Methylation status, mRNA and protein expression of the SMAD4 gene in patients with non-melanocytic skin cancers.

BACKGROUND: SMAD4 is a potent tumor suppressor. SMAD4 loss increases genomic instability and plays a critical role in the DNA damage response that leads to skin cancer development. We aimed to investigate SMAD4 methylation effects on mRNA and protein expression of SMAD4 in cancer and healthy tissues from patients with basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and basosquamous skin cancer (BSC). METHODS AND RESULTS: The study included 17 BCC, 24 cSCC and nine BSC patients. DNA and RNA were isolated from cancerous and healthy tissues following punch biopsy. Methylation-specific polymerase chain reaction (PCR) and real-time quantitative PCR methods were used to examine SMAD4 promoter methylation and SMAD4 mRNA levels, respectively. The percentage and intensity of staining of the SMAD4 protein were determined by immunohistochemistry. The percentage of SMAD4 methylation was increased in the patients with BCC (p = 0.007), cSCC (p = 0.004), and BSC (p = 0.018) compared to the healthy tissue. SMAD4 mRNA expression was decreased in the patients with BCC (p˂0.001), cSCC (p˂0.001), and BSC (p = 0.008). The staining characteristic of SMAD4 protein was negative in the cancer tissues of the patients with cSCC (p = 0.00). Lower SMAD4 mRNA levels were observed in the poorly differentiated cSCC patients (p = 0.001). The staining characteristics of the SMAD4 protein were related to age and chronic sun exposure. CONCLUSIONS: Hypermethylation of SMAD4 and reduced SMAD4 mRNA expression were found to play a role in the pathogenesis of BCC, cSCC, and BSC. A decrease in SMAD4 protein expression level was observed only in cSCC patients. This suggests that epigenetic alterations to the SMAD4 gene are associated with cSCC. TRIAL REGISTRATION: The name of the trial register: SMAD4 Methylation and Expression Levels in Non-melanocytic Skin Cancers; SMAD4 Protein Positivity. The registration number: NCT04759261 ( https://clinicaltrials.gov/ct2/results?term=NCT04759261 ).

Evaluation of Relationship Between SOD1 50-bp Deletion Gene Polymorphism, Cu, Zn Level, and Viscosity in Postmenopausal Osteoporosis Patients with Vertebral Fractures.

Oxidative stress plays a role in the pathogenesis of bone loss, causing low bone mineral density (BMD) and associated osteoporotic fractures. In our study, we aimed to investigate the relationship of SOD1 50-bp insertion(Ins)/deletion(Del) polymorphism that is involved in oxidative stress metabolism, Cu and Zn element concentrations, and plasma viscosity level, with postmenopausal osteoporosis and related vertebral fractures. The study included 167 voluntary individuals. The 50-bp Ins/Del polymorphism of SOD1 was determined by allele-specific PCR. Plasma Cu and Zn levels were measured by atomic absorption spectrophotometry (AAS). The plasma viscosity was determined using the Harkness Capillary Viscometer device. In our study, the distribution of SOD1 promoter 50-bp Ins/Del polymorphism did not indicate a significant difference between the groups and in postmenopausal osteoporosis patients with and without fractures (p > 0.05). The Ins/Ins genotype was found to be common in individuals in both groups. The Cu and Zn levels of the study group were found to be between the normal reference values (p > 0.05). It was determined that plasma viscosity increased significantly in the group of osteoporotic patients and in patients with postmenopausal osteoporosis with fractures (p < 0.01). In addition, plasma viscosity was found to significantly increase in patients with Ins/Ins genotype and fractures (p < 0.01). Postmenopausal osteoporosis and associated vertebral fracture were found not to be directly related to SOD1 50-bp polymorphism and Cu and Zn element levels. Plasma viscosity levels were found to increase due to the increase in oxidative stress products. Further studies are needed to clarify the roles and relationships of SOD genes and trace elements in the development of postmenopausal osteoporosis and vertebral fracture.

Lipoprotein(a) Gene Polymorphism Increases a Risk Factor for Aortic Valve Calcification.

Calcific aortic valve disease (CAVD) is a multifactorial condition. Both environmental andgenetic factors play an important role in its etiology. CAVD exhibits a broad spectrum, varying frommild valve thickening to severe valve calcification and stenosis. Progression of the disease consistsof chronic inflammation, lipoprotein deposition, and active leaflet calcification. It is a process similarto coronary artery disease. In this study, we investigated Lp(a) levels and gene polymorphismsassociated with calcific aortic stenosis from blood samples after echocardiography in the evaluationof 75 patients diagnosed with CAVD and 77 controls. Blood tests were run in our laboratory to ruleout certain risk factors before echocardiography examination. A significant association amongsmoking, elevated LDL level and creatinine, low albumin levels, Lp(a) level, rs10455872, andrs3798220 polymorphisms may be considered genetic risk factors for the development of calcificaortic stenosis.

Association of clinicopathological features with E-cadherin (CDH1) gene-160 C>A promoter polymorphism in Turkish colorectal cancer patients.

BACKGROUND AND AIM OF STUDY: The role of E-cadherin (CDH1) gene-160 C>A (rs16260) promoter polymorphism in colorectal cancer (CRC) still remains inconclusive. The aim of this study is to investigate the associations between the CDH1-160 C>A polymorphism with the susceptibility and clinicopathological development of CRC in the Turkish patients. To our knowledge, this is the first report examining the role of CDH1 polymorphism in Turkish CRC patients. MATERIALS AND METHODS: A total of 92 colorectal carcinoma cases (including 62 colon and 30 rectal cancer patients) and the corresponding adjacent normal tissues as controls were studied. The polymorphism was genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis. Clinicopathological features including patient's age, gender, tumor stage, and tumor location (colon/rectum) were compared statistically with the polymorphism status. RESULTS: There was no significant difference in both genotype and allele frequencies of the CDH1 polymorphism between colorectal tumor cases and normal samples (P = 0.472 and 0.508, respectively). Furthermore, no significant associations were observed between the CDH1 polymorphism status and age, gender, tumor stage, and tumor location of the colorectal tumor cases (all P > 0.05). CONCLUSIONS: These results indicate that CDH1-160 C>A polymorphism does not contribute to the genetic susceptibility of CRC and the polymorphism may not be a direct effect on the progression of the disease in Turkish CRC patients.

DNA methylation of the prestin gene and outer hair cell electromotileresponse of the cochlea in salicylate administration

Background/aim: Activity of the prestin gene may have a role in the pathogenesis of salicylate-induced ototoxicity. We investigated DNA methylation for prestin gene exon 1 in salicylate-injected guinea pigs.Materials and methods: Fifteen guinea pigs (30 ears) underwent audiological evaluation including 1000 Hz probe-tone tympanometry and a distortion product otoacoustic emission (DPOAE) test. The animals were randomly divided into three groups. Groups 2 (8 ears) and 3 (14 ears) were injected with intramuscular saline and sodium salicylate (200 mg/kg), respectively twice daily for 2 weeks. Group 1 (8 ears) received no injection. DPOAE measurements were performed at baseline; after 1, 2, 4, and 8 h (acute effect); and after 1 and 2 weeks (chronic effect). After audiological measurements, the animals were sacrificed for DNA isolation.Results: While a significant decrease (P < 0.01) was found for the acute effect in all frequencies in Group 3 according to baseline measurements, there was no difference in terms of chronic effect. DNA methylation increased during the acute phase of salicylate administration, whereas it returned to initial levels during the chronic phase.Conclusion: Salicylate-induced changes in DPOAE responses may be related to prestin-gene methylation. These results may have important implications for salicylate ototoxicity.

Glu298Asp polymorphism of the endothelial nitric oxide synthase gene in Turkish patients with ischemic stroke.

The low plasma nitric oxide concentrations and reduced vascular reactivity are considered major proatherogenic mechanisms in cardiovascular diseases. The present study aimed to assess the allelic frequency and the genotypic distribution of the Glu298Asp gene polymorphism at exon 7 of endothelial nitric oxide synthase (eNOS) gene in Turkish ischemic stroke patients compared to appropriate healthy controls, and to correlate the genetic findings with stroke subtypes. The study population included 146 (75 males, 71 females) patients with ischemic stroke which were categorized according to the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) and 133 (34 males, 99 females) healthy subjects. The eNOS polymorphism was identified with a PCR followed by RFLP with the restriction enzyme BanII. Genotypes were defined as GG, GT, and TT according to the presence of the G and T alleles. In this case-control study, we did not find any significant difference in either the genotypic distribution or allelic frequency of Glu298Asp gene polymorphism between the patients and the controls. In addition, there was also no significant difference for the genotype distribution and the allelic frequency among the stroke subtypes. The results suggested the lack of the association between the Glu298Asp gene polymorphism and ischemic stroke or subtypes of ischemic stroke in the Turkish population.

p53 gene mutations are rare in human papillomavirus-associated colon cancer.

Recent studies suggest that infection with high risk human papillomavirus (HPV) is a common event in colon tumors. Infection by oncogenic HPV may result in functional inactivation of the p53 protein in absence of mutations. Thus far no studies have been made to examine the frequency of p53 mutations in HPV-associated colon cancer. The purpose of this study was to investigate the interrelationship between p53 mutations and HPV infection. The 'hot-spot' region of the p53 gene for mutations was analyzed by PCR-SSCP and direct sequencing in HPV-positive tumor samples. Only 2 mutations were identified in 56 samples. This rate was much lower than reported for sporadic colon tumors. Our results indicate an inverse relationship between p53 mutations and HPV infection and suggest that p53 inactivation caused by HPV infection may play a role in the pathogenesis of colon cancer.