p53 polymorphisms: cancer implications

Susceptibility of Multiple Primary Cancers in Patients With Head and Neck Cancer: Nature or Nurture?

Multiple primary cancers (MPCs) are major obstacles to long-term survival in head and neck cancer (HNSCC), however, the molecular mechanism underlying multiple carcinogenesis remains unclear. “Field cancerization” is a classical theory to elaborate the malignant progression of MPCs. Apart from environmental and immune factors, genetic factors may have great potential as molecular markers for MPCs risk prediction. This review focuses on inherited and acquired gene mutations in MPCs, including germ-line mutation, single-nucleotide polymorphism, chromosomal instability, microsatellite instability and DNA methylation. And definition and prognosis of MPCs have also been discussed. These may pave the way for the early detection, prevention and effective treatment of MPCs in HNSCC.

Mutant p53 drives cancer chemotherapy resistance due to loss of function on activating transcription of PUMA

P53 is a critical tumor suppressor gene, activating p53 and its downstream targets to induce apoptosis is a promising way for cancer therapy. However, more than 50% of cancer patients have p53 mutations, which may cause cancer therapy resistance, and the underline mechanism is poorly understood. Here, we found that cell viability decrease and apoptosis induced by p53-dependent traditional drugs in colon cancer cells were eliminated in p53 mutant cells. Mutant p53 did not up-regulate the expression of its direct downstream targets PUMA and p21, due to the inhibition of PUMA transcription. Furthermore, mutant p53 could not bind to the promoter of PUMA to activate its transcription like WT p53 did, while overexpressed WT p53 rescued PUMA-induced subsequent apoptosis. In conclusion, our findings demonstrate mutant p53 may cause chemo-resistance of tumor because of inactivating PUMA transcription, which prompts some new insights for clinical therapy of cancer patients with mutant p53.Abbreviations: CRC: Colorectal cancer; CDKs: Cyclin-dependent kinases; PUMA: p53 up-regulated modulator of apoptosis; PDGF: the platelet-derived growth factor; WT p53: wild-type p53 protein; mutp53: mutant p53 proteins; BAX: Bcl-2-associated X protein; NOXA: Phorbol-12-myristate-13-acetate-induced protein 1.

Protective Effects of Garlic and Cinnamon Oils on Hepatocellular Carcinoma in Albino Rats

Natural oils are traditional medicinal herbs, which have attracted interests for its potential anti-inflammatory and anticancer activities. The present work is aimed at evaluating the protective effect of garlic oil and cinnamon oil on diethylnitrosamine- (DENA-) and 2-acetylaminofluorene- (2-AAF-) induced p53 gene mutation and hepatocarcinogenesis in rats. Forty male albino rats were divided into 4 equal groups: control, hepatocellular carcinoma (HCC), garlic oil-HCC, and cinnamon oil-HCC. The HCC-induced group showed a significant decrease in the body mass and a significant elevation in the liver weight, alpha-fetoprotein (AFP), liver enzymes, hepatic malondialdehyde (MDA), and p53 protein expression levels as well as genetic mutations in intron 5 of p53 gene in the form of Single-Nucleotide Polymorphisms (SNPs) and insertions. In addition, the glutathione (GSH) level and superoxide dismutase (SOD) activities were increased. While HCC rats pretreated with garlic oil or cinnamon oil were significantly reversed, these destructive actions increased GSH and SOD levels. The HCC-induced group showed histopathological features of liver cancer including hypercellularity, nuclear hyperchromasia, mitotic figures, and preneoplastic foci. On the other hand, HCC rats pretreated with garlic oil or cinnamon oil revealed partial reversal of normal liver architecture. The present findings proposed that these natural oils have the ability to improve liver function, significantly reduced the liver toxicity and HCC development. However, further sophisticated studies are recommended before their use as conventional therapeutics for HCC treatment.

The Dilemma of TP53 Codon 72 Polymorphism (rs1042522) and Breast Cancer Risk: A Case-Control Study and Meta-Analysis in The Iranian Population

Objective

Mutations of TP53 as a tumor suppressor gene are frequently observed in different types of cancer. A codon 72 polymorphism located on exon 4 with two alleles encoding either Proline (CCC) or Arginine (CGC) has been indicated as a common variation in association with cancers. Controversial results have been reported regarding the association of allelic polymorphism of codon 72 of TP53 gene and breast cancer risk in Iranian patients. Therefore, a case-control study was designed. A meta-analysis was also carried out to provide evidence of association between this variation and breast cancer in Iran, based on all available published data.

Materials and Methods

In this case-control study, blood sample of 622 participants, including 308 breast cancer cases and 314 controls were collected. Genotyping for rs1042522 was conducted by Allele Specific polymerase chain reaction (AS-PCR). In order to set a meta-analysis study, PubMed, Scopus and ISI Web of Knowledge and Persian databases were searched to explore relevant studies, published up to September 2018, containing information on TP53 polymorphism and the risk of breast cancer in Iran. Statistical analysis was performed using SPSS 16.0 and MetaGenyo.

Results

All retrieved available data as well as the results of our current study were consisted of 1965 breast cancer cases and 1999 healthy controls. No significant difference was observed in allele frequencies between groups (P=0.90) in our study. The cumulative results did not also show any association between rs1042522 and breast cancer risk on the dominant (P=0.61) and recessive (P=0.89) models.

Conclusion

These findings cannot support contribution of rs1042522 polymorphism to breast cancer risk in an Iranian population. Future larger studies may help confirm this finding with a greater power. .

The Spatiotemporal Pattern and Intensity of p53 Activation Dictates Phenotypic Diversity in p53-Driven Developmental Syndromes

Inappropriate activation of the p53 transcription factor contributes to numerous developmental syndromes characterized by distinct constellations of phenotypes. How p53 drives exquisitely specific sets of symptoms in diverse syndromes, however, remains enigmatic. Here, we deconvolute the basis of p53-driven developmental syndromes by leveraging an array of mouse strains to modulate the spatial expression pattern, temporal profile, and magnitude of p53 activation during embryogenesis. We demonstrate that inappropriate p53 activation in the neural crest, facial ectoderm, anterior heart field, and endothelium induces distinct spectra of phenotypes. Moreover, altering the timing and degree of p53 hyperactivation substantially affects the phenotypic outcomes. Phenotypes are associated with p53-driven cell-cycle arrest or apoptosis, depending on the cell type, with gene expression programs, rather than extent of mitochondrial priming, largely governing the specific response. Together, our findings provide a critical framework for decoding the role of p53 as a mediator of diverse developmental syndromes.

Genome-wide analysis of differentially expressed lncRNA in sporadic parathyroid tumors

Diagnosis of parathyroid carcinoma on histological examination is challenging. Thousands of differentially expressed lncRNAs were identified on the microarray data between parathyroid cancer and adenoma samples. Four lncRNAs were significantly dysregulated in further validation. The "lncRNA score" calculated from these lncRNAs differentiated parathyroid carcinomas from adenomas. LncRNAs serve as biomarkers for parathyroid cancer diagnosis.

INTRODUCTION

Diagnosis of parathyroid carcinoma (PC) on histological examination is challenging. LncRNA profile study was conducted to find diagnostic biomarkers for PC.

METHODS

LncRNA arrays containing 91,007 lncRNAs as well as 29,857 mRNAs were used to assess parathyroid specimen (5 carcinomas and 6 adenomas). Bioinformatics analyses were also conducted to compare the microarray results between parathyroid carcinomas and adenomas (PAs). Differentially expressed lncRNAs of 11 PCs and 31 PAs were validated by real-time quantitative PCR.

RESULTS

On the microarray data between PC and PA samples (fold change ≥ 2, P < 0.05), 1809 differentially expressed lncRNAs and 1349 mRNAs also were identified. All carcinomas were clustered in the same group by clustering analysis using dysregulated lncRNAs or mRNAs. Four lncRNAs (LINC00959, lnc-FLT3-2:2, lnc-FEZF2-9:2, and lnc-RP11-1035H13.3.1-2:1) identified were significantly dysregulated in further RT-PCR validation. The global "lncRNA score" calculated from the lncRNAs above also differentiated parathyroid carcinomas from adenomas.

CONCLUSIONS

LncRNA profiling shows distinct differentially expressed lncRNAs in parathyroid neoplasm. They may play a key role in parathyroid cancer and serve as potential biomarkers to distinguish parathyroid cancers from parathyroid adenomas.

Genetic polymorphisms of TP53 Arg72Pro and Pro47Ser among Egyptian patients with colorectal carcinoma

BACKGROUND

Previous reports demonstrated the role of TP53 gene polymorphisms with CRC risk among several ethnic populations. The purpose of this study is to assess the association of the TP53 Arg72Pro and Pro47Ser variants with CRC risk among Egyptian patients.

SUBJECTS AND METHODS

This work was conducted on 120 unrelated CRC Egyptian patients who were compared to 140 healthy controls. DNA was genotyped for these variants using the PCR-RFLP technique.

RESULTS

CRC patients observed a significant association of the rare genotype of TP53 Arg72Pro polymorphism compared with healthy controls. On the contrast, all genetic models showed no statistical association of TP53 Pro47Ser polymorphism among CRC patients compared with healthy controls. On the contrast, CRC patients of the TP53 gene polymorphisms indicated no significant difference regarding their clinical and laboratory markers.

CONCLUSIONS

Our findings indicate a strong association with TP53 Arg72Pro variant within increased risk of CRC among Egyptian patients.

Topological Transformation-Based Nanobarcoding for Detection and Enumeration of MicroRNAs and Single Nucleotide Polymorphism

RNA biomarkers have been recently reported to be associated tightly with the diagnosis and prognosis of many diseases. Particularly, cancers considered to be a serious threat to primates are known to be vastly dominated by genetic networks where RNA plays a key role. RNAs are thus recognized as a major target group that can be used for numerous cancer treatments and it is still required to identify and enumerate them in an effective manner. Here, a new topological transformation-based nanobarcoding technique (TNT) is first reported using fluorescence-DNA barcodes engaged with graphene oxide (GO_x ) for effectively discriminating short RNAs such as miRNAs and their single nucleotide polyporphisms in tissue and plasma. Through topological transformation into 3D DNA-RNA polygonal structures, various kinds of microRNAs have been read at the same time and analyzed quantitatively. Also, it positively discerned epidermal growth factor receptor (EGFR) mutations known as single base variations of typical lung cancer specific RNAs. A single variant of 0.785% in target EGFR mutations is explicitly detected. It is speculated that the TNT may be a versatile method for polymerase chain reaction (PCR)-free practical diagnosis of several clinical genetic deviations such as significant biotic RNA and genic fragments and would be a promising alternative to conventional PCR terrains.

Association of the TP53 rs1042522 C>G polymorphism and hepatoblastoma risk in Chinese children

The TP53 gene encodes an important class of cell cycle and tumor-suppressing factors that play critical roles in maintaining genomic stability. The TP53 Arg72Pro (rs1042522 C>G) polymorphism has been reported to be associated with the risk of several types of adult cancers; however, its risk for pediatric cancers remains unclear. Here, we analyzed the association of the TP53 gene rs1042522 C>G polymorphism with hepatoblastoma (HB) susceptibility in a hospital-based study among Chinese children. A total of 213 HB patients and 958 healthy controls were enrolled in the study. Genotypes were determined by a TaqMan assay, and the strength of the association was assessed by the odds ratios and 95% confidence intervals generated from logistic regression models, adjusted for age, gender, and clinical stage. No significant association between the TP53 rs1042522 C>G polymorphism and HB susceptibility was detected in the main analysis or in stratification analyses of age, gender, and clinical stages. Overall, the TP53 gene rs1042522 C>G polymorphism is not associated with HB susceptibility in the Chinese population, other polymorphisms alone or in combination should be investigated to further clarify HB susceptibility.

Elevated telomere dysfunction in cells containing the African-centric Pro47Ser cancer-risk variant of TP53

Subtelomeric transcription and chromatin can have a significant impact on telomere repeat maintenance and chromosome stability. We have previously found that tumor suppressor protein p53 (TP53) can bind to retrotransposon-like elements in a majority of human subtelomeres to regulate TERRA transcription and telomeric histone acetylation in response to DNA damage. TP53 also prevents the accumulation of γH2AX DNA-damage signaling at telomeres. We now show that the inherited TP53 polymorphism Pro47Ser (hereafter S47), which is enriched in populations of African descent, is associated with elevated marks of telomere dysfunction. We found that human and mouse cells carrying the S47 variant show increased γH2AX DNA-damage signals at telomeres, as well as reduced TERRA transcription and subtelomeric histone acetylation in response to DNA damage stress. Cell-lines containing inducible genes for P47 or S47 versions of p53, as well mouse embryo fibroblasts (MEFs) reconstituted with human p53, showed elevated telomere-induced DNA damage foci and metaphase telomere signal loss in cells with S47. Human lymphoblastoid cell lines (LCLs) derived from individuals homozygous for S47, show increased accumulation of subtelomeric γH2AX and unstable telomere repeats in response to DNA damage relative to age matched LCLs homozygous for P47. Furthermore, LCLs with S47 had reduced replicative lifespan. These studies indicate that the naturally occurring S47 variant of p53 can affect telomeric chromatin, telomere repeat stability, and replicative capacity. We discuss the potential evolutionary significance of the S47 variant to African populations with respect to telomere regulation and the implications for inherited health disparities.

Germline TP53 mutation spectrum in Sudanese premenopausal breast cancer patients: correlations with reproductive factors

PURPOSE

The role of non-genetic factors as modifiers of TP53-related hereditary breast cancer (BC) risk is debated. In this regard, little is known about the impact of germline TP53 mutations on BC in sub-Saharan Africa, where the disease often presents in non-contraceptive multiparous premenopausal women with extended history of breastfeeding. Herein, we report the germline TP53 mutations found in a series of 92 Sudanese premenopausal BC patients characterized for reproductive history.

METHODS

The entire TP53 coding sequence, including intron-exon boundaries and UTRs, was analyzed via DHPLC and direct sequencing, and the association of TP53 genotypes with BC risk and with individual lifetime exposures to reproductive factors was investigated with statistical tools.

RESULTS

The germline TP53 mutation spectrum comprised 20 variants, 15 in the non-coding and 5 in the coding region. The latter included a deleterious missense mutation, c.817C>T (p.Arg273Cys), in a unique patient, and the common and functionally relevant coding polymorphism at amino acid 72 [Pro72Arg (rs1042522)]. The non-coding mutations included c.919+1G>A, a known deleterious splice site mutation, also in a unique patient. Notably, the 2 carriers of deleterious TP53 mutations clustered in the subset of cases with stronger reproductive history relative to childbearing age. When analyzed in comparison to population controls, the codon 72 polymorphism did not reveal associations with BC.

CONCLUSIONS

Our study suggests that the codon 72 Arg>Pro polymorphism is not implicated in premenopausal BC susceptibility, whereas multiparity and breastfeeding might be BC risk factors for carriers of deleterious TP53 mutations.

TP53 Gene 72 Arg/Pro (rs1042522) Single Nucleotide Polymorphism Contribute to Increase the Risk of B-Chronic Lymphocytic Leukemia in the Sudanese Population

Objective::

This study aimed at exploring the association of TP53 72Arg/Pro polymorphism and Risk of Chronic Lymphocytic Leukemia and to assess the correlation between TP53 72Arg/Pro polymorphism and clinical parameter, hematological profile and some biological prognostic markers among Sudanese patients with chronic lymphocytic leukemia.

Methods:

A case-control study was conducted in Khartoum state, Sudan, during the period from April 2017 to April 2018, involved 110 B-CLL patients and 80 healthy volunteers as a control group. Physical examination, Complete Blood Count and Immunophenotype were performed in all patients to confirm the diagnosis. Clinical staging such as Rai and Binet were studied. CD38 and ZAP70 were performed by Flow Cytometry. Blood samples were collected from all participants; DNA was extracted by using ANALYTIKJENA Blood DNA Extraction Kit (Germany) and analyzed TP53 codon 72Arg/Pro Polymorphism by using AS-PCR. The statistical analysis was performed using SPSS version 23.0 software (Chicago, IL, USA).

Results:

the Arg/Pro was the most frequent genotype in B-CLL patients(50%), followed by Arg/Arg (25.5%) and Pro/Pro (24.5%), whereas in healthy control group Arg/Pro was the most frequent (47.5%), followed by Arg/Arg (45%) and Pro/Pro (7.5%). Our data indicate a higher frequency of homozygous Pro/Pro in the B-CLL patients as compared to controls with an OR of 4.01 for the Pro/Pro genotype and lower frequency of Arg/Arg genotype in CLL patients as compared to controls with an OR of .42 for the Arg/Arg genotype. Also, the Pro allele showed higher risk than Arg allele (P value=0.000, OR 2.23, 95% CI=1.45-3.41). No significant association between gender, clinical staging systems (Rai, Binet), biological prognostic markers (CD38 expression or ZAP70 expression), and TP53 codon 72Arg/Pro polymorphisms, except Arg/Arg genotype tended to be associated with younger age (P =0.04).

Conclusion:

Our data suggested that Pro/Pro genotype contribute to increased susceptibility to B-Chronic Lymphocytic Leukemia risk in our population tenfold higher than those had Arg/Arg genotype.

The Codon 72 TP53 Polymorphism Contributes to TSC Tumorigenesis through the Notch-Nodal Axis

We discovered that 90.3% of patients with angiomyolipomas, lymphangioleiomyomatosis (LAM), and tuberous sclerosis complex (TSC) carry the arginine variant of codon 72 (R72) of TP53 and that R72 increases the risk for angiomyolipoma. R72 transactivates NOTCH1 and NODAL better than the proline variant of codon 72 (P72); therefore, the expression of NOTCH1 and NODAL is increased in angiomyolipoma cells that carry R72. The loss of Tp53 and Tsc1 within nestin-expressing cells in mice resulted in the development of renal cell carcinomas (RCC) with high Notch1 and Nodal expression, suggesting that similar downstream mechanisms contribute to tumorigenesis as a result of p53 loss in mice and p53 polymorphism in humans. The loss of murine Tp53 or expression of human R72 contributes to tumorigenesis via enhancing epithelial-to-mesenchymal transition and motility of tumor cells through the Notch and Nodal pathways. IMPLICATIONS: This work revealed unexpected contributions of the p53 polymorphism to the pathogenesis of TSC and established signaling alterations caused by this polymorphism as a target for therapy. We found that the codon 72 TP53 polymorphism contributes to TSC-associated tumorigenesis via Notch and Nodal signaling.

NRAS and KRAS polymorphisms are not associated with hepatoblastoma susceptibility in Chinese children

BACKGROUND

Hepatoblastoma is the most common hepatic malignancy in children, accounting for approximately 80% of all childhood liver tumors. KRAS and NRAS, members of the RAS gene family, are closely linked to tumorigenesis, and are frequently mutated in a variety of malignancies. They may thus play critical roles in tumorigenesis. However, there are few studies on the association between the RAS gene polymorphisms and risk of hepatoblastoma.

METHODS

We investigated whether the polymorphisms at these genes are associated with hepatoblastoma susceptibility in a hospital-based study of 213 affected Chinese children and 958 cancer-free controls. Genotypes were determined by TaqMan assay, and association with hepatoblastoma risk was assessed based on odds ratios and 95% confidence intervals.

RESULTS

No significant differences were observed between patients and controls in terms of age and gender frequency. All NRAS and KRAS genotypes are in Hardy-Weinberg equilibrium in the entire study population. We did not observe any significant association between hepatoblastoma risk and polymorphisms at NRAS and KRAS. The association between selected polymorphisms and hepatoblastoma risk was assessed after stratification by age, gender, and clinical stage. However, no significant association was observed even after stratification by age, gender, and clinical stage.

CONCLUSIONS

The data suggest that NRAS and KRAS polymorphisms are irrelevant to hepatoblastoma susceptibility among Chinese population.

The Water Extract of Juniperus communis L. Induces Cell Death and Sensitizes Cancer Cells to Cytostatic Drugs through p53 and PI3K/Akt Pathways

Juniper (Juniperus communis L.) is a northern coniferous plant generally used as a spice and for nutritional purposes in foods and drinks. It was previously reported that juniper extract (JE) affects p53 activity, cellular stress, and gene expression induced cell death in human neuroblastoma cells. Therefore, the effects of juniper on p53 and Akt signaling was examined further in A549 lung, 22RV1 and DU145 prostate, and HepG2 liver cancer cells using Western blot, confocal microscopy, and MTT analysis. We found that juniper simultaneously decreased cell viability, activated the p53 pathway, and inactivated the PI3K/Akt pathway. The p53 activation was associated with increased nuclear p53 level. Akt was dephosphorylated, and its inactivation was associated with increased levels of PHLPP1 and PHLPP2 phosphatases. Parallel increases of PARP suggest that JE decreased cell viability by activating cell death. In addition, JE potentiated the effects of gemcitabine and 5-fluorouracil anticancer drugs. Thus, JE can activate cell death in different cancer cell lines through p53 and Akt pathways.

Mechanistic basis for impaired ferroptosis in cells expressing the African-centric S47 variant of p53

A population-restricted single-nucleotide coding region polymorphism (SNP) at codon 47 exists in the human TP53 gene (P47S, hereafter P47 and S47). In studies aimed at identifying functional differences between these variants, we found that the African-specific S47 variant associates with an impaired response to agents that induce the oxidative stress-dependent, nonapoptotic cell death process of ferroptosis. This phenotype is manifested as a greater resistance to glutamate-induced cytotoxicity in cultured cells as well as increased carbon tetrachloride-mediated liver damage in a mouse model. The differential ferroptotic responses associate with intracellular antioxidant differences between P47 and S47 cells, including elevated abundance of the low molecular weight thiols coenzyme A (CoA) and glutathione in S47 cells. Importantly, the disparate ferroptosis phenotypes related to the P47S polymorphism are reversible. Exogenous administration of CoA provides protection against ferroptosis in cultured mouse and human cells, as well as in a mouse model. The combined data support a positive role for p53 in ferroptosis and identify CoA as a regulator of this cell death process. Together, these findings provide mechanistic insight linking redox regulation of p53 to small molecule antioxidants and stress signaling pathways. They also identify potential therapeutic approaches to redox-related pathologies.

Association between TP53 rs1042522 gene polymorphism and the risk of malignant bone tumors: a meta-analysis

TP53 is a tumor suppressor gene which is essential for regulating cell division and preventing tumor formation. Several studies have assessed the associations of TP53 single-nucleotide polymorphisms (SNP) with susceptibility of malignant bone tumors, including osteosarcoma and Ewing sarcoma, but the results are inconsistent. In the present meta-analysis, we aimed to elucidate the associations of TP53 rs1042522 genetic polymorphism with the risk of osteosarcoma or Ewing sarcoma. We systematically searched Medline, PubMed, Web of Science, Embase, and the Cochrane Library databases. Eligible studies assessing the polymorphisms in the TP53 rs1042522 gene and risk of malignant bone tumors were incorporated. The pooled odds ratio (OR) with its 95% confidence intervals (95% CIs) were used to assess these possible associations. Five studies with a total of 567 cases and 935 controls were finally included the meta-analysis. Meta-analysis of TP53 rs1042522 polymorphism was significantly associated with an increased risk of malignant bone tumors (G versus C: OR = 1.27, 95% CI 1.08–1.50, P=0.005; GG versus GC/CC: OR = 1.55, 95% CI 1.21–2.00, P=0.001). Moreover, in a stratified analysis, a statistically significant correlation between this SNP and osteosarcoma risk was also observed. Our results suggest that there are significant associations of TP53 rs1042522 polymorphism with malignant bone tumors risk. More studies based on larger sample sizes and homogeneous samples are warranted to confirm these findings.

Ironing out the role of the cyclin-dependent kinase inhibitor, p21 in cancer: Novel iron chelating agents to target p21 expression and activity

Iron (Fe) has become an important target for the development of anti-cancer therapeutics with a number of Fe chelators entering human clinical trials for advanced and resistant cancer. An important aspect of the activity of these compounds is their multiple molecular targets, including those that play roles in arresting the cell cycle, such as the cyclin-dependent kinase inhibitor, p21. At present, the exact mechanism by which Fe chelators regulate p21 expression remains unclear. However, recent studies indicate the ability of chelators to up-regulate p21 at the mRNA level was dependent on the chelator and cell-type investigated. Analysis of the p21 promoter identified that the Sp1-3-binding site played a significant role in the activation of p21 transcription by Fe chelators. Furthermore, there was increased Sp1/ER-α and Sp1/c-Jun complex formation in melanoma cells, suggesting these complexes were involved in p21 promoter activation. Elucidating the mechanisms involved in the regulation of p21 expression in response to Fe chelator treatment in neoplastic cells will further clarify how these agents achieve their anti-tumor activity. It will also enhance our understanding of the complex roles p21 may play in neoplastic cells and lead to the development of more effective and specific anti-cancer therapies.

A Systematic p53 Mutation Library Links Differential Functional Impact to Cancer Mutation Pattern and Evolutionary Conservation

The TP53 gene is frequently mutated in human cancer. Research has focused predominantly on six major "hotspot" codons, which account for only ∼30% of cancer-associated p53 mutations. To comprehensively characterize the consequences of the p53 mutation spectrum, we created a synthetically designed library and measured the functional impact of ∼10,000 DNA-binding domain (DBD) p53 variants in human cells in culture and in vivo. Our results highlight the differential outcome of distinct p53 mutations in human patients and elucidate the selective pressure driving p53 conservation throughout evolution. Furthermore, while loss of anti-proliferative functionality largely correlates with the occurrence of cancer-associated p53 mutations, we observe that selective gain-of-function may further favor particular mutants in vivo. Finally, when combined with additional acquired p53 mutations, seemingly neutral TP53 SNPs may modulate phenotypic outcome and, presumably, tumor progression.

TP53 rs1042522 C>G polymorphism and Wilms tumor susceptibility in Chinese children: a four-center case-control study

Wilms tumor is the most common renal malignancy that occurs in children. TP53 gene is considered as a tumor-suppressing gene through controlling cell growth. TP53 gene rs1042522 C>G (Arg72Pro) polymorphism is widely investigated in various types of cancers. However, it is not established if TP53 rs1042522 C>G polymorphism is a candidate variant for Wilms tumor risk. The aim of the study was to determine whether TP53 rs1042522 C>G polymorphism is responsible for the risk of Wilms tumor in Chinese children. All subjects (355 cases and 1070 controls) from four centers of China were genotyped for rs1042522 C>G polymorphism. The effect of rs1042522 C>G polymorphism on Wilms tumor prevalence was analyzed using logistic regression models. We failed to detect a significant relationship between rs1042522 C>G polymorphism and Wilms tumor risk. Further stratification analysis also could not detect a significant relationship. We conclude that TP53 rs1042522 C>G polymorphism might not have enough impact on the risk of Wilms tumor. More validation study with larger sample size will be required to better define the role of TP53 rs1042522 C>G polymorphism in Wilms tumor risk.

Polymorphisms in MDM2 and TP53 Genes and Risk of Developing Therapy-Related Myeloid Neoplasms

One of the most severe complications after successful cancer therapy is the development of therapy-related myeloid neoplasms (t-MN). Constitutional genetic variation is likely to impact on t-MN risk. We aimed to evaluate if polymorphisms in the p53 pathway can be useful for predicting t-MN susceptibility. First, an association study revealed that the Pro variant of the TP53 Arg72Pro polymorphism and the G allele of the MDM2 SNP309 were associated with t-MN risk. The Arg variant of TP53 is more efficient at inducing apoptosis, whereas the Pro variant is a more potent inductor of cell cycle arrest and DNA repair. As regards MDM2 SNP309, the G allele is associated with attenuation of the p53 apoptotic response. Second, to evaluate the biological effect of the TP53 polymorphism, we established Jurkat isogenic cell lines expressing p53Arg or p53Pro. Jurkat p53Arg cells presented higher DNA damage and higher apoptotic potential than p53Pro cells, after treatment with chemotherapy agents. Only p53Pro cells presented t(15;17) translocation and del(5q). We suggest that failure to repair DNA lesions in p53Arg cells would lead them to apoptosis, whereas some p53Pro cells, prone to cell cycle arrest and DNA repair, could undergo misrepair, generating chromosomal abnormalities typical of t-MN.

Progressive diffuse large B-cell lymphoma with TP53 gene mutation treated with chidamide-based chemotherapy

We attempted to explore novel treatment options for progressive diffuse large B-cell lymphoma (DLBCL) with TP53 mutation that has a poor response to rituximab-based immunochemotherapy. Herein, we report the case of a patient with DLBCL having TP53 mutation who showed progression following four cycles of rituximab-based immunochemotherapy but achieved sustained partial remission following chidamide-based chemotherapy. In vitro experiments performed using the DLBCL cell lines OCI-ly1 (LY1; mutant TP53), OCI-ly10 (LY10; wild-type TP53) and OCI-ly19 (LY19, wild-type TP53) demonstrated that chidamide is more potent against cells with mutant TP53 mutant than those with wild-type TP53. Moreover, chidamide can reduce the mRNA and protein expression levels of mutant TP53 and upregulate the surface expression of the CD20 antigen in lymphoma cells.

Somatic TP53 Mutations Are Detectable in Circulating Tumor DNA from Children with Anaplastic Wilms Tumors

BACKGROUND

Diffuse anaplastic Wilms tumor (DAWT) is a rare, high-risk subtype that is often missed on diagnostic needle biopsy. Somatic mutations in TP53 are associated with the development of anaplasia and with poorer survival, particularly in advanced-stage disease. Early identification of DAWT harboring TP53 abnormalities could improve risk stratification of initial therapy and monitoring for recurrence.

METHODS

Droplet digital polymerase chain reaction (ddPCR) was used to evaluate 21 samples from 4 patients with DAWT. For each patient, we assessed TP53 status in frozen tumor, matched germline DNA, and circulating tumor DNA (ctDNA) from plasma, serum, and urine collected throughout treatment.

RESULTS

Mutant TP53 was detectable in ctDNA from plasma and serum in all patients. We did not detect variant TP53 in the same volume (200 μl) of urine. One patient displayed heterogeneity of TP53 in the tumor despite both histological sections displaying anaplasia. Concentration of ctDNA from plasma/serum taken prenephrectomy varied significantly between patients, ranging from 0.44 (0.05-0.90) to 125.25 (109.75-140.25) copies/μl. We observed variation in ctDNA throughout treatment, and in all but one patient, ctDNA levels fell significantly following nephrectomy.

CONCLUSION

We demonstrate for the first time that ddPCR is an effective method for detection of mutant TP53 in ctDNA from children with DAWT even when there is intratumoral somatic heterogeneity. This should be further explored in a larger cohort of patients, as early detection of circulating variant TP53 may have significant clinical impact on future risk stratification and surveillance.

TP53 and DNA-repair gene polymorphisms genotyping as a low-cost lung adenocarcinoma screening tool

AIM

TP53 and DNA repair polymorphisms have been proposed as cancer risk factors. This study evaluated the usability of TP53 Arg72Pro single-nucleotide polymorphism, X RCC1 Arg399Gln and RAD51 G135C as a low-cost lung adenocarcinoma screening tool.

PATIENTS AND METHODS

This case-control study included 78 atients with lung adenocarcinoma and 79 healthy matched controls. TP53, XRCC1 and RAD51 genotyping was done by PCR followed by restriction length polymorphism. Descriptive analyses included genotype and allelic frequencies and deviations of the frequencies from those expected under Hardy-Weinberg equilibrium were assessed using the χ² test. The OR and 95% CIs were calculated as an estimate of relative risk, with significance set at p value <0.05.

RESULTS

The TP53 codon 72 Pro allele and the XRCC1 codon 399 Arg allele in a homozygous state were associated with lung adenocarcinoma (p=0.037; OR (95% CI) 2.42 (1.10 to 5.31)), that is, p=0.037; OR (95% CI) 2.16 (1.08 to 4.33), respectively. Also, carriers of the TP53 codon 72 Pro allele and the XRCC1 codon 399 ArgArg genotype older than 50 showed an even higher risk of developing lung adenocarcinoma (p=0.03 in both cases).

CONCLUSIONS

The TP53 codon 72 Arg allele and XRCC1 codon 399 Gln allele are likely to have a protective effect against lung adenocarcinoma, especially in individuals older than 50 years of age. XRCC1 and TP53 genotyping might be a useful low-cost tool for evaluating individual lung cancer risk, leading to earlier detection and management of this disease.

Cancer-free aging: Insights from Spalax ehrenbergi superspecies

Cancer and ageing can be regarded as two different manifestations of the same underlying process-accumulation of cellular damage-and therefore both are closely linked. Nowadays, the ageing of populations worldwide is leading to an unprecedented increase in cancer cases and fatalities, and therefore the understanding of links between cancer and ageing is more important than ever. Spalax is considered an excellent model for ageing and, additionally, for cancer research, due to not show clear age-related phenotypic changes and not develop spontaneous tumours, despite its relatively long lifespan (∼20 years in captivity). Thereby, the purpose of this review is to summarize the recent knowledge on Spalax, with a particular emphasis on the molecular mechanisms associated with their longevity and cancer resistance.

Barrett’s esophagus with high grade dysplasia is associated with non-esophageal cancer

AIM

To study factors associated with esophageal and non-esophageal cancer morbidity among Barrett’s esophagus (BE) patients.

METHODS

A cohort study within a single tertiary center included 386 consecutive patients with biopsy proven BE, who were recruited between 2004-2014. Endoscopic and histologic data were prospectively recorded. Cancer morbidity was obtained from the national cancer registry. Main outcomes were BE related (defined as esophagus and cardia) and non-BE related cancers (all other cancers). Cancer incidence and all-cause mortality were compared between patients with high-grade dysplasia (HGD) and with low-grade or no dysplasia (non-HGD) using Kaplan-Meier curves and cox regression models.

RESULTS

Of the 386 patients, 12 had HGD, 7 had a BE related cancer. There were 75 (19.4%) patients with 86 cases of lifetime cancers, 76 of these cases were non-BE cancers. Seven (1.8%) and 18 (4.7%) patients had BE and non-BE incident cancers, respectively. Twelve (3.1%) patients had HGD as worst histologic result. Two (16.7%) and 16 (4.4%) incident non-BE cancers occurred in the HGD and non-HGD group, respectively. Ten-year any cancer and non-BE cancer free survival was 63% and 82% in the HGD group compared to 93% and 95% at the non-HGD group, respectively. Log-rank test for patients with more than one endoscopy, assuring longer follow up, showed a significant difference (P < 0.001 and P = 0.017 respectively). All-cause mortality was not significantly associated with BE HGD.

CONCLUSION

Patients with BE and HGD, may have a higher risk for all-cause cancer morbidity. The implications on cancer prevention recommendations should be further studied.

No association of TP53 codon 72 and intron 3 16-bp duplication polymorphisms with breast cancer risk in Chinese Han women: new evidence from a population-based case-control investigation

Background

Many studies have demonstrated that the genetic variants of tumor suppressor gene TP53 contribute to the prediction of breast cancer risk. However, most of them focused on Europeans and Americans; the investigations about Asians, especially Chinese women, are scarce. Thus, the aim of this study was to explore the influence of TP53 codon 72 and intron 3 16-bp duplication polymorphisms on the breast cancer risk in Chinese women, especially those from eastern China.

Methods

Blood samples collected from 254 breast cancer patients and 252 healthy female individuals were investigated. Genotypes of the two polymorphisms were determined by direct sequencing and conventional PCR, respectively.

Results

Heterozygous Arg/Pro and homozygous Del/Del were the most frequent genotypes of the two polymorphisms, respectively. Heterozygous Arg/Pro had a higher prevalence in breast cancer cases (P_adj = 0.10; OR_adj = 1.43, 95% CI 0.93–2.18), and no homozygous 16-bp duplication (Ins/Ins) genotype was found in the whole 506 clinical samples. For the distributions of allele and haplotype frequencies, no statistically significant difference was observed between the two groups when multiple (additive, dominant and recessive) genetic models were utilized in the analysis (P_adj > 0.05).

Conclusion

The results suggested that the two TP53 polymorphisms did not affect breast cancer risk in Chinese Han women, but the heterozygous Arg/Pro may exist as the possible risk genotype of the codon 72 polymorphism in contrast to the homozygous Arg/Arg and Pro/Pro.

Electronic supplementary material

The online version of this article (10.1186/s40001-018-0345-6) contains supplementary material, which is available to authorized users.

Establishment and Characterization of gc-006-03, a Novel Human Signet Ring Cell Gastric Cancer Cell Line Derived from Metastatic Ascites

Signet ring cell gastric cancer (SRCGC) is a special type of gastric cancer with rapid progression and poor prognosis. However, few available SRCGC cell lines from Chinese patients can be used for research, the molecular mechanism of its growth and metastasis is still incompletely understood. In this study, we established and characterized a novel SRCGC cell line, gc-006-03.The cells showed a tendency to pile up without contact inhibition. G-band karyotypes of gc-006-03 were revealed hypotriploid with a modal chromosome number of 51. Immunohistochemistry analysis showed that the cells were positive for CEA, CK7, CDX2 and Ki-67(45%), and negative for CK20, TTF1and Li-cadherin. Flow cytometry analysis showed that gc-006-3 had 25% of CD44⁺ cells. The cells possessed strong clonality and high plating efficiency, and the doubling time was 36h. The cells grew vigorously for more than 100 passages in serial culture. Meanwhile, the cells showed a high rate of tumor formation. Tumors were observed in all of the nude mice (5/5) given injections of the cells. The metastatic capability of the cell line was found in zebrafish injected the cells. The results of whole genome sequencing revealed the unique genomic characteristics of gc-006-03. In summary, this new stable cell line may be useful in basic and clinical research on gastric signet ring cell carcinoma.

Meta-Analysis Results on the Association Between TP53 Codon 72 Polymorphism With the Susceptibility to Oral Cancer

Objectives: TP53 is an important tumor suppressor gene to maintain genomic integrity, and its mutations increase the susceptibility to oral carcinoma. Previous published studies have reported the relation of TP53 codon 72 polymorphism with the risk of oral carcinoma, but the results remain controversial and inconclusive.

Methods: We therefore utilized meta-analysis based on a comprehensive search in PubMed, EMBASE, and Google of Scholar databases up to August 19, 2017.

Results: Total 3,525 cases and 3,712 controls from 21 case-control studies were selected. We found no significant association between TP53 codon 72 polymorphism and oral carcinoma susceptibility in all genetic contrast models, including subgroup analysis based on control source and ethnicity. Furthermore, TP53 codon 72 polymorphism was not significant associated with oral carcinoma susceptibility in tobacco or alcohol use, and HPV infection status. Our results were confirmed by sensitivity analysis and no publication bias was found.

Conclusions: Taken together, our data indicate that TP53 codon 72 polymorphism is not associated with the susceptibility to oral carcinoma.

Tailoring Chemotherapy for the African-Centric S47 Variant of TP53

The tumor suppressor TP53 is the most frequently mutated gene in human cancer and serves to restrict tumor initiation and progression. Single-nucleotide polymorphisms (SNP) in TP53 and p53 pathway genes can have a marked impact on p53 tumor suppressor function, and some have been associated with increased cancer risk and impaired response to therapy. Approximately 6% of Africans and 1% of African Americans express a p53 allele with a serine instead of proline at position 47 (Pro47Ser). This SNP impairs p53-mediated apoptosis in response to radiation and genotoxic agents and is associated with increased cancer risk in humans and in a mouse model. In this study, we compared the ability of wild-type (WT) and S47 p53 to suppress tumor development and respond to therapy. Our goal was to find therapeutic compounds that are more, not less, efficacious in S47 tumors. We identified the superior efficacy of two agents, cisplatin and BET inhibitors, on S47 tumors compared with WT. Cisplatin caused dramatic decreases in the progression of S47 tumors by activating the p53/PIN1 axis to drive the mitochondrial cell death program. These findings serve as important proof of principle that chemotherapy can be tailored to p53 genotype.Significance: A rare African-derived radioresistant p53 SNP provides proof of principle that chemotherapy can be tailored to TP53 genotype. Cancer Res; 78(19); 5694-705. ©2018 AACR.

The Nonsynonymous Polymorphisms Val276Met and Gly393Ser of E2F1 Gene are Strongly Associated with Lung, and Head and Neck Cancers

AIM

The early gene factor-2 (E2F), a family of transcription factors, is involved in cell cycle regulation. Deregulated expression of most of the members of the E2F family is associated with various human cancers. In this study, we investigated the association between the E2F1 genetic variants rs3213173 (C/T) (Val276Met) and rs3213176 (G/A) (Gly393Ser) with the risk of lung cancer (LC) and head and neck cancer (HNC) in 190 patients and 230 control samples.

MATERIALS AND METHODS

We used polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and mutagenic primer-based PCR-RFLP methods to genotype all target polymorphisms.

RESULTS

The rs3213173 (C/T) polymorphism was associated with LC risk in the homozygous model (odds ratio [OR] = 2.954, 95% confidence interval [CI] 1.366-6.386; p = 0.004) as well as in heterozygous model (OR = 2.314; 95% CI = 1.369-3.912; p = 0.001). A significant association was also observed for the rs3213176 (G/A) polymorphism with LC risk in homozygous model, GG versus AA (OR = 2.750; 95% CI = 1.236-6.118; p = 0.01); in heterozygous model, GG versus GA (OR = 2.111; 95% CI = 1.256-3.549; p = 0.004); and in combined mutant GG versus GA+AA (OR = 2.214; 95% CI = 1.343-3.650; p = 0.001). The rs3213176 (G/A) marker was also associated with HNC risk.

CONCLUSIONS

Our findings reveal that the rs3213173 (C/T) and rs3213176 (G/A) polymorphisms of the E2F1 gene are genetic risk factors for susceptibility to LC and HNC in the North Indian Population.

TP53 rs1625895 is Related to Breast Cancer Incidence and Early Death in Iranian Population

Breast cancer as the second most common cancer worldwide tend to be experienced by Iranian women 10 years earlier with a peak incidence at the premenopausal stage. Genetic mutations of TP53 tumor suppressor gene has been shown to be related to early onset of breast cancer. It has been shown already that rs1625895 polymorphic site is related to glioma as well as lung cancer. In this study, we have investigated the role of rs1625895 polymorphism in breast cancer incidence in Iranian women. DNA extraction of 86 breast cancer patients and 96 control individuals have been used for allele-specific primer-PCR and genotyping of allele A and allele G of the TP53 rs1625895. Genotypes frequencies have been shown that GG homozygosis as the most frequent genotype is a significant association with increased risk of breast cancer development in Iranian women (odds ratio = 6, p = 0.002). On the other hand and in comparison to allele G, allele A could cause early death of breast cancer patients by threefolds significantly (p = 0.011). As a conclusion, we show that allele A is the minor allele in both breast cancer patients and also control individuals and major allele G, is related to the increased risk of breast cancer development in Iranian women.

Integrative Analysis of Dysregulated lncRNA-Associated ceRNA Network Reveals Functional lncRNAs in Gastric Cancer

Mounting evidence suggests that long noncoding RNAs (lncRNAs) play important roles in the regulation of gene expression by acting as competing endogenous RNA (ceRNA). However, the regulatory mechanisms of lncRNA as ceRNA in gastric cancer (GC) are not fully understood. Here, we first constructed a dysregulated lncRNA-associated ceRNA network by integrating analysis of gene expression profiles of lncRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs). Then, we determined three lncRNAs (RP5-1120P11, DLEU2, and DDX11-AS1) as hub lncRNAs, in which associated ceRNA subnetworks were involved in cell cycle-related processes and cancer-related pathways. Furthermore, we confirmed that the two lncRNAs (DLEU2 and DDX11-AS1) were significantly upregulated in GC tissues, promote GC cell proliferation, and negatively regulate miRNA expression, respectively. The hub lncRNAs (DLEU2 and DDX11-AS1) could have oncogenic functions, and act as potential ceRNAs to sponge miRNA. Our findings not only provide novel insights on ceRNA regulation in GC, but can also provide opportunities for the functional characterization of lncRNAs in future studies.

TP53 gain-of-function mutation promotes inflammation in glioblastoma

Glioblastoma (GBM), the most severe and common brain tumor in adults, is characterized by multiple somatic mutations and aberrant activation of inflammatory responses. Immune cell infiltration and subsequent inflammation cause tumor growth and resistance to therapy. Somatic loss-of-function mutations in the gene encoding tumor suppressor protein p53 (TP53) are frequently observed in various cancers. However, numerous studies suggest that TP53 regulates malignant phenotypes by gain-of-function (GOF) mutations. Here we demonstrate that a TP53 GOF mutation promotes inflammation in GBM. Ectopic expression of a TP53 GOF mutant induced transcriptomic changes, which resulted in enrichment of gene signatures related to inflammation and chemotaxis. Bioinformatics analyses revealed that a gene signature, upregulated by the TP53 GOF mutation, is associated with progression and shorter overall survival in GBM. We also observed significant correlations between the TP53 GOF mutation signature and inflammation in the clinical database of GBM and other cancers. The TP53 GOF mutant showed upregulated C-C motif chemokine ligand 2 (CCL2) and tumor necrosis factor alpha (TNFA) expression via nuclear factor kappa B (NFκB) signaling, consequently increasing microglia and monocyte-derived immune cell infiltration. Additionally, TP53 GOF mutation and CCL2 and TNFA expression correlated positively with tumor-associated immunity in patients with GBM. Taken together, our findings suggest that the TP53 GOF mutation plays a crucial role in inflammatory responses, thereby deteriorating prognostic outcomes in patients with GBM.

Association of two FOXP3 polymorphisms with breast cancer susceptibility in Chinese Han women

BACKGROUND

Forkhead box P3 (FOXP3) is a key gene in the immune system which also plays a role in tumor development. This study aims to explore the association of two FOXP3 polymorphisms (rs3761548 and rs3761549) with susceptibility to breast cancer (BC).

METHOD

A case-control study was conducted, involving 560 patients and 583 healthy individuals from the Chinese Han population. The genotypes of FOXP3 polymorphisms were detected using the Sequenom MassARRAY method. The association between FOXP3 polymorphisms and BC risk was evaluated using a χ2 test with an odds ratio (OR) and 95% confidence intervals (95% CIs) under six genetic models. False-positive report probability was utilized to examine whether the significant findings were noteworthy.

RESULTS

We observed that rs3761548 was associated with a higher BC risk in heterozygous, dominant, overdominant, and allele genetic models (CA vs CC: OR =1.32, P=0.031; CA/AA vs CC: OR =1.32, P=0.023; CA vs CC/AA: OR =1.29, P=0.042; A vs C: OR =1.26, P=0.029), whereas no significant association was found between rs3761549 and BC risk. In addition, CA, CA/AA genotype, and A allele of rs3761548 were related to larger tumor size, and the A allele was also correlated with a positive status of Her-2 in BC patients.

CONCLUSION

Our study suggests that FOXP3 polymorphism rs3761548 is associated with BC susceptibility in the Chinese and may be involved in tumor progression. Future studies are needed to confirm the results in a larger population with more races.

Arginine deiminase expressed in vivo, driven by human telomerase reverse transcriptase promoter, displays high hepatoma targeting and oncolytic efficiency

Arginine starvation has the potential to selectively treat both primary tumor and (micro) metastatic tissue with very low side effects. Arginine deiminase (ADI; EC 3.5.3.6), an arginine-degrading enzyme, has been studied as a potential anti-tumor drug for the treatment of arginine-auxotrophic tumors. Though ADI-PEG20 (pegylated ADI by PEG 20,000) already passed the phase I/II clinical trials [1], it is just used as adjuvant therapy because of its low efficiency and less targeting. Then, this paper discussed the efficiency of arginine starvation mediated by ADI expressed in cytoplasm for liver cancers. In order to guarantee the tumor targeting, human telomerase reverse transcriptase (hTERT) promoter was used to drive the expression of ADI in vivo. To access the anti-tumor efficiency of ADI, p53 gene was used as the positive control. Thus, ADI displayed obvious cytotoxicity to BEL7402 and HUH7 cell lines in cytoplasm. The apoptosis rates rose from 15% to nearly 60% after changing the expression vectors from pcDNA4 plasmid to adenovirus. Compared with p53-adenovirus, ADI-adenovirus showed the higher oncolytic activity in the intratumoral injection model of mice. Tumor disappeared after the treatment of ADI-adenovirus for two weeks, and the mice pulled through all. Therefore, ADI is an ideal anti-tumor gene for caner targeting therapy with the help of hTERT promoter.

A polymorphism in the tumor suppressor p53 affects aging and longevity in mouse models

Tumor suppressor p53 prevents early death due to cancer development. However, the role of p53 in aging process and longevity has not been well-established. In humans, single nucleotide polymorphism (SNP) with either arginine (R72) or proline (P72) at codon 72 influences p53 activity; the P72 allele has a weaker p53 activity and function in tumor suppression. Here, employing a mouse model with knock-in of human TP53 gene carrying codon 72 SNP, we found that despite increased cancer risk, P72 mice that escape tumor development display a longer lifespan than R72 mice. Further, P72 mice have a delayed development of aging-associated phenotypes compared with R72 mice. Mechanistically, P72 mice can better retain the self-renewal function of stem/progenitor cells compared with R72 mice during aging. This study provides direct genetic evidence demonstrating that p53 codon 72 SNP directly impacts aging and longevity, which supports a role of p53 in regulation of longevity.

How long most animals live depends on the balance between the biological processes that allow them to regenerate their tissues when damaged and those that prevent them from developing cancer. Regeneration relies mostly on cells, in particular stem cells, dividing to make new cells, while cancer occurs when cell division becomes uncontrolled.

Tumor suppressor genes protect against cancer. One such gene encodes a protein called p53 that eliminates damaged cells before they can become cancerous. The p53 protein is also believed to be involved in regulating how quickly an animal ages and how long it lives, but this second role has not yet been clearly established.

Previous studies using different strategies to change the activity of p53 in several mouse models have led to inconsistent results. However, the mouse models used in these earlier studies did not reflect how p53 works under normal conditions.

Zhao et al. have now used mice in which the mouse gene for p53 was replaced with one of two versions of the equivalent human gene to study its impact on lifespan and the aging process. The two versions of p53 only differ slightly; a single building block of the protein, the amino acid at position 72, is a proline in one version but an arginine in the other. This difference makes one version of p53 weaker than the other; in other words, it is less able to eliminate damaged cells. Zhao et al. revealed that the mice with the weaker p53 lived for longer and appeared to age more slowly too. Further experiments showed that the stem cells in the mice with a weaker p53 were able to keep dividing and create new cells for longer. This is important because a decline in this activity – which is known as self-renewal – is a hallmark of aging.

Together these findings show that a small yet common change in p53 impacts both aging and lifespan, possibly by altering how stem cells are regulated. Further work is now needed to better understand why the different versions of p53 have different effects on stem cells.

Genomic and Bioinformatics Approaches for Analysis of Genes Associated With Cancer Risks Following Exposure to Tobacco Smoking

Cancer is a significant health problem in the Middle East and global population. It is well established that there is a direct link between tobacco smoking and cancer, which will continue to pose a significant threat to human health. The impact of long-term exposure to tobacco smoke on the risk of cancer encouraged the study of biomarkers for vulnerable individuals to tobacco smoking, especially children, who are more susceptible than adults to the action of environmental carcinogens. The carcinogens in tobacco smoke condensate induce DNA damage and play a significant role in determining the health and well-being of smokers, non-smoker, and primarily children. Cancer is a result of genomic and epigenomic malfunctions that lead to an initial premalignant condition. Although premalignancy genetic cascade is a much-delayed process, it will end with adverse health consequences. In addition to the DNA damage and mutations, tobacco smoke can cause changes in the DNA methylation and gene expression associated with cancer. The genetic events hint on the possible use of genomic–epigenomic changes in genes related to cancer, in predicting cancer risks associated with exposure to tobacco smoking. Bioinformatics provides indispensable tools to identify the cascade of expressed genes in active smokers and non-smokers and could assist the development of a framework to manage this cascade of events linked with the evolvement of disease including cancer. The aim of this mini review is to cognize the essential genomic processes and health risks associated with tobacco smoking and the implications of bioinformatics in cancer prediction, prevention, and intervention.

The Role of Oncogenic Tyrosine Kinase NPM-ALK in Genomic Instability

Genomic stability is crucial for cell life and transmitting genetic material is one of the primary tasks of the cell. The cell needs to be able to recognize any possible error and quickly repair it, and thus, cells have developed several mechanisms to detect DNA damage and promote repair during evolution. The DNA damage response (DDR) and DNA repair pathways ensure the control of possible errors that could impair the duplication of genetic information and introduce variants in the DNA. Endogenous and exogenous factors compromise genomic stability and cause dysregulation in the DDR and DNA repair pathways. Cancer cells often impair these mechanisms to overcome cellular barriers (cellular senescence and/or apoptosis), leading to malignancy. NPM (nucleophosmin)-ALK (anaplastic lymphoma kinase) is an oncogenic tyrosine kinase that is involved in the development of anaplastic large cell lymphoma (ALCL). NPM-ALK is known to be involved in the activation of proliferative and anti-apoptotic signaling pathways. New evidence reveals that NPM-ALK translocation also impairs the ability of cells to maintain the genomic stability through both DDR and DNA repair pathways. This review aims to highlight the role of the oncogenic tyrosine kinase NPM-ALK in the cell, and pointing to new possible therapeutic strategies.

TP53 codon 72 polymorphism may predict early tumour progression in paediatric pilocytic astrocytoma

Pilocytic astrocytoma and ganglioglioma may occur in inaccessible or surgically difficult areas. In case of incomplete resection, the availability of biological predictors of tumour progression could be particularly important. To this end, an analysis of p53 codon 72 polymorphism and assessment of its role as prognostic marker were performed.

The status of the p53 Arg72Pro polymorphism was evaluated by pyrosequencing method in a multicenter cohort of 170 paediatric patients. Genotype/phenotype associations were investigated either by means of bivariate or multivariate analyses.

In the partially resected pilocytic astrocytomas, the Arg/Arg variant predicts early tumour progression (median survival time: 23.1 months) and is associated with poor event-free survival (p value = 0.0009). This finding remains true also in case of adjuvant therapies, with a 5-year event-free survival of 30.6% for cases with Arg/Arg variant vs. 78.7% for those with other genotypes. There is no association between ganglioglioma and the polymorphism.

The assessment of Arg/Arg variant could improve the management of pilocytic astrocytoma. TP53 codon 72 analysis could distinguish low-risk cases, in which surgery could be conservative, from high-risk cases needing an aggressive surgery plan.

The beneficial effects of Zn on Akt-mediated insulin and cell survival signaling pathways in diabetes

Zinc is one of the essential trace elements and participates in numerous physiological processes. Abnormalities in zinc homeostasis often result in the pathogenesis of various chronic metabolic disorders, such as diabetes and its complications. Zinc has insulin-mimetic and anti-diabetic effects and deficiency has been shown to aggravate diabetes-induced oxidative stress and tissue injury in diabetic rodent models and human subjects with diabetes. Akt signaling pathway plays a central role in insulin-stimulated glucose metabolism and cell survival. Anti-diabetic effects of zinc are largely dependent on the activation of Akt signaling. Zn is also an inducer of metallothionein that plays important role in anti-oxidative stress and damage. However, the exact molecular mechanisms underlying zinc-induced activation of Akt signaling pathway remains to be elucidated. This review summarizes the recent advances in deciphering the possible mechanisms of zinc on Akt-mediated insulin and cell survival signaling pathways in diabetes conditions. Insights into the effects of zinc on epigenetic regulation and autophagy in diabetic nephropathy are also discussed in the latter part of this review.

Comprehensive review of genetic factors contributing to head and neck squamous cell carcinoma development in low-risk, nontraditional patients

BACKGROUND

The past 2 decades have seen an increased incidence of head and neck squamous cell carcinoma (HNSCC) in a nontraditional, low-risk patient population (ie, ≤45 years of age, no substance use history), owing to a combination of human papillomavirus (HPV) infection and individual genetic variation.

METHODS

Articles positing genetic variants as contributing factors in HNSCC incidence in low-risk, nontraditional patients were identified using a PubMed search, reviewed in detail, and concisely summarized herein.

RESULTS

Recent data suggest that common polymorphisms in DNA repair enzymes, cell-cycle control proteins, apoptotic pathway members, and Fanconi anemia-associated genes likely modulate susceptibility to HNSCC development in low-risk, nontraditional patients.

CONCLUSION

At present, there is a lack of robust, comprehensive data on genetic drivers of oncogenesis in low-risk patients and a clear need for further research on genetic alterations underlying the rising incidence of HNSCC in low-risk, nontraditional patients.

TP53 Germline Variations Influence the Predisposition and Prognosis of B-Cell Acute Lymphoblastic Leukemia in Children

Purpose Germline TP53 variation is the genetic basis of Li-Fraumeni syndrome, a highly penetrant cancer predisposition condition. Recent reports of germline TP53 variants in childhood hypodiploid acute lymphoblastic leukemia (ALL) suggest that this type of leukemia is another manifestation of Li-Fraumeni syndrome; however, the pattern, prevalence, and clinical relevance of TP53 variants in childhood ALL remain unknown. Patients and Methods Targeted sequencing of TP53 coding regions was performed in 3,801 children from the Children's Oncology Group frontline ALL clinical trials, AALL0232 and P9900. TP53 variant pathogenicity was evaluated according to experimentally determined transcriptional activity, in silico prediction of damaging effects, and prevalence in non-ALL control populations. TP53 variants were analyzed for their association with ALL presenting features and treatment outcomes. Results We identified 49 unique nonsilent rare TP53 coding variants in 77 (2.0%) of 3,801 patients sequenced, of which 22 variants were classified as pathogenic. TP53 pathogenic variants were significantly over-represented in ALL compared with non-ALL controls (odds ratio, 5.2; P < .001). Children with TP53 pathogenic variants were significantly older at ALL diagnosis (median age, 15.5 years v 7.3 years; P < .001) and were more likely to have hypodiploid ALL (65.4% v 1.2%; P < .001). Carrying germline TP53 pathogenic variants was associated with inferior event-free survival and overall survival (hazard ratio, 4.2 and 3.9; P < .001 and .001, respectively). In particular, children with TP53 pathogenic variants were at a dramatically higher risk of second cancers than those without pathogenic variants, with 5-year cumulative incidence of 25.1% and 0.7% ( P < .001), respectively. Conclusion Loss-of-function germline TP53 variants predispose children to ALL and to adverse treatment outcomes with ALL therapy, particularly the risk of second malignant neoplasms.