD133 and Oct4 expression. Overall, results support consideration of fenofibrate as an anti-glioma agent and establish its potential as an adjunct treatment strategy for HGG. Translation to the clinical setting could be rapid given its current use as a clinical agent and its low toxicity profile.

Cryptotanshinone inhibits human glioma cell proliferation by suppressing STAT3 signaling

Malignant gliomas (MGs) are among the most aggressive types of cancers in the human brain. Frequent tumor recurrence caused by a lack of effective therapeutic approaches results in a poor prognosis. Signal transducer and activator of transcription 3 (STAT3), an oncogenic protein, is constitutively activated in MGs and predicts a poor clinical outcome. STAT3 therefore is considered to be a promising target for the treatment of MGs. Cryptotanshinone (CTS), the main bioactive compound from the root of Salvia miltiorrhiza Bunge, has been reported to have various pharmacological effects. However, little is known about its function in MG cells. In this study, we evaluated the effect of CTS on the proliferation of human glioma cell lines (T98G and U87). Our results revealed that CTS significantly suppresses glioma cell proliferation. The phosphorylation of STAT3 Tyr705, but not Ser727, was inhibited by CTS, and STAT3 nuclear translocation was attenuated. Overexpression of constitutively active mutant STAT3C reversed the inhibitory effect of CTS, while knockdown STAT3 showed a similar inhibitory effect as CTS treatment. Following the downregulation of STAT3-regulated proteins cyclinD1 and survivin, cell cycle progression significantly arrested in G1/G0 phase. These results indicate that CTS may be a potential antiproliferation agent for the treatment of MGs and that its mechanism may be related to the inhibition of STAT3 signaling.

Progesterone receptor and SRC-1 participate in the regulation of VEGF, EGFR and Cyclin D1 expression in human astrocytoma cell lines

Astrocytomas are the most common primary brain tumors in humans. It has been reported that vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR), cyclin D1 and progesterone receptor (PR) expression levels are elevated in patients with high-grade astrocytomas. Progesterone (P) regulates astrocytomas growth through its interaction with PR, which recruits coregulatory proteins such as steroid receptor coactivator-1 (SRC-1) that are required for efficient transcriptional activation. The regulation of VEGF, EGFR and cyclin D1 expression by P in human astrocytoma cells is not known. We studied the role of PR and SRC-1 in the expression of VEGF, EGFR and cyclin D1 mediated by P in human astrocytoma cell lines grade III (U373) and IV (D54). P significantly increased VEGF and EGFR mRNA expression after 12h of treatment in D54 cells that was reflected at protein level 24h after treatment. This effect was blocked by the PR antagonist, RU 486. In U373 cells cyclin D1 mRNA and protein expression was induced by P after 6 and 8h of treatment, respectively, and this effect was blocked with RU 486. Transfection with short hairpin RNA targeting coactivator SRC-1 significantly reduced VEGF expression after 24h of treatment. Collectively, our results indicate that P regulates VEGF and EGFR expression in D54 cells and cyclin D1 expression in U373 through PR, and that SRC-1 participates in the regulation of VEGF expression.

Increased signal transducer and activator of transcription 3 (STAT3) and decreased cyclin D1 in recurrent astrocytic tumours compared with paired primary astrocytic tumours

This study compared the levels of signal transducer and activator of transcription 3 (STAT3) and cyclin D1 protein in paired primary and recurrent astrocytic tumours, and analysed their correlation with clinicopathological and treatment factors. A total of 48 samples from 24 patients who had undergone surgical removal of primary and recurrent astrocytic tumours were analysed. Levels of STAT3 and cyclin D1 protein were detected using immunohistochemistry. Increased STAT3 and decreased cyclin D1 levels were observed in recurrent astrocytic tumours compared with their paired primary tumours. There was a significant correlation between higher levels of STAT3 protein and shorter progression-free survival in primary tumours after surgery (r = 0.417), and a significant correlation between decreased cyclin D1 protein levels and radiotherapy in recurrent tumours (r = 0.468). It was concluded that increased STAT3 and decreased cyclin D1 protein levels may contribute to the recurrence of astrocytic tumours. Detection of STAT3 may be useful in predicting progressionfree survival in primary astrocytic tumours after surgery. In addition, radiotherapy may decrease cyclin D1 levels in astrocytic tumours, but the nature of this association requires further investigation.

In vitro activities of novel 4-HPR derivatives on a panel of rhabdoid and other tumor cell lines

BACKGROUND

Rhabdoid tumors (RTs) are aggressive pediatric malignancies with poor prognosis. N-(4-hydroxy phenyl) retinamide (4-HPR or fenretinide) is a potential chemotherapeutic for RTs with activity correlated to its ability to down-modulate Cyclin D1. Previously, we synthesized novel halogen-substituted and peptidomimetic-derivatives of 4-HPR that retained activity in MON RT cells. Here we analyzed the effect of 4-HPR in inhibiting the growth of several RT, glioma, and breast cancer cell lines and tested their effect on cell cycle, apoptosis and Cyclin D1 expression.

METHODS

Effect of compounds on RT cell cycle profiles, and cell death were assessed by MTS cell survival assays and FACS analysis. The effects of treatment on Cyclin D1 expression were determined by immunoblotting. The efficacy of these compounds on glioma and breast cancer cell lines was also determined using MTS assays.

RESULTS

Low micromolar concentrations of 4-HPR derivatives inhibited cell survival of all RT cells tested. The 4-HPR derivatives altered RT cell cycle profiles and induced high levels of cell death that was correlated with their potency. ATRA exhibited high IC50 values in all cell lines tested and did not cause cell death. In MON RT cells, the iodo-substituted compounds were more active than 4-HPR in inducing cell cycle arrest and apoptosis. Additionally, the activity of the compounds correlated with their ability to down-modulate Cyclin D1: while active compounds reduced Cyclin D1 levels, inactive ATRA did not. In glioma and breast cancer cell lines, 4-HPR and 4-HPR derivatives showed variable efficacy.

CONCLUSIONS

Here we demonstrate, for the first time, that the inhibitory activities of novel halogen-substituted and peptidomimetic derivatives of 4-HPR are correlated to their ability to induce cell death and down-modulate Cyclin D1. These 4-HPR derivatives showed varied potencies in breast cancer and glioma cell lines. These data indicate that further studies are warranted on these derivatives of 4-HPR due to their low IC50s in RT cells. These derivatives are of general interest, as conjugation of halogen radioisotopes such as 18F, 124I, or 131I to 4-HPR will allow us to combine chemotherapy and radiotherapy with a single drug, and to perform PET/SPECT imaging studies in the future.

Knockdown of cyclin D1 inhibits proliferation, induces apoptosis, and attenuates the invasive capacity of human glioblastoma cells

Elevated cyclin D1 (CCND1) in human glioblastoma correlates with poor clinical prognosis. In this study, the human glioblastoma cell lines SHG-44 and U251 were stably transfected with short hairpin RNA (shRNA) targeting cyclin D1 or with ectogenic cyclin D1 by lentivirus-mediated transfection. Glioblastoma cells overexpressing or underexpressing cyclin D1 were then examined by in vitro growth assays, apoptosis assays, cell cycle analysis, and invasion assays. Cyclin D1 knockdown in SHG-44 cells inhibited cell proliferation, induced apoptosis, and attenuated migration across Matrigel, a model of invasive capacity. Western blot analysis and quantitative reverse-transcription polymerase chain reaction (RT-PCR) revealed that cells underexpressing CCND1 exhibited decreased multidrug resistance protein 1 (MDR1) and B-cell lymphoma-2 (Bcl-2) expression, but enhanced apoptosis effector caspase-3 expression. In contrast, cyclin D1 overexpression promoted cell proliferation, attenuated apoptosis, and enhanced invasive capacity. Furthermore, cyclin D1 overexpression was associated with increased expression of MDR1 and Bcl-2, and decreased caspase-3 expression. Results using the U251 cell line confirmed the effects of CCND1-targeted shRNA and lentivirus-mediated overexpression on proliferation and apoptosis of glioblastoma cells. Overexpression of cyclin D1 enhanced the proliferation and invasive potential of human glioblastoma cells, while reducing apoptosis. The ability to suppress the malignant phenotype by downregulating cyclin D1 expression may provide a new gene therapy approach for patients with malignant glioma.

Connexin43 inhibits the oncogenic activity of c-Src in C6 glioma cells

One of the characteristics of gliomas is a decrease in the expression of connexin43, a protein that forms gap junctions. Restoring connexin43 expression in glioma cells reduces their exacerbated rate of cell growth, although it is not yet known how connexin43 modifies the expression of genes involved in cell proliferation. Here, we show that restoring connexin43 to C6 glioma cells impedes their progression from G0/G1 to the S phase of the cell cycle by reducing retinoblastoma phosphorylation and cyclin E expression through the upregulation of p21 and p27. Interestingly, connexin43 diminishes the oncogenic activity of c-Src exhibited by glioma cells. By studying a Tyr247 and Tyr265 mutant connexin43, we show that these residues are required for connexin43 to inhibit c-Src activity and cell proliferation. In conclusion, by acting as a substrate of c-Src, connexin43 reduces its oncogenic activity and decreases the rate of glioma cell proliferation, potentially an early step in the antiproliferative effects of connexin43. Although c-Src is known to phosphorylate connexin43, this study provides the first evidence that connexin43 can also inhibit c-Src activity.

Eukaryotic initiation factors (eIF) 2alpha and 4E expression, localization, and phosphorylation in brain tumors

Increased protein synthesis is regulated, in part, by two eukaryotic translation initiation factors (eIFs): eIF4E and eIF2alpha. One or both of these factors are often overexpressed in several types of cancer cells; however, no data are available at present regarding eIF4E and eIF2alpha levels in brain tumors. In this study, we analyzed the expression, subcellular localization and phosphorylation states of eIF4E and eIF2alpha in 64 brain tumors (26 meningiomas, 16 oligodendroglial tumors, and 22 astrocytomas) and investigated the correlation with the expression of MIB-1, p53, and cyclin D1 proteins as well. There are significant differences in the phosphorylated eIF4E levels between the tumors studied, being the highest in meningiomas and the lowest in the oligodendroglial tumors. Relative to subcellular localization, eIF4E is frequently found in the nucleus of the oligodendroglial tumors and rarely in the same compartment of the meningiomas, whereas eIF2alpha showed an inverse pattern. Finally, cyclin D1 levels directly correlate with the phosphorylation status of both factors. The different expression, phosphorylation, or/and subcellular distribution of eIF2alpha and eIF4E within the brain types of tumors studied could indicate that different pathways are activated for promoting cell cycle proliferation, for instance, leading to increased cyclin D1 expression.

Cloning and morphological properties of Nicgl;CYCD3;1 gene in genetic tumors from interspecific hybrid of N. langsdorffii and N. glauca

Plant genetic tumors represent neoplastic growths, which arise spontaneously in hybrid plants without apparent external induction. To understand the molecular nature of unregulated cell proliferation, a cyclin D cDNA clone encoding a cyclin D of 1104bp was isolated from a genetic tumor and designated Nicgl;CYCD3;1 gene. DNA gel blot analysis suggested that there are two copies of Nicgl;CYCD3;1 in the genetic tumors. Northern analysis showed that this gene had the highest expression level in genetic tumor compared to Nicotiana glauca, N. langsdorffii and hybrid plants. Plant morphology of hybrid plant was an intermediate between N. glauca and N. langsdorffii and was altered in the genetic tumors. The cell cycle distribution in N. glauca was G0/G1, 90.59; S, 0.60; G2/M, 8.81; in N. langsdorffii it was G 0/G1, 86.22; S, 6.90; G2/M, 6.88; in hybrid plants it was G 0/G1, 96.40; S, 1.79; G2/M, 1.81; and in genetic tumors G 0/G1, 74.70; S, 2.35; G2/M, 22.94. These data provide new insights into the molecular mechanisms underlying genetic tumor formation from interspecific hybrid between N. langsdorffii and N. glauca.

The effect of cyclin D expression on cell proliferation in human gliomas

The expression of three cyclin D subtypes was defined immunohistochemically with cyclin D1, D2 and D3 monoclonal antibodies in 52 human glioma biopsies and eight control samples of normal brain tissue. PCNA labeling indices (LI) were used to evaluate proliferation in the glioma biopsies. LI of cyclin D1, D2 and D3 were compared with histological grade and the proliferating cell nuclear antigen (PCNA) LI. Cyclin D1 expression only was observed in normal brain tissue, but marked overexpression of cyclin D1 and cyclin D3 was observed in glioma. Cyclin D1 LI increased with malignancy, in parallel with an increase in PCNA LI. Lower expression of cyclin D2 was found in a small fraction of the gliomas, but its LI did not vary significantly with grade. Cyclin D3 was mainly expressed by malignant gliomas and was rarely observed in low-grade glioma. Cyclin D2 and D3 expression correlated with PCNA LI, but not as strongly as for cyclin D1. Expression of cyclin D1 is closely related to both the oncogenesis and progression of glioma, while cyclin D3 is associated with transformation to a malignant phenotype. Cyclin D2 is weakly expressed and shows no marked relationship with any aspect of tumorigenesis. The exact contribution of cyclin D subtypes to cell cycle progression in neoplastic and reactive cells remains to be defined.

Gemistocytic astrocytomas: histomorphology, proliferative potential and genetic alterations – a study of 32 cases

Gemistocytic astrocytomas (GAs) are a distinct variant of astrocytomas, generally classified as WHO grade II, and are associated with an aggressive biological behavior. This study was undertaken to determine the histomorphological spectrum, and correlate these with their proliferative potential and genetic alterations, in order to establish a biological basis for their unfavorable prognosis.A total of 32 GAs diagnosed during an 11-year period (1993-2003) were included in the study. Immunoreactivity for CD3 (T-cells), CD20 (B-cells) and CD68 (macrophages) were evaluated to characterize the perivascular inflammatory infiltrates, while p53, epidermal growth factor receptor (EGFR), cyclin D1 and p27-immunolabeling were studied to analyze the tumor biology.Overall, the mean gemistocytic index in the study was 39.6% (range, 12.2-80.8%), with multinucleation in gemistocytes and mitosis being present in 56.2% and 15.6% respectively. Perivascular mononuclear cell cuffing was seen in 56.2% cases, which was immunopositive for CD3 and CD68 in 14 cases each, with 13 cases being immunopositive for both. Similar type of inflammatory infiltrates was also present within the tumor parenchyma. Proliferation index depicted by MIB-1 LI was low (mean: 3.7%; range: 0.5-10.5%), with 70% cases having LI of <5%. MIB-1 labeling was restricted to the small astrocytic cells, similar to p27 and cyclin D1 immunoreactivity, both of which were present in 71.5% cases. In contrast, p53 protein expression was present in 75% cases, and was strongly positive in both gemistocytes and small cells, denoting neoplastic population. However, EGFR protein expression was consistently negative in all cases. Gemistocytes lack proliferative activity possibly indicating terminal differentiation, while small cells are the proliferating cells and their overall percentage may reflect the biological aggressiveness of these tumors and help to identify GAs of higher grade undergoing malignant progression. Therefore it appears that GAs should not be uniformly graded as grade II but should be subdivided into grades II and III neoplasms based on histological features and MIB-1 LI. The poor prognosis in GAs could be attributed both to the high frequency of p53 mutations and low p27 LI.

Amplification and expression of cyclin D genes (CCND1, CCND2 and CCND3) in human malignant gliomas

Malignant gliomas frequently show genetic aberrations of genes coding for cell cycle regulatory proteins involved in the control of G1/S phase transition. These include mutation and/or deletion of the retinoblastoma (RB1) gene, homozygous deletion of the CDKN2A and CDKN2B genes, as well as amplification and overexpression of the CDK4 and CDK6 genes. The D-type cyclins (cyclin D1, D2, and D3) promote cell cycle progression from G1 to S phase by binding to and activating the cyclin dependent kinases Cdk4 and Cdk6. Here, we have investigated a series of 110 primary malignant gliomas and 8 glioma cell lines for amplification and expression of the D-type cyclin genes CCND1 (11q13), CCND2 (12p13), and CCND3 (6p21). We found the CCND1 gene amplified and overexpressed in one anaplastic astrocytoma of our tumor series. Two glioblastomas and one anaplastic astrocytoma showed CCND2 gene amplification, but lacked significant overexpression of CCND2 transcripts. Amplification and overexpression of the CCND3 gene was detected in the glioblastoma cell line CCF-STTG1, as well as in one primary glioblastoma and in the sarcomatous component of one gliosarcoma. Our data thus suggest that amplification and increased expression of CCND1 and CCND3 contribute to the loss of cell cycle control in a small fraction of human malignant gliomas.

p27Kip1 and cyclin D1 are necessary for focal adhesion kinase regulation of cell cycle progression in glioblastoma cells propagated in vitro and in vivo in the scid mouse brain

We have reported previously that the expression of focal adhesion kinase (FAK) is elevated in glioblastomas and that expression of FAK promotes the proliferation of glioblastoma cells propagated in either soft agar or in the C.B.17 severe combined immunodeficiency (scid) mouse brain. We therefore determined the effect of FAK on cell cycle progression in these cells. We found that overexpression of wild-type FAK promoted exit from G(1) in monolayer cultures of glioblastoma cells, enhanced the expression of cyclins D1 and E while reducing the expression of p27(Kip1) and p21(Waf1), and enhanced the kinase activity of the cyclin D1-cyclin-dependent kinase-4 (cdk4) complex. Transfection of the monolayers with a FAK molecule in which the autophosphorylation site is mutated (FAK397F) inhibited exit from G(1) and reduced the expression of cyclins D1 and E while enhancing the expression of p27(Kip1) and p21(Waf1). Small interfering RNA (siRNA)-mediated down-regulation of cyclin D1 inhibited the enhancement of cell cycle progression observed on expression of wild-type FAK, whereas siRNA-mediated down-regulation of cyclin E had no effect. siRNA-mediated down-regulation of p27(Kip1) overcame the inhibition of cell cycle progression observed on expression of FAK397F, whereas down-regulation of p21(Waf1) had no effect. These results were confirmed in vivo in the scid mouse brain xenograft model in which propagation of glioblastoma cells expressing FAK397F resulted in a 50% inhibition of tumor growth and inhibited exit from G(1). Taken together, our results indicate that FAK promotes proliferation of glioblastoma cells by enhancing exit from G(1) through a mechanism that involves cyclin D1 and p27(Kip1).

Expression of cyclins, cyclin-dependent kinases and cyclin-dependent kinase inhibitors in oligodendrogliomas in humans

Cyclins are regulatory proteins of the cell cycle which bind and activate kinases. In gliomas, contrary to many malignancies, cyclin D1 is rarely amplified, but together with other cyclins, it increases with anaplasia. In a series of 23 surgical biopsies of grade II and III oligodendroglioma, cyclin D1, E, A, B1, CDK4-6, CDK2, Cdc2 and p27/Kip.1 have been studied by immunohistochemistry and Western blot. Cyclin D1 and A increased with anaplasia, showing a linear correlation with MIB.1 labeling index and an inverse correlation with p27/Kip.1 expression. Cyclin E and B1 and kinases were almost only expressed in grade III tumors. Normal oligodendrocytes and microglia cells of the cortex and white matter showed a clear positivity for cyclin D1, but not for other cyclins or kinases.

Features of proliferation and in vitro drug resistance in central primitive neuro-ectodermal tumours

The features of proliferation in brain tumours are related with clinical prognosis for several types of brain tumours, especially gliomas. For childhood central primitive neuro-ectodermal tumours (cPNET), including medulloblastoma, this relation has previously been unclear. The aim of this study is to investigate the relationship between proliferative features of cPNET and in vitro resistance for cytostatic drugs measured with the 3-4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium-bromide (MTT) assay. Tumour material was obtained from 23 surgical specimens of cPNET. The expression of the proliferation markers Ki-67, proliferating cell nuclear antigen (PCNA) and cyclin D1 was determined with immunohistochemistry, while S-phase and DNA ploidy were analysed by flowcytometric analysis cell scan (FACS). The in vitro resistance for 10 cytostatic drugs was determined with the MTT assay. Drug resistance levels were available in 19 (83%) of the 23 samples with a complete profile of 10 cytostatic drugs tested in 14 samples. An excellent correlation in drug resistance scores was found between pharmacologically related drugs. The Ki-67 staining in 20 samples varied from 10 to 60% and from 30 to 100% for PCNA. Cyclin D1 staining was negative in 11 out of 18 samples. The S-phase in 16 samples ranged from 2 to 16%. Increased staining of Ki-67 was related with actinomycin D sensitivity (r -.603; P=0.022), while cells with a higher S-phase percentage were more resistant to ifosfamide (r.952; P<0.0001). In vitro drug resistance testing of central primitive neuro-ectodermal tumours (PNET) is feasible with the MTT assay. Ifosfamide resistance was related with increased Ki-67 and S-phase percentage of the tumour cells, while increased Ki-67 was also related with actinomycin D sensitivity. These findings suggest a cell cycle dependent activity of cytostatic drugs in vitro.

Human papillomavirus infection and cyclin D1 gene amplification in laryngeal squamous cell carcinoma: biologic function and clinical significance

BACKGROUND

Human papillomavirus (HPV) infection is suspected to be a risk factor for head and neck, and in particular for laryngeal, carcinogenesis. Cyclin D1 gene (CCND1) overexpression and amplification have been shown to play a role as prognostic factors in many human cancers, among which are head and neck cancers.

METHODS

A literature review of the role in head and neck cancers of HPV infection and CCND1 overexpression and amplification was undertaken. We have evaluated the extent of the current knowledge in this field under the light of recent acquisitions, in particular, about a correlation between HPV infection, a suspected risk factor, and CCND1 amplification, a frequent mutation (about 20% of laryngeal cancers) and a prognostic factor in laryngeal SCC.

RESULTS AND DISCUSSION

The significant correlation between HPV infection and CCND1 amplification supports the hypothesis of the involvement of HPV infection in laryngeal carcinogenesis and suggests that HPV positive laryngeal cancers may constitute a different subset of tumors with a peculiar molecular pattern and thus with a different clinical behavior. HPV infection may be considered a synergistic risk factor with smoking and/or alcohol consumption to be investigated in heavy smokers and drinkers, thus contributing to the identification of patient at high-risk for the development of laryngeal cancer who should undergo strict follow-up and primary and secondary prevention.

Cyclin D1 expression in normal oligodendroglia and microglia cells: its use in the differential diagnosis of oligodendrogliomas

Cyclin D1 regulates G1-S progression. In many carcinomas it is overexpressed and it might even correlate with prognosis. However, the amplification of CCND1 contributes to the loss of cell cycle control only in a small fraction of malignant gliomas. Cyclin D1 can be immunohistochemically demonstrated by DCS-6 mAb. In astrocytic gliomas the fraction of tumor cells with positive nuclei is almost null in well differentiated tumors and increases with the increase of proliferation rate that occurs in anaplasia. The correct evaluation of this fraction is hindered by the positive staining of normal oligodendrocytes and microglia cells. The cyclin D1-positive staining of normal oligodendrocytes and microglia cells has been studied in a series of 20 oligodendrogliomas, five diffuse astrocytomas and five oligoastrocytomas and in 10 samples of normal cortex and white matter, using cyclin D1 DCS-6 mAb, Feulgen reaction and CR3.43 mAb for microglia cells. As well as microglial nuclei, the nuclei of normal oligodendrocytes of the cortex and white matter, including peri-neuronal satellites and pericapillary cells, were immunostained by DCS-6 mAb. In infiltrative areas of oligodendrogliomas, normal, cyclin D1-positive oligodendrocytes and cyclin D1-negative tumor cells coexisted. In anaplastic oligodendrogliomas, cycling tumor oligodendrocytes may regain the capacity to express cyclin D1, which is thus positive in some tumor cells. The occurrence of positive oligodendrocytes in the peripheral parts of tumors can be useful in distinguishing astrocytomas from oligoastrocytomas.

Overexpression of cyclin A and cyclin B1 proteins in astrocytomas

BACKGROUND

Cyclins are proteins that are expressed during the progression of a normal cell through the cell cycle. In a number of cancers, overexpression of cyclin A and cyclin B1 proteins has been reported, and in some instances the levels of expression correlated well with the grades of malignancy. The expression of cyclin A and cyclin B1 proteins in astrocytoma may be linked to the histologic grade or proliferative activities.

OBJECTIVE

To study the expression of cyclin A and cyclin B1 proteins in astrocytomas and correlate the labeling indices (LIs) of cyclin A and cyclin B1 with histologic grade and Ki-67 LI.

DESIGN

The surgical biopsy specimens from 65 adults with astrocytomas were reviewed and divided into grades based on the World Health Organization system. The paraffin sections were immunostained using primary antibodies against Ki-67, cyclin A, and cyclin B1. The LIs of these astrocytomas for the 3 different antibodies were determined by computerized image analysis.

RESULTS

The cyclin A LI showed good correlation with astrocytoma grade and Ki-67 LI. Both the nuclear and cytoplasmic cyclin B LIs correlated well with the tumor grade but showed poor correlation with Ki-67 LI.

CONCLUSIONS

This study suggests that although both cyclin A and B protein expression are related to the grade of malignancy in astrocytomas, cyclin A levels more generally reflect the proliferative state of these tumors. We also provide indirect evidence that cyclin B1 is associated with the aberrant progression through the G2-M phase checkpoint in astrocytomas.

Over-expression of cyclin D1 induces glioma invasion by increasing matrix metalloproteinase activity and cell motility

In order to define the role of cyclin D1 in the progression of malignant glioma, cells over-expressing cyclin D1 were constructed (a-1 cells). They exhibited significantly increased invasiveness as compared with mock-transfected cells. Since cellular invasion is thought to depend on extracellular-matrix degradation, we determined whether cyclin-D1 expression modifies the activity of matrix metalloproteinases (MMPs). Increased gelatinolytic activity of latent type MMP-2 (proMMP-2) and active MMP-2 was observed in a-1 cells. Moreover, cyclin-D1 expression was associated with increased activation of proMMP-9 through MMP-3. Wound assays showed an increase of cell motility in a-1 cells. Cyclin-D1 expression was found to be associated with up-regulation of Rac1, which modulates the formation of ruffling membranes and cell motility. Our results show that cyclin D1 may modulate invasive ability by increasing MMP activity and cell motility, and suggests a novel function of cyclin D1 in the progression of malignant gliomas.

Cyclin D1 expression in astrocytomas is associated with cell proliferation activity and patient prognosis

An important positive regulator of the cell cycle, cyclin D1, is often amplified and overexpressed in malignancies. Cyclin D1 aberrations were analysed in grade II-IV astrocytomas by fluorescence in situ hybridization (FISH), mRNA in situ hybridization and immunohistochemistry. Proliferation activity was determined by Ki-67(MIB-1) immunolabelling and mitotic counting. High cyclin D1 expression was observed in grade IV astrocytomas (grades II-III versus grade IV; mRNA expression: p<0.001; immunoexpression: p=0.013), and correlated with poor patient survival (p<0.001, n=46). Upregulated cyclin D1 expression was also closely associated with poor patient prognosis in grade II-III astrocytomas (p<0.001, n=30). Cyclin D1 gene was not found to be amplified (n=7). Cell proliferation activity was significantly increased in tumours exhibiting high cyclin D1 mRNA levels (Ki-67(MIB-1): p<0.001; mitotic count: p<0.001) and high cyclin D1 protein expression (Ki-67(MIB-1): p=0.002; mitotic count: p=0.012). These results indicate that increased production of cyclin D1 is closely associated with high cell proliferation activity and aggressive behaviour in diffusely infiltrating astrocytomas.

Frequent alterations of cell-cycle regulators in astrocytic tumors as detected by molecular genetic and immunohistochemical analyses

Alterations of CDKN2A, RB, and cyclin D1 genes and expression of their products in astrocytic tumors were studied using a combination of molecular genetic and immunohistochemical assays. In addition, the association of gene status with clinical outcome was evaluated. Alterations of CDKN2A and RB gene in 30 lesions were analyzed by single-strand conformation polymorphism of polymerase chain reaction (PCR-SSCP), direct sequencing, and Western blotting. Methylation of the CDKN2A promoter was detected by methylation-specific PCR. Immunohistochemistry was applied to determine the expression of gene products in tumors from 94 patients for whom clinical outcome was also evaluated. Analyses of the CDKN2A gene revealed 12 homozygous or hemizygous deletions, one mutation in exon 1, and three methylations in the promoter. Expression of p 16 protein was not detected in 18 of 30 cases. RB mutations leading to loss of expression of the pRb were found in four (13%) cases, and six were immunohistochemically negative for this protein. Overexpression of cyclin D1 was obtained in 51 (54%) of 94 cases. Patients with pRb-negative tumors had a significantly greater risk of earlier death than those with p16 and cyclin D1 alterations, Both p16 and pRb immunohistochemistry provides useful complementary information and may provide valuable predictive information in screening. The biological consequences of deregulating individual components along cell control pathways are unequal, perhaps reflecting their hierarchical roles in the G1 checkpoint.