Molecular genetic profiling of Filipino patients with retinoblastoma: A preliminary study

Objective@#To detect and characterize retinoblastoma susceptibility gene (RB1) mutations in tumor samples collected from Filipino patients with retinoblastoma.@*Methods@#Six tumor samples were obtained from Filipino patients diagnosed with retinoblastoma. DNA was extracted from the tumor samples and exons 13-21 of the RB1 gene were amplified by polymerase chain reaction (PCR). PCR amplification products were subsequently purified and sequenced. Mutation detection and characterization were done by alignment of obtained sequences to the RB1 reference sequence from NCBI GenBank using Bioedit® software. The identified mutations were correlated with clinical presentation and family history. These mutations were also compared to known mutations reported in the RB1 Gene Mutation Leiden Open Variation Database (LOVD).@*Results@#Mutations were detected in two out of the six samples. In a patient with unilateral disease and no family history, two mutations were identified: a novel CGT>AGT (Arginine → Serine) missense mutation in position c.1861 of exon 19 and a previously reported CGA>TGA (Arginine → STOP) nonsense mutation in position c. 1735 of exon 18. A possible large exonic deletion was identified in a case of unilateral disease with no family history.@*Conclusion@#We were able to identify both novel and known mutations in the RB1 gene of Filipino retinoblastoma cases using DNA sequencing techniques. These techniques may be applied to further characterize the genetic mutations of Filipino retinoblastoma cases and their families in developing a rational method of genetic testing for early diagnosis and counseling.

The Genetic Alterations of Retinoblastoma Gene in Human Gliomas

The formation and malignant progression of gliomas are generally considered to undergo multistepped process like other tumors. Loss of 13q is implicated in the later stage of progression of gliomas. The retinoblastoma susceptibility gene(RB gene), located at the 13q14, is a prototypic tumor suppressor gene. Many kinds of tumors are noted to have mutations of the RB gene. To determine whether the loss of 13q is associated with RB gene or not, and to find the intragenic mutation of RB, we examined 28 gliomas for loss of heterozygosity(LOH) at the RB locus using a polymerase chain reaction-based restriction fragment length polymorphism(PCR-based RFLP) assay. We found LOH in 13 of 28(46%) gliomas. Eight of 12(67%) high-grade astrocytomas, 3 of 6(50%) differentiated astrocytomas showed LOH. And we also detected LOH in 1 of 2 anaplastic oligodendrogliomas and in 1 of 7(14%) differentiated oligodendrogliomas. When we classify them into low-grade and high-grade gliomas, 4 of 14(29%) low-grade gliomas, and 9 of 14(64%) high-grade gliomas showed LOH, PCR-SSCP analysis was performed on exon, 8, 14, 15, 16, 19, 20, 21, 22, 24 to find mutations in remaining allele, and one case of mobility shift was identified in glioblastoma multiforme which showed LOH in PCR-based RFLP study. Our results demonstrate that RB deletions are detected in both low-grade high-grade gliomas, and unlike the p53 gene, genetic alterations of the RB gene in gliomas are mainly deletions rather than point mutations.

Expression and clinical significance of Rb gene and MCM2 in prostate cancer / 重庆医科大学学报

Objective: To study the expression of retinoblastoma susceptibility gene(Rb) and minichromosome maintenance protein 2(MCM2) in primary prostate cancer(PCa) and its clinical significance.Methods: The expression of MCM2 protein and pRb were detected in 49 cases of PCa,20 cases of benign prostate hyperplasia(BPH),10 cases of normal prostate tissues(NP) by EliVisionTM plus immunohistochemical staining.Results: The positive expression rate of pRb in PCa,BPH,NP were 44.90%,80% and 90% respectively.The expression level of pRb in PCa was significantly lower than that in BPH(P