Analysis of mutations in tumour supressor gene p53 in breast cancer patients from poznan area

The p53 is transcriptional factor that enhances the rate of transcription of six or seven known genes which play important role in cell cycle regulation. The human p53 protein contains 393 amino acids and has been divided structurally and functionally into four domains. The p53 gene and its protein product have been studied since it became clear that slightly more than 50% of human cancers contain mutations in this gene. A study of mutational spectrum at the p53 gene are localized predominantly in the DNA-binding domain of the protein (exons 4–9). The nature of this changes is most commonly a missense mutation in one allele followed by a reduction to homozygosity, producing a faulty protein. Deletions or chain termination mutations are more rarely.Mutations in p53 gene have been also found in breast cancer in 30–40% of cases. Kind of these mutations suggest that enviromental mutagens may play important role in arising of this type of cancer. It is observed that in West Poland breast cancer occures more frequently then in other areas of the country; the highest numbers of cases are found in GreatPoland still now for unknown reasons. In this work 48 cases of breast cancer were studied. 12 different mutations in p53 were found. This mutations were then compared with datebase catalogs containing mutations in p53. Only 3 from 12 found mutations are the same as reported in datebase. Nine of them were not observed before what may suggest that specific mutational spectrum in patients with breast cancer from GreatPoland exists. Futher studies involving greater number of cases are needed to confirm this observation

miRNA in head and neck squamous cell carcinomas: promising but still distant future of personalized oncology

Head and neck squamous cell carcinoma is one of the most common and fatal cancers worldwide. Lack of appropriate preventive screening tests, late detection, and high heterogeneity of these tumors are the main reasons for the unsatisfactory effects of therapy and, consequently, unfavorable outcomes for patients. An opportunity to improve the quality of diagnostics and treatment of this group of cancers are microRNAs (miRNAs) — molecules with a great potential both as biomarkers and therapeutic targets. This review aims to present the characteristics of these short non-coding RNAs (ncRNAs) and summarize the current reports on their use in oncology focused on medical strategies tailored to patients’ needs

Expression of p16 in sporadic primary uveal melanoma

Expression of p16 protein, intragenic mutations of CDKN2A and hypermethylation of CDKN2A promoter region in 41 sporadic primary uveal melanomas were studied. There were 2 cases of spindle cell B histological type, 11 of A + B and 28 of mixed type. All melanomas infiltrated sclera but in 28 cases infiltration was superficial while in 13 profound. In 7 cases the tumor infiltrated the optic nerve. Expression of p16 was studied by immunohistochemistry and recorded by assessment of the proportion of positive tumor cells and staining intensity. Results were expressed as staining index (IRS). Intragenic mutations were studied by PCR-SSCP followed by sequencing, while hypermethylation of the promoter region by CpG methylation assay. In 15% of cases less than 10% of melanoma cells were p16 positive, in 70% of cases less than 50% of cells, while in 7% more than 80% of cells stained for p16 (mean IRS for all cases was 4.87 ± 2.43). In B type the IRS was 8.5 ± 0.7, in A + B type 6.0 ± 2.1 and in the mixed type 4.17 ± 2.43 (differences statistically significant). In melanomas profoundly infiltrating sclera mean IRS was 4.16, while in those infiltrating optic nerve 3.71 (statistically not significant). Analysis of the intragenic mutations revealed in two patients a GAC/GAT substitution in codon 84 - a silent mutation. No hypermethylation of the CpG island of the p16 promoter region was found. In conclusion, we found that the degree of p16 expression is related to the histological type of tumor but not to the histological indicators of tumor invasiveness and that intragenic mutations and promoter hypermethylation are not major mechanisms of p16 inactivation in sporadic uveal melanoma

Midsize noncoding RNAs in cancers: a new division that clarifies the world of noncoding RNA or an unnecessary chaos?

Most of the human genome is made out of noncoding RNAs (ncRNAs). These ncRNAs do not code for proteins but carry a vast number of important functions in human cells such as: modification and processing other RNAs (tRNAs, rRNAs, snRNAs, snoRNAs, miRNAs), help in the synthesis of ribosome proteins, initiation of DNA replication, regulation of transcription, processing of pre-messenger mRNA during its maturation and much more. The ncRNAs also have a significant impact on many events that occur during carcinogenesis in cancer cells, such as: regulation of cell survival, cellular signaling, apoptosis, proliferation or even influencing the metastasis process. The ncRNAs may be divided based on their length, into short and long, where 200 nucleotides is the “magic” border. However, a new division was proposed, suggesting the creation of the additional group called midsize noncoding RNAs, with the length ranging from 50–400 nucleotides. This new group may include: transfer RNA (tRNA), small nuclear RNAs (snRNAs) with 7SK and 7SL, small nucleolar RNAs (snoRNAs), small Cajal body-specific RNAs (scaRNAs) and YRNAs. In this review their structure, biogenesis, function and influence on carcinogenesis process will be evaluated. What is more, a question will be answered of whether this new division is a necessity that clears current knowledge or just creates an additional misunderstanding in the ncRNA world

Biological role of long non-coding RNA in head and neck cancers

AimHead and neck squamous cell carcinoma (HNSCC) are one of the worst prognosis cancers with high mortality of patients. The treatment strategy is primarily based on surgery and radiotherapy but chemotherapy is also used. Every year the knowledge concerning HNSCC biology is updated with new elements such as the recent discovered molecules – long non-coding RNAs. Long non-coding RNAs are involved in regulatory processes in the cells. It has been revealed that the expression levels of lncRNAs are disturbed in tumor cells what results in the acquisition of their specific phenotype. lncRNAs influence cell growth, cell cycle, cell phenotype, migration and invasion ability as well as apoptosis. Development of the lncRNA panel characteristic for HNSCC and validation of specific lncRNA functions are yet to be elucidated. In this work, we collected available data concerning lncRNAs in HNSCC and characterized their biological role. We believe that the tumor examination, in the context of lncRNA expression, may lead to understanding complex biology of the cancer and improve therapeutic methods in the future

Host gene and its guest: short story about relation of long-noncoding MIR31HG transcript and microRNA miR-31

Epigenetics is the changes in a cellular phenotype without changes in the genotype. This term is not limited only to the modification of chromatin and DNA but also relates to some RNAs, like non-coding RNAs (ncRNAs), both short and long RNAs (lncRNAs) acting as molecular modifiers. Mobile RNAs, as a free form or encapsulated in exosomes, can regulate neighboring cells or be placed in distant locations. It underlines the vast capacity of ncRNAs as epigenetic elements of transmission information and message of life. One of the amazing phenomena is long non-coding microRNA-host-genes (lnc-MIRHGs) whose processed transcripts function as lncRNAs and also as short RNAs named microRNAs (miRNAs). MIR31HG functions as a modulator of important biological and cellular processes including cell proliferation, apoptosis, cell cycle regulation, EMT process, metastasis, angiogenesis, hypoxia, senescence, and inflammation. However, in most cases, the role of MIR31HG is documented only by one study and there is a lack of exact description of molecular pathways implicated in these processes, and for some of them, such as response to irradiation, no studies have been done. In this review, MIR31HG, as an example of lnc-MIRHGs, was described in the context of its known function and its potential uses as a biomarker in oncology

Analysis of mutations in the p16/ CDKN2A gene in sporadic and familial melanoma in the Polish population.

Mutations in CDKN2A have been found in sporadic cutaneous malignant (CMM), in familial CMM and in other syndromes associated with melanoma. In this study DNA was obtained from 207 individuals and five cell lines. There were 157 CMM patients and 50 healthy members of melanoma patients families. The CMM group included patients with one or two melanoma cases in the family, families with dysplastic nevus syndrom (DNS) and patients with a spectrum of other types of cancers in the family. PCR-SSCP analysis and sequencing identified: six substitutions in codon 58 CGA/TGA (Arg/Stop), 16 substitutions GAC/GAT in codon 84 (Asp/Asp), six substitutions CGA /TGA in codon 148 (Arg/Thr), 14 substitutions G/C in 3'UTR and 4 double changes (two in codon 84 and 3'UTR; two in codon 148 and 3'UTR). The mutation identified in codon 58 was found in tissue only. Other substitutions were polymorphisms found in DNA from tissue and blood samples. Most of them were identified in sporadic CMM (six in codon 148 Ala /Thr, 12 in codon 84 Asp/Asp and six in 3'UTR). The frequency of the polymorphisms was also high in DNS and CMM/DNS families (four in codon 84 Asp/Asp and six in 3'UTR). No mutations or polymorphisms were found in CMM patients with one or two melanoma cases and CMM patients, with other cancers in family history. The analysis of the CDKN2A gene mutations in the Polish population demonstrated: (i) no germline mutations; (ii) a relatively high number of genetic changes in sporadic melanoma; (iii) a high number of polymorphisms in DNS and CMM/DNS families

The CDKN2a common variants: 148 Ala/Thr and 500 C/G in 3' UTR, and their association with clinical course of melanoma

Changes in CDKN2a gene are known to be linked with sporadic melanoma and hereditary predisposition to this cancer. In the Polish population mutations in the coding region of the CDKN2a gene are rather rare, therefore the attention has been focused on polymorphisms and alterations in uncoding regions such as 3' UTR. The aim of this study was to analyze two common polymorphisms, Ala148Thr and 500 C/G, and correlate them with the clinical course of melanoma. DNA from 285 patients was analyzed and found polymorphisms were correlated with the clinical parameters employing statistical methods. The obtained results allow us to conclude: (i) survival times of 500 C/G carriers vs. cumulating proportion surviving was not statistically significant; (ii) CDKN2a polymorphism 500 C/G correlated with Ala148Thr; (iii) no correlation was observed between the 500 C/G polymorphism and age of diagnosis, localization of primary melanoma and survival time; (iv) we did not find correlation between 500 C/G and type of cancer in the family; (v) changes in the CDKN2a gene were not found in patients with second cancer