Nasta Tanic

The impact of PTEN tumor suppressor gene on acquiring resistance to tamoxifen treatment in breast cancer patients

Tamoxifen is a standard therapeutical treatment in patients with estrogen receptor positive breast carcinoma. However, less than 50% of estrogen receptor positive breast cancers do not respond to tamoxifen treatment whereas 40% of tumors that initially respond to treatment develop resistance over time. The underlying mechanisms for tamoxifen resistance are probably multifactorial but remain largely unknown. The primary aim of this study was to investigate the impact of PTEN tumor suppressor gene on acquiring resistance to tamoxifen by analyzing loss of heterozygosity (LOH) and immunohystochemical expression of PTEN in 49 primary breast carcinomas of patients treated with tamoxifen as the only adjuvant therapy. The effect of PTEN inactivation on breast cancer progression and disease outcome was also analyzed. Reduced or completely lost PTEN expression was observed in 55.1% of samples, while 63.3% of samples displayed LOH of PTEN gene. Inactivation of PTEN immunoexpression significantly correlated with the PTEN loss of heterozygosity, suggesting LOH as the most important genetic mechanism for the reduction or complete loss of PTEN expression in primary breast carcinoma. Most importantly, LOH of PTEN and consequential reduction of its immunoexpression showed significant correlation with the recurrence of the disease. Besides, our study revealed that LOH of PTEN tumor suppressor was significantly associated with shorter disease free survival, breast cancer specific survival and overall survival. In summary, our results imply that LOH of PTEN could be used as a good prognostic characteristic for the outcome of breast cancer patients treated with tamoxifen.

Genomic instability and tumor-specific DNA alterations in oral leukoplakias

Leukoplakias, clinically identifiable premalignant lesions, often precede oral squamous cell carcinoma (OSCC). Identification of leukoplakias that have the potential for transformation to malignancy is a key clinical problem. The aim of this study was to assess genomic instability, and to detect tumor-specific genomic alterations, in leukoplakias. Genomic instability was analyzed by comparing the DNA fingerprints of 32 leukoplakias with those of paired normal tissue. In addition, the mutational status of the p53 gene was analyzed using polymerase chain reaction-single-stranded conformational polymorphism (PCR-SSCP) and polymerase chain reaction-heteroduplex DNA (PCR-HET), and the mutations were subsequently confirmed by DNA sequencing. Moderate-to-significant genomic instability was detected in all leukoplakias analysed. Nine unique amplicons, present in leukoplakias but not in normal tissue, were retrieved and successfully characterized. The p53 gene was mutated in 40.6% of patients. Four patients with moderate instability and mutated p53 developed OSCC. The data obtained in this study support and concretize the thesis that premalignant lesions possess many of the alterations found in cancer before the development of a malignant phenotype. Inactivation or mutation of the p53 tumor-suppressor might be an early event contributing to genomic instability and increasing the risk of malignant transformation.

Impairment of acetylcholine-mediated endothelium-dependent relaxation in isolated parotid artery of the alloxan-induced diabetic rabbit

The aim of this study was to assess the effect of type 1 diabetes mellitus (induced by a single intravenous injection of 100 mg kg(-1) of alloxan) on acetylcholine (ACh)-induced relaxation in isolated rabbit parotid gland feeding artery. Isometric force measurements and quantification of inducible nitric oxide synthase (iNOS) mRNA by real-time RT-PCR were made in parotid artery rings from diabetic and control rabbits. Acetylcholine induced concentration- and endothelium-dependent vasorelaxation that was significantly decreased in parotid artery rings from diabetic rabbits. Schild analysis of the ACh vasorelaxant effect, in the presence of selective muscarinic receptor antagonists, revealed involvement of the M(3) receptor subtype in parotid artery rings from both control and diabetic rabbits, with no change in antagonist affinity constants. The inhibitory effects of indomethacin, a non-selective inhibitor of cyclooxygenase, and of high potassium, an inhibitor of hyperpolarization, on ACh vasorelaxation were increased. The effect of N(G) -nitro-l-arginine, a non-selective inhibitor of NOS, was decreased in diabetes. S-methylisothiourea, a selective inhibitor of iNOS, significantly reduced ACh vasorelaxation only in parotid artery rings from diabetic rabbits. Also, up-regulation of iNOS mRNA expression was detected in parotid artery rings from diabetic rabbits. These results suggest that in parotid artery rings from diabetic rabbits, impaired endothelium-dependent vasorelaxation to ACh appears to be caused by the loss of a nitric oxide-mediated component and increased iNOS expression, and is unlikely to be caused by a change at the M(3) receptor level.

High frequency of p16 and p14 promoter hypermethylation and marked telomere instability in salivary gland tumors.

OBJECTIVESnto investigate p16(INK4a) and p14(ARF) tumor suppressor gene methylation status, determine telomere length and assess the importance of these epigenetic and genetic parameters in the development of pleomorphic adenoma and carcinoma ex pleomorphic adenoma of the parotid salivary glands.nnnMATERIALS AND METHODSnGenomic DNA from paraffin-embedded samples of 50 pleomorphic adenomas and 10 carcinomas ex pleomorphic adenoma was subjected to methylation specific polymerase chain reaction for hypermethylation analyses and real time polymerase chain reaction for the relative telomere length calculations.nnnRESULTSnPromoter hypermethylation of the two genes was a very frequent event in both neoplasms - between 60% and 90% of samples were hypermethylated - but without significant difference between the groups. The mean relative telomere length in the pleomorphic adenoma group was significantly increased in comparison to the control group (P=0.00), and significantly decreased in comparison to the carcinoma group (P=0.05). Telomeres were also longer in myxoid and cellular histological subtypes of adenomas than in the classic type (P=0.044 and P=0.018, respectively). Longer telomeres were more frequent in tumors with hypermethylated p14(ARF) alleles (P=0.013).nnnCONCLUSIONnPromoter hypermethylations seems to be an important mechanism of p16(INK4a) and p14(ARF) inactivation in parotid gland tumors. Telomeric lengthening appears to be involved in the pathogenesis of both benign and malignant tumors of the parotid glands.

Comparative analyses of individual and multiple alterations of p53, PTEN and p16 in non-small cell lung carcinoma, glioma and breast carcinoma samples.

p53, p16 and PTEN are the most commonly altered tumor suppressor genes in human cancers. In the present study, we compared the presence of individual and multiple alterations of these tumor suppressors in non-small cell lung carcinoma (NSCLC), glioma and breast carcinoma, in order to evaluate specificity of each tumor type regarding the number of altered genes, as well as their combinations. We tested the mutational status, loss of heterozygosity and methylation status of these genes. Effects of gene alterations on patients survival were also assessed. In NSCLC samples, single gene alterations occurred rarely, while there was considerable increase in incidence of double gene alterations. Furthermore, coexistence of aberrant p53, PTEN and p16 was the most frequent and had significant adverse effect on the survival of NSCLC patients. On the contrary, in glioma and breast cancer specimens, substantial number of cases had aberrant single gene only. Moreover, glioma and breast carcinoma also differ in genotypes that were predominant. Specifically, in glioma samples, prevalent were co-alterations of PTEN and p16, followed by aberrant only PTEN. In breast cancer samples, alterations in all three genes as well as in p53 and p16 were the most common. Moreover, PTEN was altered exclusively with aberrant p53, with statistically significant correlation among them. Overall, our results suggest that NSCLC, glioma and breast cancer need different approaches in molecular diagnosis and treatment with particular attention toward the number and combination of targeted genes.

Immuno-histomorphometric and -fluorescent characteristics of GH cells after treatment with genistein or daidzein in an animal model of andropause

Abstract Somatopause, the complex aspect of andropause, is recognizable by reduced growth hormone - GH/insulin-like growth factor 1 axis function in the ageing male. Soy isoflavones (usually genistein and daidzein), which are known for their beneficial effects in the treatment of ageing symptoms, are active in the pituitary, as well. The immunohistomorphometric and -fluorescent characteristics of pituitary growth hormone secreting cells, in an animal model of andropause, were examined after a treatment with genistein or daidzein. Andropausal Wistar rats were divided into sham operated, orchidectomized and genistein or daidzein treated orchidectomized groups. Genistein or daidzein (30 mg/kg/day) were administered subcutaneously for three weeks, while sham operated and orchidectomized groups received the vehicle alone. Growth hormone secreting cells were identified by the peroxidase-antiperoxidase immuno-histochemical, and immuno-fluorescent procedure. The main characteristic of growth hormone secreting cells in soy isoflavones treated groups is a weaker immuno-histochemical staining and immuno-fluorescent signal compared to sham operated and orchidectomized groups. The growth hormone secreting cell volume in orchidectomized +genistein or +daidzein groups is by 13.8% and 11.9% (p<0.05) smaller respectively, in comparison with the orchidectomized group. In orchidectomized +genistein or +daidzein groups, the growth hormone secreting cells relative volume density is by 62.5% and 61.0% lower (p<0.05) respectively than for the sham operated group, and decreased by 65.4% and 64.0% (p<0.05) respectively, compared to the orchidectomized group. It can be concluded that chronic genistein or daidzein treatment, in an animal model of andropause, attenuates immunohistomorphometric and -fluorescent characteristics of growth hormone secreting cells.

Amplification of Cycline D1, C-MYC And EGFR Oncogenes in Tumour Samples of Breast Cancer Patients / AMPLIFIKACIJA CIKLIN D1, C-MYC AND EGFR ONKOGENA U TUMORSKIM UZORCIMA PACIJENTKINJA OBOLELIH OD KANCERA DOJKE

Summary Background: Breast cancer is the most common form of cancer in women. It arises from multiple genetic changes in oncogenes and tumor suppressor genes. Among so far studied oncogenes relatively few, including epdermal growth factor receptor (EGFR), cyclinD1 (CCND1)and cmyc, have been found to play an important role in progression of this type of human malignancy. The aim of this study was to examine the prognostic potential of CCND1, c-myc and EGFR amplification and their possible cooperation in breast carcinogenesis. Methods: Copy number analyses of CCND1 and c-myc genes were done by TaqMan based quantitative real time PCR. Am pli fication status of EGFR was determined by differential PCR. Results: Amplification of CCND1, c-myc and EGFR onco- gene has been found in 20.4%, 26.5% and 26.5% of breast cancer cases, respectively. Analysis showed that amplification of CCND1 oncogene was significantly associated with the stage II of disease while amplification of EGFR gene was sig- nificantly associated with overexpression of HER-2/neu. Tu- mour stage and expression of HER-2/neu appeared to be significant predictors of patients outcome. Stage I patients lived significantly longer then stage III patients (p=0.04) while patients with FiER-2/neu overexpression had worse prognoses and lived significantly shorter (p=0.001). Finally, survival of patients who underwent hormone therapy only was significantly longer (p=0.001) then survival of the rest of patients. Conclusions: Amplification of CCND1 or EGFR oncogene is associated with the progression of breast cancer and bad prognosis. No co-ordination in amplification of CCND1, c- myc and EGFR oncogenes were established in this cohort of breast cancer patients. Kratak sadržaj Uvod: Kancer dojke je najčešči tip maligniteta koji se javlja kod žena. Tumori dojke nastaju kao rezultat akumulacije genetičkih promena kako u onkogenima tako i u tumor supresorskim genima. Medu mnogim onkogenima čija je uloga u genezi tumora dojke ispitivana do danas, samo se neki smatraju značajnim za razviče ovih karcinoma. U tu se grupu svakako ubrajaju receptor za epidermalni factor rasta (EGFR), c-myc i ciklinDI (CCND7). Cilj rada je bio utvrditi prognostickí značaj amplifikacije CCND1, c-myc i EGFR onkogena u razvicu tumora dojke kao i eventualne medusob- ne koalteracije ovih gena. Metode: Amplifikacioni status CCND1 i c-myc gena odreden je kvantitativnim PCR-om u reálnom vremenu, a amplifikacioni status EGFR onkogena je definisan diferencijalnim PCR-om. Rezultati: Amplifikacija CCND1 gena detektovana je kod 20,4%, a c-myc i EGFR onkogena kod 26,5% ispitanih uzo- raka. Analize su pokazale da je amplifikacija CCND1 onko- gena statistički značajno povezana sa stadijumom II tumora dojke kao i da amplifikacija EGFR-a značajno korelira sa povečanom ekspresijom HER2/neu. Analize kliničkih i histo- patoloških parametara su jasno pokazale da stadijum tumo- ra i nivo ekspresije HER2/neu gena predstavljaju značajne pokazatelje daljeg toka bolesti, odnosno sudbine pacijenta. Utvrdeno je da pacijentkinje sa tumorima dojke stadijuma I žive značajno duže od onih sa tumorom stadijuma III (p= 0,04) kao i da pacijentkinje sa HER2/neu pozitivnim statu- som imaju goru prognózu i žive značajno krače (p=0,001). Na kraju, študija je pokazala da pacijentkinje podvrgnute samo hormonskoj terapiji imaju najbolju prognózu i žive značajno duže od ostalih (p=0,001). Zaključak: Amplifikacija CCND1 i EGFR onkogena je po- vezana sa losom prognozom i progresijom karcinoma dojke. U ispitivanom tumorskom uzorku nisu detektovane nikakve koalteracije CCND1, c-myc i EGFR onkogena.

Concurrent quantitation of the A and D genotypes of hepatitis B virus

Hepatitis B virus (HBV) infection is a global health problem associated with severe liver disorders. Viral load and HBV genotype affect the clinical outcome, guide antiviral therapy and provide long term prognosis for HBV infected patients. Various types of detection and quantitation assays are currently in use with a different effectiveness. The aim of this study was to develop a method that would provide simultaneous identification and quantitation of genotypes A and D in a single-tube reaction. Sera from infected patients were analyzed by a TaqMan based real time PCR. Optimized reagents were used for HBV DNA quantitation while the genotypes A and D were quantified separately by our design of the assay. Multiplex real time PCR was achieved and was specific for HBV genotypes A and D within a single-tube reaction. Simulation of mixed virus populations was identified reproducibly in vitro. Quantitation of these individual genotypes was exceptionally reliable, so much so that the sum of individual genotypes was equal to the total viral load determined in a separate reaction. Therefore, a straightforward, conceptually simple and reliable approach to issues involving HBV genotypes A and D is submitted. Identity and exact titer of these genotypes in the Caucasian population can now be determined easily.

P14 methylation: an epigenetic signature of salivary gland mucoepidermoid carcinoma in the Serbian population

OBJECTIVEnTo investigate the prevalence of p16INK4 a, p14ARF, tumor protein p53 (TP53), and human telomerase reverse transcriptase (hTERT) promoter hypermethylation in mucoepidermoid carcinomas (MECs) and search for a possible association between methylation status and clinicopathological parameters.nnnSTUDY DESIGNnDNA extracted from 35 formalin-fixed and paraffin-embedded MEC samples and 10 normal salivary gland (NSG) tissue samples was analyzed for the presence of promoter hypermethylation using methylation-specific polymerase chain reaction testing.nnnRESULTSnThe percentages of gene hypermethylation in MECs versus NSGs were the following: p14: 100% versus 20% (P<.001); p16: 60% versus 20% (Pu2009=u2009.035); hTERT: 54.3% versus 20% (Pu2009=u2009.078); and TP53: 31.4% versus 30% (Pu2009=u2009.981). Multiple sites were found to be methylated in 86% of MECs compared with 10% in NSGs (P<u2009.001). TP53 and hTERT were more often methylated in lower clinical stages (Pu2009=u2009.033 and Pu2009=u2009.005, respectively).nnnCONCLUSIONSnHypermethylation of p14 appears to be an important event in the development of mucoepidermoid carcinoma. High frequency of gene hypermethylation and high incidence of methylation at multiple sites point to the importance of epigenetic phenomena in the pathogenesis of MECs, although with modest impact on clinical parameters.

TP53 and C-MYC Co-Alterations – A Hallmark of Oral Cancer Progression / SIMULTANA ALTERACIJA TP53 I C-MYC GENA – OBELEŽJE PROGRESIJE ORALNIH KARCINOMA

Summary Background: Head and neck squamous cell carcinoma, including oral cancer, is the sixth most common cancer worldwide. Despite advances in surgery and treatment, the 5-year survival rate has not improved significantly. There- fore, reliable molecular markers for oral cancer progression are badly needed. Methods: We conducted a copy number analysis to esti- mate amplification status of c-myc, cycD1 and EGFR onco- genes, mutational PCR-SSCP analysis to determine activa- tion of H-ras oncogene and inactivation of TP55 tumour suppressor gene and methylation specific PCR analysis to evaluate hypermethylation of p16 and MGMT genes. Results: c-myc oncogene was amplified in 56.7%, cycD1 in 20% and EGFR in 16.7% of Oral Squamous Cell Carci- noma (OSCC) cases while H-ras was activated in 33.3% of samples. Amplification of c-myc was significantly associat- ed with the tumour grade 2. Interestingly, EGFR and H-ras alterations were mutually exclusive. p16 and MGMT were inactivated by hypermethylation in 30% and 13.3% of cases. Co-alteration of cycD1 and p16 were not observed in any of the analyzed samples. TP53 was inactivated in 56.7% of samples and was significantly associated with progression of OSCC, grade 2 and stage 2. Moreover, TP55 and c-myc oncogene were simultaneously altered in grade 2 OSCC. Conclusions: The most promising marker of OSCC pro- gression remains the TP53 tumour suppressor, which is the most frequently mutated gene in oral cancers. Since there is synergism between TP55 and c-myc, it seems that co- alteration of these two genes could be also a good marker of OSCC progression from gradel to grade 2 tumours. Kratak sadržaj Uvod: Skvamocelularni karcinomi glave i vrata (HNSCC) uključujud i skvamocelularni karcinom usne duplje (OSCC) ubrajaju se u šest najčesdh tipova humanih maligniteta. Uprkos značajnim napredcima u hirurškom i terapijskom tretmanu, stopa petogodišnjeg preživljavanja kod ovog tipa maligniteta nije značajnije popravljena. Upravo zato, defin- isanje pouzdanih molekularjnih markera progresije kod OSSC predstavlja apsolutni prioritetet. Metode: Amplifikacioni status c-myc, cycD1 i EGFR gena od reden je pomoču eseja za detekciju broja genskih kopi- ja, aktivacija H-ras onkogena i inaktivacija TP53 tumor supresora odredena je PCR-SSCP mutacionom analizom, a hipermetilacija promotora p16 i MGMT gena je ispitana metil specifičnim PCR-om (MSP). Rezultati: Amplifikacija c-myc onkogena detektovana je kod 56,7%, cycD1 onkogena kod 20%, a EGFR onkogena kod 16,7% analiziranih oralnih skvamocelularnih carcino- ma. Istovremeno, mutaciona aktivacija H-ras onkogena detektovana je kod 33,3% ispitanih uzoraka. Amplifikovani c-myc, statisticki značajno korelira sa gradusom 2 OSCC. Posebno intrigantan je bio nalaz po kom se onkogene akti- vacije u EGFR i H-ras genu medjusobno isključuju. Hipermetilacija promotora p16 gena detektovana je kod 30%, a MGMT kod 13,3% analiziranih uzoraka. Ko-altera- cije cycD1 i p16 gena nisu zapažene ni u jednom od ana- liziranih uzoraka. Inaktivacija TP53 gena detektovana je kod 56,7% uzoraka i utvrdeno je da statistički značajno korelira sa gradusom 2 i statusom 2 OSCC. Pored ovoga, utvrdeno je da statistički značajan broj uzoraka gradusa 2, sa aktiviranim TP53 genom ima istovremeno aktiviran i c-myc onkogen. Zaključak: TP53, najčešče mutirani gen u oralnim karcino- mima, ostaje za sada i najpouzdaniji marker progresije kod OSCC. Obzirom na detektovani sinergizam izmedu TP53 i c-myc gena, možemo reči da su istovremene promene u ova dva gena još pouzdaniji pokazatelj progresije OSSC iz gradusa 1 u gradus 2.