Higher frequency of p53 gene mutations in diffuse large B-cell lymphoma with MALT component.
ABSTRACT p53 gene mutation is not a frequent event in the tumorigenesis of lymphomas and the expression of p53 protein is independent of p53 gene mutations. The present study aimed to investigate mutations in the p53 gene in a series of extranodal B-cell lymphomas, and its association with p53 protein expression. A total of 52 cases were graded histologically into Grade 1, Grade 2 and Grade 3 tumors and p53 protein expression was detected using immunohistochemistry. Mutations in the p53 gene were analyzed using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) and mobility shifts were confirmed by direct sequencing. The tumors comprised 26 (50%) Grade 1, 9 (17%) Grade 2 and 15 (29%) Grade 3. A high proportion of Grade 2 (25%) tumors expressed p53 protein (P = 0.051) and carried p53 gene mutation (33%) (P = 0.218). However, p53 protein expression was not associated with p53 gene mutations (P = 0.057). Transversion mutations (88%) were more frequently detected than transition mutations (12%). The present study revealed that p53 gene mutations and p53 protein expression occurred in higher frequencies in Grade 2 tumors, which may be of pathogenetic importance. The high frequency of transversion mutations may reflect the influence of an etiological agent in the tumorigenesis of mucosa-associated lymphoid tissue (MALT lymphoma).
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- "In lymphomas , the incidence of TP53 mutations and other abnormalities varies significantly according to histological subtype and disease stage . Generally , a low mutation rate is observed in low - grade non - Hodgkin lymphoma ( NHL ) , whereas a higher incidence is observed in many aggressive NHL subtypes , especially in those derived from transformation of low - grade NHL ( Lo Coco et al , 1993 ; Sander et al , 1993 ; Tai et al , 2004 ) . Studies have consistently demonstrated that TP53 abnormalities , including overexpression , allelic loss , and mutations , have all been associated with poor treatment response and shorter survival ( Peller & Rotter , 2003 ) . "
ABSTRACT: The tumour suppressor TP53 (previously termed p53) mediates a pathway that is considered to be one of the most important mechanisms in the maintenance of genomic stability. The function of TP53 can be abrogated by genomic deletion, mutation, or deregulation of upstream and downstream participants in the TP53 pathway. While aberrations of TP53 are widely prevalent in non-haematological malignancies (over 60%), they are present in much lower frequency in haematological malignancies (<20%). Nevertheless, in those cases where TP53 function or expression is aberrant, correlation with inferior clinical outcome (such as overall survival and progression or transformation) has generally been strong. In this review, we focus our discussion on the relationship between TP53 and lymphoid malignancies as defined by the World Health Organization. Specifically, we examine the prevalence of TP53 aberrations and their prognostic significance in various types of lymphoid cancer. Next, we discuss the various mechanisms of TP53 inactivation. Finally, we summarize progress in the use of recent therapeutic modalities that target TP53.British Journal of Haematology 06/2009; 146(3):257-69. DOI:10.1111/j.1365-2141.2009.07739.x · 4.96 Impact Factor
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ABSTRACT: Mutations in p53 gene exons 5-9 were studied in 44 non-Hodgkin's lymphomas (NHL) consisting of 35 B-NHL and 9 T-NHL. Missense mutations were found in two diffuse large B-cell lymphomas (DLBL) and one peripheral T-cell lymphoma (unspecified). Double transversion missense and nonsense mutations were detected in one DLBL and one adult T-cell leukemia/lymphoma. Silent mutations were found in two DLBL. Detailed histomorphological study showed that cases harboring p53 missense mutation with/without nonsense mutation tended to have larger nuclei with much more prominent nucleoli. Cytomorphometric analysis was therefore conducted by measuring the gross area of 100 lymphoma cell nuclei in 44 cases and the results were compared between lymphomas harboring p53 missense mutation with/without nonsense mutation and lymphomas harboring p53 silent mutation or lacking mutation. It was found that the lymphomas harboring p53 missense mutation with/without nonsense mutation had a highly significantly larger nuclear gross area than lymphomas with silent p53 mutation or lacking mutation (two-sample t-test, P < 0.00001; Exact Wilcoxon rank-sum test, P < 0.00001). This result suggests that p53 mutation might induce enlargement of neoplastic cell nuclei by some molecular mechanism.Pathology International 08/2007; 57(7):430-6. DOI:10.1111/j.1440-1827.2007.02119.x · 1.59 Impact Factor
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ABSTRACT: Although lymphomas involving the prostate gland are rare, they should always be considered in the differential diagnosis. We report a case of primary prostatic NHL in a 70-year-old man presented with hematuria and urinary obstructive symptoms. Routine laboratory tests were within normal limits and prostate-specific antigen (PSA) was 0,01 ng/ml. The patient underwent radical prostatectomy. Histologically, two different coexisting patterns of non-Hodgkin lymphoma, infiltrating the prostatic tissue, were identified. The diagnosis of diffuse large B-cell lymphoma (DLBCL) presenting with an associated low-grade lymphoma of MALT-type was confirmed by immunohistochemistry. The patient received chemotherapy without any complication and has been followed-up for 2 years since surgical resection with no recurrence. The clinicopathologic characteristics of prostatic lymphomas are discussed, while reviewing the current English-language literature.Hippokratia 01/2012; 16(1):86-9. · 0.36 Impact Factor