Tumor Progression of Skin Carcinoma Cells in Vivo Promoted by Clonal Selection, Mutagenesis, and Autocrine Growth Regulation by Granulocyte Colony-Stimulating Factor and Granulocyte-Macrophage Colony-Stimulating Factor

Abstract

The development of cancer is a multistep process, in which cells accumulate genetic alterations thereby gradually progressing from a normal to a malignant phenotype. The stepwise evolution from premalignant lesions to malignant and finally metastasizing tumors is understood as the result of an increasing dysregulation of endogenous growth control mechanisms and independence of environmental growth regulatory factors. 1 One of the best studied models for tumor development and progression is that proposed by Fearon and Vogelstein 2 for colon carcinogenesis. Detailed genetic analysis of different stages in the process of tumor development revealed that an accumulation of multiple changes in tumor suppressor genes as well as oncogenes is necessary for the evolution of malignant tumors. To date it is not clear whether a specific number of genetic alterations or a defined sequence in which these alterations occur is prerequisite for a malignant tumor to develop. The understanding of the molecular mechanisms underlying tumor progression has been greatly improved by the development of in vitro model systems such as that for colon carcinoma. 3 However, the specific role of the in vivo microenvironment in controlling or facilitating the transition to a more advanced stage of cell transformation is still poorly understood because of the complexity of the tissue influences.We have previously developed an in vitro cell transformation system of human skin keratinocytes and characterized the genetic and phenotypic alterations associated with the subsequent stages of carcinogenesis to squaSupported by the Verein zur Foerderung der Krebsforschung e.V. and DFG SPP "Angiogenesis" (Fu 91-5).M. M. M. and W. P. both contributed equally to this article.

Serpin Peptidase Inhibitor Clade A Member 1 (SerpinA1) Is a Novel Biomarker for Progression of Cutaneous Squamous Cell Carcinoma

“…In addition, the level of SerpinA1 expression in Ha-ras-transformed HaCaT cell lines correlated with their tumorigenic potential, being lowest in the benign tumorigenic cell line (A5) and highest in RT3 cells, which form metastatic SCCs in vivo. 23,24 These results also show that inactivation of p53 tumor suppressor, an early event in UV-induced epidermal carcinogenesis, is not sufficient to induce SerpinA1 expression in HaCaT cells, whereas additional activation of ras signaling pathway enhances basal SerpinA1 expression. Second, examination of DMBA-TPA-induced mouse skin SCCs, which harbor an activating H-ras1 mutation in addition to a p53 mutation, 36 Figure 6.…”

“…19 -21 SCC cells were cultured in Dulbecco's modified Eagle's medium supplemented with 6 mmol/L glutamine, nonessential amino acids, and 10% fetal calf serum. 20,21 HaCaT, a spontaneously immortalized, nontumorigenic human epidermal keratinocyte-derived cell line, 22 and the Ha-rastransformed tumorigenic HaCaT cell lines A5, II4, and RT3 23,24 (a gift from Dr. Norbert E. Fusenig, German Cancer Research Center, Heidelberg, Germany) were cultured in Dulbecco's modified Eagle's medium containing 10% fetal calf serum. G418 (200 g/mL) was added to the medium of the Ha-ras-transformed HaCaT cell lines.…”

“…G418 (200 g/mL) was added to the medium of the Ha-ras-transformed HaCaT cell lines. 23,24 Normal human epidermal keratinocytes (NHEKs) were cultured from nonmalignant skin of patients (n ϭ 4) undergoing surgery for mammoplasty at Turku University Hospital, Turku, Finland. In addition, normal keratinocytes were purchased from PromoCell (Heidelberg, Germany).…”

“…Specifically, A5 is a benign tumorigenic HaCaT-derived cell line, II4 forms invasive malignant tumors, and RT3 cells form metastatic tumors in vivo. 23,24 Nontumorigenic HaCaT cells, with inactivation of both alleles of p53 tumor suppressor, express low levels of SerpinA1 mRNA ( Figure 2B). In contrast, significantly higher expression of SerpinA1 mRNA was noted in Ha-ras-transformed HaCaT cell lines, and the expression correlated with tumorigenic potential because it was lowest in the A5 cell line and highest in the RT3 cell line ( Figure 2B).…”

High‐resolution three‐dimensional MR angiography of rodent tumors: Morphologic characterization of intratumoral vasculature

“…It is known from previous studies that HaCaT-ras-A-5RT3 tumors have a high vascularity with multiple large intratumoral vessels evident at histology (15,16). Tumors were induced by subcutaneous injection of 2 ϫ 10 5 cells into the back of nude mice weighing approximately 20 g. Animals were studied approximately three weeks after cell injection, when each had developed well vascularized tumors with diameters in the range of 6 to 10 mm.…”