Expression patterns of cyclin D1 and related proteins regulating G1-S phase transition in uveal melanoma and retinoblastoma

Locally advanced choroidal melanoma with favorable molecular prognosis - case report

Uveal malignant melanoma is a rare malignant tumor comprising less than 5% of melanoma cases. It is nevertheless the intraocular tumor with the highest incidence in adults, that arises from the melanocytes in the uveal tract. The authors present the case of a patient with locally advanced choroidal melanoma: from presentation to diagnosis, treatment, and prognosis. A 63-year-old female patient presented in the Ambulatory of the Emergency County Hospital, Craiova, Romania, on the February 1, 2021, accusing visual acuity drop and photophobia in her left eye for about three weeks. Pathology examination in Hematoxylin-Eosin (HE) staining reveals a dense cell proliferation, with small and medium spindle cells and pigment production. The following immunohistochemical markers were used in our study: human melanoma black 45 (HMB45), Ki67, cyclin D1, B-cell lymphoma 2 (Bcl2), S100, Wilms' tumor 1 (WT1), p16, and p53. Uveal melanoma is a malignant tumor that can arise in all the uveal components: iris, ciliary body, and choroid. Out of the three components, iris melanomas have the best prognosis, while ciliary body melanomas have the worst prognosis. It is mandatory for the patient to respect the follow-up schedule, as follow-ups can provide early diagnosis of eventual metastasis.

Protective Effect of Genistein on Cyclin D1 Expression in Malignant Ocular Melanoma Cells

Background:

Ocular melanoma is a disorder that is rarely found but is deadly. Four tissues in the eye that can be attacked by melanoma include the uveal tract, conjunctiva, eyelids, and orbit. Uveal melanoma is the most common case, while melanoma conjunctiva is very rare.

Objective:

This study aimed to investigate the effect of giving genistein on cyclin D1 expression in malignant melanoma.

Methods:

When confluent, CRL1872 malignant melanoma cells will be divided into treatment groups, the group giving genistein dose 25 μM, the group giving genistein a dose of 50 μM, and the group giving genistein a dose of 100 μM. Cyclin D1 analysis was measured by immunofluorescence using confocal laser scan microscopy.

Results:

There was a significant increase in the expression of cyclin D1, in the group given genistein 25 μM and 50 μM (p < 0.05). For the administration of the genistein dose of 100 μM, cyclin D1 expression decreased significantly compared to the control group (p < 0.05).

Conclusion:

It was concluded that genistein had a biphasic effect on cyclin D1 expression in malignant melanoma cells. Thus, genistein at the right dose can be a treatment of malignant melanoma.

Novel Prognostic Immunohistochemical Markers in Uveal Melanoma-Literature Review

Simple Summary

The following study provides an overview of the English-language literature on the search for new prognostic factors for uveal melanoma. Uveal melanoma is the most common primary intraocular tumor in adults, and although it is a relatively rare disease, it poses a significant health problem. About half of the patients develop distant metastases, and unfortunately there are currently no effective treatments for the disease at such an advanced stage. The search for new prognostic factors is important to understand the biology of the disease and to be able to monitor patients more effectively. At the same time, it creates an opportunity to find new therapeutic targets. We focused our attention on immunohistochemical research because it is a widely used method, relatively cheap, technically simple, and gives reproducible results. The analysis of this study will enable other researchers to verify their research plans and may also be a source of inspiration for creating new ones.

Abstract

Uveal melanoma is the most common primary intraocular neoplasm in adults. As there are currently no effective methods of treating the disease in the metastatic stage, there is a need to search for new prognostic factors that would enable a reliable assessment of the patient’s condition and constitute a possible therapeutic target. In this review, we have prepared the results of English-language studies on new prognostic factors determined with immunohistochemical methods. We found 64 articles in which the expression of various proteins was associated in a statistically significant manner with the histopathological and clinical prognostic factors identified by AJCC. The results of our work clearly show that the biology of uveal melanoma is extraordinarily complex. Numerous studies have shed new light on the complexity of the processes involved in the development of this cancer. Moreover, a careful analysis of the expression of individual proteins may allow the identification of homogeneous groups of patients requiring different treatment regimens.

Dual Targeting of CDK4/6 and cMET in Metastatic Uveal Melanoma

Simple Summary

Up to 50% of uveal melanoma patients subsequently develop metastases, for which no effective treatment has been identified. In this study, 87.5% of uveal melanoma patients’ samples were positive for phosphorylated retinoblastoma (RB), and ex vivo incubation of patients’ biopsy specimens with CDK4/6 inhibitor decreased the phosphorylation of RB. Hepatocyte growth factor (HGF), which is rich in the liver microenvironment, diminished the efficacy of CDK4/6 inhibitor. In human HGF knock-in NOD.Cg-Prkdc scid Il2rg tm1Wjl/SzJ mice, combination of CDK4/6 inhibitor and cMET inhibitor showed significant growth suppression in implanted metastatic uveal melanoma cells, compared to CDK4/6 inhibitor alone. Taken together, our preclinical study indicated that combining CDK4/6 inhibitor and cMET inhibitor would provide significant clinical benefit to patients with metastatic uveal melanoma.

Abstract

Uveal melanoma (UM) is the most common cancer of the eye in adults. Up to 50% of UM patients subsequently develop metastases, especially in the liver. It has been reported that the retinoblastoma (RB) pathway is deregulated in more than 90% of UM despite the rarity of mutations in the RB1 gene itself. CDK4/6 inhibition (CDK4/6i) is a rational strategy for treatment of UM. In this report, we investigated the antiproliferative activity of a selective CDK4/6 inhibitor on metastatic UM. A CDK4/6 inhibitor suppressed UM cell lines growth in in vitro and in vivo experiments. Hepatocyte growth factor (HGF) decreased the effect of CDK4/6 inhibitor on metastatic UM cell lines. When CDK4/6i was combined with cMET inhibitor, enhanced growth suppression was observed in metastatic UM tumors grown in human-HGF knock-in xenograft mouse models. HGF is enriched in the liver and the majority of liver metastases from UM express activated forms of cMET; therefore, signaling through cMET could contribute to the resistance mechanisms against CDK4/6i, especially in UM patients with hepatic metastasis. Together, these results provide a rationale for the use of cMET inhibitor in combination with a CDK4/6 inhibitor for the treatment of metastatic UM.

Transcriptome Profiling Reveals New Insights into the Immune Microenvironment and Upregulation of Novel Biomarkers in Metastatic Uveal Melanoma

Simple Summary

Uveal melanoma (UM) is a rare aggressive eye cancer. Although treatment of the eye tumour is successful, about 50% of UM patients develop a relapse of their cancer in the liver. At present, such advanced disease is not curable. A better understanding of the metastatic UM (mUM) in the liver is essential to improve patient survival. This study examines both the response of immune cells within the liver to the UM secondaries (metastases), as well as the expression of various proteins by the UM cells. Our study demonstrates that there is a limited immune response to the mUM, but reveals that a certain type of reactive immune cell: a protumourigenic subset of macrophage is dominant within the mUM. Our research also reveals novel proteins within the mUM, which are specific to these cells and therefore may be targetable in future therapies.

Abstract

Metastatic uveal melanoma (mUM) to the liver is incurable. Transcriptome profiling of 40 formalin-fixed paraffin-embedded mUM liver resections and 6 control liver specimens was undertaken. mUMs were assessed for morphology, nuclear BAP1 (nBAP1) expression, and their tumour microenvironments (TME) using an “immunoscore” (absent/altered/high) for tumour-infiltrating lymphocytes (TILs) and macrophages (TAMs). Transcriptomes were compared between mUM and control liver; intersegmental and intratumoural analyses were also undertaken. Most mUM were epithelioid cell-type (75%), amelanotic (55%), and nBAP1-ve (70%). They had intermediate (68%) or absent (15%) immunoscores for TILs and intermediate (53%) or high (45%) immunoscores for TAMs. M2-TAMs were dominant in the mUM-TME, with upregulated expression of ANXA1, CD74, CXCR4, MIF, STAT3, PLA2G6, and TGFB1. Compared to control liver, mUM showed significant (p < 0.01) upregulation of 10 genes: DUSP4, PRAME, CD44, IRF4/MUM1, BCL2, CD146/MCAM/MUC18, IGF1R, PNMA1, MFGE8/lactadherin, and LGALS3/Galectin-3. Protein expression of DUSP4, CD44, IRF4, BCL-2, CD146, and IGF1R was validated in all mUMs, whereas protein expression of PRAME was validated in 10% cases; LGALS3 stained TAMs, and MFGEF8 highlighted bile ducts only. Intersegmental mUMs show differing transcriptomes, whereas those within a single mUM were similar. Our results show that M2-TAMs dominate mUM-TME with upregulation of genes contributing to immunosuppression. mUM significantly overexpress genes with targetable signalling pathways, and yet these may differ between intersegmental lesions.

Preclinical evaluation of drug combinations identifies co-inhibition of Bcl-2/XL/W and MDM2 as a potential therapy in uveal melanoma

INTRODUCTION

Uveal melanoma (UM) is a rare and malignant intraocular tumour with a dismal prognosis. Despite a good control of the primary tumour by radiation or surgery, up to 50% of patients subsequently develop metastasis for which no efficient treatment is yet available.

METHODOLOGY

To identify therapeutic opportunities, we performed an in vitro screen of 30 combinations of different inhibitors of pathways that are dysregulated in UM. Effects of drug combinations on viability, cell cycle and apoptosis were assessed in eight UM cell lines. The best synergistic combinations were further evaluated in six UM patient-derived xenografts (PDXs).

RESULTS

We demonstrated that the Bcl-2/X_L/W inhibitor (ABT263) sensitised the UM cell lines to other inhibitors, mainly to mammalian target of rapamycin (mTOR), mitogen-activated protein kinase kinase (MEK) and murine double minute 2 (MDM2) inhibitors. mTOR (RAD001) and MEK1/2 (trametinib) inhibitors were efficient as single agents, but their combinations with ABT263 displayed no synergism in UM PDXs. In contrast, the combination of ABT263 with MDM2 inhibitor (HDM201) showed a trend for a synergistic effect.

CONCLUSION

We showed that inhibition of Bcl-2/X_L/W sensitised the UM cell lines to other treatments encouraging investigation of the underlying mechanisms. Furthermore, our findings highlighted Bcl-2/X_L/W and MDM2 co-inhibition as a promising strategy in UM.

Emerging Therapeutic Opportunities Based on Current Knowledge of Uveal Melanoma Biology

Uveal Melanoma (UM) is a rare and malignant intraocular tumor with dismal prognosis. Despite the efficient control of the primary tumor by radiation or surgery, up to 50% of patients subsequently develop metastasis, mainly in the liver. Once the tumor has spread from the eye, the treatment is challenging and the median survival is only nine months. UM represents an intriguing model of oncogenesis that is characterized by a relatively homogeneous histopathological architecture and a low burden of genetic alterations, in contrast to other melanomas. UM is driven by recurrent activating mutations in Gαq pathway, which are associated with a second mutation in BRCA1 associated protein 1 (BAP1), splicing factor 3b subunit 1 (SF3B1), or eukaryotic translation initiation factor 1A X-linked (EIF1AX), occurring in an almost mutually exclusive manner. The monosomy of chromosome 3 is also a recurrent feature that is associated with high metastatic risk. These events driving UM oncogenesis have been thoroughly investigated over the last decade. However, no efficient related therapeutic strategies are yet available and the metastatic disease remains mostly incurable. Here, we review current knowledge regarding the molecular biology and the genetics of uveal melanoma and highlight the related therapeutic applications and perspectives.

Histopathologic and molecular comparative analyses of intravesical Aurora kinase-A inhibitor Alisertib with bacillus Calmette-Guérin on precancerous lesions of bladder in a rat model

PURPOSE

Recent studies have shown that Aurora-A expression is associated with bladder cancer initiation and progression. In this study, the effects of intravesical Aurora-A inhibitor Alisertib (ALS) and bacillus Calmette-Guérin (BCG) were compared on bladder carcinogenesis.

METHODS

Two mg N-Methyl-N-nitrosourea was administered intravesically to forty of Wistar-albino rats every other week for 8 weeks. At week 10, rats were divided into four groups (10/group): No-treatment (vehicle), ALS-alone, BCG-alone, and ALS + BCG. The intravesical treatment of ALS, BCG, and ALS plus BCG was performed once a week for 6 weeks. At week 16, bladders were collected for immunohistopathological and Western blot analysis. The cell cycle regulators p53, p21, Aurora-A, phosphorylated Aurora-A (p-Aurora-A), and apoptotic marker cleavage of poly [ADP-ribose] polymerase (c-PARP) were determined by Western blot.

RESULTS

Histopathologically relatively healthy urothelium was observed in ALS + BCG group (87.5%) compared to the ALS-alone (50%) and the BCG-alone (50%) groups. The lowest expression of p21 and p53 was detected in the BCG-alone, while the highest level of expression was evident in no-treatment group. The ALS treatment alone caused a slight decrease in Aurora-A while there was a dramatic decrease in p-Aurora-A in comparison to no-treatment group. In overall combined treatment with ALS + BCG significantly increased c-PARP compared to all mono-treatments, and decreased all cell cycle parameters compared to no-treatment group.

CONCLUSIONS

Although intravesical ALS treatment has similar antiproliferative effects like BCG, ALS + BCG combined treatment led to a best histopathologic and apoptotic response. Consequently, BCG combined with Aurora-A inhibition may provide a new intravesical treatment modality in the prevention of bladder carcinogenesis.

A novel combinatorial treatment option for metastatic uveal melanoma

Uveal melanoma (UM) is the most frequent intraocular tumor in adult patients. When metastases occur, systemic therapy with alkylating agents (fotemustine or dacarbazine (DTIC)) has shown only modest efficacy. The common chemotherapeutic drug doxorubicin (DOX) is not used to treat metastatic UM (mUM). To expand the chemotherapeutic arsenal for mUM, we tested the effect of DOX on UM cell mortality. We have previously shown that CREB knockdown enhances sensitivity to DOX. UM cells infected with recombinant MuLV-based replicative competent retroviruses (RCR) expressing shRNA targeting CREB were co-treated with either DTIC or DOX. We found that CREB knockdown increases the sensitivity of these cells to both DOX and DTIC in normoxia and more so in hypoxia as measured by cell survival and Caspase 3 activation. The ability to combine CREB knockdown by infection with the RCR recombinant virus which preferentially infects replicating tumor cells and chemotherapy to achieve the same amount of cell death in lower concentrations may result in fewer side effects of the drugs. This combination is a possible new treatment for mUM.

Bcl-2 Expression in Primary Uveal Melanoma

Aims

Uveal malignant melanoma is the most common intraocular tumor. The aim of this study was the analysis of bcl-2 oncoprotein expression in this tumor type. The melanomas were evaluated according to tumor location and patient age and sex. The relationship between bcl-2 expression and histological type, clinicopathologic stage and the presence of a set of predetermined morphological parameters was analyzed.

Methods

The study involved 39 patients with ocular melanomas treated with surgery alone between 1983 and 1997. Formalin-fixed, paraffin-embedded tissues were treated with anti-bcl-2 antibody (Dako No M0887). Immunolocalization of the bcl-2 oncoprotein was performed using the labeled streptavidin biotin (LSAB) method. bcl-2 expression in neoplastic cells was evaluated in a semiquantitative manner: lack of reactivity was defined as bcl-2 negative, reactivity present in less than 30% of cells as low bcl-2, and reactivity in more than 30% of cells as high bcl-2. The percentage of cells with a positive reaction was assessed independently by two pathologists, and the results were subjected to statistical analysis using Fischer's exact test.

Results and conclusion

No statistically significant correlation was found between the expression of bcl-2 oncoprotein and the clinicopathologic features analyzed. However, the high percentage of tumors with positive expression of this oncoprotein suggests that it plays a significant role in the biology of uveal melanoma.

Dual inhibition of protein kinase C and p53-MDM2 or PKC and mTORC1 are novel efficient therapeutic approaches for uveal melanoma

Uveal melanoma (UM) is the most common cancer of the eye in adults. Many UM patients develop metastases for which no curative treatment has been identified. Novel therapeutic approaches are therefore urgently needed. UM is characterized by mutations in the genes GNAQ and GNA11 which activate the PKC pathway, leading to the use of PKC inhibitors as a rational strategy to treat UM tumors. Encouraging clinical activity has been noted in UM patients treated with PKC inhibitors. However, it is likely that curative treatment regimens will require a combination of targeted therapeutic agents. Employing a large panel of UM patient-derived xenograft models (PDXs), several PKC inhibitor-based combinations were tested in vivo using the PKC inhibitor AEB071. The most promising approaches were further investigated in vitro using our unique panel of UM cell lines. When combined with AEB071, the two agents CGM097 (p53-MDM2 inhibitor) and RAD001 (mTORC1 inhibitor) demonstrated greater activity than single agents, with tumor regression observed in several UM PDXs. Follow-up studies in UM cell lines on these two drug associations confirmed their combination activity and ability to induce cell death. While no effective treatment currently exists for metastatic uveal melanoma, we have discovered using our unique panel of preclinical models that combinations between PKC/mTOR inhibitors and PKC/p53-MDM2 inhibitors are two novel and very effective therapeutic approaches for this disease. Together, our study reveals that combining PKC and p53-MDM2 or mTORC1 inhibitors may provide significant clinical benefit for UM patients.

Immunohistochemistry of apoptosis-related proteins in retinoblastoma

Retinoblastoma is the most common intraocular malignant neoplasia during childhood and results from the partial or total inactivity of the retinoblastoma protein (pRb). In the absence of pRb, the E2F transcription factors increase the levels of cell cycle proteins as well as some pro-apoptotic proteins. We intended to study the immunohistochemistry profile of apoptotic-related proteins in retinoblastoma. We also evaluated the association between the expression of apoptotic protein and stage of tumor or survivor after a 5year follow up. Apoptosis-related proteins (Apaf-1, Bak, Bax, Bcl-2, Bcl-xL, Bim-long, MDM2, p53, pro-caspase-3, PUMA, Smac/DIABLO and cleaved caspase-3) were evaluated using immunohistochemistry on tissue microarrays which contained samples of retinoblastoma tumors taken from ninety-three patients without any treatment previous to surgery. The immunohistochemistry reactions were evaluated using an optical microscope as well as the ACIS III^® platform. The pro-apoptotic proteins (APAF-1, Bax, p53, PUMA, Smac/DIABLO) were more frequently expressed than the anti-apoptotic proteins (Bcl-2, Bcl-xL and MDM2). The protein Bcl-xL had a negative correlation with cleaved caspase-3, a marker of cell apoptosis. Bcl-xL may be implicated in an apoptosis block.

Quercetin reduces cyclin D1 activity and induces G1 phase arrest in HepG2 cells

Quercetin is able to inhibit proliferation of malignant tumor cells; however, the exact mechanism involved in this biological process remains unclear. The current study utilized a quantitative proteomic analysis to explore the antitumor mechanisms of quercetin. The leucine of HepG2 cells treated with quercetin was labeled as d3 by stable isotope labeling by amino acids in cell culture (SILAC). The isotope peaks of control HepG2 cells were compared with the d3-labeled HepG2 cells by mass spectrometry (MS) to identify significantly altered proteins. Reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses were subsequently employed to verify the results of the MS analysis. A flow cytometry assay was designed to observe the influence of various quercetin treatment concentrations on the cell cycle distribution of HepG2 cells. The results indicated that quercetin is able to substantially inhibit proliferation of HepG2 cells and induce an obvious morphological alteration of cells. According to the MS results, the 70 credibly-changed proteins that were identified may play important roles in multiple cellular processes, including protein synthesis, signaling, cytoskeletal processes and metabolism. Among these functional proteins, the expression of cyclin D1 (CCND1) was found to be significantly decreased. RT-PCR and western blot analyses verified the SILAC-MS results of decreased CCND1 expression. In summary, flow cytometry revealed that quercetin is able to induce G1 phase arrest in HepG2 cells. Based on the aforementioned observations, it is suggested that quercetin exerts antitumor activity in HepG2 cells through multiple pathways, including interfering with CCND1 gene expression to disrupt the cell cycle and proliferation of HepG2 cells. In the future, we aim to explore this effect in vivo.

Simvastatin increases the antineoplastic actions of paclitaxel carried in lipid nanoemulsions in melanoma-bearing mice

PURPOSE

Lipid nanoemulsions (LDEs) that bind to low-density lipoprotein (LDL) receptors used as carriers of paclitaxel (PTX) can decrease toxicity and increase PTX antitumoral action. The administration of simvastatin (Simva), which lowers LDL-cholesterol, was tested as an adjuvant to commercial PTX and to PTX associated with LDE (LDE-PTX).

MATERIALS AND METHODS

B16F10 melanoma-bearing mice were treated with saline solution or LDE (controls), Simva, PTX, PTX and Simva, LDE-PTX, and LDE-PTX and Simva: PTX dose 17.5 μmol/kg (three intraperitoneal injections, 3 alternate days): Simva 50 mg/kg/day by gavage, 9 consecutive days.

RESULTS

Compared with saline controls, 95% tumor-growth inhibition was achieved by LDE-PTX and Simva, 61% by LDE-PTX, 44% by PTX and Simva, and 43% by PTX. Simva alone had no effect. Metastasis developed in only 37% of the LDE-PTX and Simva, 60% in LDE-PTX, and 90% in PTX and Simva groups. Survival rates were higher in LDE-PTX and Simva and in LDE-PTX groups. The LDE-PTX and Simva group presented tumors with reduced cellular density and increased collagen fibers I and III. Tumors from all groups showed reduction in immunohistochemical expression of ICAM, MCP-1, and MMP-9; LDE-PTX and Simva presented the lowest MMP-9 expression. Expression of p21 was increased in the Simva, LDE-PTX, and LDE-PTX and Simva groups. In the Simva and LDE-PTX and Simva groups, expression of cyclin D1, a proliferation and survival promoter of tumor cells, was decreased. Therapy with LDE-PTX and Simva showed negligible toxicity compared with PTX and Simva, which resulted in weight loss and myelosuppression.

CONCLUSION

Simva increased the antitumor activity of PTX carried in LDE but not of PTX commercial presentation, possibly because statins increase the expression of LDL receptors that internalize LDE-PTX.

Drosophila as a Potential Model for Ocular Tumors

Drosophila has made many contributions to our understanding of cancer genes and mechanisms that have subsequently been validated in mammals. Despite anatomical differences between fly and human eyes, flies offer a tractable genetic model in which to dissect the functional importance of genetic lesions found to be affected in human ocular tumors. Here, we discuss different approaches for using Drosophila as a model for ocular cancer and how studies on ocular cancer genes in flies have begun to reveal potential strategies for therapeutic intervention. We also discuss recent developments in the use of Drosophila for drug discovery, which is coming to the fore as Drosophila models are becoming tailored to study tumor types found in the clinic.

p16(INK4a) expression in retinoblastoma: a marker of differentiation grade

Background

The tumor suppressor protein p16^INK4a has been extensively studied in many tumors with very different results, ranging from its loss to its clear overexpression, which may be associated with degree of tumor differentiation and prognosis. However, its expression remains unclear in human retinoblastoma (RB), a common malignant tumor of retina in childhood. The aim of this study was to explore the expression pattern of p16^INK4a in RB, and the correlation between p16^INK4a expression and histopathological features of RB.

Methods

Sixty-five cases of RB were retrospectively analyzed. Paraffin-embedded blocks were retrieved from the archives of ocular pathology department at Zhongshan Ophthalmic Center of Sun Yat-sen University, China. Serial sections were cut and subjected to hematoxylin and eosin staining. Immunohistochemical staining was further done with antibodies p16^INK4a, CRX and Ki67. The correlation of p16 ^INK4a expression with CRX and Ki67 and clinicopathological features of RB were analyzed.

Results

RB tumor histologically consists of various differentiation components including undifferentiated (UD) cells, Homer-Wright rosettes (HWR) or Flexner-Winterstein rosettes (FWR) and fleurettes characteristic of photoreceptor differentiation or Retinocytoma (RC). p16^INK4a expression was negative in both fleurette region and the residual retinal tissue adjacent to the tumor, weakly to moderately positive in FWR, strongly positive in both HWR and UD region. However, CRX had the reverse expression patterns in comparison with p16^INK4a. It was strongly positive in photoreceptor cells within the residual retina and fleurettes, but weakly to moderately positive in UD area. Together with Ki67 staining, high p16^INK4a expression was associated with poor histological differentiation of RB tumors, which had higher risk features with the optic nerve invasion and uveal invasion.

Conclusions

p16^INK4a expression increased with the decreasing level of cell differentiation of RBs. RB tumors extensively expressing p16^INK4a tended to have higher risk features with poor prognosis. This study suggested that p16^INK4a would be a valuable molecular marker of RB to distinguish its histological phenotypes and to serve as a predictor of its prognosis.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_180

Expression of neddylation-related proteins in melanoma cell lines and the effect of neddylation on melanoma proliferation

Neddylation promotes the process of ubiquitination, which plays a critical role in the degradation of numerous proteins, including cell cycle and apoptosis regulators. In our previous study, an increase in neddylation was identified in melanoma cell lines. In the present study, the upregulation of neddylation was detected in melanoma tissues which confirmed the results of our previous study on melanoma cell lines. To explore the mechanism by which the process of neddylation was increased, the enzymes that regulate the process were investigated. These neddylation-related regulatory enzymes are potential targets for melanoma therapy. Downregulation of UBA3, a subunit of the E1 enzyme, by RNA interference caused cell cycle arrest at G0^/G1 in the M14 cell line. In addition, cyclin D expression declined, whereas p27, p21 and bax expression increased. These findings suggest that interfering with the neddylation pathway may decrease the proliferation of melanoma through the modulation of cell cycle regulators and apoptosis promoters.

Targeting Bcl-2/Bcl-XL induces antitumor activity in uveal melanoma patient-derived xenografts

PURPOSE

Uveal melanoma (UM) is associated with a high risk of metastases and lack of efficient therapies. Reduced capacity for apoptosis induction by chemotherapies is one obstacle to efficient treatments. Human UM is characterized by high expression of the anti-apoptotic protein Bcl-2. Consequently, regulators of apoptosis such as Bcl-2 family inhibitors may constitute an attractive approach to UM therapeutics. In this aim, we have investigated the efficacy of the Bcl-2/Bcl-XL inhibitor S44563 on 4 UM Patient-Derived Xenografts (PDXs) and derived-cell lines.

EXPERIMENTAL DESIGN

Four well characterized UM PDXs were used for in vivo experiments. S44563 was administered alone or combined with fotemustine either concomitantly or after the alkylating agent. Bcl-2, Bcl-XL, and Mcl-1 expressions after S44563 administration were evaluated by immunohistochemistry (IHC).

RESULTS

S44563 administered alone by at 50 and 100 mg/kg i.p. induced a significant tumour growth inhibition in only one xenograft model with a clear dose effect. However, when S44563 was concomitantly administered with fotemustine, we observed a synergistic activity in 3 out of the 4 tested models. In addition, S44563 administered after fotemustine induced a tumour growth delay in 2 out of 3 tested xenografts. Finally, IHC analyses showed that Bcl-2, Bcl-XL, and Mcl-1 expression were not modified after S44563 administration.

CONCLUSION

The novel anti-apoptotic experimental compound S44563, despite a relative low efficacy when administered alone, increased the efficacy of fotemustine in either concomitant or sequential combinations or indeed subsequent to fotemustine. These data support further exploration of potential therapeutic effect of Bcl-2/Bcl-xl inhibition in human UM.

Molecular pathology of uveal melanoma

Like other cancers, uveal melanomas (UM) are characterised by an uncontrolled, clonal, cellular proliferation, occurring as a result of numerous genetic, and epigenetic aberrations. Signalling pathways known to be disrupted in UM include: (1) the retinoblastoma pathway, probably as a result of cyclin D1 overexpression; p53 signalling, possibly as a consequence of MDM2 overexpression; and the P13K/AKT and mitogen-activated protein kinase/extracellular signal-related kinase pathway pathways that are disturbed as a result of PTEN and GNAQ/11 mutations, respectively. Characteristic chromosomal abnormalities are common and include 6p gain, associated with a good prognosis, as well as 1p loss, 3 loss, and 8q gain, which correlate with high mortality. These are identified by techniques such as fluorescence in situ hybridisation, comparative genomic hybridisation, microsatellite analysis, multiplex ligation-dependent probe amplification, and single-nucleotide polymorphisms. UM can also be categorised by their gene expression profiles as class 1 or class 2, the latter correlating with poor survival, as do BRCA1-associated protein-1 (BAP1) inactivating mutations. Genetic testing of UM has enhanced prognostication, especially when results are integrated with histological and clinical data. The identification of abnormal signalling pathways, genes and proteins in UM opens the way for target-based therapies, improving prospects for conserving vision and prolonging life.

High levels of Hdmx promote cell growth in a subset of uveal melanomas

The p53 tumor suppressor pathway is inactivated in cancer either via direct mutation or via deregulation of upstream regulators or downstream effectors. P53 mutations are rare in uveal melanoma. Here we investigated the role of the p53 inhibitor Hdmx in uveal melanoma. We found Hdmx over-expression in a subset of uveal melanoma cell lines and fresh-frozen tumor samples. Hdmx depletion resulted in cell-line dependent growth inhibition, apparently correlating with differential Hdm2 levels. Surprisingly, p53 knockdown hardly rescued cell cycle arrest and apoptosis induction upon Hdmx knockdown, whereas it effectively prevented growth suppression induced by the potent p53 activator Nutlin-3. In addition, two compounds inhibiting Hdmx function or expression, SAH-p53-8 and XI-011, also elicited a growth inhibitory effect in a partly p53-independent manner. These findings suggest a novel, growth-promoting function of Hdmx that does not rely on its ability to inhibit p53. We provide evidence for a contribution of p27 protein induction to the observed p53-independent G1 arrest in response to Hdmx knockdown. In conclusion, our study establishes the importance of Hdmx as an oncogene in a subset of uveal melanomas and widens the spectrum of its function beyond p53 inhibition.

The genetics of uveal melanoma: an emerging framework for targeted therapy

Uveal melanoma is the second most common form of melanoma and the most common primary intraocular malignancy. Until recently, very little was known about the genetics of this aggressive cancer. Mutations in oncogenes and tumor suppressors that are common in other cancers are conspicuously absent in uveal melanoma. In recent years, however, uveal melanoma has begun to yield its secrets, and a fascinating picture is emerging of how it develops and progresses. Mutations in the G(q) alpha subunits, encoded by GNAQ and GNA11, appear to be early or perhaps initiating events that require further mutations for malignant transformation. On the other hand, mutations in the BRCA1-associated protein-1 (BAP1) appear to occur later and demarcate a molecular brink beyond which metastasis becomes highly likely. BAP1 mutations can also occur in the germline, leading to a distinctive cancer predisposition syndrome. These mutations appear to be key events that provide the potential for targeted therapy. This article will review the genetic findings in uveal melanoma over the past two decades and suggest important areas for future work.

Status of RASSF1A in uveal melanocytes and melanoma cells

RASSF1A gene, found at the 3p21.3 locus, is a tumor suppressor gene frequently hypermethylated in human cancers. In this study, we report that compared with melanocytes in normal choroid, RASSF1A is downregulated in uveal melanoma samples and in uveal melanoma cell lines. LOH at 3p21.3 was detected in 50% of uveal melanoma. Moreover, methylation of the RASSF1A promoter was detected in 35 of 42 tumors (83%) and RASSF1A was also weakly expressed at the mRNA level. These data indicate that LOH at the RASSF1A locus or RASSF1A promoter methylation may partly account for the suppression of RASSF1A expression observed in uveal melanoma. Furthermore, following ectopic expression in three RASSF1A-deficient melanoma cell lines (OCM-1, Mel270, and 92.1), RASSF1A weakly reduces cell proliferation and anchorage-independent growth of uveal melanoma cells without effect on ERK1/2 activation, cyclin D1 and p27(Kip1) expression. This study explored biological functions and underlying mechanisms of RASSF1A in the ERK1/2 pathway in normal uveal melanocytes. We showed that siRNA-mediated depletion of RASSF1A increased ERK1/2 activation, cyclin D1 expression, and also decreased p27(Kip1) expression in normal uveal melanocytes. Moreover, that the depletion of RASSF1A induced senescence-associated β-galactosidase activity and increased p21(Cip1) expression suggests that RASSF1A plays a role in the escape of cellular senescence in normal uveal melanocytes. Interestingly, we found that RASSF1A was epigenetically inactivated in long-term culture of uveal melanocytes. Taken together, these data show that depletion of RASSF1A could be an early event observed during senescence of normal uveal melanocytes and that additional alterations are acquired during malignant transformation to uveal melanoma.

Resistance of uveal melanoma to the interstrand cross-linking agent mitomycin C is associated with reduced expression of CYP450R

BACKGROUND

Uveal melanoma (UM) is the most common primary intraocular tumour of adults, frequently metastasising to the liver. Hepatic metastases are difficult to treat and are mainly unresponsive to chemotherapy. To investigate why UM are so chemo-resistant we explored the effect of interstrand cross-linking agents mitomycin C (MMC) and cisplatin in comparison with hydroxyurea (HU).

METHODS

Sensitivity to MMC, cisplatin and HU was tested in established UM cell lines using clonogenic assays. The response of UM to MMC was confirmed in MTT assays using short-term cultures of primary UM. The expression of cytochrome P450 reductase (CYP450R) was analysed by western blotting, and DNA cross-linking was assessed using COMET analysis supported by γ-H2AX foci formation.

RESULTS

Both established cell lines and primary cultures of UM were resistant to the cross-linking agent MMC (in each case P<0.001 in Student's t-test compared with controls). In two established UM cell lines, DNA cross-link damage was not induced by MMC (in both cases P<0.05 in Students's t-test compared with damage induced in controls). In all, 6 out of 6 UMs tested displayed reduced expression of the metabolising enzyme CYP450R and transient expression of CYP450R increased MMC sensitivity of UM.

CONCLUSION

We suggest that reduced expression of CYP450R is responsible for MMC resistance of UM, through a lack of bioactivation, which can be reversed by complementing UM cell lines with CYP450R.

Genetics of uveal melanoma and cutaneous melanoma: two of a kind?

Cutaneous melanoma and uveal melanoma both derive from melanocytes but show remarkable differences in tumorigenesis, mode of metastatic spread, genetic alterations, and therapeutic response. In this review we discuss the differences and similarities along with the genetic research techniques available and the contribution to our current understanding of melanoma. The several chromosomal aberrations already identified prove to be very strong predictors of decreased survival in CM and UM patients. Especially in UM, where the overall risk of metastasis is high (45%), genetic research might aid clinicians in selecting high-risk patients for future systemic adjuvant therapies.

Molecular prognostic testing and individualized patient care in uveal melanoma

PURPOSE

To critically assess the status of molecular prognostic testing and its use for individualized patient care in uveal melanoma.

DESIGN

Perspective, literature review, evidence assessment, and commentary.

METHODS

Evaluation of selected articles from the literature and the authors' clinical and laboratory studies.

RESULTS

The most accurate molecular tests for predicting metastatic death in patients with uveal melanoma currently involve automated techniques for assessing deoxyribonucleic acid (DNA) copy number alterations and gene expression profiling. Most tests reported in the literature to date do not provide adequate scientific and statistical validation to be used outside of an ethically supervised investigational environment.

CONCLUSIONS

Many cytogenetic and molecular prognostic tests for uveal melanoma have been reported, yet few have reached the standards required for routine clinical testing. Clinicians must understand the statistical and scientific limitations of the tests they are using, and appropriate ethical oversight is essential until such time that validated testing instruments are available that are performed in a standardized clinical testing environment. Well-controlled prospective studies are necessary to identify the most accurate, widely accessible, and affordable tests for routine clinical use.

The apoptotic paradox in retinoblastoma

The purpose of this study was to investigate the clinicopathological features and the expression of proteins involved in cell proliferation and the different pathways of apoptosis in retinoblastoma. Nineteen retinoblastoma patients were included, and mitotic index (MI) and apoptotic index (AI) were assessed. The expression of MIB-1, p53, caspase-3, Bcl-2, and Fas protein was assessed by immunohistochemistry. Mann-Whitney U test and Fisher's exact test were used for statistical comparison. High MI (mean 16.84, range 0-66) and high MIB-1 expression (mean 57.89, range 0-90) were found. The MI was significantly related to MIB-1 expression (P= 0.01). The tumors showed a high apoptotic index (mean 40.26, range 1-110), and the AI was associated with the mitotic index (P= 0.02). The caspase-3 expression was positively related to the AI (P= 0.03), although a small number of tumors with no significant or very low caspase-3 staining showed a high number of apoptotic cells, suggestive of a caspase-3-independent apoptosis pathway. Bcl-2 expression was not significantly related to AI (P= 0.07). No striking relationship was found in expression patterns of p53, Bcl-2, caspase-3, and Fas. In conclusion, we found that (1) cell proliferation and apoptosis are linked in retinoblastoma; (2) activation of effector caspase-3 induces apoptosis in retinoblastoma, but Bcl-2 overexpression does not prevent apoptosis in many tumors; (3) there is a p53-independent pathway in approximately one-quarter of cases; (4) the findings suggesting a caspase-3-independent pathway might lead to apoptosis in retinoblastoma; and, finally, we found no consistent pattern of expression of apoptotic and antiapoptotic molecules, suggesting that in retinoblastoma there is no preference for any single pathway of apoptosis. Confirmation of the results in a large set of tumors would be useful.

Immune expression and inhibition of heat shock protein 90 in uveal melanoma

PURPOSE

To examine the immunohistochemical profile of heat shock protein 90 (Hsp90) in uveal melanoma and the cytotoxicity of an Hsp90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in uveal melanoma cell lines.

EXPERIMENTAL DESIGN

Hsp90 expression was determined by immunohistochemistry in 44 paraffin-embedded sections of primary human uveal melanoma and in five uveal melanoma cell lines (92.1, OCM-1, MKT-BR, SP6.5, and UW-1). Sulforhodamine B-based proliferation assay was used to compare uveal melanoma cell growth with a range of concentrations of 17-AAG. Changes in cell migration, invasion, cell cycle fractions, and apoptotic activity were also evaluated. Expression of intracellular proteins was determined by Western blot analysis after 17-AAG exposure.

RESULTS

Immunohistochemical expression of Hsp90 was identified in 68% of the paraffin-embedded sections and significantly associated with largest tumor dimension (P = 0.03). 17-AAG significantly reduced the proliferation rates of uveal melanoma cell lines, with concentrations of 100 to 0.1 micromol/L. 17-AAG also significantly reduced the migratory and invasive capabilities of uveal melanoma cell lines. Cell cycle analysis showed that 17-AAG induced accumulations of cells in G(1). Caspase-3 protease activity analysis, a marker for apoptosis, showed a significant increase after drug exposure. The cytotoxic effect of 17-AAG was associated with decreased levels of phosphorylated Akt and cyclin-dependent kinase 4.

CONCLUSIONS

The immunohistochemical expression of Hsp90 in uveal melanoma indicates worse prognosis. To the best of our knowledge, this is the first report showing the inhibitory effect on uveal melanoma cells using 17-AAG to target Hsp90. Therefore, Hsp90 may be used as a potential target for treatment of patients with uveal melanoma.

Targeted therapy for uveal melanoma

Uveal melanoma is the most common primary intra-ocular malignancy in adults. Overall mortality rate remains high because of the development of metastatic disease, which is highly resistant to systemic therapy. Improved understanding of the molecular pathogenesis of cancers has led to a new generation of therapeutic agents that interfere with a specific pathway critical in tumor development or progression. Although no specific genes have been linked to the pathogenesis of uveal melanoma, which differs from that of cutaneous melanoma, progress has been made in identifying potential targets involved in uveal melanoma apoptosis, proliferation, invasion, metastasis, and angiogenesis. This review focuses on the prospects for improving the systemic therapy of uveal melanoma using molecularly targeted agents that are currently in clinical use as well as agents being tested in clinical trials. Preclinical studies suggest potential benefit of inhibitors of Bcl-2, ubiquitin-proteasome, histone deactylase, mitogen-activated protein kinase and phosphatidylinositol-3-kinase-AKT pathways, and receptor tyrosine kinases. Modifiers of adhesion molecules, matrix metalloproteinase, and angiogenic factors also have demonstrated potential benefit. Clinical trials of some of these approaches have been initiated in patients with metastatic uveal melanoma as well as in the adjuvant setting after primary therapy.

Proteomics in uveal melanoma research: opportunities and challenges in biomarker discovery

Uveal melanoma (UM) is the most frequent primary intraocular tumor in adult humans. Despite the significant advances in diagnosis and treatment of UM in the last decades, the prognosis of UM sufferers is still poor. Metastatic liver disease is the leading cause of death in UM and can develop after a long disease-free interval, suggesting the presence of occult micrometastasis. Proteomics technology has opened new opportunities for elucidating the molecular mechanism of complex diseases, such as cancer. This article will review the recent developments in biomarker discovery for UM research by proteomics. In the last few years, the first UM proteomics-based analyses have been launched, yielding promising results. An update on recent developments on this field is presented.

The role of cell cycle regulatory proteins in the pathogenesis of melanoma

The transformation of melanocytes to melanoma cells is characterised by abnormal proliferation resulting from alterations in cell cycle regulatory mechanisms. This occurs through alterations in the two major cell cycle regulatory pathways, the retinoblastoma (Rb) and p53 tumour suppressor pathways. This review summarises the current knowledge of alterations in these two pathways at G1/S transition and specifically the role of the key cell cycle regulatory proteins pRb, p16INK4a (p16), cyclin D1, p27Kip1 (p27), p53 and p21Waf1/Cip1 (p21) in the pathogenesis of melanoma. It also considers their prognostic significance. Current data indicate that alterations of cyclin kinase inhibitor (cdki) levels are implicated in the pathogenesis of melanoma and may be useful prognostic markers. However, large validation studies linked to comprehensive clinical follow up data are necessary to clarify the prognostic significance of cell cycle regulatory proteins in individual patients.

Cyclin D1 expression in melanocytic lesions of the skin

BACKGROUND

Progression through the cell cycle is controlled by cyclins, cyclin-dependent kinases, and cyclin-dependent kinase inhibitory proteins. The role of cyclin D1 in the development and progression of melanomas is controversial. The goal of this study is to evaluate the role of cyclin D1 in benign and malignant melanocytic lesions of the skin.

METHODS

A total of 126 pigmented lesions of the skin including compound nevi (21), intradermal nevi (18), melanoma in situ (28), primary invasive melanomas (30), and metastatic melanoma (29) were evaluated for cyclin D1 expression. The following tiered system was used for scoring: 0% nuclear staining (score 0), 1% to 19% nuclear staining (score 1), 20% to 49% nuclear staining (score 2), and 50% or greater nuclear staining (score 3).

RESULTS

Average scores were significantly higher for primary melanomas compared with nevi and for in situ melanomas compared with primary invasive melanomas. The average score for metastatic melanomas was not significantly different compared with primary invasive melanomas. Scores for primary invasive melanomas did not correlate with depth of invasion or presence of metastases. Compound nevi exhibited a slightly higher level of cyclin D1 expression compared with intradermal nevi.

CONCLUSION

Although primary melanomas show a higher level of cyclin D1 expression compared with nevi, cyclin D1 appears to have little role in development of a metastatic phenotype. It is not clear why lesions localized near the dermal-epidermal junction express higher levels of cyclin D1. Further studies are indicated to ascertain the biologic role and practical utility of cyclin D1 in melanocytic lesions of the skin.

p16 expression in psoriatic lesions following therapy with propylthiouracil, an antithyroid thioureylene

Plaque formation is a characteristic finding in patients with psoriasis and reflects cytokine-induced keratinocyte proliferation and/or impaired apoptosis of keratinocytes. Antithyroid thioureylenes such as propylthiouracil (PTU) and methimazole (MMI) are effective in the treatment of plaque psoriasis. Following PTU and MMI treatment, proliferative cell nuclear antigen (PCNA) expression is significantly reduced, suggesting that these medications have an antiproliferative effect. p16 is an antiapoptotic protein that is present in relative abundance in psoriatic plaques and is believed to play a potential role in the persistent senescence and impaired apoptosis of the keratinocytes in the plaque. This study examined p16 expression in biopsy samples of eight patients with plaque psoriasis given 300 mg of propylthiouracil in divided doses for 3 months. Despite significant clinical and histological improvement with PTU treatment, p16 expression was essentially unchanged, suggesting that the beneficial effect of PTU in psoriasis is not mediated through a decrease in p16 expression. The effect of PTU on other antiapoptotic proteins such as bcl-xL remains to be determined.

Abnormal cell cycle regulation in primary human uveal melanoma cultures

Uveal malignant melanoma is the most frequent primary intraocular tumor in adult humans. The cellular events leading to neoplasic transformation of normal uveal melanocytes are not well known when compared to other cancers. In this study, we investigated the role of G1 and G1/S regulatory proteins of the cell cycle in human uveal melanoma (UM) primary cell cultures, since these proteins are common targets in tumor development. Further, freshly established and characterized tumor cells are a better model for in vitro studies when compared to cell lines established long ago. Human primary cell cultures from eight different UM were established, as well as one primary culture from rhesus uveal normal melanocytes (UNM). Primary human UM cultures were characterized by a low establishment and growing rate. From four successful cultures, three showed a high expression of cyclin D1, cyclin E, p16NK4A, and p27KIP1 with no variations in cyclin A, cyclin-dependent kinase 2 (CDK2), and CDK4. Interestingly, in one of the cultured tumors, tumor suppressor protein retinoblastoma (Rb) did not bind E2F despite the fact that Rb was found in its hypophosphorylated form. No mutations in either RB1 or the Rb-binding pocket of E2F-1 were detected. Furthermore, we identified seven proteins co-immunoprecipitating with Rb in this tumor, including Lamin A/C and six proteins not previously reported to bind Rb: Hsc70, high mobility group protein 1 (HMG-1), hnRPN, glyceraldehyde 3 phosphate dehydrogenase (G3PDH), EF-1, and EF-2. Our results indicate that the overexpression of cyclins D1/E and CDKIs p16 and p27, together with a deregulation of the Rb/E2F pathway, may be implicated in the development of human UM.

Tumor promotion by metanil yellow and malachite green during rat hepatocarcinogenesis is associated with dysregulated expression of cell cycle regulatory proteins

Metanil yellow (MY) and malachite green (MG) are textile dyes, which, despite a ban, are used as food-coloring agents. MY and MG have promoter effects on the development of hepatic preneoplastic lesions induced by N-nitrosodiethylamine (DEN). Tumor-promoting agents are not mutagenic but may alter the expression of genes whose products are associated with hyper-proliferation, tissue remodeling, and inflammation. Cell cycle controls normally function to ensure the integrity of the genome and arrest of cells at G1/S or G2/M checkpoints until all the prerequisite events are completed. In order to understand the mechanism(s) of tumor promotion by MY and MG, we have studied the levels of PCNA, a marker of cell proliferation and cell cycle regulatory proteins, cyclin D1, and its associated kinase, cdk4, cyclin B1, and associated kinase, cdc2. Immunohistochemical staining showed an elevated level of PCNA in animals administered MY and MG subsequent to DEN treatment. Western and Northern blot hybridization showed an increased expression of both cyclin D1 and its associated kinase cdk4, and cyclin B1 and its associated kinase cdc2, in livers of rats administered MY and MG after administration of DEN as compared to untreated or DEN controls. The increased level of mRNA was due to the increased rate of transcription of these genes as studied by run-on transcription assay. These data obtained by the in vivo model of liver tumor development provide strong evidence for a link between dysregulation of the two critical checkpoints of the cell cycle as one of the possible mechanism(s) during tumor promotion by malachite green and metanil yellow.

1,25-dihydroxyvitamin D3-induced apoptosis of retinoblastoma cells is associated with reciprocal changes of Bcl-2 and bax

The active vitamin D metabolite 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) and related substances have previously been tested in tissue culture and animal models of retinoblastoma for their use as anti-tumor drugs. However, despite of the potential therapeutic value, the molecular mechanisms through which 1,25-(OH)(2)D(3) inhibits the growth of retinoblastoma cells are incompletely understood. To elucidate possible signalling pathways for the anti-proliferative action of vitamin D compounds in retinal tumor cells, we analyzed the effect of 1,25-(OH)(2)D(3) and its synthetic analogue KH1060 on the growth of human retinoblastoma-derived Y79 cells. Vitamin D receptor (VDR) mRNA was detected by reverse transcription PCR in Y79 cells and in tissue specimens of human retinoblastoma. VDR transcripts were confirmed at the protein level by strong immunostaining of solid retinal tumors for VDR. Incubation with 1,25-(OH)(2)D(3) and KH1060 (10(-10)-10(-6)moll(-1)) decreased the number of Y79 cells in a timely and dose-dependent manner. Treatment with 1,25-(OH)(2)D(3) (10(-10)moll(-1)) for 24 hr caused cell cycle arrest in the G0/1 phase. Apoptosis of Y79 cells in response to 1,25-(OH)(2)D(3) was demonstrated by the means of TdT-dUTP terminal nick-end labelling (TUNEL), annexin V staining, and detection of DNA fragmentation on agarose gels. 1,25-(OH)(2)D(3)-induced programmed death of Y79 cells was accompanied by a concentration-dependent increase in Bax protein and a reduction in Bcl-2 content. These findings suggest that 1,25-(OH)(2)D(3) inhibits the growth of retinoblastoma cells by causing cell cycle arrest and apoptosis. 1,25-(OH)(2)D(3)-induced programmed death of retinoblastoma cells appears to involve reciprocal changes in Bcl-2 and Bax proteins.

NF-kappa B-dependent induction of cyclin D1 by retinoblastoma protein (pRB) family proteins and tumor-derived pRB mutants

The retinoblastoma protein (pRB) and its homologues, p107 and p130, prevent cell cycle progression from G(0)/G(1) to S phase by forming complexes with E2F transcription factors. Upon phosphorylation by G(1) cyclin-cyclin-dependent kinase (Cdk) complexes such as cyclin D1-Cdk4/6 and cyclin E-Cdk2, they lose the ability to bind E2F, and cells are thereby allowed to progress into S phase. Functional loss of one or more of the pRB family members, as a result of genetic mutation or deregulated phosphorylation, is considered to be an essential prerequisite for cellular transformation. In this study, we found that pRB family proteins have the ability to stimulate cyclin D1 transcription by activation of the NF-kappaB transcription factor. The cyclin D1-inducing activity of pRB is abolished by adenovirus E1A oncoprotein but not by the deletion of the A-box, the B-box, or the C-terminal region of the pocket, indicating that multiple pocket sequences are independently involved in cyclin D1 activation. Intriguingly, tumor-derived pRB pocket mutants retain the cyclin D1-inducing activity. Our results reveal a novel role of pRB family proteins as potential activators of NF-kappaB and inducers of G(1) cyclin. Certain pRB pocket mutants may give rise to a cellular situation in which deregulated E2F and cyclin D1 cooperatively promote abnormal cell proliferation.

Altered expression of Rb and p53 in uveal melanomas following plaque radiotherapy

PURPOSE

To examine the expression of proteins in the Rb and p53 tumor suppressor pathways in uveal melanomas following plaque radiotherapy.

METHODS

Immunohistochemistry and cell culture studies. Immunohistochemistry for Rb, p16, cyclin D1, p53, HDM2, and Bcl-2 was performed on twelve eyes containing posterior uveal melanomas that were enucleated following plaque radiotherapy. Cell culture studies were performed in three cases.

RESULTS

The irradiated eyes were enucleated for radiation complications (five cases), local tumor recurrence (three cases), and other reasons (four cases). On histopathologic examination, all cases showed evidence of tumor cell loss. However, residual tumor cells were present in all cases, including those that were clinically regressed. Residual cells from three of the clinically regressed cases were cultured and demonstrated minimal cell division, marked cell death, and extensive chromosomal damage. Strong p53 staining was observed in six cases (50%) and was significantly associated with recent radiotherapy (P = .04). Abnormal cytoplasmic staining for Rb was observed in four cases (33%).

CONCLUSIONS

Plaque radiotherapy of uveal melanomas induces DNA damage, inhibits cell division, and promotes cell death. These changes may be due, at least in part, to induction of p53, which activates genes involved in both cell cycle arrest and apoptosis. Plaque radiotherapy can also cause alterations in the expression of Rb, but the significance of this finding will require further study.

Risk factors for metastasis in retinoblastoma

Children with retinoblastoma typically survive their cancer due to advances in early diagnosis and treatment. Despite this success, risk factors persist for metastasis that are thought to be related to patient age, sex, laterality, treatment, genetics, histopathology, and extraocular extension. This review has found that invasion of the uvea, orbit, and optic nerve continue to be the most important predictors of metastatic retinoblastoma. Bilaterality and delays in diagnosis are also important factors. We examine molecular and genetic studies that offer the potential of predicting which tumors are likely to metastasize, which will recur within the eye, and which will undergo senescence. In this review, we describe which clinical evaluations, genetic studies, and histopathologic evaluations of retrieved specimens are currently used widely. This review has been performed to help those caring for patients with retinoblastoma and to aid informed consent.

Deregulation of the Rb and p53 pathways in uveal melanoma

Uveal melanoma is the most common primary eye cancer, yet its molecular pathogenesis is poorly understood. In this study, we investigated the immunohistochemical expression of proteins in the Rb and p53 tumor suppressor pathways in 33 uveal melanomas from enucleated eyes. Strong nuclear staining for Rb was present in most tumors. However, a few cases displayed weak nuclear staining and strong cytoplasmic staining (possibly indicating Rb mutation), and this aberrant staining correlated strongly with failed radiotherapy or thermotherapy before enucleation. Staining for cyclin D1 was positive in most tumors and was associated with advanced age and larger tumor size, which are both poor prognostic factors. Generally, immunostaining for p53 was weak (suggesting a lack of p53 mutations), although p53 positivity correlated strongly with staining for phosphorylated Rb, supporting the notion that inappropriate phosphorylation of Rb can induce p53. Strong immunostaining for MDM2, which can functionally block p53 activity, was observed in most tumors and correlated significantly with female sex. Strong cytoplasmic staining was observed for Bcl2, which can inhibit both p53-dependent and -independent apoptosis. We conclude that Rb and p53 are mutated infrequently in uveal melanoma, but their respective pathways may be functionally inactivated.

Cell cycle and melanoma--two different tumours from the same cell type

Melanoma of the uvea of the eye and melanoma of the skin share a common cell of origin, but differ substantially in their behaviour and response to chemotherapy. There is increasing evidence that this is related to differences in their molecular phenotype, particularly in relation to the expression of cell cycle-associated proteins. Since many cytotoxic agents act by damaging DNA, resistance is often associated with intact mechanisms which allow the neoplastic cells to arrest their growth while DNA is repaired, or to resist apoptosis in response to detection of DNA damage. p53 is important to these processes, but mutation appears to be a less common event in uveal melanoma than in skin melanoma, probably due to the lack of UV exposure in the uvea. There are also differences in proliferation-associated proteins such as c-myc and cyclin D1. Overexpression of the former molecule is associated with a poor prognosis in skin melanoma, but is associated with a good prognosis in uveal melanoma, although there is considerable genetic heterogeneity within each type. While prognostic studies may therefore be of little relevance to individual patients, they continue to inform our understanding of tumour biology.

The prognostic value of cyclin D1, p53, and MDM2 protein expression in uveal melanoma

Malignant uveal melanoma is the commonest primary intraocular tumour in adults. It metastasizes frequently and 50% of patients die within 10 years of diagnosis. The expression of cyclin D1, p53, and MDM2 in uveal melanoma and their relationship to metastasis-free 5-year survival was determined, in order to investigate whether these proteins help to distinguish those patients with a favourable prognosis from those with a poorer one. Ninety-six eyes enucleated for uveal melanomas were immunohistochemically analysed for the protein expression of cyclin D1 and related cell-cycle markers, p53 and MDM2. The evaluation of the specimens was undertaken by two independent pathologists without knowledge of the outcome. Statistical analysis of clinical, morphological, and immunohistological features was performed. A 'favourable outcome' was defined as survival of at least 5 years after diagnosis, without metastases (n=57). An 'unfavourable outcome' was defined as death from metastases within the first 5 years after diagnosis of uveal melanoma (n=39). Cyclin D1 positivity (>15% positive tumour cells) as well as p53 positivity (>15% positive tumour cells) was associated with an unfavourable outcome (for cyclin D1: odds ratio=4. 2, 95% confidence interval 1.5-11.8, p=0.006; for p53: odds ratio=3. 2, 95% confidence interval 1.1-9.3, p=0.03). In addition, cyclin D1 positivity was associated with the presence of extraocular extension of the tumour (p=0.01), with the mixed or epithelioid cell type (p=0. 02), and with the tumour cell MIB-1 positivity (p=0.0001). MDM2 immunoreactivity of the tumour cells showed a potential correlation with clinical outcome (odds ratio=2.1, 95% confidence interval 0.8-5. 8, p=0.13). Multiple logistic regression models showed that cyclin D1 positivity is an independent prognostic factor after control for other prognostic markers. The expression of cyclin D1 in uveal melanoma is associated with a more aggressive course and histologically unfavourable disease. This could serve as a further independent prognostic factor in uveal melanoma.

Telomerase expression in uveal melanoma

BACKGROUND/AIMS

Accumulating evidence indicates that telomerase activity is repressed in normal human somatic cells but reactivated in cancers and immortal cells, suggesting that activation of telomerase activity has a role in carcinogenesis and immortalisation. To date, telomerase in uveal melanoma and, whether, it may have a role in the development or progression of these tumours has not been described. The expression patterns and the activity of telomerase were investigated in 14 uveal melanoma and these results were correlated with histological and immunohistological features of these tumours.

METHODS

A modified PCR based telomeric repeat amplification protocol (TRAP) assay was used to demonstrate telomerase activity in 14 uveal melanomas. In addition, in situ hybridisation was used to demonstrate the expression pattern of the telomerase RNA component (hTR) at the single cell level in eight of these globes.

RESULTS

The TRAP assay revealed moderate telomerase activity in all uveal melanomas examined. In situ hybridisation visualised a moderate to high upregulation of hTR in the melanoma cells but not in the admixed reactive cells. There was no correlation among tumour location, cell type, or growth fraction and the amount of telomerase activity. In addition, the cells of the germinative zone of the lens demonstrated a strong hTR expression.

CONCLUSION

Telomerase activity is upregulated in uveal melanomas. The expression of hTR was located to the tumour cells and not the reactive tumour infiltrating cells. Strong telomerase expression was also demonstrated in cells of the germinative zone of the lens.

Effects of proton beam irradiation on uveal melanomas: a comparative study of Ki-67 expression in irradiated versus non-irradiated melanomas

AIMS

To assess the cellular proliferation using the monoclonal antibody Ki-67, in paraffin embedded uveal melanomas irradiated by proton beam, as well as in non-irradiated uveal melanomas.

METHODS

30 enucleated eyes were included for histopathological study and Ki-67 immunostaining. Patients were enucleated between 1991 and 1996 for uveal melanoma, 14 after proton beam irradiation and 16 without treatment (control group). The mean follow up period was 2.5 years after diagnosis and 1 year after enucleation.

RESULTS

A significant relation was found between Ki-67 score and mitotic index (r = 0.56, p = 0.001), histological largest tumour diameter (r = 0.38, p = 0. 03), fibrosis (r = -0.35, p = 0.05), absence of tumoral pigmentation (p = 0.05), and presence of vascular thrombosis (p = 0.03). The Ki-67 score was significantly higher in the non-irradiated group (p = 0.01) and in the group of patients whose cause of enucleation was tumoral evolution (p = 0.005) compared with the group of patients enucleated after neovascular glaucoma. The Ki-67 score was very high in a case of orbital recurrence of uveal melanoma and metastatic death. 70% of metastasised tumours showed a Ki-67 score higher than the median value.

CONCLUSION

Ki-67 labelling is a reliable method of estimating the proliferative activity in uveal melanomas after proton beam irradiation. The Ki-67 score is significantly correlated with prognostic variables (mitotic index and histological largest tumour diameter), and with radiation effects after proton beam irradiation.

Unilateral angiolymphoid hyperplasia with eosinophilia involving the left arm and hand

A case report of recurrent angiolymphoid hyperplasia with eosinophilia (ALHE) in an otherwise healthy 20-year-old female with manifestation of the disease limited to the left arm and hand is presented together with brief evaluation of the literature as well as the features distinguishing ALHE and Kimura's disease. Immunohistochemical investigations support the hypothesis that ALHE represents a reactive inflammatory lesion rather than a benign vascular neoplasm. A viral cause of ALHE (e.g., HHV8 or Epstein-Barr virus (EBV)) could not be demonstrated. The recurrent nature of the disease is shown by this case, which also demonstrates the need for frequent medical and surgical management.