SPOP is essential for DNA replication licensing through maintaining translation of CDT1 and CDC6 in HaCaT cells.

Speckle-type pox virus and zinc finger (POZ) protein (SPOP), a substrate recognition receptor for the cullin-3/RING ubiquitin E3 complex, leads to the ubiquitination of >40 of its target substrates. Since a variety of point mutations in the substrate-binding domain of SPOP have been identified in cancers, including prostate and endometrial cancers, the pathological roles of those cancer-associated SPOP mutants have been extensively elucidated. In this study, we evaluated the cellular functions of wild-type SPOP in non-cancerous human keratinocyte-derived HaCaT cells expressing wild-type SPOP gene. SPOP knockdown using siRNA in HaCaT cells dramatically reduced cell growth and arrested their cell cycles at G1/S phase. The expression of DNA replication licensing factors CDT1 and CDC6 in HaCaT cells drastically decreased on SPOP knockdown as their translation was inhibited. CDT1 and CDC6 downregulation induced p21 expression without p53 activation. Our results suggest that SPOP is essential for DNA replication licensing in non-cancerous keratinocyte HaCaT cells.

Anti-psoriasis activities of hydroxytyrosol on HaCaT cells under psoriatic inflammation in vitro.

BACKGROUND: Psoriasis is a prevalent chronic inflammatory dermatosis, which can significantly impact life quality of patients. The treatment of psoriasis is no cure and novel therapeutic options are urgently needed. Hydroxytyrosol (HT) possesses multiple biological activities, such as anti-inflammatory and anti-proliferation properties, suggesting its potential to counteract hallmarks of psoriasis. However, its role in the regulation of psoriasis remains unknown. OBJECTIVE: In the current study, we explored the anti-proliferative activity and anti-inflammatory responses of HT in psoriatic keratinocytes in vitro. METHODS: We used M5 cytokines cocktail, which includes tumor necrosis factor (TNF)-α, oncostatin-M, interleukin (IL)-17A, IL-1α, and IL-22, to simulate HaCaT cells to establish the cell model of psoriasis and explore the effects of HT on psoriasis in vitro. RESULTS: This study showed that HT exerted potent anti-inflammatory effect via influencing the expression of IL-6, IL-8, and TNF-α in M5-induced cell model of psoriasis. Moreover, it suppressed the expression of antimicrobial proteins in psoriatic keratinocytes. Additionally, it inhibited cell proliferation in psoriasis cell model. CONCLUSIONS: Altogether, our results suggested that HT has anti-psoriasis effects in vitro and HT may be a promising therapeutic agent in psoriasis treatment.

Anti-inflammatory effects of amarogentin on 2,4-dinitrochlorobenzene-induced atopic dermatitis-like mice and in HaCat cells.

BACKGROUND: Amarogentin (AMA) is a secoiridoid glycoside extracted from Swertia and Gentiana roots and exhibits many biological effects such as antioxidative, anti-inflammatory, and antitumor activities. Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by disorders in the regulation of multiple inflammatory cytokines. No effective cure has been found for AD now. METHODS: We constructed the HaCat and splenocyte model and tested the inhibitory effect of AMA on IL-4, IL-6, and IL-13 secretions using enzyme-linked immunosorbent assay (ELISA). The AD mouse model was constructed and treated with AMA, the severity of skin lesions was observed, epidermal tissue was collected, and epidermal thickness and mast cell infiltration were observed using hematoxylin and eosin and toluidine blue staining, respectively. The expression of kallikrein-related peptidase 7 (KLK7) and filaggrin (FLG) was detected using immunostaining and Western blot analysis. The mRNA expression of KLK7 and FLG was detected using quantitative polymerase chain reaction (qPCR). Blood immunoglobulin E (IgE) secretion was detected. RESULTS: AMA inhibited IL-6 secreted by tumor necrosis factor (TNF)-α-induced HaCaT cells and reduced IL-4 and IL-13 secreted by phytohemagglutinin (PHA)-induced primary cells in the mice spleen. It was found that the treatment of AMA with 2,4-dinitrochlorobenzene-induced AD-like mice could promote the recovery of dermatitis, reduce the score of dermatitis severity and the scratching frequency, treat the skin lesions, reduce the epidermal thickness, decrease the infiltration of mast cells, reduce the IgE level in serum, decrease the expression levels of AD-related cytokines, increase protein and mRNA expression of FLG, and reduce the protein and mRNA expression of KLK7 in the skin tissues of AD-like mice. CONCLUSION: In conclusion, AMA inhibits inflammatory response at the cellular level, and AMA reduces the validation response of specific dermatitis mice, relieves pruritus, and repairs the damaged skin barrier.