Abstract：
To study mechanisms driving/inhibiting skin carcinogenesis, stage-specific expression of 14-3-3σ (Stratifin) was analyzed in skin carcinogenesis driven by activated rasHa/fos expression (HK1.ras/fos) and ablation of PTEN-mediated AKT regulation (K14.creP/Δ5PTENflx/flx). Consistent with 14-3-3σ roles in epidermal differentiation, HK1.ras hyperplasia and papillomas displayed elevated 14-3-3σ expression in supra-basal keratinocytes, paralleled by supra-basal p-MDM2166 activation and sporadic p-AKT473 expression. In bi-genic HK1.fos/Δ5PTENflx/flx hyperplasia, basal-layer 14-3-3σ expression appeared, and alongside p53/p21, was associated with keratinocyte differentiation and keratoacanthoma etiology. Tri-genic HK1.ras/fos-Δ5PTENflx/flx hyperplasia/papillomas initially displayed increased basal-layer 14-3-3σ, suggesting attempts to maintain supra-basal p-MDM2166 and protect basal-layer p53. However, HK1.ras/fos-Δ5PTENflx/flx papillomas exhibited increasing basal-layer p-MDM2166 activation that reduced p53, which coincided with malignant conversion. Despite p53 loss, 14-3-3σ expression persisted in well-differentiated squamous cell carcinomas (wdSCCs) and alongside elevated p21, limited malignant progression via inhibiting p-AKT1473 expression; until 14-3-3σ/p21 loss facilitated progression to aggressive SCC exhibiting uniform p-AKT1473. Analysis of TPA-promoted HK1.ras-Δ5PTENflx/flx mouse skin, demonstrated early loss of 14-3-3σ/p53/p21 in hyperplasia and papillomas, with increased p-MDM2166/p-AKT1473 that resulted in rapid malignant conversion and progression to poorly differentiated SCC. In 2D/3D cultures, membranous 14-3-3σ expression observed in normal HaCaT and SP1ras61 papilloma keratinocytes was unexpectedly detected in malignant T52ras61/v-fos SCC cells cultured in monolayers, but not invasive 3D-cells. Collectively, these data suggest 14-3-3σ/Stratifin exerts suppressive roles in papillomatogenesis via MDM2/p53-dependent mechanisms; while persistent p53-independent expression in early wdSCC may involve p21-mediated AKT1 inhibition to limit malignant progression.
摘要：
为了研究驱动/抑制皮肤癌发生的机制，在激活的rasHa/fos表达驱动的皮肤癌发生中分析了14-3-3σ（Stratifin）的阶段特异性表达（HK1。ras/fos）和PTEN介导的AKT调节的消融（K14。creP/Δ5PTENflx/flx)。与14-3-3σ在表皮分化中的作用一致，HK1.ras增生和乳头状瘤在超基底角质形成细胞中显示14-3-3σ表达升高，与超基础p-MDM2166激活和散发性p-AKT473表达平行。在双基因HK1中。fos/Δ5PTENflx/flx增生，基底层出现14-3-3σ表达，与p53/p21一起，与角质形成细胞分化和角化棘皮瘤的病因有关。三基因HK1。ras/fos-Δ5PTENflx/flx增生/乳头状瘤最初显示基底层14-3-3σ增加，建议尝试维持基底上p-MDM2166并保护基底层p53。然而,HK1.ras/fos-Δ5PTENflx/flx乳头状瘤表现出增加的基底层p-MDM2166激活，从而降低了p53，这与恶性转化相吻合。尽管p53丢失，14-3-3σ表达在高分化鳞状细胞癌（wdSCC）中持续存在，并伴随着p21升高，通过抑制p-AKT1473表达限制了恶性进展；直到14-3-3σ/p21缺失促进了进展为侵袭性SCC，表现出均匀的p-AKT1473。TPA促进的HK1分析。ras-Δ5PTENflx/flx小鼠皮肤，在增生和乳头状瘤中显示14-3-3σ/p53/p21的早期丢失，p-MDM2166/p-AKT1473增加，导致快速恶性转化和进展为低分化SCC。在2D/3D文化中，在单层培养的恶性T52ras61/v-fosSCC细胞中意外检测到正常HaCaT和SP1ras61乳头状瘤角质形成细胞中观察到的膜14-3-3σ表达，但不是侵入性的3D细胞。总的来说，这些数据提示14-3-3σ/Stratifin通过MDM2/p53依赖性机制在乳头状瘤形成中发挥抑制作用;而在早期wdSCC中持续的p53非依赖性表达可能涉及p21介导的AKT1抑制,从而限制恶性进展.
