PCR-SSCP-DNA sequencing method in detecting PTEN gene mutation and its significance in human gastric cancer

The cellular distribution of Na+/H+ exchanger regulatory factor 1 is determined by the PDZ-I domain and regulates the malignant progression of breast cancer

The oncogenic role of ectopic expression of Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) was recently suggested. Here, we show that NHERF1 was upregulated in high grades compared with low grades. Increased NHERF1 expression was correlated with poor prognosis and poor survival. NHERF1 expression was higher in the nucleus of cancer cells than in contiguous non- mammary epithelial cells. A novel mutation, namely NHERF1 Y24S, was identified in human breast cancer tissues and shown to correspond to a conserved residue in the PDZ-I domain of NHERF1. Truncation and mutation of the PDZ-I domain of NHERF1 increased the nuclear distribution of the NHERF1 protein, and this redistribution was associated with the malignant phenotype of breast cancer cells, including growth, migration, and adhesion. The present results suggest a role for NHERF1 in the progression of breast cancer mediated by the nuclear distribution of the NHERF1 protein, as determined by the truncation or key site mutation of the PDZ-I domain.

Effects of PTEN gene alteration in patients with gallbladder cancer

Gallbladder cancer (GBC) is an aggressive malignancy usually diagnosed in an advanced stage. We investigated the effects of alterations of the phosphatase and tensin homologue (PTEN) gene on the occurrence and development of GBC, which has not been previously reported. A total 141 cases of GBC were analyzed for mutation, expression, and methylation across the nine exons of the PTEN gene. DNA sequencing methods were applied for mutation detection, whereas protein expression and methylation status were evaluated by immunohistochemical and methylation-specific PCR analysis, respectively. Novel PTEN mutations were observed in 6.3% of cases (9/141), and they included two silent mutations. In mutant cases, according to changes in codons, the respective amino acid sequences were also changed, which caused of proteins. A high percentage (72%) of loss of protein expression was observed more often in cases than in control samples. Interestingly, all nine cases with mutations showed loss of PTEN expression, whereas four of these nine cases showed positive promoter methylation. Hypermethylation was significantly more common in older patients than in younger ones (P<0.02). These findings suggest that PTEN mutations and inactivation may play an important role in the development and progression of gallbladder carcinoma.

Promoter region methylation and loss of protein expression of PTEN and significance in cervical cancer

The genetic basis underlying cervical tumorigenesis and progression are largely unknown. Phosphatase and tensin homologue (PTEN) is a tumor suppressor gene, and genetic changes of PTEN occurs in various types of cancer suggesting that the inactivation of PTEN may play an important role in the pathogenesis of a variety of human malignancies. In the present study, 102 cervical cancer specimens were examined for the expression of the PTEN gene and promoter methylation using methylation-specific-polymerase chain reaction and immunohistochemistry. The PTEN gene mutation was also assessed using PCR single-strand conformational polymorphism. We examined the correlation between PTEN expression and its associated methylation status and the clinical characteristics of cervical cancer. The results showed that there was one case of an A to G point mutation on exon 9 of the PTEN gene in the cervical cancer tissues. This mutation caused the change of aspartic acid to glycine, and the rate of mutation was 1%. The PTEN gene methylation rate of cervical cancer was 62% (63/102) and the rate was associated with the International Federation of Gynecology and Obstetrics stage, cell differentiation, tumor size and lymph node metastasis (P<0.05). The positive rate of PTEN expression was 49% (50/102) in cervical carcinoma and the PTEN expression between stage I-II and III-IV [60 (27/45) vs. 40% (23/57)] was statistically significant (P<0.01). The PTEN gene expression between the metastasis and no lymph node metastasis groups [26 (10/38) vs. 63% (40/64)] was significantly different (P<0.01). The PTEN gene promoter methylation and its protein expression had a significant correlation (P=0.042). These results suggest that hypermethylation can inactivate the transcription of PTEN and reduce its protein expression. Downregulated PTEN expression is involved in the pathogenesis, invasion and metastasis of cervical cancer, possibly by regulating the balance between apoptosis and proliferation. Therefore, the PTEN expression may be a good marker for the prognosis of cervical cancer.

Occipital anaplastic oligodendroglioma with multiple organ metastases after a short clinical course: a case report and literature review

Background

It is generally believed that malignant gliomas never metastasize outside the central nervous system (CNS). However, the notion that oligodendrogliomas (OGDs) cells cannot spread outside CNS is being challenged.

Methods

We described in detail the clinical story of one patient with anaplastic OGD, which metastasized to lymph nodes, bone marrowand bones Genetic analyses included detection of 1p and 19q chromosomal arms, methylation status of MGMT promoter, and PTEN exon mutations. A search of worldwide literature was conducted for reports of metastatic OGDs using NCBI-PubMed, with the keywords “extracranial”, “extraneural”, “oligodendroglioma”, “oligodendrogliomas”, “metastatic”, “metastasis”, and “metastases”, in different combinations.

Results

An open biopsy of the infiltrated bones in our patient revealed that malignant cells had replaced the patient’s marrow. Moreover, the diagnosis of multiple-organ metastases of anaplastic OGD was confirmed based on immunohistochemical staining. Genetic analyses showed that the tumors originated from previously resected brain lesions. None of the lesions had 1p and 19q deletions, but hypermethylation of MGMT promoter, and the G → A transversion at codon 234 of PTEN exon 2 were detected. Literatures review yielded 60 reports of metastatic OGDs from 1951 to the present, which with our patient makes 61 cases. Concerning these 61 patients, there were 110 infiltrated sites correlated closely with primary OGDs. The most frequent metastatic sites were bone and bone marrow (n = 47; 42.7%), lymph nodes (n = 22; 20.0%), liver (n = 7; 6.4%), scalp (n = 6; 5.5%), lung (n = 6; 5.5%), pleura (n = 4; 3.6%), chest wall (n = 3; 2.7%), iliopsoas muscle (n = 2; 1.8%), soft tissue (n = 2; 1.8%), and parotid gland (n = 2; 1.8%).

Conclusions

Extracranial metastases in anaplastic OGD are very rare but they do occur; bone and bone marrow may be the most common sites. Detection of certain molecular markers such as deletion of 1p and 19q chromosomal arms, hypermethylation of MGMT promoter, and characteristic PTEN exon mutations may help differentiate subtypes which are more prone to extracranial metastases.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/8749838611478560.

Gastric cancer-molecular and clinical dimensions

Gastric cancer imposes a considerable health burden around the globe despite its declining incidence. The disease is often diagnosed in advanced stages and is associated with a poor prognosis for patients. An in-depth understanding of the molecular underpinnings of gastric cancer has lagged behind many other cancers of similar incidence and morbidity, owing to our limited knowledge of germline susceptibility traits for risk and somatic drivers of progression (to identify novel therapeutic targets). A few germline (PLCE1) and somatic (ERBB2, ERBB3, PTEN, PI3K/AKT/mTOR, FGF, TP53, CDH1 and MET) alterations are emerging and some are being pursued clinically. Novel somatic gene targets (ARID1A, FAT4, MLL and KMT2C) have also been identified and are of interest. Variations in the therapeutic approaches dependent on geographical region are evident for localized gastric cancer-differences that are driven by preferences for the adjuvant strategies and the extent of surgery coupled with philosophical divides. However, greater uniformity in approach has been noted in the metastatic cancer setting, an incurable condition. Having realized only modest successes, momentum is building for carrying out more phase III comparative trials, with some using biomarker-based patient selection strategies. Overall, rapid progress in biotechnology is improving our molecular understanding and can help with new drug discovery. The future prospects are excellent for defining biomarker-based subsets of patients and application of specific therapeutics. However, many challenges remain to be tackled. Here, we review representative molecular and clinical dimensions of gastric cancer.

Gastric cancer-molecular and clinical dimensions

Gastric cancer imposes a considerable health burden around the globe despite its declining incidence. The disease is often diagnosed in advanced stages and is associated with a poor prognosis for patients. An in-depth understanding of the molecular underpinnings of gastric cancer has lagged behind many other cancers of similar incidence and morbidity, owing to our limited knowledge of germline susceptibility traits for risk and somatic drivers of progression (to identify novel therapeutic targets). A few germline (PLCE1) and somatic (ERBB2, ERBB3, PTEN, PI3K/AKT/mTOR, FGF, TP53, CDH1 and MET) alterations are emerging and some are being pursued clinically. Novel somatic gene targets (ARID1A, FAT4, MLL and KMT2C) have also been identified and are of interest. Variations in the therapeutic approaches dependent on geographical region are evident for localized gastric cancer-differences that are driven by preferences for the adjuvant strategies and the extent of surgery coupled with philosophical divides. However, greater uniformity in approach has been noted in the metastatic cancer setting, an incurable condition. Having realized only modest successes, momentum is building for carrying out more phase III comparative trials, with some using biomarker-based patient selection strategies. Overall, rapid progress in biotechnology is improving our molecular understanding and can help with new drug discovery. The future prospects are excellent for defining biomarker-based subsets of patients and application of specific therapeutics. However, many challenges remain to be tackled. Here, we review representative molecular and clinical dimensions of gastric cancer.

Increased gastric cancer risk with PTEN IVS4 polymorphism in a Turkish population

We aimed to investigate the association of the phosphatase and tensin homolog (PTEN) IVS4 polymorphism with a gastric cancer (GC) risk in the Turkish population. A hospital-based case-control study was conducted in 93 patients with GC, and 113 healthy controls. The PTEN IVS4 (rs no: 3830675) polymorphism was determined by using polymerase chain reaction-restriction fragment length polymorphism analysis. The PTEN IVS4 (-/-) genotype exhibited a significantly elevated risk for GC compared to controls (p<0.005; odds ratio: 1.6, 95% confidence interval: 1.19-2.14). Analyses on clinicopathological parameters showed that PTEN IVS4 genotypes were not associated with any of the variables of patients with GC (p>0.05). In conclusion, the PTEN IVS4 polymorphism might contribute to the development of GC in a Turkish population. Further studies, including comparison of the PTEN IVS4 polymorphism with plasma and tissue expressions of PTEN in larger study size groups will provide a further assessment of the PTEN IVS4 polymorphism in GC patients.

Immunohistochemical expression of mTOR negatively correlates with PTEN expression in gastric carcinoma

The phosphoinositide-3 kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) pathway is a cellular pathway involved in cell growth, tumorigenesis and cell invasion which is frequently activated in various types of cancer. The downstream effector of the pathway is mTOR which is important in cellular growth and homeostasis and aberrant activation of mTOR has been reported in several types of cancer. The tumor suppressor gene phosphatase and tensin homolog (PTEN) is essential in this pathway for inhibiting tumor invasion and metastasis. However, the involvement of mTOR and PTEN in the progression of human gastric cancer remains to be identified. Immunohistochemical staining was performed to detect the expression of mTOR and PTEN in paraffin-embedded gastric tissue sections obtained from 33 patients with gastric cancer and 30 normal controls. The expressed mTOR was mainly distributed in the cytoplasm, while PTEN was mainly localized to the nucleus. By considering negative mTOR expression with positive PTEN expression as one group and negative PTEN expression with positive mTOR expression as the other, significant statistical differences were observed in various categories, including histological types and metastatic and clinical pathology stages, between the 2 groups (P<0.01 or 0.05). The results indicated that the expression levels of mTOR and PTEN were negatively correlated in the PI3K-AKT-mTOR signaling pathway. Combined detection of mTOR and PTEN expression may be used to evaluate the degree of malignancy in gastric cancer and may be a useful marker for the early diagnosis of gastric cancer.

Aberrant promoter methylation and inactivation of PTEN gene in cervical carcinoma from Indian population

PURPOSE

PTEN, a tumor-suppressor gene located on chromosome 10q23.3 is implicated in multiple tumors including cervical carcinoma.

METHODS

We examined 135 cervical cancer specimens for PTEN gene expression and promoter methylation using methylation-specific PCR and immunohistochemistry and also studied the mutation in PTEN gene through PCR-single-stranded conformational polymorphism. PTEN expression and its methylation status were also correlated with clinicopathologic parameters.

RESULTS

The results showed an abnormal band on exon 5 and exon 9 of the PTEN gene. In PTEN gene, 61% specimen showed methylation. PTEN methylation was found in 39% cases of stage I, 60% of stage II, and 75% of stages III-IV. The correlation between PTEN methylation and clinical stage was found to be statistically significant (P = 0.003). Nuclear PTEN expression was detected in 84 of 135 (62%) cases of cervical carcinoma, and the remaining 51 of 135 (38%) cases were observed as expressional loss. The loss of PTEN expression was significantly correlated clinical stage (P = 0.001). Loss of PTEN expression was observed in 34 (41%) cases among 83 methylation positive cases, whereas among 52 methylation-negative cases, only 13 (25%) cases were seen as immunostaining negative with the statistically significant value (P = 0.05).

CONCLUSION

Promoter methylation and loss of PTEN expression occur frequently in carcinoma of uterine cervix. Our results suggest that PTEN plays an important role in the carcinogenesis of cervical cancer.

Role of PTEN in gastric carcinogenesis

The PTEN (phosphatase and tensin homolog deleted on chromosome ten) gene is another important tumor suppressor gene found after p53 gene, and its encoded protein is involved in cellular differentiation, reproduction and apoptosis, as well as cellular adhesion and mobility, and genetic stability that is often lost in various human cancers. Recently, some studies have indicated that down-regulation of PTEN protein expression due to genetic or epigenetic changes, like mutation, loss of heterozygosity (LOH) and promoter hypermethylation, participates in gastric carcinogenesis. These studies could help us understand the pathogenesis of gastric cancer (GC), and show us a new molecular marker that could be used to evaluate TNM stage, histological type, or differentiation grade of GC biopsies, and GC treatment. In this article, we will focus on the functions of PTEN, the mechanisms of its inactivation in GC, and the important role of its inactivation in the development and prognosis of GC.

Expression of PTEN and P16 proteins in varioliform gastritis and gastric cancer

AIM: To explore the relationship between varioliform gastritis and gastric cancer.

METHODS: The expression of PTEN and P16 proteins in chronic superficial gastritis, varioliform gastritis and gastric cancer was detected by immunohistochemistry.

RESULTS: The positive rate of PTEN protein expression in varioliform gastritis was significantly lower than that in chronic superficial gastritis (44.4% vs 92%, χ² = 14.47, P < 0.01) though no significant difference was noted between varioliform gastritis and gastric cancer (44.4% vs 25.8%, χ² = 2.51, P > 0.05). The positive rate of P16 protein expression in varioliform gastritis was significantly lower than that in chronic superficial gastritis (50% vs 96%, χ² = 14.56, P < 0.01), but significantly higher than that in gastric cancer (50% vs 19.4%, χ² = 6.80, P < 0.01).

CONCLUSION: Both PTEN and P16 proteins may be involved in the evolution of varioliform gastritis to gastric cancer.

Correlation of PTEN expression with microvessel density and pathological parameters in esophageal carcinoma

AIM: To investigate the expression of PTEN and analyze its correlation with microvessel density (MVD) and pathological parameters in esophageal squamous cell carcinoma (ESCC).

METHODS: Forty-eight ESCC specimens and 40 normal esophageal tissues closely adjacent to carcinomas were used in the study. The expression of PTEN and CD31 in these specimens was detected by immunohistochemistry using the streptavidin-peroxidase method.

RESULTS: The positive rate of PTEN expression in ESCC was significantly lower than that in normal esophageal tissue (52.08% vs 92.50%, P < 0.01). The positive rate of PTEN expression in ESCC was correlated with pathological grade (Grade I: 75.0%; Grade II; 55.0%; and Grade III: 33.33%; all P < 0.05), infiltrative deepness (superficial infiltration: 77.27%; deep infiltration: 42.31%, P < 0.01), but not with lymph node metastasis. The MVD was significantly higher in ESCC than in normal esophageal tissue (41.72 ± 8.67 vs 21.01 ± 3.85, P < 0.01). The MVD in ESCC was correlated with infiltrative deepness (superficial infiltration: 35.49 ± 5.89; deep infiltration: 46.01 ± 6.27, P < 0.01) and lymph node metastasis (46.71 ± 7.89 vs35.92 ± 2.54, P < 0.01), but not with pathological grade.

CONCLUSION: PTEN expression and MVD in esophageal carcinoma are related to tumor growth, invasion and metastasis. Loss or decreased expression of PTEN plays a critical role in tumor angiogenesis. PTEN expression can be used as a diagnostic and prognostic marker for ESCC.