Mutational analysis of genes p14ARF, p15INK4b, p16INK4a, and PTEN in human nervous system tumors.

Cancer is one of the most common and severe problems in clinical medicine, and nervous system tumors represent about 2% of the types of cancer. The central role of the nervous system in the maintenance of vital activities and the functional consequences of the loss of neurons can explain how severe brain cancers are. The cell cycle is a highly complex process, with a wide number of regulatory proteins involved, and such proteins can suffer alterations that transform normal cells into malignant ones. The INK4 family members (CDK inhibitors) are the cell cycle regulators that block the progression of the cycle through the R point, causing an arrest in G1 stage. The p14ARF (alternative reading frame) gene is a tumor suppressor that inhibits p53 degradation during the progression of the cell cycle. The PTEN gene is related to the induction of growth suppression through cell cycle arrest, to apoptosis and to the inhibition of cell adhesion and migration. The purpose of the present study was to assess the mutational state of the genes p14ARF, p15INK4b, p16INK4a, and PTEN in 64 human nervous system tumor samples. Homozygous deletions were found in exon 2 of the p15INK4b gene and exon 3 of the p16INK4a gene in two schwannomas. Three samples showed a guanine deletion (63 codon) which led to a loss of heterozygosity in the p15 gene, and no alterations could be seen in the PTEN gene. Although the group of patients was heterogeneous, our results are in accordance with other different studies that indicate that homozygous deletion and loss of heterozygosity in the INK4 family members are frequently observed in nervous system tumors.

Mutational analysis of genes p14ARF, p15INK4b, p16INK4a, and PTEN in human nervous system tumors

The cancer is one of the most common and severe problems in clinical medicine, and nervous system tumors represent about 2% of the types of cancer. The central role of the nervous system in the maintenance of vital activities and the functional consequences of the loss of neurons can explain how severe brain cancers are. The cell cycle is a highly complex process, with a wide number of regulatory proteins involved, and such proteins can suffer alterations that transform normal cells into malignant ones. The INK4 family members (CDK inhibitors) are the cell cycle regulators that block the progression of the cycle through the R point, causing an arrest in G1 stage. The p14ARF (alternative reading frame) gene is a tumor suppressor that inhibits p53 degradation during the progression of the cell cycle. The PTEN gene is related to the induction of growth suppression through cell cycle arrest, to apoptosis and to the inhibition of cell adhesion and migration. The purpose of the present study was to assess the mutational state of the genes p14ARF, p15INK4b, p16INK4a, and PTEN in 64 human nervous system tumor samples. Homozygous deletions were found in exon 2 of the p15INK4b gene and exon 3 of the p16INK4a gene in two schwannomas. Three samples showed a guanine deletion (63 codon) which led to a loss of heterozygosity in the p15 gene, and no alterations could be seen in the PTEN gene. Although the group of patients was heterogeneous, our results are in accordance with other different studies that indicate that homozygous deletion and loss of heterozygosity in the INK4 family members are frequently observed in nervous system tumors.

Molecular study of the tumour suppressor gene PTEN in gastric adenocarcinoma in Brazil.

Among all tumours diagnosed worldwide, gastric adenocarcinoma is the second most frequent type of malignancy. In Brazil, it is estimated to be the fifth most frequent type of neoplasia. According to the classification of Laurén, these tumours are divided into well differentiated and ill differentiated gastric adenocarcinomas. There are studies suggesting that the first type develops through remodulation of genes involved in the suppressor pathway and the second through remodulation of genes belonging to the mutational pathway. The gene PTEN is located in region 10q23 and is altered in several human tumours. In gastric cancer, this gene is thought to take part in the suppressor pathway. In our study, DNA was obtained from 48 gastric adenocarcinoma samples, amplified, screened for all exons of the PTEN gene by PCR-SSCP and then confirmed by sequencing. There was only one sample that presented an alteration and that was a transversion. Our results corroborate the hypothesis that somatic alterations in the PTEN gene are rare events in gastric cancer.

Carcinoma of the breast: analysis of total lymph node involvement versus level of metastasis.

The histologic presence of axillary lymph node metastasis is the most commonly used indicator or prognosis for patients with operable breast cancer. The record of 385 patients treated by 380 radical mastectomies between the years 1944 and 1972 were reviewed to clarify this. The axillary nodes recovered were evenly distributed. The median number of positive lymph nodes at each level was two; 50% had involvement of only one level. The number of lymph nodes identified increased with the number of positive nodes. When compared with similar patients, survival curves for those having a single involved node and also those having multiple metastatic nodes were similar whether the node were in the proximal, middle, or distal levels. The 10-year determinate survival for patients with fewer than five positive positive nodes was just under 50%. High positive nodal counts, or involvement of more than one level, were associated with local recurrence of disease.

Mucinous adenocarcinomas of nose and paranasal sinuses.

This study concerns the Clinicopathologic findings for 18 patients with mucinous adenocarcinomas of nose and/or paranasal sinuses. Males in the 5th decade of life predominated in the series. Nasal obstruction, a growing mass in a sinus, or epistaxis were the most frequent complaints. Ten patients had tumors in the maxillary antrum, and the nasal cavity was the site in 5 patients. Histopathologically, the tumors were moderately to well differentiated, with a few poorly differentiated types. Tumor with the solid pattern of growth were anaplastic; these patients had poorer prognoses. For most patients, treatment consisted of radical surgery alone or in combination with radiotherapy. Of 13 patients for whom survival could be adequately evaluated, 7 died from the tumors, 5 are alive and free of disease more than 4 years, and 1 is living with recurrent tumor 14 months after diagnosis.