Outcomes associated with retinoblastoma and c-myc gene expression in patients with testicular cancer: A ten-year experience

Abstract

14656 Purpose: To determine and correlate the protein and mRNA expression of c-myc and Rb genes in normal testicular tissue and testicular cancer as possible markers of pharmacological response. Methods: Eleven fresh testicular cancer surgical specimens were obtained from untreated patients with histological diagnosis of seminoma (9/11) and non seminoma (2/11) during the period of 1992 to 1995. Age patient average was 35 (16–74). Two normal human testicular tissues also were evaluated as control. Single and double immunohistochemical assay was performed with peroxidase anti-peroxidase system using polyclonal antibody anti-pRb C-15 and monoclonal antibody anti- c-myc 1. Non radioactive in situ hybridization with cRNA probes was performed with cDNA from Rb (exons 2–27) and c-myc (exons 2,3). All seminomas were stage I and were treated with radiotherapy. Non-seminomas were stage III and were treated with chemotherapy. Results: Histological findings: Rb protein was expressed in mature cells toward the lumen of normal testicular tissue while c-myc was located in basal cells but decreasing the expression toward the lumen. High correlation between mRNA and protein levels for both genes was observed in normal testicular tissue. Rb protein and mRNA was absent in 6/11 (55%) tumors while the remaining showed a low level expression (45%). A high c-myc expression was observed in 6/11 (55%) seminomas specimens correlating in a few cases with absent Rb expression. Percentage of positive cells to c-myc gene expression (mRNA and protein) was highly increased in tumoral samples. Clinical findings: All patients with seminoma (9/11) and one of non seminoma (1/11) are alive and without tumoral activity a ten years of the diagnosis. A non-seminoma patient (1/11) have 11-year survival, a high expression of c-myc gene and absent retinoblastoma expression was observed in this case. Conclusion: The semiquantitative differences observed on c-myc and Rb gene expression in seminoma and non-seminoma tumors might correlate with the biological behavior including their high proliferation rate and the chemosensitivity. No significant financial relationships to disclose.