Spontaneous keratinocyte cell lines representing early and advanced stages of malignant transformation of the epidermis

Abstract

A unique series of epidermal cell lines representing different stages of malignant transformation were spontaneously derived from a single adult immunosuppressed individual. Four keratinocyte lines (PM1-4) established from forehead skin are here compared with 4 squamous cell carcinoma (SCC) lines (MET1-4) derived respectively from a primary cutaneous tumour, two local recurrences and a distant metastasis of invasive SCC. Despite altered growth properties, the PM lines retained many features of normal keratinocytes including keratin phenotype, differentiation capacity and non-tumorigenicity in athymic mice. In contrast, from early passage, the MET lines displayed markedly reduced growth requirements, abnormal differentiation, aberrant K18 expression and tumorigenicity in athymic mice. The abnormal keratin profile of individual MET lines closely reflected the keratin phenotype of the tumour of origin. Although unusual HPV types were identified in the original tissue, there was no evidence of persistent virus within any cell line and it appears that HPV is not critical for maintenance of the immortal phenotype. The PM lines were distinctly different from invasive SCC lines and are likely to be useful for studies of mutations important early in neoplastic progression. The SCC series represent primary, recurrent and metastatic carcinoma. Availability of such a series from the same individual will facilitate genetic analysis of the malignant process.

Expression of Betapapillomavirus Oncogenes Increases the Number of Keratinocytes with Stem Cell-Like Properties

“…PM1 cells are spontaneously immortalized noninvasive cells that retain the morphology and keratin expression profile of normal cultured keratinocytes and are HPV negative (38). Colony formation assays revealed a 1.3-fold increase in the number of colonies in HPV8 E2-expressing cultures, a 1.7-fold increase in HPV8 E6-expressing cultures, and a 1.9-fold increase in HPV8 E7-expressing cultures (Fig.…”

“…The PM1 cell line (38) Ϫ10 M cholera toxin, 5 g/ml transferrin, 2 ϫ 10 Ϫ11 M liothyronine, 5 g/ml insulin, 10 ng/ml epidermal growth factor, 1ϫ penicillin-streptomycin mixture). The cell line was cultivated at 37°C and 6% CO 2 .…”

Cancer Stem Cells in Squamous Cell Carcinoma Switch between Two Distinct Phenotypes That Are Preferentially Migratory or Proliferative

“…1H) Epithelial-to-mesenchymal transition cancer stem cells are present in cell lines generated from progressive stages of cutaneous squamous cell carcinoma We next investigated whether the CD44 high ESA low EMT CSC population identified in OSCC is also present in cell lines derived from cutaneous SCC. Such cells were present in 3 matched specimens derived from the same patient (26) and measurement of the size of the CD44 high ESA low populations in each of these three cell lines revealed stark differences between different stages of malignancy ( Fig. 2A).…”

“…The PM1, Met1, and Met2 cell lines were derived from matched premalignant and malignant cutaneous SCC tissues (26). All cell lines were grown in the highly supplemented epithelial growth medium (termed FAD) with 10% FBS (23).…”

Metastatic cutaneous squamous cell carcinoma shows frequent deletion in the protein tyrosine phosphatase receptor Type D gene

“…Biopsies obtained for short-term culture were prepared directly from patient material as previously described. 24 The study was undertaken in accordance with ethical approval from the East London and City Health Authority Local Research Ethics Committee.…”