α6 Integrin and CD44 enrich for a primary keratinocyte population that displays resistance to UV-induced apoptosis.
Epidermal human keratinocytes are exposed to a wide range of environmental genotoxic insults, including the UV component of solar radiation. Epidermal homeostasis in response to cellular or tissue damage is maintained by a population of keratinocyte stem cells (KSC) that reside in the basal layer of the epithelium. Using cell sorting based on cell-surface markers, we have identified a novel α6 integrin(high+)/CD44(+) sub-population of basal keratinocytes. These α6 integrin(high+)/CD44(+) keratinocytes have both high proliferative potential, form colonies in culture that have characteristics of holoclones and have a unique pattern of resistance to apoptosis induced by UVB radiation or by agents that induce single- or double strand DNA breaks. Resistance to UVB induced apoptosis in the α6 integrin(high+)/CD44(+) cells involved increased expression of TAp63 and was overcome by PI-3 kinase inhibition. In marked contrast, the α6 integrin(high+)/CD44(+) cells were sensitive to apoptosis induced by the cross-linking agent cisplatin, and imatinib inhibition of c-Abl blocked the ability of cisplatin to kill α6 integrin(high+)/CD44(+) cells. Our findings reveal a population of basal keratinocytes with long-term proliferative properties that display specific patterns of apoptotic resistance that is dependent upon the genotoxic stimulus, and provide insights into how these cells can be targeted with chemotherapeutic agents.
Blizard Institute of Cell and Molecular Science, Queen Mary's School of Medicine and Dentistry, Whitechapel, London, United Kingdom.
Helen
H
Wray
Ian C
IC
Mackenzie
Alan
A
Storey
Harshad
H
Navsaria
D000730:Androstadienes / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D001549:Benzamides; D002166:Camptothecin / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D002945:Cisplatin / Q000494:pharmacology; D004351:Drug Resistance; D005047:Etoposide / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D000068877:Imatinib Mesylate; D039503:Integrin alpha6 / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010879:Piperazines / Q000494:pharmacology; D061251:Primary Cell Culture; D011743:Pyrimidines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics; D014466:Ultraviolet Rays; D000077191:Wortmannin
D000730:Androstadienes; D000970:Antineoplastic Agents; D001549:Benzamides; D002166:Camptothecin; D002945:Cisplatin; D005047:Etoposide; D018960:Hyaluronan Receptors; D000068877:Imatinib Mesylate; D039503:Integrin alpha6; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010879:Piperazines; D011743:Pyrimidines; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000077191:Wortmannin; C497483:CD44 protein, human; C115051:TP63 protein, human