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The nuclear matrix is a nonchromatin structure of the nucleus normally concealed by a much larger mass of chromatin. Several methods have been developed to remove chromatin from nucleus while preserving the underlying matrix architecture to some degree. The present study showed that after extraction of PtK2 cells and cervical carcinoma cells (CC3) with Triton X-100, ammonium sulfate and DNase, the nucleolar-nuclear matrix-intermediate filament (Nu-Nm-L-IF) network remained. The nucleolus was oval in shape and appeared as a fibrillar mass with an accentric dense fibrillar centre. This nucleolar skeleton was in direct connection with the nuclear matrix which in turn is connected with cytoplasmic intermediate filaments by lamins. It is concluded from these observations that the Nu-NM-L-IF system forms a continuous system which plays an important role in the maintenance of the nucleolar, nuclear and cytoplasmic integrity and cellular function.

A new cell line, designated CC2/CUHK2, was established from a squamous carcinoma of the uterine cervix from a Chinese patient. The cell line grew well without interruption for over 12 months and over 90 passages. The doubling time of CC2/CUHK2 was 72 hours at passage 57. When seeded at a density of 1.5 x 10(3) cells per 25 cm2 tissues culture flask, the plating efficiency was 2.15%. Chromosome analysis showed a range of 30 to 130 with a modal number of 75. Immunoperoxidase staining of keratin showed positive reaction. Most of the CC2/CUHK2 cells showed weak nuclear staining of HPV capsid antigens with the ABC detection system. Analysis of the DNA samples extracted from the cervical cancer cells showed the presence of HPV type 16 DNA.

Two new cell lines derived from squamous cell carcinoma of the tongue, T1/CUHK and T2/CUHK, have been established in culture. Analysis of the morphology, ultrastructure, chromosome number, spheroid formation and immunohistochemical properties of the two cell lines demonstrated that they are both well characterized. T1/CUHK cells grew relatively faster than T2/CUHK cells. Both cell lines were tumorigenic after inoculation into made mice and showed positive reactivity with HPV 16 DNA probe. The reactivity of both cell lines with HPV 18 DNA probe was weak.

Terminal differentiation is usually achieved in normal as well as transformed squamous epithelial cells when cultured. On the other hand, tumor cells at various differentiation stages and with different biological characteristics comprise the heterogeneous properties of tumors which have been one of the barriers to effective treatments. Recently, a surface membrane protein has been reported in squamous cell carcinomas of the head and neck, which is recognized by a murine monoclonal antibody, SQM1. This glycoprotein was further suggested to be related to squamous cell differentiation and intercellular adhesion. In a recent study, the esophageal carcinoma cells of EC/CUHK2 cell line were induced to various differentiation stages as evidenced by the increasing amount of intracellular desmosomes and tonofilaments and greater binding ratios of cytokeratin and involucrin antibodies than in those cells that maintained lower calcium ion concentrations. The expression of SQM1 antigen was found to increase in intensity when the tumor cells were cultured in moderate to high calcium ion levels for 10 to 15 hours when the differentiation patterns were beginning to appear. The intensity declined gradually thereafter. Thus SQM1 protein might be related to the stage when the cells started committing with squamous differentiation.

The cell surface carbohydrate profile of formalin-fixed paraffin-embedded tissue sections of normal and neoplastic epithelium was evaluated using 9 plant lectins. Three lectins, namely Con A, RCA and WGA, showed a similar pattern and staining intensity from normal epithelium to metaplastic squamous epithelium and nasopharyngeal intraepithelial neoplasia (NPIN). However, a decrease in staining reactivity was observed in undifferentiated nasopharyngeal carcinoma. Significant differences in intensity and distribution were seen in UEA and cryptic PNA residue (after neuraminidase pretreatment) from normal nasopharyngeal epithelium to NPIN. Infiltrative undifferentiated carcinomas showed a heterogenous lectin binding pattern and altered intensity of lectin binding in one case of DBA and three cases of PNA (no neuraminidase pretreatment), suggesting a variation in expression of carbohydrate by tumour cells. These results indicate that neoplasia in nasopharyngeal epithelium is associated with alterations in terminal sialic acid, -Fucose residues and -Gal-D-GalNac residues present in the outer parts of glycoconjugates. SBA, VVL and BSL failed to stain any types of epithelia. Desialylation of tissues by preincubation with neuraminidase did not expose DBA, SBA, VVL and BSL binding sites. These findings may be used as a baseline for evaluation of lectin binding in preinvasive and invasive lesions of the nasopharynx.

A recently established cell line, designated CC3/CUHK3, derived from a squamous cell carcinoma of the uterine cervix of a Hong Kong Chinese patient was investigated for its association with human papillomavirus (HPV) by Southern blot hybridization studies. A "grafted tumour" or xenograft of CC3/CUHK3 has also been successfully established in athymic mice, which showed similar histology to that of the original biopsy. The epithelial nature of the xenografts, like the original biopsy. The epithelial nature of the xenografts, like the original tumour specimen, was also confirmed by transmission electron microscopy which demonstrated the presence of desmosomes and tonofilaments. Moreover transmission electron microscopic examination revealed no HPV particle in either the tumour biopsy or the xenograft tissues. Analysis of the DNA samples extracted from the cervical cancer cell line and the xenograft tissues derived from it showed the presence of HPV type 16 DNA. No DNA sequence related to HPV type 6, 11, or 18 was demonstrated. The viral DNA was found to be integrated into the cellular genome at multiple sites as single copy or head-to-tail tandem repeats. Deletion or rearrangement of the HPV DNA had probably occurred on or subsequent to integration. Viral sequence deletion has also been observed in the grafted tumours derived from CC3/CUHK3.

A new cell line, CC3/CUHK3, was established from a squamous carcinoma of the uterine cervix from a Chinese patient. Light microscopy of the cell line revealed keratin and electron microscopy demonstrated tonofilaments and desmosomes, thereby confirming its epithelial nature. The population doubling time of CC3/CUHK3, estimated from the exponential growth phase of the growth curve established from the cell line was 42 hours. When the tumour cells were inoculated into athymic mouse, a tumour, microscopically diagnosed as a well-differentiated carcinoma, developed. These cells are highly invasive in vitro.

An epithelial cell line, EC/CUHKI was established from a human squamous cell carcinoma of the oesophagus. The cells were polygonal in shape with numerous microvilli. Transmission electron microscopy (TEM) revealed the presence of desmosomes and tonofilaments. Karyotypic analysis of cells from the cell line demonstrated an aneuploid human type with a modal chromosome number of 85. Epstein-Barr viral nuclear antigen (EBNA) has not been demonstrated in the cells from the primary culture or subcultures. The tumour cells form colonies in agar and have a plating efficiency of 20%. The cells are highly invasive in vitro and are tumorigenic in nude mouse.

A long-term cell culture epithelioid cell line was established from a recurrent squamous carcinoma of the nasopharynx of a Chinese male 17 1/2 years after radiation therapy. The cell line, designated NPC/HK1, has been passed 72 times over a period 1 year. The cells have been shown by light and electron microscopies to be of the squamous epithelial type. When they were transplanted subcutaneously into the back of athymic nude BALB/c (nu/nu) mice, tumors developed at the sites of inoculation, which on histological examination were shown to be well-differentiated squamous carcinomas, similar in morphology to the recurrent human tumor from which they were derived. Karyotypic analysis of cells from the cell line demonstrates an aneuploid human type with a modal chromosome number of 74 with both numerical and structural aberrations. Viral particles or Epstein-Barr viral nuclear antigen (EBNA) has not been demonstrated in the cells from the primary culture or several of the subcultures tested. The presence of EBNA in touch smears prepared from the biopsy tissue was inconclusive. Infection of the subcultured cells with EBV from P3HR1 and B95-8 cells was unsuccessful.