Neue Therapiestrategien beim Retinoblastom: Nichtsystemische Chemotherapie

Islet Co-Expression of CD133 and ABCB5 in Human Retinoblastoma Specimens

BACKGROUND

The role of CD133 und ABCB5 is discussed in treatment resistance in several types of cancer. The objective of this study was to evaluate whether CD133⁺/ABCB5⁺ colocalization differs in untreated, in beam radiation treated, and in chemotherapy treated retinoblastoma specimens. Additionally, CD133, ABCB5, sphingosine kinase 1, and sphingosine kinase 2 gene expression was analyzed in WERI-RB1 (WERI RB1) and etoposide-resistant WERI RB1 subclones (WERI ETOR).

METHODS

Active human untreated retinoblastoma specimens (n = 12), active human retinoblastoma specimens pretreated with beam radiation before enucleation (n = 8), and active human retinoblastoma specimens pretreated with chemotherapy before enucleation (n = 7) were investigated for localization and expression of CD133 and ABCB5 by immunohistochemistry. Only specimens with IIRC D, but not E, were included in this study. Furthermore, WERI RB1 and WERI ETOR cell lines were analyzed for CD133, ABCB5, sphingosine kinase 1, and sphingosine kinase 2 by the real-time polymerase chain reaction (RT-PCR).

RESULTS

Immunohistochemical analysis revealed the same amount of CD133⁺/ABCB5⁺ colocalization islets in untreated and treated human retinoblastoma specimens. Quantitative RT-PCR analysis showed a statistically significant upregulation of CD133 in WERI ETOR (p = 0.002). No ABCB5 expression was detected in WERI RB1 and WERI ETOR. On the other hand, SPHK1 (p = 0.0027) and SPHK2 (p = 0.017) showed significant downregulation in WERI ETOR compared to WERI RB1.

CONCLUSIONS

CD133⁺/ABCB5⁺ co-localization islets were noted in untreated and treated human retinoblastoma specimens. Therefore, we assume that CD133⁺/ABCB5⁺ islets might play a role in retinoblastoma genesis, but not in retinoblastoma treatment resistance.

[Tumors and Pseudotumors of the Retina and the Ciliary Epithelium]

The variety of retinal tumors ranges from harmless lesions to benign, locally destructive tumors and life-threatening diseases, and they are not always easy to distinguish from each other. The differential diagnosis includes real neoplasia, reactive inflammatory pathologies and vascular anomalies of the fundus as well. If possible, the diagnosis should be made clinically in order to avoid the danger of tumor cell spread via invasive diagnostic tools. Nevertheless, genetic analysis of the pathology is gaining more importance and adds to the precise characterization of the diagnosis. Depending on the tumor entity, therapy in a specialized center is necessary.

Tumoren und Pseudotumoren der Netzhaut und des Ziliarepithels

Die Varietät retinaler Tumoren reicht von harmlosen Läsionen über benigne, lokal destruierende Tumoren bis hin zu lebensbedrohlichen Erkrankungen. Nicht immer lassen sie sich einfach voneinander unterscheiden. Die Diagnose sollte nach Möglichkeit klinisch gestellt werden wegen der Gefahr einer Tumorzellverschleppung durch invasive Diagnostik. Jedoch rückt die genetische Charakterisierung der Läsion immer mehr in den Vordergrund. Je nach Entität ist eine Therapie in einem spezialisierten Zentrum notwendig.

The Interdisciplinary Diagnosis and Treatment of Intraocular Tumors

BACKGROUND

Recent years have seen major changes in the diagnosis and treatment of solid intraocular tumors, mainly owing to an improved molecular biological understanding of their pathogenesis, new therapeutic approaches for the local treatment of tumors in children, and long-term follow-up observations in clinical trials.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

Retinoblastoma is the most common type of primary intraocular tumor, with approximately 8000 new cases per year around the world, while malignant melanoma of the uvea is the most common primary intraocular tumor in adults, with approximately 7000 new cases per year around the world. Intraocular metastases of malignant tumors are ten times more common, in terms of incidence, than primary intraocular tumors and are therefore the most common intraocular tumors overall. Improved methods of intraocular biopsy, diagnostic imaging, and molecular genetic investigation have led to steady improvement in clinical and predictive diagnostic assessment. In the treatment of retinoblastoma, local techniques including brachytherapy and intra-arterial and intravitreal chemotherapy play a prominent role. Prognostic molecular-genetic testing now enables the highly selective identification of uveal melanomas that have a high potential to metastasize. Cutaneous and uveal melanomas differ both in their clinical behavior and in their basic biological features; to date, effective systemic treatment has been established for melanoma of the skin, but not for metastatic melanoma of the uvea. Intraocular metastases are common and often the initial manifestation of an extraocular tumor, particularly lung cancer.

CONCLUSION

Modern diagnostic and therapeutic concepts for intraocular tumors can only be implemented through the close interdisciplinary collaboration of ophthal - mologists, oncologists, radiologists, radiotherapists, pathologists, and human geneticists.