The sonic hedgehog signaling pathway is reactivated in human renal cell carcinoma and plays orchestral role in tumor growth

Abstract

BackgroundHuman clear cell renal cell carcinoma (CRCC) remains resistant to therapies. Recent advances in Hypoxia Inducible Factors (HIF) molecular network led to targeted therapies, but unfortunately with only limited clinical significance. Elucidating the molecular processes involved in kidney tumorigenesis and resistance is central to the development of improved therapies, not only for kidney cancer but for many, if not all, cancer types. The oncogenic PI3K/Akt, NF-kB and MAPK pathways are critical for tumorigenesis. The sonic hedgehog (SHH) signaling pathway is crucial to normal development.ResultsBy quantitative RT-PCR and immunoblot, we report that the SHH signaling pathway is constitutively reactivated in tumors independently of the von Hippel-Lindau (VHL) tumor suppressor gene expression which is inactivated in the majority of CRCC. The inhibition of the SHH signaling pathway by the specific inhibitor cyclopamine abolished CRCC cell growth as assessed by cell counting, BrdU incorporation studies, fluorescence-activated cell sorting and β-galactosidase staining. Importantly, inhibition of the SHH pathway induced tumor regression in nude mice through inhibition of cell proliferation and neo-vascularization, and induction of apoptosis but not senescence assessed by in vivo studies, immunoblot and immunohistochemistry. Gli1, cyclin D1, Pax2, Lim1, VEGF, and TGF-β were exclusively expressed in tumors and were shown to be regulated by SHH, as evidenced by immunoblot after SHH inhibition. Using specific inhibitors and immunoblot, the activation of the oncogenic PI3K/Akt, NF-kB and MAPK pathways was decreased by SHH inhibition.ConclusionsThese findings support targeting SHH for the treatment of CRCC and pave the way for innovative and additional investigations in a broad range of cancers.

LIM-class homeobox gene Lim1, a novel oncogene in human renal cell carcinoma

“…Consequently, Sjolund et al (2008) and Hueber et al (2006Hueber et al ( , 2008 have shown that the developmental Notch signaling cascade and Pax2, critical for nephrogenesis, are constitutively active in human CCC cell lines and have growth-promoting effect. More recently, we have reached similar conclusions concerning the involvement of the developmental sonic hedgehog (SHH) signaling pathway in human CCC progression, and we showed further that the SHH signaling pathway has orchestral roles in the activation of oncogenic pathways in this disease, including the phosphoinositide kinase-3 (PI3K)/ Akt, the nuclear factor-kappaB (NF-kB) and mitogenactivated protein kinase (MAPK) signaling pathways (Dormoy et al, 2009). This is particularly important as all these pathways, critical during kidney development (Reidy and Rosenblum, 2009), are constitutively reactivated in CCC tumors (Sourbier et al, 2006Schedl, 2007;Huang et al, 2008).…”

“…We have shown, very recently, by western blot analysis on nine normal/tumoral tissue pairs that Lim1 is almost exclusively reexpressed in tumors (Dormoy et al, 2009). Here, we have considerably extended this analysis.…”

“…We have recently shown that the developmental SHH-Gli signaling is reactivated in human CCC and that Lim1 is a SHH-Gli signaling target (Dormoy et al, 2009). Here, we show that Lim1 is expressed in our panel of human CCC cells and that Lim1 is exclusively reexpressed in human tumors compared with normal corresponding tissues, thus extending substantially the results of our previous studies on Lim1 expression in CCC tumors (Dormoy et al, 2009). There was no difference in Lim1 expression depending on the tumoral stage and grade, suggesting that Lim1 expression levels are maintained throughout CCC growth.…”

“…In our recent studies dealing with the involvement of the SHH pathway in human CCC progression (Dormoy et al, 2009), we observed that Lim1 expression was under the regulation of the SHH pathway through the activity of the Glis transcription factors and that, more interestingly it appears to be exclusively expressed in tumors compared with the normal corresponding tissues in nine tumor/normal tissue pairs sampling. These data, added to the importance of Lim1 in fundamental steps of kidney development, including Notch pathways regulation, prompted us to study whether this transcription factor is part of the molecular mechanisms involved in human kidney progression; and consequently, whether targeting Lim1 may have therapeutic potential against this therapy-refractory disease.…”

Carcinogenesis of renal cell carcinoma reflected in HLA ligands: A novel approach for synergistic peptide vaccination design

“…20,21,[30][31][32][33][34][35] Furthermore, a vast array of new TAAs with corresponding peptides from HLA class I and II were discovered (Table 3). These included LOX and PLOD2, with high potential in engaging metastasis, [36][37][38] GRB2, ITPR3, and BCAR1, all of which are part of the EGFR pathway 39 and other growth factor receptor pathways, plus ENPEP, NRP2, TGFBI, THBS1, and THBS2, which are essential for angiogenesis.…”