Malignant transformation of immortalized HaCaT keratinocytes through deregulated nuclear factor kappaB signaling.
Previous studies addressing functional aspects of nuclear factor kappaB (NF-kappaB) activation in normal and transformed keratinocytes revealed complex and seemingly contradictory roles of this transcription factor in this cell type. In normal skin, NF-kappaB signaling seems to inhibit squamous cell carcinoma development whereas, in squamous cell carcinoma themselves, deregulated NF-kappaB expression and/or signaling is frequently observed. To further investigate this paradox, we focused on NF-kappaB activation as it relates to the transformed phenotype of immortalized but nontumorigenic human keratinocytes (HaCaT cells). We observed that NF-kappaB activity contributed to survival and growth of cultured HaCaT keratinocytes as shown by use of pharmacologic NF-kappaB inhibitors, RNA interference, and inducible overexpression of a dominant interfering IkappaB construct. NF-kappaB activation was largely provided through interaction with extracellular matrix components because preventing cell attachment by forced suspension culture markedly reduced NFkappaB signaling associated with cell death (anoikis); conversely, anoikis was partially reversed by NF-kappaB activation induced either by tumor necrosis factor-alpha treatment or by overexpressing the NF-kappaB p65 subunit in HaCaT cells. Furthermore, overexpression of NF-kappaBp65 in HaCaT cells induced colony formation in soft agar and tumorigenicity in nude mice. In summary, as opposed to normal keratinocytes, immortalized HaCaT keratinocytes provide a cellular context in which deregulated NF-kappaB signaling supports multiple malignant traits in vitro and in vivo.
Ren
Qing
Q
Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Kari
Csaba
C
Quadros
Marlene R D
MR
Burd
Randy
R
McCue
Peter
P
Dicker
Adam P
AP
Rodeck
Ulrich
U
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000378:metabolism* / Q000473:pathology; D005109:Extracellular Matrix / Q000473:pathology; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D051996:Transcription Factor RelA / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016328:NF-kappa B; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha