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1.
Cancers (Basel) ; 13(3)2021 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-33513745

RESUMO

The disruption of genomic integrity due to the accumulation of various kinds of DNA damage, deficient DNA repair capacity, and telomere shortening constitute the hallmarks of malignant diseases. DNA damage response (DDR) is a signaling network to process DNA damage with importance for both cancer development and chemotherapy outcome. DDR represents the complex events that detect DNA lesions and activate signaling networks (cell cycle checkpoint induction, DNA repair, and induction of cell death). TP53, the guardian of the genome, governs the cell response, resulting in cell cycle arrest, DNA damage repair, apoptosis, and senescence. The mutational status of TP53 has an impact on DDR, and somatic mutations in this gene represent one of the critical events in human carcinogenesis. Telomere dysfunction in cells that lack p53-mediated surveillance of genomic integrity along with the involvement of DNA repair in telomeric DNA regions leads to genomic instability. While the role of individual players (DDR, telomere homeostasis, and TP53) in human cancers has attracted attention for some time, there is insufficient understanding of the interactions between these pathways. Since solid cancer is a complex and multifactorial disease with considerable inter- and intra-tumor heterogeneity, we mainly dedicated this review to the interactions of DNA repair, telomere homeostasis, and TP53 mutational status, in relation to (a) cancer risk, (b) cancer progression, and (c) cancer therapy.

2.
Artigo em Inglês | MEDLINE | ID: mdl-33318029

RESUMO

BACKGROUND: Evidence for aspirin's chemopreventative properties on colorectal cancer (CRC) is substantial, but its mechanism of action is not well-understood. We combined a proteomic approach with Mendelian randomization (MR) to identify possible new aspirin targets that decrease CRC risk. METHODS: Human colorectal adenoma cells (RG/C2) were treated with aspirin (24 hours) and a stable isotope labeling with amino acids in cell culture (SILAC) based proteomics approach identified altered protein expression. Protein quantitative trait loci (pQTLs) from INTERVAL (N = 3,301) and expression QTLs (eQTLs) from the eQTLGen Consortium (N = 31,684) were used as genetic proxies for protein and mRNA expression levels. Two-sample MR of mRNA/protein expression on CRC risk was performed using eQTL/pQTL data combined with CRC genetic summary data from the Colon Cancer Family Registry (CCFR), Colorectal Transdisciplinary (CORECT), Genetics and Epidemiology of Colorectal Cancer (GECCO) consortia and UK Biobank (55,168 cases and 65,160 controls). RESULTS: Altered expression was detected for 125/5886 proteins. Of these, aspirin decreased MCM6, RRM2, and ARFIP2 expression, and MR analysis showed that a standard deviation increase in mRNA/protein expression was associated with increased CRC risk (OR: 1.08, 95% CI, 1.03-1.13; OR: 3.33, 95% CI, 2.46-4.50; and OR: 1.15, 95% CI, 1.02-1.29, respectively). CONCLUSIONS: MCM6 and RRM2 are involved in DNA repair whereby reduced expression may lead to increased DNA aberrations and ultimately cancer cell death, whereas ARFIP2 is involved in actin cytoskeletal regulation, indicating a possible role in aspirin's reduction of metastasis. IMPACT: Our approach has shown how laboratory experiments and population-based approaches can combine to identify aspirin-targeted proteins possibly affecting CRC risk.

3.
Mutagenesis ; 35(6): 491-497, 2020 12 31.
Artigo em Inglês | MEDLINE | ID: mdl-33367858

RESUMO

Disruption of telomere length (TL) homeostasis in peripheral blood lymphocytes has been previously assessed as a potential biomarker of breast cancer (BC) risk. The present study addressed the relationship between lymphocyte TL (LTL), prognosis and clinicopathological features in the BC patients since these associations are insufficiently explored at present. LTL was measured in 611 BC patients and 154 healthy controls using the monochrome multiplex quantitative Polymerase Chain Reaction assay. In addition, we genotyped nine TL-associated single-nucleotide polymorphisms that had been identified through genome-wide association studies. Our results showed that the patients had significantly (P = 0.001, Mann-Whitney U-test) longer LTL [median (interquartile range); 1.48 (1.22-1.78)] than the healthy controls [1.27 (0.97-1.82)]. Patients homozygous (CC) for the common allele of hTERT rs2736108 or the variant allele (CC) of hTERC rs16847897 had longer LTL. The latter association remained statistically significant in the recessive genetic model after the Bonferroni correction (P = 0.004, Wilcoxon two-sample test). We observed no association between LTL and overall survival or relapse-free survival of the patients. LTL did not correlate with cancer staging based on Union for International Cancer Control (UICC), The tumor node metastasis (TNM) staging system classification, tumour grade or molecular BC subtypes. Overall, we observed an association between long LTL and BC disease and an association of the hTERC rs16847897 CC genotype with increased LTL. However, no association between LTL, clinicopathological features and survival of the patients was found.

4.
Carcinogenesis ; 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33319241

RESUMO

One of the principal mechanisms of chemotherapy resistance in highly frequent solid tumors like colorectal cancer (CRC) is the decreased activity of drug transport into tumor cells due to low expression of important membrane proteins, such as solute carrier (SLC) transporters. Sequence complementarity is a major determinant for target gene recognition by microRNAs (miRNAs). Single nucleotide polymorphisms (SNPs) in target sequences transcribed into messenger RNA may therefore alter miRNA binding to these regions by either creating a new site or destroying an existing one. miRSNPs may explain the modulation of expression levels in association with increased/decreased susceptibility to common diseases as well as in chemoresistance and the consequent interindividual variability in drug response. In the present study, we investigated whether miRSNPs in SLC transporter genes may modulate CRC susceptibility and patient's survival. Using an in silico approach for functional predictions, we analyzed twenty-six miRSNPs in nine SLC genes in a cohort of 1368 CRC cases and 698 controls from the Czech Republic. After correcting for multiple tests, we found several miRSNPs significantly associated with patient's survival. SNPs in SLCO3A1, SLC22A2, and SLC22A3 genes were defined as prognostic factors in the classification and regression tree analysis. In contrast, we did not observe any significant association between miRSNPs and CRC risk. To the best of our knowledge, this is the first study investigating miRSNPs potentially affecting miRNA binding to SLC transporter genes and their impact on CRC susceptibility or patient's prognosis.

5.
Mutat Res ; 858-860: 503253, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33198934

RESUMO

Genomic instability is a characteristic of a majority of human malignancies. Chromosomal instability is a common form of genomic instability that can be caused by defects in mitotic checkpoint genes. Chromosomal aberrations in peripheral blood are also indicative of genotoxic exposure and potential cancer risk. We evaluated associations between inherited genetic variants in 33 mitotic checkpoint genes and the frequency of chromosomal aberrations (CAs) in the presence and absence of environmental genotoxic exposure. Associations with both chromosome and chromatid type of aberrations were evaluated in two cohorts of healthy individuals, namely an exposed and a reference group consisting of 607 and 866 individuals, respectively. Binary logistic and linear regression analyses were performed for the association studies. Bonferroni-corrected significant p-value was 5 × 10-4 for 99 tests based on the number of analyzed genes and phenotypes. In the reference group the most prominent associations were found with variants in CCNB1, a master regulator of mitosis, and in genes involved in kinetochore function, including CENPH and TEX14, whereas in the exposed group the main association was found with variants in TTK, also an important gene in kinetochore function. How the identified variants may affect the fidelity of mitotic checkpoint remains to be investigated, however, the present study suggests that genetic variation may partly explain interindividual variation in the formation of CAs.

6.
Oncol Rep ; 44(5): 2219-2230, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33000239

RESUMO

Accumulation of non­specific structural chromosomal aberrations (CAs) and telomere shortening contribute to genome instability, which constitutes as one of the hallmarks of cancer. CAs arise due to direct DNA damage or telomere shortening. CAs in peripheral blood lymphocytes (PBL), which are considered to be markers of exposure, have been previously reported to serve a role in the pathophysiology and progression of cancer through mechanisms that are poorly understood. In addition, the prognostic relevance of telomere length (TL) in patients with cancer remains to be elucidated. In the present study, CAs and TL in PBL isolated from patients with newly diagnosed cancer (151 breast, 96 colorectal, 90 lung) and 335 cancer­free control individuals were investigated. These results were then correlated with clinicopathological factors and follow­up data. The accumulation of CAs in PBL was observed with increased susceptibility to breast and lung cancer (P<0.0001), while individuals with longer TL were found to be at a higher risk of breast cancer (P<0.0001). Increased chromatid­type aberrations were also revealed to be associated with lower overall survival of patients with breast and colorectal cancers using a multivariate model. Compared with control individuals, no association was observed between TL and CAs or age in patients with cancer. In conclusion, the present study demonstrates the association between CAs/TL in PBL and the susceptibility, prognosis and survival of patients with breast, colorectal and lung cancer.

7.
Int J Mol Sci ; 21(15)2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32756484

RESUMO

The phenotypic effects of single nucleotide polymorphisms (SNPs) in the development of sporadic solid cancers are still scarce. The aim of this review was to summarise and analyse published data on the associations between SNPs in mismatch repair genes and various cancers. The mismatch repair system plays a unique role in the control of the genetic integrity and it is often inactivated (germline and somatic mutations and hypermethylation) in cancer patients. Here, we focused on germline variants in mismatch repair genes and found the outcomes rather controversial: some SNPs are sometimes ascribed as protective, while other studies reported their pathological effects. Regarding the complexity of cancer as one disease, we attempted to ascertain if particular polymorphisms exert the effect in the same direction in the development and treatment of different malignancies, although it is still not straightforward to conclude whether polymorphisms always play a clear positive role or a negative one. Most recent and robust genome-wide studies suggest that risk of cancer is modulated by variants in mismatch repair genes, for example in colorectal cancer. Our study shows that rs1800734 in MLH1 or rs2303428 in MSH2 may influence the development of different malignancies. The lack of functional studies on many DNA mismatch repair SNPs as well as their interactions are not explored yet. Notably, the concerted action of more variants in one individual may be protective or harmful. Further, complex interactions of DNA mismatch repair variations with both the environment and microenvironment in the cancer pathogenesis will deserve further attention.

8.
Cancers (Basel) ; 12(7)2020 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-32605254

RESUMO

There is ample evidence for the essential involvement of DNA repair and DNA damage response in the onset of solid malignancies, including ovarian cancer. Indeed, highpenetrance germline mutations in DNA repair genes are important players in familial cancers: BRCA1, BRCA2 mutations or mismatch repair, and polymerase deficiency in colorectal, breast, and ovarian cancers. Recently, some molecular hallmarks (e.g., TP53, KRAS, BRAF, RAD51C/D or PTEN mutations) of ovarian carcinomas were identified. The manuscript overviews the role of DNA repair machinery in ovarian cancer, its risk, prognosis, and therapy outcome. We have attempted to expose molecular hallmarks of ovarian cancer with a focus on DNA repair system and scrutinized genetic, epigenetic, functional, and protein alterations in individual DNA repair pathways (homologous recombination, non-homologous end-joining, DNA mismatch repair, base- and nucleotide-excision repair, and direct repair). We suggest that lack of knowledge particularly in non-homologous end joining repair pathway and the interplay between DNA repair pathways needs to be confronted. The most important genes of the DNA repair system are emphasized and their targeting in ovarian cancer will deserve further attention. The function of those genes, as well as the functional status of the entire DNA repair pathways, should be investigated in detail in the near future.

9.
Int J Mol Sci ; 21(15)2020 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-32722130

RESUMO

Colorectal cancer (CRC) remains a serious health problem worldwide. Approximately half of patients will develop distant metastasis after CRC resection, usually with very poor prognosis afterwards. Because patient performance after distant metastasis surgery remains very heterogeneous, ranging from death within 2 years to a long-term cure, there is a clinical need for a precise risk stratification of patients to aid pre- and post-operative decisions. Furthermore, around 20% of identified CRC cases are at IV stage disease, known as a metastatic CRC (mCRC). In this review, we overview possible molecular and clinicopathological biomarkers that may provide prognostic and predictive information for patients with distant metastasis. These may comprise sidedness of the tumor, molecular profile and epigenetic characteristics of the primary tumor and arising metastatic CRC, and early markers reflecting cancer cell resistance in mCRC and biomarkers identified from transcriptome. This review discusses current stage in employment of these biomarkers in clinical practice as well as summarizes current experience in identifying predictive biomarkers in mCRC treatment.

10.
Int J Cancer ; 147(8): 2065-2074, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32270874

RESUMO

Early onset pancreatic cancer (EOPC) is a rare disease with a very high mortality rate. Almost nothing is known on the genetic susceptibility of EOPC, therefore, we performed a genome-wide association study (GWAS) to identify novel genetic variants specific for patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) at younger ages. In the first phase, conducted on 821 cases with age of onset ≤60 years, of whom 198 with age of onset ≤50, and 3227 controls from PanScan I-II, we observed four SNPs (rs7155613, rs2328991, rs4891017 and rs12610094) showing an association with EOPC risk (P < 1 × 10-4 ). We replicated these SNPs in the PANcreatic Disease ReseArch (PANDoRA) consortium and used additional in silico data from PanScan III and PanC4. Among these four variants rs2328991 was significant in an independent set of 855 cases with age of onset ≤60 years, of whom 265 with age of onset ≤50, and 4142 controls from the PANDoRA consortium while in the in silico data, we observed no statistically significant association. However, the resulting meta-analysis supported the association (P = 1.15 × 10-4 ). In conclusion, we propose a novel variant rs2328991 to be involved in EOPC risk. Even though it was not possible to find a mechanistic link between the variant and the function, the association is supported by a solid statistical significance obtained in the largest study on EOPC genetics present so far in the literature.

11.
Int J Mol Sci ; 21(7)2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32252452

RESUMO

Oxidative stress with subsequent premutagenic oxidative DNA damage has been implicated in colorectal carcinogenesis. The repair of oxidative DNA damage is initiated by lesion-specific DNA glycosylases (hOGG1, NTH1, MUTYH). The direct evidence of the role of oxidative DNA damage and its repair is proven by hereditary syndromes (MUTYH-associated polyposis, NTHL1-associated tumor syndrome), where germline mutations cause loss-of-function in glycosylases of base excision repair, thus enabling the accumulation of oxidative DNA damage and leading to the adenoma-colorectal cancer transition. Unrepaired oxidative DNA damage often results in G:C>T:A mutations in tumor suppressor genes and proto-oncogenes and widespread occurrence of chromosomal copy-neutral loss of heterozygosity. However, the situation is more complicated in complex and heterogeneous disease, such as sporadic colorectal cancer. Here we summarized our current knowledge of the role of oxidative DNA damage and its repair on the onset, prognosis and treatment of sporadic colorectal cancer. Molecular and histological tumor heterogeneity was considered. Our study has also suggested an additional important source of oxidative DNA damage due to intestinal dysbiosis. The roles of base excision repair glycosylases (hOGG1, MUTYH) in tumor and adjacent mucosa tissues of colorectal cancer patients, particularly in the interplay with other factors (especially microenvironment), deserve further attention. Base excision repair characteristics determined in colorectal cancer tissues reflect, rather, a disease prognosis. Finally, we discuss the role of DNA repair in the treatment of colon cancer, since acquired or inherited defects in DNA repair pathways can be effectively used in therapy.

12.
Mutagenesis ; 35(3): 261-271, 2020 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-32083302

RESUMO

Colorectal cancer (CRC) continues to be one of the leading malignancies and causes of tumour-related deaths worldwide. Both impaired DNA repair mechanisms and disrupted telomere length homeostasis represent key culprits in CRC initiation, progression and prognosis. Mechanistically, altered DNA repair results in the accumulation of mutations in the genome and, ultimately, in genomic instability. DNA repair also determines the response to chemotherapeutics in CRC treatment, suggesting its utilisation in the prediction of therapy response and individual approach to patients. Telomere attrition resulting in replicative senescence, simultaneously by-passing cell cycle checkpoints, is a hallmark of malignant transformation of the cell. Telomerase is almost ubiquitous in advanced solid cancers, including CRC, and its expression is fundamental to cell immortalisation. Therefore, there is a persistent effort to develop therapeutics, which are telomerase-specific and gentle to non-malignant tissues. However, in practice, we are still at the level of clinical trials. The current state of knowledge and the route, which the research takes, gives us a positive perspective that the problem of molecular models of telomerase activation and telomere length stabilisation will finally be solved. We summarise the current literature herein, by pointing out the crosstalk between proteins involved in DNA repair and telomere length homeostasis in relation to CRC.

13.
Mutagenesis ; 35(3): 273-281, 2020 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-31922572

RESUMO

The chemotherapeutic efficacy in colorectal cancer (CRC) is limited due to the inter-individual variability in drug response and the development of tumour resistance. ATP-binding cassette (ABC) transporters are crucial in the development of resistance by the efflux of anticancer agents from cancer cells. In this study, we identified 14 single nucleotide polymorphisms (SNPs) in 11 ABC transporter genes acting as an expression of quantitative trait loci (eQTLs), i.e. whose variation influence the expression of many downstream genes. These SNPs were genotyped in a case-control study comprising 1098 cases and 1442 healthy controls and analysed in relation to CRC development risk and patient survival. Considering a strict correction for multiple tests, we did not observe any significant association between SNPs and CRC risk. The rs3819720 polymorphism in the ABCB3/TAP2 gene was statistically significantly associated with shorter overall survival (OS) in the codominant, and dominant models [GA vs. GG, hazard ratio (HR) = 1.48; P = 0.002; AA vs. GG, HR = 1.70; P = 0.004 and GA + AA vs. GG, HR = 1.52; P = 0.0006]. Additionally, GA carriers of the same SNP displayed worse OS after receiving 5-FU based chemotherapy. The variant allele of rs3819720 polymorphism statistically significantly affected the expression of 36 downstream genes. Screening for eQTL polymorphisms in relevant genes such as ABC transporters that can regulate the expression of several other genes may help to identify the genetic background involved in the individual response to the treatment of CRC patients.

15.
Int J Cancer ; 146(2): 363-372, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31209889

RESUMO

Interindividual differences in DNA repair systems may play a role in modulating the individual risk of developing colorectal cancer. To better ascertain the role of DNA repair gene polymorphisms on colon and rectal cancer risk individually, we evaluated 15,419 single nucleotide polymorphisms (SNPs) within 185 DNA repair genes using GWAS data from the Colon Cancer Family Registry (CCFR) and the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), which included 8,178 colon cancer, 2,936 rectum cancer cases and 14,659 controls. Rs1800734 (in MLH1 gene) was associated with colon cancer risk (p-value = 3.5 × 10-6 ) and rs2189517 (in RAD51B) with rectal cancer risk (p-value = 5.7 × 10-6 ). The results had statistical significance close to the Bonferroni corrected p-value of 5.8 × 10-6 . Ninety-four SNPs were significantly associated with colorectal cancer risk after Binomial Sequential Goodness of Fit (BSGoF) procedure and confirmed the relevance of DNA mismatch repair (MMR) and homologous recombination pathways for colon and rectum cancer, respectively. Defects in MMR genes are known to be crucial for familial form of colorectal cancer but our findings suggest that specific genetic variations in MLH1 are important also in the individual predisposition to sporadic colon cancer. Other SNPs associated with the risk of colon cancer (e.g., rs16906252 in MGMT) were found to affect mRNA expression levels in colon transverse and therefore working as possible cis-eQTL suggesting possible mechanisms of carcinogenesis.


Assuntos
Neoplasias do Colo/genética , Reparo do DNA/genética , Predisposição Genética para Doença , Neoplasias Retais/genética , Adulto , Idoso , Variação Biológica da População/genética , Carcinogênese/genética , Estudos de Casos e Controles , Colo/patologia , Neoplasias do Colo/patologia , Metilases de Modificação do DNA/genética , Enzimas Reparadoras do DNA/genética , Proteínas de Ligação a DNA/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Proteína 1 Homóloga a MutL/genética , Polimorfismo de Nucleotídeo Único , Neoplasias Retais/patologia , Reto/patologia , Sistema de Registros/estatística & dados numéricos , Medição de Risco , Proteínas Supressoras de Tumor/genética , Adulto Jovem
16.
Cancer Med ; 9(4): 1473-1484, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31869529

RESUMO

OBJECTIVE: The TLR3/cGAS-STING-IFN signaling has recently been reported to be disturbed in colorectal cancer due to deregulated expression of the genes involved. Our study aimed to investigate the influence of potential regulatory variants in these genes on the risk of sporadic colorectal cancer (CRC) in a Czech cohort of 1424 CRC patients and 1114 healthy controls. METHODS: The variants in the TLR3, CGAS, TMEM173, IKBKE, and TBK1 genes were selected using various online bioinformatic tools, such as UCSC browser, HaploReg, Regulome DB, Gtex Portal, SIFT, PolyPhen2, and miRNA prediction tools. RESULTS: Logistic regression analysis adjusted for age and sex detected a nominal association between CRC risk and three variants, CGAS rs72960018 (OR: 1.68, 95% CI: 1.11-2.53, P-value = .01), CGAS rs9352000 (OR: 2.02, 95% CI: 1.07-3.84, P-value = .03) and TMEM173 rs13153461 (OR: 1.53, 95% CI: 1.03-2.27, P-value = .03). Their cumulative effect revealed a threefold increased CRC risk in carriers of 5-6 risk alleles compared to those with 0-2 risk alleles. Epistatic interactions between these genes and the previously genotyped IFNAR1, IFNAR2, IFNA, IFNB, IFNK, IFNW, IRF3, and IRF7 genes, were computed to test their effect on CRC risk. Overall, we obtained nine pair-wise interactions within and between the CGAS, TMEM173, IKBKE, and TBK1 genes. Two of them remained statistically significant after Bonferroni correction. Additional 52 interactions were observed when IFN variants were added to the analysis. CONCLUSIONS: Our data suggest that epistatic interactions and a high number of risk alleles may play an important role in CRC carcinogenesis, offering novel biological understanding for the CRC management.

17.
Pharmacogenomics ; 20(17): 1225-1233, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31691643

RESUMO

DNA repair, a complex biological process, ensures genomic integrity. Alterations in DNA repair, occurring in many cancers, contribute to the accumulation of mutations in the genome, resulting in genomic instability and cancer progression. DNA repair also plays a substantial role in response to chemotherapeutics: rapidly dividing colon cancer cells, vulnerable to DNA-damaging agents and overcoming DNA repair, undergo cell death. DNA repair capacity represents a complex biomarker, integrating gene variants, gene expressions, the stability of gene products, the effect of inhibitors/stimulators, lifestyle and environmental factors. Here, we discuss DNA repair capacity in sporadic colon cancer, a frequent malignancy worldwide, in relation to tumor heterogeneity, prognosis and prediction, measurements in surrogate and target tissues and suggest important tasks to be addressed.


Assuntos
Neoplasias do Colo/tratamento farmacológico , Reparo do DNA/efeitos dos fármacos , Epigênese Genética/genética , Instabilidade Genômica/genética , Morte Celular/efeitos dos fármacos , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Dano ao DNA/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Instabilidade Genômica/efeitos dos fármacos , Humanos , Mutação , Prognóstico
18.
Cell Death Dis ; 10(11): 818, 2019 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-31659152

RESUMO

Protein phosphatase magnesium-dependent 1 delta (PPM1D) terminates cell response to genotoxic stress by negatively regulating the tumor suppressor p53 and other targets at chromatin. Mutations in the exon 6 of the PPM1D result in production of a highly stable, C-terminally truncated PPM1D. These gain-of-function PPM1D mutations are present in various human cancers but their role in tumorigenesis remains unresolved. Here we show that truncated PPM1D impairs activation of the cell cycle checkpoints in human non-transformed RPE cells and allows proliferation in the presence of DNA damage. Next, we developed a mouse model by introducing a truncating mutation in the PPM1D locus and tested contribution of the oncogenic PPM1DT allele to colon tumorigenesis. We found that p53 pathway was suppressed in colon stem cells harboring PPM1DT resulting in proliferation advantage under genotoxic stress condition. In addition, truncated PPM1D promoted tumor growth in the colon in Apcmin mice and diminished survival. Moreover, tumor organoids derived from colon of the ApcminPpm1dT/+ mice were less sensitive to 5-fluorouracil when compared to ApcminPpm1d+/+and the sensitivity to 5-fluorouracil was restored by inhibition of PPM1D. Finally, we screened colorectal cancer patients and identified recurrent somatic PPM1D mutations in a fraction of colon adenocarcinomas that are p53 proficient and show defects in mismatch DNA repair. In summary, we provide the first in vivo evidence that truncated PPM1D can promote tumor growth and modulate sensitivity to chemotherapy.


Assuntos
Proteína da Polipose Adenomatosa do Colo/genética , Neoplasias do Colo/tratamento farmacológico , Proteína Fosfatase 2C/genética , Proteína Supressora de Tumor p53/genética , Animais , Carcinogênese/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/genética , Proliferação de Células/efeitos dos fármacos , Cromatina/efeitos dos fármacos , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Dano ao DNA/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Éxons/genética , Fluoruracila/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos , Mutação/genética
19.
Mutagenesis ; 34(4): 323-330, 2019 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-31586183

RESUMO

Non-specific structural chromosomal aberrations (CAs) observed in peripheral blood lymphocytes of healthy individuals can be either chromosome-type aberrations (CSAs) or chromatid-type aberrations (CTAs) depending on the stage of cell division they are induced in and mechanism of formation. It is important to study the genetic basis of chromosomal instability as it is a marker of genotoxic exposure and a predictor of cancer risk. For that purpose, we conducted two genome-wide association studies (GWASs) on healthy individuals in the presence and absence of apparent genotoxic exposure from the Czech Republic and Slovakia. The pre-GWAS cytogenetic analysis reported the frequencies of CSA, CTA and total CA (CAtot). We performed both linear and binary logistic regression analysis with an arbitrary cut-off point of 2% for CAtot and 1% for CSA and CTA. Using the statistical threshold of 1.0 × 10-5, we identified five loci with in silico predicted functionality in the reference group and four loci in the exposed group, with no overlap between the associated regions. A meta-analysis on the two GWASs identified further four loci with moderate associations in each of the studies. From the reference group mainly loci within genes related to DNA damage response/repair were identified. Other loci identified from both the reference and exposed groups were found to be involved in the segregation of chromosomes and chromatin modification. Some of the discovered regions in each group were implicated in tumourigenesis and autism.


Assuntos
Aberrações Cromossômicas/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Frequência do Gene , Genética Populacional , Mutagênicos/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Alelos , Análise Citogenética , Feminino , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Masculino , Metanálise como Assunto , Pessoa de Meia-Idade , Razão de Chances , Polimorfismo de Nucleotídeo Único , Adulto Jovem
20.
Mutat Res ; 845: 403065, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31561886

RESUMO

The first-line chemotherapy of colorectal cancer (CRC), besides surgery, comprises administration of 5-Fluorouracil (5FU). Apart from cytotoxic effect on cancer cells, 5FU may also cause adverse side effects. Ganoderma Lucidum (GLC) is a mushroom used in Traditional Eastern Medicine. We propose that natural compounds, particularly GLC extracts, may sensitize cancer cells to conventional chemotherapeutics. This combination therapy could lead to more selective cancer cell death and may improve the response to the therapy and diminish the adverse effects of anticancer drugs. Here we demonstrate that GLC induced oxidative DNA damage selectively in colorectal cancer cell lines, whereas it protected non-malignant cells from the accumulation of reactive oxygen species. Accumulation of DNA damage caused sensitization of cancer cells to 5FU resulting in improved anticancer effect of 5FU. The results obtained in colorectal cell lines were confirmed in in vivo study: GLC co-treatment with 5FU increased the survival of treated mice and reduced the tumor volume in comparison with group treated with 5FU alone. Combination of conventional chemotherapeutics and natural compounds is a promising approach, which may reduce the effective curative dose of anticancer drugs, suppress their adverse effects and ultimately lead to better quality of life of CRC patients.


Assuntos
Adenocarcinoma/tratamento farmacológico , Antimetabólitos Antineoplásicos/farmacologia , Neoplasias Colorretais/tratamento farmacológico , Dano ao DNA , Fluoruracila/farmacologia , Extratos Vegetais/farmacologia , Reishi/química , Adenocarcinoma/patologia , Animais , Antimetabólitos Antineoplásicos/uso terapêutico , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Neoplasias Colorretais/patologia , Ensaio Cometa , DNA de Neoplasias/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Sinergismo Farmacológico , Feminino , Fluoruracila/uso terapêutico , Camundongos , Camundongos Endogâmicos BALB C , Invasividade Neoplásica , Estresse Oxidativo , Extratos Vegetais/isolamento & purificação , Espécies Reativas de Oxigênio/metabolismo , Carga Tumoral/efeitos dos fármacos , Ensaio Tumoral de Célula-Tronco
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