Stage-independent expression and genetic analysis of tp73 in neuroblastoma

Association between TP73 G4C14-A4T14 polymorphism and different cancer types: an updated meta-analysis of 55 case-control studies

OBJECTIVE

The TP73 G4C14-A4T14 variant has been associated with elevated cancer risk, but the evidence is inconclusive. We performed a meta-analysis to clarify the role of this variant in cancer development.

METHODS

Eligible literature was selected by searching PubMed, Google Scholar, Cochrane Library, and Embase. The meta-analysis was performed using Review Manager 5.4.

RESULTS

A meta-analysis of 55 case-control studies showed that the G4C14-A4T14 variant was significantly associated with overall cancer development in five genetic models, including the allele model (AM), codominant model 1 (COD1), COD2, dominant model (DM), and over-dominant model (OD). Sub-group analysis based on ethnicity showed significantly higher risks in Africans in COD2 and RM and in Whites in AM, COD2, DM, and recessive model (RM). Cancer-specific subgroup analysis identified significant risks of gynecological (ovarian, cervical, and endometrial cancer), colorectal, oral, head and neck, and other cancers. Moreover, hospital-based controls revealed significant cancer risks in the AM, COD1, COD2, DM, and RM genetic models. Our findings were confirmed by trial sequential analysis.

CONCLUSION

This meta-analysis confirmed that TP73 G4C14-A4T14 significantly elevates the overall cancer risk, especially in White, African, and hospital-based populations, and specifically predisposes individuals to gynecological, colorectal, oral, and head and neck cancers.This meta-analysis was registered at INPLASY (registration number: INPLASY202210070).

Mutations of 1p genes do not consistently abrogate tumor suppressor functions in 1p-intact neuroblastoma

Background

Deletion of 1p is associated with poor prognosis in neuroblastoma, however selected 1p-intact patients still experience poor outcomes. Since mutations of 1p genes may mimic the deleterious effects of chromosomal loss, we studied the incidence, spectrum and effects of mutational variants in 1p-intact neuroblastoma.

Methods

We characterized the 1p status of 325 neuroblastoma patients, and correlated the mutational status of 1p tumor suppressors and neuroblastoma candidate genes with survival outcomes among 100 1p-intact cases, then performed functional validation of selected novel variants of 1p36 genes identified from our patient cohort.

Results

Among patients with adverse disease characteristics, those who additionally had 1p deletion had significantly worse overall survival. Among 100 tumor-normal pairs sequenced, somatic mutations of 1p tumor suppressors KIF1Bβ and CHD5 were most frequent (2%) after ALK and ATRX (8%), and BARD1 (3%). Mutations of neuroblastoma candidate genes were associated with other synchronous mutations and concurrent 11q deletion (P = 0.045). In total, 24 of 38 variants identified were novel and predicted to be deleterious or pathogenic. Functional validation identified novel KIF1Bβ I1355M variant as a gain-of-function mutation with increased expression and tumor suppressive activity, correlating with indolent clinical behavior; another novel variant CHD5 E43Q was a loss-of-function mutation with decreased expression and increased long-term cell viability, corresponding with aggressive disease characteristics.

Conclusions

Our study showed that chromosome 1 gene mutations occurred frequently in 1p-intact neuroblastoma, but may not consistently abrogate the function of bonafide 1p tumor suppressors. These findings may augment the evolving model of compounding contributions of 1p gene aberrations toward tumor suppressor inactivation in neuroblastoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09800-0.

TP73 G4C14-A4T14 polymorphism and cancer susceptibility: evidence from 36 case-control studies

G4C14-A4T14 polymorphism of TP73 gene has been reported with a potential association in cancer risks through affected cell homeostasis; however the results were not consistent. We performed a comprehensive meta-analysis to explore the associations between G4C14-A4T14 polymorphism and cancer susceptibility. Extensive retrieve was performed in PubMed, EMBASE, Google Scholar, Web of Science, Wanfang database and CNKI database up to May 20, 2018. Odds ratios (ORs) and 95% confidence intervals (CIs) were conducted to evaluate the overall strength of the associations in five genetic models, as well as in subgroup analyses. Q-test, false-positive report probability analysis and trial sequential analysis, Egger’s test and Begg’s funnel plot were applied to evaluate the robustness of the results. In silico analysis was managed to demonstrate the relationship of TP73 expression correlated with cancer tissues. Finally, 36 case–control studies with a total of 9493 cancer cases and 13,157 healthy controls were enrolled into the meta-analysis. The pooled results present a significantly higher risk of G4C14-A4T14 polymorphism in all the five genetic models, as well as in the subgroups of Caucasian, cervical cancer, colorectal cancer, H-B subgroup and comfort to Hardy–Weinberg equilibrium subgroup. In silico analysis revealed that the expression of TP73 in cervical cancer tissue is higher than it in corresponding normal tissue, as well as in cervical cancer. All in all, TP73 G4C14-A4T14 polymorphism causes an upgrade cancer risk, especially in Caucasian population. G4C14-A4T14 polymorphism might be a potential biomarker for judging the tumorigenesis of cervical cancer and colorectal cancer.

Clinical implications of the deregulated TP73 isoforms expression in cancer

TP73 is a member of the TP53 family whose expression has been observed altered in most human cancers and associated with the prognosis. TP73 translates into a complex number of isoforms with both oncogenic and tumour-suppressor functions and presents a complex cross-talk with other members of the family (TP53 and TP63). In this revision, we focus on the evidence that may support TP73 variants as prognostic markers in cancer. Nowadays, most publications in this topic highlight the association between overexpression of the oncogenic variants and failure to respond to chemotherapy and/or shorter survival. In addition, we comment on the putative possibilities that the detection through a liquid biopsy of TP73 variants may provide, and finally, the significance of determining the value of the combined alteration of the TP53 family members in the clinical setting.

Characterization of three human cell line models for high-throughput neuronal cytotoxicity screening

More than 75 000 man-made chemicals contaminate the environment; many of these have not been tested for toxicities. These chemicals demand quantitative high-throughput screening assays to assess them for causative roles in neurotoxicities, including Parkinson's disease and other neurodegenerative disorders. To facilitate high throughput screening for cytotoxicity to neurons, three human neuronal cellular models were compared: SH-SY5Y neuroblastoma cells, LUHMES conditionally-immortalized dopaminergic neurons, and Neural Stem Cells (NSC) derived from human fetal brain. These three cell lines were evaluated for rapidity and degree of differentiation, and sensitivity to 32 known or candidate neurotoxicants. First, expression of neural differentiation genes was assayed during a 7-day differentiation period. Of the three cell lines, LUHMES showed the highest gene expression of neuronal markers after differentiation. Both in the undifferentiated state and after 7 days of neuronal differentiation, LUHMES cells exhibited greater cytotoxic sensitivity to most of 32 suspected or known neurotoxicants than SH-SY5Y or NSCs. LUHMES cells were also unique in being more susceptible to several compounds in the differentiating state than in the undifferentiated state; including known neurotoxicants colchicine, methyl-mercury (II), and vincristine. Gene expression results suggest that differentiating LUHMES cells may be susceptible to apoptosis because they express low levels of anti-apoptotic genes BCL2 and BIRC5/survivin, whereas SH-SY5Y cells may be resistant to apoptosis because they express high levels of BCL2, BIRC5/survivin, and BIRC3 genes. Thus, LUHMES cells exhibited favorable characteristics for neuro-cytotoxicity screening: rapid differentiation into neurons that exhibit high level expression neuronal marker genes, and marked sensitivity of LUHMES cells to known neurotoxicants. Copyright © 2016 John Wiley & Sons, Ltd.

The TP73 complex network: ready for clinical translation in cancer?

TP73 is a member of the TP53 family, whose deregulated expression has been reported in a wide variety of cancers and linked to patients' outcome. The fact that TP73 encodes a complex number of isoforms (TAp73 and ΔTAp73) with opposing functions and the cross-talk with other members of the family (TP53 and TP63) make it difficult to determine its clinical relevance. Here, we review the molecular mechanisms driving TAp73 and ΔTAp73 expression and how these variants inhibit or promote carcinogenesis. We also highlight the intricate interplay between TP53 family members. In addition, we comment on current pharmacological approaches targeting the TP73 pathway and those affecting the TAp73/ΔTAp73 ratio. Finally, we discuss the current data available in the literature that provide evidence on the role of TP73 variants in predicting prognosis. To date, most of the studies that evaluate the status levels of TP73 isoforms have been based on limited-size series. Despite this limitation, these publications highlight the correlation between high levels of the oncogenic forms and failure to respond to chemotherapy and/or shorter survival. Finally, we emphasize the need for studies to evaluate the significance of combining the deregulation of various members of the TP53 family in order to define patient outcome or their responsiveness to specific therapies.

Inhibition of the nicotinic acetylcholine receptors by cobra venom α-neurotoxins: is there a perspective in lung cancer treatment?

Nicotine exerts its oncogenic effects through the binding to nicotinic acetylcholine receptors (nAChRs) and the activation of downstream pathways that block apoptosis and promote neo-angiogenesis. The nAChRs of the α7 subtype are present on a wide variety of cancer cells and their inhibition by cobra venom neurotoxins has been proposed in several articles and reviews as a potential innovative lung cancer therapy. However, since part of the published results was recently retracted, we believe that the antitumoral activity of cobra venom neurotoxins needs to be independently re-evaluated.

We determined the activity of α-neurotoxins from Naja atra (short-chain neurotoxin, α-cobrotoxin) and Naja kaouthia (long-chain neurotoxin, α-cobratoxin) in vitro by cytotoxicity measurements in 5 lung cancer cell lines, by colony formation assay with α7nAChRs expressing and non-expressing cell lines and in vivo by assessing tumor growth in an orthotopic Non-Obese Diabetic/Severe Combined Immunodeficient (NOD/SCID) mouse model system utilizing different treatment schedules and dosages.

No statistically significant reduction in tumor growth was observed in the treatment arms in comparison to the control for both toxins. Paradoxically α-cobrotoxin from Naja atra showed the tendency to enhance tumor growth although, even in this case, the statistical significance was not reached.

In conclusion our results show that, in contrast with other reports, the nAChR inhibitors α-cobratoxin from N. kaouthia and α-cobrotoxin from N. atra neither suppressed tumor growth nor prolonged the survival of the treated animals.

Relationship between TP73 polymorphism (G4C14-A4T14) and cancer risk: a meta-analysis based on literatures

The tumor protein p73 (TP73) gene belongs to the TP53 gene family and functions in the induction of apoptosis or cell-cycle arrest. The TP73 polymorphism (G4C14-A4T14) has been reported and many studies have focused on the role of this polymorphism in various cancers. However, the data reported for most individual cancer types were limited and not able to support a convincible conclusion. Hence, in this study, we explored the relationship between TP73 polymorphism (G4C14-A4T14) and cancer risk by carrying out a comprehensive meta-analysis. Performing both the overall and subgroup meta-analyses with a total of 23 eligible studies (6635 cases and 7378 controls in all), we detected significant cancer risk variations in the overall analysis, as well as the subgroup analysis based on ethnicity for both Asians and Caucasians. In the subgroup analysis based on source of controls, significant associations were also observed in the hospital-based controls' subgroup yet not in the population-based controls' subgroup. Furthermore, in the subgroup analysis based on cancer types, significant associations were found in colorectal cancer's subgroup but not in other cancer types' subgroups. In summary, according to the results of our meta-analysis, the TP73 polymorphism (G4C14-A4T14) probably associates with cancer risk.

Distinct CpG methylation profiles characterize different clinical groups of neuroblastic tumors

The hypermethylation of CpG islands within gene promoter regions is an epigenetic phenomenon that is often, but not always, associated with the transcriptional silencing of downstream genes and contributes to carcinogenesis. We have determined the pattern of methylation of several genes involved in distinct biological pathways, including cell proliferation and apoptosis, in neuroblastoma and in the nonmalignant ganglioneuroma. The purpose of this work was to search for epigenetic signatures that could be associated with defined clinical and biological parameters and that, in prospective, could identify specific risk categories among the patients. We have analysed 31 malignant neuroblastoma with or without MYCN amplification and 13 benign ganglioneuroma and we have observed dramatic differences in the methylation pattern of five genes (CASP8, 14.3.3sigma, DeltaN-p73, RASSF1A and DCR2) between these tumors indicating that this phenomenon is not tissue-specific and can be considered as cancer-dependent. Furthermore, the methylation pattern of 14.3.3sigma, RASSF1A and of an intragenic segment of CASP8 was significantly different between MYCN amplified and single copy neuroblastoma suggesting a specific role of epigenetic alterations in aggressive neuroblastoma.

Biological and clinical role of p73 in neuroblastoma

The p73 gene is a p53 homologue localized at 1p36.3, a chromosomal region frequently deleted in neuroblastoma. p73 was originally considered an oncosuppressor gene. However, it was soon realized that its mode of action did not resemble that of a classic anti-oncogene. The recent discovery of N-terminal truncated isoforms, with oncogenic properties, showed that p73 has a 'two in one' structure. Indeed, the full-length variants are strong inducers of apoptosis while the truncated isoforms inhibit the pro-apoptotic activity of p53 and of the full-length p73. This review summarizes some aspects of p73 biology with particular reference to its possible role in neuroblastoma.

Expression of DeltaNp73 is a molecular marker for adverse outcome in neuroblastoma patients

The p73 gene is a p53 homologue which induces apoptosis and inhibits cell proliferation. Although p73 maps at 1p36.3 and is frequently deleted in neuroblastoma (NB), it does not act as a classic oncosuppressor gene. In developing sympathetic neurons of mice, p73 is predominantly expressed as a truncated anti-apoptotic isoform (DeltaNp73), which antagonizes both p53 and the full-length p73 protein (TAp73). This suggests that p73 may be part of a complex tumor-control mechanism. To determine the role of DeltaNp73 in NB we analyzed the pattern of expression of this gene in vivo and evaluated the prognostic significance of its expression. Our results indicate that DeltaNp73 expression is associated with reduced apoptosis in a NB tumor tissue. Expression of this variant in NB patients significantly correlates with age at diagnosis and VMA urinary excretion. Moreover it is strongly associated with reduced survival (HR=7.93; P<0.001) and progression-free survival (HR=5.3; P<0.001) and its role in predicting a poorer outcome is independent from age, primary tumor site, stage and MYCN amplification (OS: HR=5.24, P=0.012; PFS: HR=4.36, P=0.005). In conclusion our data seem to indicate that DeltaNp73 is a crucial gene in neuroblastoma pathogenesis.

Methylation-independent silencing of the p73 gene in neuroblastoma

p73 is a p53 homolog that, in vitro, inhibits cell growth and induce apoptosis. In some tumors p73 is monoallelically expressed and this raised the possibility that this gene is subjected to imprinting. Silencing of p73 in acute leukemia and in Burkitt's lymphoma occurs in association with the aberrant methylation of the first exon of the gene. We have analysed the methylation pattern of the p73 promoter and of upstream and downstream sequences in neuroblastoma. Our results demonstrate that p73 expression in this tumor is not regulated by methylation. We concluded that it is unlikely that p73 is imprinted in neuroblastoma and that the methylation-dependent silencing of this gene, thus far, is a characteristic of hematologic malignancies. Oncogene (2000) 19, 4553 - 4556.