Prostate Cancer Cell Lines under Hypoxia Exhibit Greater Stem-Like Properties

Hypoxia is an important environmental change in many cancers. Hypoxic niches can be occupied by cancer stem/progenitor-like cells that are associated with tumor progression and resistance to radiotherapy and chemotherapy. However, it has not yet been fully elucidated how hypoxia influences the stem-like properties of prostate cancer cells. In this report, we investigated the effects of hypoxia on human prostate cancer cell lines, PC-3 and DU145. In comparison to normoxia (20% O2), 7% O2 induced higher expressions of HIF-1α and HIF-2α, which were associated with upregulation of Oct3/4 and Nanog; 1% O2 induced even greater levels of these factors. The upregulated NANOG mRNA expression in hypoxia was confirmed to be predominantly retrogene NANOGP8. Similar growth rates were observed for cells cultivated under hypoxic and normoxic conditions for 48 hours; however, the colony formation assay revealed that 48 hours of hypoxic pretreatment resulted in the formation of more colonies. Treatment with 1% O2 also extended the G0/G1 stage, resulting in more side population cells, and induced CD44 and ABCG2 expressions. Hypoxia also increased the number of cells positive for ABCG2 expression, which were predominantly found to be CD44bright cells. Correspondingly, the sorted CD44bright cells expressed higher levels of ABCG2, Oct3/4, and Nanog than CD44dim cells, and hypoxic pretreatment significantly increased the expressions of these factors. CD44bright cells under normoxia formed significantly more colonies and spheres compared with the CD44dim cells, and hypoxic pretreatment even increased this effect. Our data indicate that prostate cancer cells under hypoxia possess greater stem-like properties

A mutation in human keratin K6b produces a phenocopy of the K17 disorder pachyonychia congenita type 2

Type I and type II keratins form the heteropolymeric intermediate filament cytoskeleton, which is the main stress-bearing structure within epithelial cells. Pachyonychia congenita (PC) is a group of autosomal dominant disorders whose most prominent phenotype is hypertrophic nail dystrophy accompanied by other features of ectodermal dysplasia, It has been shown previously that mutations in either K16 or K6a, which form a keratin expression pair, produce the PC-1 variant (MIM 184510), Mutations in K17 alone, an unpaired accessory keratin, result in the PC-2 phenotype (MIM 184500), Here, we describe a family with PC-2 in which the K17 locus on 17q was excluded and linkage to the type II keratin locus on 12q was obtained (Z(max) 3.31 at theta = 0). Mutation analysis of candidate keratins revealed the first reported missense mutation in K6b, implying that this keratin is the previously unknown expression partner of K17, analogous to the K6a/K16 pair. Go-expression of these genes was confirmed by in situ hybridization and immunohistochemical staining. These results reveal the hitherto unknown role of the K6b isoform in epithelial biology, as well as genetic heterogeneity in PC-2

Keratin 17 mutations cause either steatocystoma multiplex or pachyonychia congenita type 2

Pachyonychia congenita type 2 (PC-2; Jackson-Lawler syndrome) is an autosomal dominant disorder characterized by hypertrophic nail dystrophy, mild focal keratoderma, multiple pilosebaceous cysts and other features of ectodermal dysplasia, Keratin 17 (K17) is a differentiation-specific keratin expressed in the nail bed, hair follicle, sebaceous gland and other epidermal appendages, Previously, we have demonstrated that PC-2 is caused by mutations in K17 and that similar mutations in this gene can present as steatocystoma multiplex with little or no nail dystrophy Here, we describe three unrelated kindreds carrying K17 mutations. Two of these families have identical missense mutations (R94C) in the IA domain of K17, However, while affected members of one kindred have the classical features of PC-2, affected persons in the other family have the steatocystoma multiplex phenotype, In a third family with PC-2. mutation N92S was detected, bringing the total number of distinct mutations reported in K17 thus far to 11, These results demonstrate that K17 mutations commonly underlie both PC-2 and steatocystoma multiplex and that the alternate phenotypes which arise from these genetic lesions in K17 are independent of the specific mutation involved