Expression of proangiogenic chemokine Gro 1 in low and high metastatic variants of Pam murine squamous cell carcinoma is differentially regulated by IL-1 alpha, EGF and TGF-beta 1 through NF-kappa B dependent and independentmechanisms

We previously reported that chemokine Growth Regulated Oncogene 1 (Gro 1) i s over-expressed in murine squamous cell carcinoma (SCC) with metastatic tu mor progression. The enhanced expression of Gro-1 gene by SCC is regulated by activation of nuclear factor-kappaB (NF-kappaB), leading to accelerated tumor growth, angiogenesis and metastasis in vivo. In our study, we investi gated the effect of the regulatory cytokines, IL-1 alpha, EGF and TGF-beta1 on activation of NF-kappaB and Gro 1 in primary and metastatic sublines of the murine SCC Pam 212. We found that Gro 1 expression could be induced by IL-1 alpha or EGF in the low cytokine producing Pam 212 cells, but no sign ificant induction was observed in high cytokine producing and metastatic LY -2 cells. Conditioned medium from LY-2 containing functional IL-1 alpha ind uced Gro 1 expression in Pam 212 cells, which can be blocked by IL-1 recept or antagonist (IL-1 RA).IL-1 RA, however, had a minimal effect on constitut ive Gro 1 production by LY-2 cells. TGF-beta1 suppressed constitutive as we ll as IL-1 alpha and EGF-inducible Gro 1 production in both Pam 212 and LY- 2 cells. IL-1 alpha and EGF, but not TGF-beta1, were found to activate NF-k appaB in Pam 212, whereas none of the stimulants showed a significant effec t on constitutive activation of NF-kappaB in LY-2 cells. Overexpression of a super repressor I kappaB alphaM in Pam 212 inhibited NF-kappaB binding ac tivity, which led to impaired Gro 1 induction by IL-1 alpha and EGF. These results demonstrate that IL-1 alpha, EGF, and TGF-beta1 are important modul ators of Gro 1 expression in SCC. Different responses to these modulators o bserved along with SCC metastatic progression may suggest a transition mech anism(s) for Gro 1 expression from host factor dependent to an independent stage involving NF-kappaB activation.