Penile squamous cell cancer (PSCC) is the most frequent penile malignant disease. Infections with human papillomaviruses (HPV) are a major etiologic driver of PSCC. However, the molecular details of the underlying carcinogenesis are understudied because of rare clinical specimens and missing cell lines. Here, we investigated if the expression of high-risk HPV16 oncogenes causes an augmentation of the Wnt pathway using unique HPV-positive penile cancer (PeCa) cell lines in monolayer and organotypic 3D raft cultures as well as tissue micro arrays containing clinical tissue specimens. The HPV oncoproteins enhanced the expression of Leucine-rich repeat-containing G-protein coupled receptor 6 (LGR6) and the HPV-positive PeCa cells expressed a signature of Wnt target and stemness-associated genes. However, the notable lack of nuclear β-catenin in vitro and in situ raised the question if the enhanced expression of Wnt pathway factors is tantamount to an active Wnt signaling. Subsequent TOP-flash reporter assays revealed Wnt signaling as absent and not inducible by respective Wnt ligands in PeCa cell lines. The HPV-positive PeCa cells and especially HPV-positive PeCa specimens of the tumor core expressed the Wnt antagonist and negative feedback-regulator Dickkopf1 (DKK1). Subsequent neutralization experiments using PeCa cell line-conditioned media demonstrated that DKK1 is capable to impair ligand-induced Wnt signaling. While gene expression analyses suggested an augmented and active canonical Wnt pathway, the respective signaling was inhibited due to the endogenous expression of the antagonist DKK1. Subsequent TMA stainings indicated Dkk1 as linked with HPV-positivity and metastatic disease progression in PeCa suggesting potential as a prognostic marker.
Translational oncology. 2021 Nov 10 [Epub ahead of print]
Isabelle Ariane Bley, Anabel Zwick, Muriel Charlotte Hans, Katrin Thieser, Viktoria Wagner, Nicole Ludwig, Oybek Khalmurzaev, Vsevolod Borisovich Matveev, Philine Loertzer, Alexey Pryalukhin, Arndt Hartmann, Carol-Immanuel Geppert, Hagen Loertzer, Heiko Wunderlich, Carsten Maik Naumann, Holger Kalthoff, Kerstin Junker, Sigrun Smola, Stefan Lohse
Institute of Virology, Saarland University Medical Center, Kirrberger Str. Building 47, Homburg 66421, Germany., Clinical Bioinformatics, Saarland University, Saarbrücken, Germany., Department of Human Genetics, Saarland University, Homburg, Germany., Department of Urology and Pediatric Urology, Saarland University Medical Center, Homburg, Germany; Department of Urology, Federal State Budgetary Institution, "N.N. Blokhin National Medical Research Center of Oncology" оf the Ministry of Health of the Russian Federation, Moscow, Russian Federation., Department of Urology, Federal State Budgetary Institution, "N.N. Blokhin National Medical Research Center of Oncology" оf the Ministry of Health of the Russian Federation, Moscow, Russian Federation., Department of Urology and Pediatric Urology, Saarland University Medical Center, Homburg, Germany., Institute of Pathology, Saarland University Medical Centre, Homburg, Germany; Institute of Pathology, University Medical Centre Bonn, Bonn, Germany., Institute of Pathology, University Erlangen-Nuremberg, Erlangen, Germany., Department of Urology and Pediatric Urology, Westpfalz Klinikum, Kaiserslautern, Germany., Department of Urology and Paediatric Urology, St. Georg Klinikum, Eisenach, Germany., Department of Urology and Pediatric Urology, University Hospital Schleswig Holstein, Kiel, Germany., Division of Molecular Oncology, Institute of Experimental Cancer Research, University Hospital Schleswig Holstein, Kiel, Germany., Institute of Virology, Saarland University Medical Center, Kirrberger Str. Building 47, Homburg 66421, Germany. Electronic address: .