Manabu Fujioka

Tumor-doubling time and onset of pulmonary metastasis from adenoid cystic carcinoma of the salivary gland

Adenoid cystic carcinoma (ACC), an uncommon malignancy in the head and neck region, invades diffusely and often metastasizes to the lung, although the growth rate is very slow. A retrospective study was conducted in 30 patients with ACC to ascertain the frequency of pulmonary metastasis, the doubling time of metastatic tumor deposits, and the time of onset for pulmonary metastasis. The following results were obtained: (1) Of 30 patients with ACC, 21 had pulmonary metastases (4 initially and 17 during observation), 7 were free of metastases but have not been observed for 5 years, and 2 were free of metastases for more than 5 years but less than 10 years after the initial treatment. The cumulative metastasis rate at 5 and 10 years for this group of patients was 70% and 100%, respectively. (2) Patients with T1 or T2 tumors that have a tubular or cribriform histopathologic pattern showed pulmonary metastases about 20 months later than those with T3 or T4 tumors and a solid pattern. However, the final metastasis rate did not differ between the 2 groups after a long period. (3) The tumor doubling time of the metastatic deposits of ACC was 86 to 1064 days with an average of 393 days, which was much longer than that of most other malignant neoplasms reported previously. (4) The time of onset of pulmonary metastasis was calculated to be much earlier (average of 227 months) before the first visit. These findings suggest that the treatment method for ACC should be chosen with the consideration that many of the patients may have occult pulmonary metastases at the time of their initial evaluation.

Molecular characterization of a novel cancer cell line established from human carcinoma in pleomorphic adenoma (CaPA-4).

A cultured cell line (CaPA‐4), derived from an undifferentiated carcinoma in a pleomorphic adenoma of the submandibular gland, was established through xenografted tumors in nude mice. Geneticin treatment eliminated surrounding mouse fibroblasts and yielded enriched tumor cells at an early stage of cell passage. In vitro, the line grew in a cobblestone pattern, revealing its epithelial origin. Chromosomal analysis by Giemsa‐banding confirmed its human origin, while electron microscopic examination showed its squamous‐cell characteristics. CaPA‐4 cells stained positive for the c‐myc and Ha‐ras antibodies. Molecular analysis showed over‐expression of both c‐myc and Ha‐ras mRNA, with point mutation of p53 at codon 248 and of Ha‐ras at codon 61. Amplification and rearrangement of the Ha‐ras gene were observed; however, no loss of heterozygosity (LOH) of the p53 gene was detected by Southern blotting. This sequence of cancer‐related gene activation may represent the malignant transformation from benign pleomorphic adenoma. This report describes the establishment and molecular characterization of this novel cell line from carcinoma in pleomorphic adenoma exhibiting squamous‐cell differentiation. This could represent a useful model for investigating the cause of malignant transformation from human salivary‐gland mixed tumors.

Transfection of wild-type TP53 induces differentiation in human gingival carcinoma cells

We investigated the effects of transfection of wild-type TP53 on the growth properties of a human gingival carcinoma cell line, KOSC-3, in which the TP53 gene is mutated at codon 248 and overexpressed. The wild-type TP53 expression plasmid, pCDM8-p53/neo and the control plasmid, pCDM8/neo, were each stably transfected into KOSC-3 cells by using the calcium phosphate method. The number of G418-resistant colonies from wild-type TP53-transfected cells was approximately half that from plasmid controls. Exogenous wild-type TP53 transcripts were identified in four of the 20 G418-resistant clones analysed by reverse transcription PCR. Although the growth rates of the wild-type TP53+ clones did not drastically change during log phase, their saturation density was significantly reduced. The wild-type TP53+ cells were morphologically flat and enlarged when cultured in vitro, and were less able to form colonies in soft agar. In nude mice, the wild-type TP53+ clones formed subcutaneous tumours with conspicuous keratinisation and notable cell death that was not manifested in the parental and plasmid control cells. These findings indicate that the wild-type TP53 gene, even when it coexists with a mutated form, may function as a growth suppressor and differentiation inducer under restricted conditions in gingival squamous cell carcinoma.

A clinical study of local recurrence after surgery in patients with squamous cell carcinoma of the oral mucosa.

1990年～1991年の口腔粘膜扁平上皮癌手術症例のうち, 原発巣再発をきたした22例について臨床的に検討し, 以下の結果を得た。1.舌癌22例中原発巣再発は9例に認められた。再発は局所進展例で舌半側切除, 亜全摘, 全摘を施行した症例に多かった。2.下顎歯肉癌の原発巣再発は42例中7例に認められた。再発はT4の局所進展例だけではなくT1・T2で口内法による下顎骨辺縁切除を施行した症例にも生じた。また, X線所見や組織学的悪性度と再発との関連性は認められなかった。3.口底癌の原発巣再発は17例中4例に認められた。再発はT2・T3で下顎骨辺縁切除を施行した症例に生じた。組織学的悪性度と再発との関連性は認められなかった。4.上顎歯肉癌の原発巣再発は22例中2例に認められた。再発はT1～T3の症例にはみられなかった。5.再発例22例のうち予後良好は7例のみで, 5年累積生存率は34.1%であった。