p53-Independent activation of the gadd45 promoter by Delta12-prostaglandin J2.

A p53-inducible gene, the growth arrest and DNA damage-inducible gene 45 (gadd45), is associated with cell growth inhibition, DNA damage response and DNA repair. Here we report that Delta12-prostaglandin J2 (Delta12-PGJ2), an in vivo metabolite of arachidonic acid, which inhibits cell proliferation, induces gadd45 mRNA in HeLa cells. Because the p53 protein in HeLa cells is inactivated by papilloma virus E6, this type of gadd45 induction appears to be p53-independent. The induction was dose-dependent, and the maximum induction was observed at a concentration of 7.5 microgram/ml. In a time course study, gadd45 mRNA was induced 3 h after the addition of 7.5 microgram/ml Delta12-PGJ2. To investigate the transcriptional mechanism of gadd45 mRNA induction, we cloned a human genomic DNA fragment containing the gadd45 promoter region, and investigated the effect of Delta12-PGJ2 on the gadd45 promoter activity. In HeLa cells, 7.5 microgram/ml Delta12-PGJ2 markedly stimulated the gadd45 gene promoter about 20-fold or more. On the other hand, Delta12-PGJ2 did not stimulate the promoter activity of a reporter plasmid containing only p53 binding sites in HeLa cells, indicating that the gadd45 promoter activation by Delta12-PGJ2 was not mediated by p53. These results suggest that one of the mechanisms of cell growth arrest by Delta12-PGJ2 is mediated through a p53-independent induction of gadd45.

Case report: glomus tumour of the nasal cavity and paranasal sinuses.

Glomus tumours are relatively rare in the head and neck. We present a glomus tumour of the nasal cavity and paranasal sinuses in a 55-year-old man and describe the CT appearances of this tumour and its histopathology.

Genetic instability of p53-deficient mouse cells.

We established fibroblast cultures from p53-deficient mouse embryos, which were originally constructed by Dr. S. Aizawa (Kumamoto Univ.). These p53-deficient fibroblasts showed the same sensitivity to UV and X-ray as wild-type fibroblasts. There was no difference between repair activity of UV-induced DNA damages in p53-deficient and wild-type cells, either. However, UV-induced sister chromatid exchanges were significantly increased and delay of entering S-phase after UV-irradiation was reduced in p53-deficient cells indicating abnormality in the checkpoint function of the cell cycle in p53-deficient cells. We also used the supF gene on a shuttle vector to analyze UV-induced mutations in p53-deficient cells. Although frequencies of UV-induced mutations were not different between p53-deficient and wild-type cells, distributions of base-substitution mutations on the supF gene were different.

UV-induced mutations of supF gene on a shuttle vector plasmid in p53-deficient mouse cells are qualitatively different from those in wild-type cells.

To verify the genetic instability of p53-deficient cells, UV-induced mutation of the supF gene on a shuttle vector was analyzed. UV-irradiated or non-irradiated shuttle vector plasmid carrying the supF gene as a target of mutation (pYZ289) was introduced into p53-deficient and p53-proficient mouse embryonic fibroblasts, and then the plasmid DNA replicated in mouse cells was recovered. Survival of UV-irradiated plasmid was almost equivalent in both p53-deficient and p53-proficient cells. The frequencies of UV-induced mutation of the supF gene were also the same in both types of cells. However, the distributions of base change mutations in the supF sequence were different between p53-deficient and p53-proficient cells; especially the locations of tandem CpC to TpT changes exhibited a marked difference. Since DNA repair activities of these two types of cell were almost the same, these qualitative differences in UV-induced mutations were probably caused by as yet unidentified differences in other than DNA repair activity.

[Immunohistological investigation of type IV collagen in the basement membrane surrounding the cancer nest (cancer nest membrane) of head and neck squamous cell carcinoma--its relation to frequency of cervical lymph node metastasis].

Lymphoducts and blood vessels exist in the stroma, while none can be detected in the cancer nest itself within cancerous tissue. This explains why metastasis of carcinoma cannot occur without the escape of tumor cells through the basement membrane surrounding the cancer nest into the stroma. Accordingly, observation of the continuity of the basement membrane, what we call the cancer nest membrane, is essential for elucidating the first step of metastasis. Since type IV collagen is the most important structure composing the basement membrane, investigation of the immunohistological localization and continuity of type IV collagen is of value in predicting the metastatic aggressiveness of squamous cell carcinoma. We therefore studied biopsy tissues from the advancing lesion of head and neck squamous cell carcinoma in 95 untreated patients. The tissues were fixed in 85% ethanol and embedded in paraffin, and 5-um thin sections prepared were then immunohistochemically stained for type IV collagen by the ABC method for observation of the continuity status of the cancer nest membrane in relation to metastasis. The basement membranes of normal mucosal epithelium and normal interstitial capillaries were utilized as positive controls, and negative controls were obtained by using PBS in place of the primary antibodies for the immunohistochemical reaction. Membrane discontinuity (breaks or absence) correlated significantly with cervical lymph node metastasis, while intact membrane was associated with a low frequency of cervical lymph node metastasis. There was no obvious relation between the clinical T category and the continuity of the membrane; pN (+) carcinomas with membrane discontinuity included even T1 supraglottic and hypopharyngeal carcinomas, as well as T2 or higher oral mucosal carcinomas and T3 or higher glottic carcinomas, suggesting variation with tumor site. Hypopharyngeal and supraglottic carcinoma was associated with membrane discontinuity and a high incidence of cervical lymph node metastasis. On the other hand, glottic and oral carcinoma more often presented with intact membranes and had a lower incidence of metastasis, although carcinomas in these sites that did present with discontinuity of the membrane were associated with a high incidence of cervical metastasis. Therefore, observation of the continuity of the cancer nest membrane by the expression of type IV collagen may be useful in selecting better specific therapies and determining the necessity of prophylactic neck dissection. A correlation between the degree of tumor differentiation and the continuity of the membrane was also found; well-differentiated tumors with discontinuity of the membrane were frequently associated with cervical lymph node metastasis.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of high-resolution CT after tympanoplasty.

The temporal bones of 28 patients who underwent tympanoplasty were evaluated with high-resolution CT (HRCT). Seventeen patients had undergone tympanoplasty with a columella, used to form an ossicular reconstruction. The incus body was used as the columella in 4 patients and a prosthesis was used in 13 patients. No columella was used in the other 11 patients. After tympanoplasty, CT demonstrated normal appearance in 8 patients. Of the other 20 patients, 16 were diagnosed with chronic otitis media, and 4 were diagnosed with recurrent cholesteatoma on the basis of follow-up CT examinations. Seven underwent reoperation. In all 4 patients with recurrent cholesteatoma, the diagnosis was pathologically confirmed at reoperation. In 1 patient diagnosed with chronic otitis media, the pathological diagnosis was recurrent cholesteatoma. The columellae in 8 of the 17 patients could not be identified on CT because of surrounding soft tissue mass, but in the other 9 patients the condition of the ossicular reconstruction was well demonstrated. Prosthesis dislocation was apparent in 2 patients. We recommend HRCT examination in the follow-up of tympanoplasty patients.

[Immunohistological investigation of epithelial components of adenolymphoma of the parotid gland].

In order to develop a more objective method of evaluating the origin of adenolymphoma, we immunohistochemically investigated the expression of cytokeratins, vimentin, S-100 protein, and alpha-smooth-muscle actin using the avidin-biotin-peroxidase (ABC) method in ethanol-fixed paraffin-embedded specimens from 8 adenolymphomas. Several kinds of monoclonal antibodies which react monospecifically with each subclass of cytokeratins were used. Results were compared with specimens of 8 normal parotid glands by radical neck dissection in patients with other diseases who had not undergone radiotherapy. In the adenolymphoma specimens, basal cells were strongly positive for CK-6, but reactivity of columnar cells was apparently reduced. In contrast, columnar cells were strongly positive for CK-7, but reactivity of basal cells was reduced. In normal parotid gland specimens, CK-7 was also detected in all columnar cells in the ductal system, although some duct cells around the columnar cells, which showed strong CK-6 expression, showed poor CK-7 expression. alpha-smooth-muscle actin was present in myoepithelial cells in normal parotid gland specimens, but not in basal cells of adenolymphoma or of the normal ductal system, which were CK-6-positive. As these characteristic findings were consistently observed in all specimens, the demonstration of CK-6, CK-7, and alpha-smooth-muscle actin may be useful in the recognition and classification of columnar and basal cells. CK-8 was present in both columnar and basal cells of adenolymphoma and of the normal duct, but in the normal parotid gland, acinus cells were also strongly positive for CK-8.(ABSTRACT TRUNCATED AT 250 WORDS)

Pedunculated intraluminal osteochrondromatous hamartoma of the esophagus.

Pedunculated intraluminal hamartoma of the cervical esophagus of an adult female was treated by surgical resection. The patient presented with bloody sputum. A barium swallow revealed a pedunculated intraluminal tumor just below the conus of the thyroid cartilage. The tumor had a stalk of 6 cm in length and was attached to the cricopharyngeal muscle. Histopathologic examination showed a predominance of osseous and cartilaginous tissue. The tumor also contained fibrous tissue, adipose tissue and glandular structure. The embryology of such a cartilaginous tumor at the proximal esophagus was interesting.