Genes differentially expressed with malignant transformation and metastatic tumor progression of murine squamous cell carcinoma

Abstract

Molecular changes occurring with tumor formation and metastasis need to be identified in order to define novel markers and targets for chemoprevention and therapy. Cell lines from a multistage model of murine squamous cell carcinoma were analyzed for differences in gene expression using mRNA differential display. mRNA was isolated from primary keratinocytes, an in vitro transformed keratinocyte line (Pam 212), and three metastatic cell lines derived from Pam 212 following tumor progression in vivo. cDNA was synthesized by reverse transcription and amplified by PCR using 72 primer combinations to screen and compare approximately 3,600 sequences. Five cDNAs with a differential expression pattern confirmed by Northern blot analysis were cloned and sequenced, revealing homology with known genes. The gene encoding tropomyosin ␣ was preferentially expressed in primary keratinocytes; genes for tyrosine kinase Yes-associated protein (YAP65) and ribosomal protein L18a were preferentially expressed in transformed and metastatic tumor cell lines; and genes for the Gro-␣ family cytokine KC and antigen Sp17 exhibited increased expression in the three metastatic cell lines. The structure and function of the genes identified suggest that they may possibly be linked to cell shape and motility, signal transduction, protein synthesis, growth, granulocyte chemotaxis, and angiogenesis. This study demonstrates the ability of mRNA differential display to detect altered gene expression in this tumor progression model of murine squamous cell carcinoma, and the potential usefulness of this approach for identification of candidate genes as chemoprevention markers and targets. J. Cell. Biochem. Suppls. 28/29:90-100. 1998 Wiley-Liss, Inc. †

Growth Regulated Oncogene-α expression by murine squamous cell carcinoma promotes tumor growth, metastasis, leukocyte infiltration and angiogenesis by a host CXC Receptor-2 dependent mechanism

“…We previously detected increased expression of KC mRNA encoding murine GRO-a by di erential display in SCC reisolated from lymph node and lung following metastatic tumor progression of the in vitro transformed keratinocyte line PAM 212 (Dong et al, 1997). Figure 1a shows a Northern blot analysis con®rming that KC mRNA expression is increased in representative PAM LY and LU cell lines reisolated from lymph node and lung metastases when compared with normal BALB/c and transformed PAM 212 keratinocytes.…”

“…We found that KC mRNA and protein was uniformly expressed at high concentration by 15/15 cell lines reisolated from lymph node and lung metastases of the murine SCC line PAM 212 (Smith et al, 1998). These reisolated metastatic cells, exhibited an increased potential for growth and metastasis in vivo when compared with the low KC expressing PAM 212 cell line Dong et al, 1997). Conversely, clones of PAM 212 which expressed no detectable KC by ELISA grew even more slowly than the low KC expressing PAM 212 cell line (Smith et al, 1998).…”

“…We found previously that variants of murine squamous cell carcinoma PAM 212 which grow and metastasize more rapidly in vivo di erentially express increased levels of murine GRO-a (mGRO-a), originally named KC (Dong et al, 1997). GRO-a is an autocrine growth factor identi®ed in melanoma (Balentien et al, 1991), and is a member of the C-X-C family of chemokines which promote chemotaxis of granulocytes and endothelia (Strieter et al, 1996).…”

“…We previously developed a syngeneic murine model of SCC in our laboratory that has provided an opportunity to examine the expression of cytokines and chemokines during the early and late extremes of tumor progression in a homologous system Smith et al, 1998;Dong et al, 1997Dong et al, , 1999. The model consists of the spontaneously transformed keratinocyte line PAM 212, and lines isolated from rare PAM metastases which spontaneously arose following inoculation of PAM 212 in mice.…”

Cancer immunotherapy targeting Sp17: When should the laboratory findings be translated to the clinics?

“…In contrast, Sp17 mRNA could not be detected in normal somatic tissues, suggesting the restricted normal tissue expression of Sp17 [18,25]. Expression of Sp17 in malignant cells was first discovered by Dong et al [26]. High expression of the mouse homologue Sp17 was observed in metastatic cell lines derived from a murine model of squamous cell carcinoma but not in the non-metastatic parental line.…”