Squamous cell carcinoma of the lung

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The incidence of lung cancer in Okinawa has been the highest in Japan since 1975, and squamous cell carcinoma (SCC), especially the well differentiated form, is the most prevalent form in Okinawa, although well differentiated SCC is relatively rare in mainland Japan. Furthermore, a high proportion of SCC of the lung in Okinawa was positive for human papillomavirus (HPV). In this study, we report recent striking changes in histological features and in the incidence of HPV infection.Up until 1994 SCC, especially the well differentiated form, was the most prevalent type of tumour. However, since 1995 the number of such cases has diminished steadily, accompanied by a slight rise in the incidence of adenocarcinoma. Although most present and past patients are heavy smokers, the incidence of SCC, especially the well differentiated form, continues to decrease steadily. Furthermore, in 1993, HPV was detected in 79% of all cases, and was particularly prevalent in the well differentiated form, bu … More t the rate fell to 68% in 1995, 35% in 1996, 23% in 1997, and 24% in 1998.Up until 1994 SCC, especially the well differentiated form, was the most prevalent type of tumour. However, since 1995 the number of such cases has diminished steadily, accompanied by a slight rise in the incidence of adenocarcinoma. Although most present and past patients are heavy smokers, the incidence of SCC, especially the well differentiated form, continues to decrease steadily. Furthermore, in 1993, HPV was detected in 79% of all cases, and was particularly prevalent in the well differentiated form, but the rate fell to 68% in 1995, 35% in 1996, 23% in 1997, and 24% in 1998.Transfection of human papillomavirus (HPV) type 6 in plasmid pML2, and types 16 and 18 in pBR322 into cultured adenocarcinoma DLD-1 (moderately differentiated colonic adenocarcinoma) and PC-14 (poorly differentiated lung adenocarcinoma) cells respectively using the calcium phosphate method was carried out. Neomycin or hygromycin B was used as selectable makers. 49 HPV transfected cell clones were obtained. The effects of HPV transfection into adenocarcinoma cells were examined.Transfection of the virus into the cultured adenocarcinoma cells increased the G0-G1 cell population markedly. The virus transfected cells showed squamous metaplasia when they were injected into SCID mice, expressing the high molecular weight keratin (Moll's No. 1 keratin) and involucrin molecules immunohistochemically, and transglutaminase I mRNA by RT-PCR.The squamous metaplasia was most conspicuous in the HPV 16 transfected DLD-l (16D2) when compared with HPV 6 and 18 transfected cells. Less