MDM2 gene SNP309 T/G and p53 gene SNP72 G/C do not influence diffuse large B-cell non-Hodgkin lymphoma onset or survival in central European Caucasians

Pharmacogenetics in diffuse large B-cell lymphoma treated with R-CHOP: Still an unmet challenge

DLBCL is the most common lymphoma representing approximately one third of all non-Hodgkin lymphomas and about 40% of patients do not benefit of the standard first-line immune-chemotherapeutic treatment (i.e., R-CHOP - rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) that is administered as upfront therapy to substantially all patients independently from the stage of disease and other prognostic parameters. The administration of other pharmacological treatments is in fact limited to selected patients, unfitting for R-CHOP. Although clinical prognostic scores, i.e. International Prognostic Index (IPI), and molecular classifiers based on the cell of origin are available, at present no biomarkers predictive of R-CHOP response has been identified and validated. Constitutional polymorphisms of genes involved in the mechanism of action of drugs included in R-CHOP have been suggested by many authors to play a role in the efficacy and in some case in the toxicity of this treatment. Thus, it is conceivable that in the future, after proper validation, some polymorphisms can be used as pharmacogenetic biomarkers of therapeutic outcome in this disease setting. This review discusses the status of the art on molecular biomarkers predictive of DLBCL prognosis and deals with the relevant issue of the variability in response to DLBCL drug treatment. Overall, this review focuses on single nucleotide polymorphisms (SNPs) that, based on a candidate gene approach or on a GWAS analysis, have been suggested to play a role in response to R-CHOP. In particular, SNPs discovered by a candidate gene approach are related to gene involved in drug transport (i.e. ATP-binding cassette transporters), drug metabolism, drug detoxification enzymes, oxidative stress, apoptosis, DNA repair, immunity and angiogenesis. Data from a GWAS analysis performed in DLBCL patients treated with R-CHOP, identified two SNPs associated with clinical outcomes related to genes involved in pivotal cellular processes and in transcriptional regulation and cell cycle progression, respectively. Ongoing prospective pharmacogenetic clinical trials, including a GWAS study we performed, have also been discussed.

A comprehensive evaluation of single nucleotide polymorphisms associated with hepatocellular carcinoma risk in Asian populations: A systematic review and network meta-analysis

BACKGROUND

Single nucleotide polymorphisms (SNPs) have been inconsistently associated with hepatocellular carcinoma (HCC) risk. This meta-analysis aimed to synthesize relevant data on SNPs associated with HCC in the Asian population.

METHODS

Databases were searched to identify association studies of SNPs and HCC in Asians published through January 2019. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated based on 41 studies (13,167 patients with HCC and 15,886 noncancer controls). Network meta-analysis and Thakkinstian's algorithm were used to select the most appropriate genetic model, along with false positive report probability (FPRP) for noteworthy associations.

RESULTS

Eleven SNPs meeting the inclusion criteria were tested for association with HCC, including CCND1 rs9344, PTGS2 rs689466, IL18 rs187238 and rs1946518, KIF1B rs17401966, MDM2 rs2279744, MIR146A rs2910164, MIR149 rs2292832, MIR196A2 rs11614913, MIR499A rs3746444, and TGFB1 rs1800469. A significant increase for HCC risk was observed for MDM2 rs2279744, and the dominant (pooled OR = 1.59, 95% CI: 1.26-2.00) and codominant (pooled OR = 1.37, 95% CI: 1.18-1.60) models were determined to be the most appropriate models. MIR499A rs3746444 also showed a significant association with HCC risk under the allele contrast model (pooled OR = 1.36, 95% CI: 1.05-1.77). Only the significance of MDM2 rs2279744 was noteworthy (FPRP < 0.2).

CONCLUSIONS

MDM2 rs2279744 is associated with HCC susceptibility in Asians, and the dominant and codominant models are likely the most appropriate models to estimate HCC risk.

TP53 Arg72 as a favorable prognostic factor for Chinese diffuse large B-cell lymphoma patients treated with CHOP

Background

TP53 Arg72Pro (SNP rs1042522) is associated with risk of non-Hodgkin lymphoma (NHL). Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of NHL. However, the relationship between this SNP and prognosis of DLBCL in Asians is unknown.

Methods

Genotyping of TP53 Arg72Pro was done in 425 Chinese DLBCL patients. Two hundred and eighty-nine patients were treated with R-CHOP, and 136 patients received CHOP or CHOP-like as frontline regimen. Three hundred and ninety-six patients were assessable for the efficacy.

Results

Patients with Arg/Arg and Arg/Pro at codon 72 of TP53 had a higher complete response rate (61% vs. 44%, P = 0.007) than those with Pro/Pro. In the subgroup treated with CHOP or CHOP-like therapy, patients with Arg/Arg and Arg/Pro showed a higher 5-year overall survival (OS) rate than those with Pro/Pro (68.8% vs. 23.2%, P = 0.001). Multivariate Cox regression analysis revealed TP53 Arg72 as a favorable prognostic factor in this group. However, the combination of rituximab with CHOP significantly increased the 5-year OS rate of patients with Pro/Pro to 63%.

Conclusion

This study revealed TP53 Arg72 as a favorable prognostic factor for Chinese DLBCL patients treated with CHOP or CHOP-like as frontline therapy.

Diffuse large B-cell lymphoma with combined TP53 mutation and MIR34A methylation: Another "double hit" lymphoma with very poor outcome?

MiR34A, B and C have been implicated in lymphomagenesis, but information on their role in normal CD19+ B-cells (PBL-B) and de novo diffuse large B-cell lymphoma (DLBCL) is limited.

We show that in normal and activated B-cells miR34A-5p plays a dominant role compared to other miR34 family members. Only miR34A-5p is expressed in PBL-B, and significantly induced in activated B-cells and reactive lymph nodes. In PBL-B, the MIR34A and MIR34B/C promoters are unmethylated, but the latter shows enrichment for the H3K4me3/H3K27me3 silencing mark.

Nine de novo DLBCL cases (n=150) carry both TP53 mutation and MIR34A methylation (“double hit”) and these patients have an exceedingly poor prognosis with a median survival of 9.4 months (P<0.0001), while neither TP53 mutation, MIR34A or MIR34B/C promoter methylation alone (“single hit”) influence on survival. The TP53/MIR34A “double-hit” is an independent negative prognostic factor for survival (P=0.0002). In 2 DLBCL-cell lines with both TP53 mutation and promoter methylation of MIR34A, miR34A-5p is upregulated by 5-aza-2'deoxycytidine. Thus, the TP53/MIR34A “double hit” characterizes a very aggressive subgroup of DLBCL, which may be treatable with epigenetic therapy prior to or in combination with conventional immunochemotherapy.

The functional TP53 rs1042522 and MDM4 rs4245739 genetic variants contribute to Non-Hodgkin lymphoma risk

As a heterogeneous kind of malignances, Non-Hodgkin lymphoma (NHL) is the most common hematologic cancer worldwide with the significantly increased morbidity in China. Accumulated evidences demonstrated that oncoprotein MDM4 plays a crucial role in the TP53 tumor suppressor signaling pathway. An rs4245739 A>C polymorphism locating in the MDM4 3′-untranslated region creates a miR-191 target site and results in allele-specific MDM4 expression. In this study, we examined the association between this polymorphism as well as the TP53 Arg72Pro (rs1042522 G>C) genetic variant and Non-Hodgkin Lymphoma (NHL) risk in a Chinese Han population. Genotypes were determined in 200 NHL cases and 400 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression. We found significantly increased NHL risk among carriers of the TP53 72Pro allele compared with those with the 72Arg allele (P = 0.002 for the Pro/Pro genotype). We also observed a significantly decreased NHL risks among carriers of the MDM4 rs4245739 C allele compared with those with the A allele in Chinese (P = 0.014 for the AC genotype). Stratified analyses revealed the associations between these SNPs and NHL risk are especially noteworthy in young or male individuals. Additionally, the associations are much pronounced in NHL patients with B-cell lymphomas or grade 3 or 4 disease. Our results indicate that the TP53 Arg72Pro and the MDM4 rs4245739 polymorphisms contribute to NHL susceptibility and support the hypothesis that genetic variants in the TP53 pathway genes can act as important modifiers of NHL risk.

The p53 Mutation/Deletion Profile in a Small Cohort of the Omani Population with Diffuse Large B-Cell Lymphoma

OBJECTIVES

Mutations/deletions affecting the TP53 gene are considered an independent marker predicting a poor prognosis for patients with diffuse large B-cell lymphoma (DLBCL). A cohort within a genetically isolated population was investigated for p53 mutation/deletion status.

METHODS

Deoxyribonucleic acid (DNA) samples were extracted from 23 paraffin-embedded blocks obtained from DLBCL patients, and subjected to polymerase chain reaction (PCR) amplification and sequencing of exons 4-9 of the p53 gene.

RESULTS

While 35% of patients analysed displayed allelic deletions (P <0.01), immunohistochemical analysis revealed a mutation rate of 69.5%. It is noteworthy that the rate of p53 mutations/deletions in this small cohort was found to be higher than that previously reported in the literature. Interestingly, patients with p53 mutations displayed a better overall survival when compared to those without. The survival of patients treated with rituximab-containing combination chemotherapy was significantly better than those who did not receive rituximab (P <0.05). Furthermore, a modelling analysis of the deleted form of p53 revealed a huge structural change affecting the DNA-binding domain.

CONCLUSION

The TP53 mutation/deletion status plays a role in mechanism(s) ruling the pathogenesis of DLBCL and may be useful for stratifying patients into distinct prognostic subsets.

MDM2 phenotypic and genotypic profiling, respective to TP53 genetic status, in diffuse large B-cell lymphoma patients treated with rituximab-CHOP immunochemotherapy: a report from the International DLBCL Rituximab-CHOP Consortium Program

MDM2 is a key negative regulator of the tumor suppressor p53, however, the prognostic significance of MDM2 overexpression in diffuse large B-cell lymphoma (DLBCL) has not been defined convincingly. In a p53 genetically-defined large cohort of de novo DLBCL patients treated with rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone (R-CHOP) chemotherapy, we assessed MDM2 and p53 expression by immunohistochemistry (n = 478), MDM2 gene amplification by fluorescence in situ hybridization (n = 364), and a single nucleotide polymorphism in the MDM2 promoter, SNP309, by SNP genotyping assay (n = 108). Our results show that MDM2 overexpression, unlike p53 overexpression, is not a significant prognostic factor in overall DLBCL. Both MDM2 and p53 overexpression do not predict for an adverse clinical outcome in patients with wild-type p53 but predicts for significantly poorer survival in patients with mutated p53. Variable p53 activities may ultimately determine the survival differences, as suggested by the gene expression profiling analysis. MDM2 amplification was observed in 3 of 364 (0.8%) patients with high MDM2 expression. The presence of SNP309 did not correlate with MDM2 expression and survival. This study indicates that evaluation of MDM2 and p53 expression correlating with TP53 genetic status is essential to assess their prognostic significance and is important for designing therapeutic strategies that target the MDM2-p53 interaction.

p53 codon 72 polymorphism and hematological cancer risk: an update meta-analysis

Background

Previous studies on the association of p53 codon 72 (Arg72Pro) polymorphism with hematological malignancies risk have produced conflicting results. The purpose of this meta-analysis is to define the effect of p53 Arg72Pro polymorphism on hematological malignancies risk.

Methodology/Principal Findings

Through searching PubMed databases (or hand searching) up to April 2012 using the following MeSH terms and keywords: “p53”, “codon 72” “polymorphism” and “leukemia”, or “lymphoma”, or “myeloma”, thirteen were identified as eligible articles in this meta-analysis for p53 Arg72Pro polymorphism (2,731 cases and 7, 356 controls), including nine studies on leukemia (1,266 cases and 4, 474 controls), three studies on lymphoma (1,359 cases and 2,652 controls), and one study on myeloma. The overall results suggested that p53 Arg72Pro polymorphism was not associated with hematological malignancies risk. In stratified analyses, significantly increased non-Hodgkin lymphomas risk was found in p53 Arg72Pro polymorphism heterozygote model (Arg/Pro vs. Arg/Arg: OR = 1.18, 95%CI: 1.02–1.35) and dominant model (Arg/Pro+Pro/Pro vs. Arg/Arg: OR = 1.18, 95%CI: 1.03–1.34), but no significant association was found between leukemia risk and p53 Arg72Pro polymorphism. Further studies showed no association between leukemia risk and p53 Arg72Pro polymorphism when stratified in subtypes of leukemias, ethnicities and sources of controls.

Conclusions/Significance

This meta-analysis indicates that the p53 Arg72Pro polymorphism may contribute to susceptibility to non-Hodgkin lymphomas.

Influence of MDM2 and MDM4 on development and survival in hereditary retinoblastoma

BACKGROUND

Retinoblastoma (RB) accounts for 3% of all childhood malignancies, with different incidences around the world. This malignancy results from loss-of-function of both RB1 alleles although other genes, like MDM2 and MDM4, have been proposed to be involved in tumor development.

PROCEDURE

We genotyped rs2279744T>G and rs937283A>G in MDM2, and rs4252668T>C and rs116197192G>A in MDM4, in 104 unrelated RB patients and 104 controls. Sixty-month survival Kaplan-Meier curves and χ(2)-tests were performed for estimating the putative effect of MDM2 and MDM4 alleles on disease progression and survival of RB patients.

RESULTS

MDM2 rs2279744G was significantly more frequent in controls, indicating an apparently protective effect on RB development. However, survival of patients who carried a constitutional RB1 mutation was significantly lower with rs2279744TG or GG than with rs2279744TT. Presence of rs2279744G and a constitutional RB1 mutation was sixfold more frequent in the 0-12 month age group than other age groups at onset of symptoms (P = 0.0401). MDM4 rs4252668C was present at a significantly higher frequency in controls while the frequency of MDM4 rs116197192G was significantly higher in RB patients, suggesting that this allele might increase the risk of developing RB.

CONCLUSION

Our results indicate that MDM2 and MDM4 polymorphisms may influence development and/or survival in RB.

No association between the TP53 codon 72 polymorphism and risk or prognosis of Hodgkin and non-Hodgkin lymphoma

The role of the TP53 gene's R72P polymorphism in non-Hodgkin lymphoma (NHL) has been analyzed in several studies but it has not been studied in Hodgkin lymphoma (HL). We have evaluated the role of R72P in 340 NHL and 298 HL patients. There was no difference in the R72P frequency between analyzed lymphoma cases and 749 controls. We found no association of R72P with the risk of NHL and HL development [OR(ArgPro/ProPro)=0.9 (95% CI 0.7-1.2) and 1.2 (95% CI 0.9-1.5), respectively] or with survival. Our results support the evidence that R72P is not a prognostic factor in Caucasian NHL patients, and they indicate its irrelevance for HL development or prognosis.

A single-nucleotide polymorphism in the TP53 and MDM-2 gene modifies breast cancer risk in an ethnic Arab population

Breast cancer is the most common oncological disease in women worldwide. Genetic predisposition to breast cancer can be associated with single-nucleotide polymorphisms (SNPs), which are observed in many women. Such gene polymorphisms, in combination with nutritional and environmental factors, can affect breast cancer development. The tumor suppressor TP53 and its negative regulator MDM2 play crucial roles in carcinogenesis. Previous case-control studies have revealed that TP53 72Arg > Pro and MDM2 309T > G polymorphisms contribute to the risk of common cancers. However, the relationship between these two functional polymorphisms and breast cancer susceptibility in the Saudi population has not been explored. In this study, we performed a case-control study of patients with breast cancer and healthy controls in a Saudi population using TaqMan-based real-time PCR. We found an increased breast cancer risk associated with the MDM2 GG [odds ratio (OR) = 2.79, 95% confidence interval (CI) = 2.04-3.92] and TG [OR = 1.43, 95% CI = 1.12-2.02] genotypes. An increased risk was also associated with the TP53 Pro/Pro genotype (OR = 2.19, 95% CI = 1.54-3.06) compared with the Arg/Arg genotype. The gene-gene interaction of MDM2 and TP53 polymorphisms increased breast cancer risk in a multiplicative manner (OR for the presence of both MDM2 GG and TP53 Pro/Pro genotypes = 7.71, 95% CI = 3.49-17.54). These findings suggest that polymorphisms of MDM2 and TP53 genes may be a genetic modifier for developing breast cancer in this ethnic population in the Arab world.

Prognostic impact of the MDM2SNP309 allele in leukemia and lymphoma

A T-to-G germline single nucleotide polymorphism in the promoter region of MDM2 (SNP309) has been reported to markedly accelerate tumor formation in humans suggesting that it may represent a powerful cancer predisposing allele. Since its first description in 2004, a large number of retrospective analyses involving a wide variety of human malignancies have been reported, showing conflicting results regarding the impact of Mdm2SNP309 status on cancer risk and response to cancer therapy. Here, we appraise the available information on the effect of Mdm2SNP309 in lymphoma and leukemia and discuss the factors that likely account for the conflicting results observed in the studies reported to date.

Prognostic impact of the MDM2SNP309 allele in leukemia and lymphoma

A T-to-G germline single nucleotide polymorphism in the promoter region of MDM2 (SNP309) has been reported to markedly accelerate tumor formation in humans suggesting that it may represent a powerful cancer predisposing allele. Since its first description in 2004, a large number of retrospective analyses involving a wide variety of human malignancies have been reported, showing conflicting results regarding the impact of Mdm2SNP309 status on cancer risk and response to cancer therapy. Here, we appraise the available information on the effect of Mdm2SNP309 in lymphoma and leukemia and discuss the factors that likely account for the conflicting results observed in the studies reported to date.

Single-nucleotide polymorphisms in the p53 signaling pathway

The p53 tumor suppressor pathway is central both in reducing cancer frequency in vertebrates and in mediating the response of commonly used cancer therapies. This article aims to summarize and discuss a large body of evidence suggesting that the p53 pathway harbors functional inherited single-nucleotide polymorphisms (SNPs) that affect p53 signaling in cells, resulting in differences in cancer risk and clinical outcome in humans. The insights gained through these studies into how the functional p53 pathway SNPs could help in the tailoring of cancer therapies to the individual are discussed. Moreover, recent work is discussed that suggests that many more functional p53 pathway SNPs are yet to be fully characterized and that a thorough analysis of the functional human genetics of this important tumor suppressor pathway is required.

Genetic polymorphisms of MDM2 and TP53 genes are associated with risk of nasopharyngeal carcinoma in a Chinese population

Background

The tumor suppressor TP53 and its negative regulator MDM2 play crucial roles in carcinogenesis. Previous case-control studies also revealed TP53 72Arg>Pro and MDM2 309T>G polymorphisms contribute to the risk of common cancers. However, the relationship between these two functional polymorphisms and nasopharyngeal carcinoma (NPC) susceptibility has not been explored.

Methods

In this study, we performed a case-control study between 522 NPC patients and 722 healthy controls in a Chinese population by using PCR-RFLP.

Results

We found an increased NPC risk associated with the MDM2 GG (odds ratio [OR] = 2.83, 95% confidence interval [CI] = 2.08-3.96) and TG (OR = 1.49, 95% CI = 1.16-2.06) genotypes. An increased risk was also associated with the TP53 Pro/Pro genotype (OR = 2.22, 95% CI = 1.58-3.10) compared to the Arg/Arg genotype. The gene-gene interaction of MDM2 and TP53 polymorphisms increased adult NPC risk in a more than multiplicative manner (OR for the presence of both MDM2 GG and TP53 Pro/Pro genotypes = 7.75, 95% CI = 3.53-17.58).

Conclusion

The findings suggest that polymorphisms of MDM2 and TP53 genes may be genetic modifier for developing NPC.

Mutational analysis of TP53, PTEN, PIK3CA and CTNNB1/beta-catenin genes in human herpesvirus 8-associated primary effusion lymphoma

Human herpesvirus 8 (HHV-8)-associated primary effusion lymphoma is a rare non-Hodgkin's lymphoma often associated with Epstein-Barr virus (EBV) infection. Mutations in TP53, PTEN, PIK3CA, CTNNB1/beta-catenin genes and deletion of CDKN2A-ARF (p14(ARF)-p16(NK4a I) ) locus were investigated in sixteen primary primary effusion lymphoma tumors and seven primary effusion lymphoma cell lines using PCR and sequencing. TP53 mutations were detected in one primary primary effusion lymphoma tumor (6.2%) and two primary effusion lymphoma cell lines (28.6%). BC-3 and BCP-1 cell lines showed PTEN gene mutations, associated with a loss of PTEN protein expression in both cases. No mutations were detected in PIK3CA and CTNNB1/beta-catenin hotspot sequences. Only BC-3 contained a homozygous deletion of CDKN2A-ARF locus. Although detected at a higher frequency in primary effusion lymphoma cell lines than in primary primary effusion lymphoma tumors, TP53 and/or PTEN mutations, as well as deletion of CDKN2A-ARF locus are uncommon in primary effusion lymphoma, and are found to correlate with the EBV-negative status of primary effusion lymphoma tumors.