Proliferation Of HaCaT Keratinocytes Research Articles

Radiofrequency Currents Modulate Inflammatory Processes in Keratinocytes.

Keratinocytes play an essential role in the inflammatory phase of wound regeneration. In addition to migrating and proliferating for tissue regeneration, they produce a large amount of cytokines that modulate the inflammatory process. Previous studies have shown that subthermal treatment with radiofrequency (RF) currents used in capacitive resistive electric transfer (CRET) therapy promotes the proliferation of HaCat keratinocytes and modulates their cytokine production. Although physical therapies have been shown to have anti-inflammatory effects in a variety of experimental models and in patients, knowledge of the biological basis of these effects is still limited. The aim of this study was to investigate the effect of CRET on keratinocyte proliferation, cytokine production (IL-8, MCP-1, RANTES, IL-6, IL-11), TNF-α secretion, and the expression of MMP9, MMP1, NF-κB, ERK1/2, and EGFR. Human keratinocytes (HaCat) were treated with an intermittent 448 kHz electric current (CRET signal) in subthermal conditions and for different periods of time. Cell proliferation was analyzed by XTT assay, cytokine and TNF-α production by ELISA, NF-κB expression and activation by immunofluorescence, and MMP9, MMP1, ERK1/2, and EGF receptor expression and activation by immunoblot. Compared to a control, CRET increases keratinocyte proliferation, increases the transient release of MCP-1, TNF-α, and IL-6 while decreasing IL-8. In addition, it modifies the expression of MMPs and activates EGFR, NF-κB, and ERK1/2 proteins. Our results indicate that CRET reasonably modifies cytokine production through the EGF receptor and the ERK1/2/NF-κB pathway, ultimately modulating the inflammatory response of human keratinocytes.

LncRNA MIR181A2HG inhibits keratinocytes proliferation through miR-223-3p/SOX6 axis.

Psoriasis is a complex and recurrent chronic inflammatory skin disease, and the abnormal proliferation of keratinocytes plays a crucial role in the pathogenesis of psoriasis. Long non-coding RNAs (lncRNAs) play an indispensable role in regulating cellular functions. This research aims to explore the potential impact of lncRNA MIR181A2HG on the regulation of keratinocyte proliferation. The expression level of MIR181A2HG and the mRNA level of KRT6, KRT16, and SOX6 were assessed using qRT-PCR. The viability and proliferation of keratinocytes were evaluated using CCK-8 and EdU assays. Cell cycle analysis was performed using flow cytometry. Dual-luciferase reporter assays were applied to test the interaction among MIR181A2HG/miR-223-3p/SOX6. Protein level was detected by Western blotting analysis. The findings indicated that psoriasis lesions tissue exhibited lower levels of MIR181A2HG expression compared to normal tissue. The overexpression of MIR181A2HG resulted in the inhibition of HaCaT keratinocytes proliferation. The knockdown of MIR181A2HG promoted cell proliferation. The dual-luciferase reporter assay and rescue experiments provided evidence of the interaction among MIR181A2HG, SOX6, and miR-223-3p. The lncRNA MIR181A2HG functions as a miR-223-3p sponge targeting SOX6 to regulate the proliferation of keratinocytes, which suggested that MIR181A2HG/miR-223-3p/SOX6 might be potential diagnostic and therapeutic targets for psoriasis.

MiR-181a/b-5p negatively regulates keratinocytes proliferation by targeting MELK.

Accumulating evidence indicates that microRNAs (miRNAs) have a vital effect on the pathogenesis of psoriasis. This study is conducted to investigate the potential involvement of miR-181a-5p and miR-181b-5p in the proliferation of HaCaT keratinocytes. Cell viability and proliferation were evaluated respectively in this study using the CCK-8 and the 5-ethynyl-2'-deoxyuridine (EdU) assays. The expression of Maternal Embryonic Leucine Zipper Kinase (MELK) and Keratin 16 (KRT16) mRNA and protein in tissues and cells was assessed using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. The Luciferase reporter system analyzes the connection between miR-181a-5p/miR-181b-5p and MELK. The results showed that miR-181a/b-5p expression was downregulated in the psoriasis lesions and negatively regulated the proliferation of keratinocytes. MELK was directly targeted by miR-181a-5p/miR-181b-5p. In addition, HaCaT keratinocytes proliferation was inhibited by knockdown of MELK while promoted dramatically by MELK overexpression. Notably, miR-181a/b-5p mimics could attenuate the effects of MELK in keratinocytes. In conclusion, our research findings suggested miR-181a-5p and miR-181b-5p negatively regulate keratinocyte proliferation by targeting MELK, providing potential diagnostic biomarkers and therapeutic targets for psoriasis.

Tanshinone IIA, a component of the self-made Xiao-Yin decoction, ameliorates psoriasis by inhibiting IL-17/IL-23 and PTGS2/NF-κB/AP-1 pathways.

Psoriasis is a persistent inflammatory dermatological disorder. Tanshinone IIA (tan-IIA) is a biologically active compound in the self-made Xiao-Yin decoction (SMXYD) and exhibits diverse biological properties, such as anti-proliferative and anti-inflammatory effects. The objective of this investigation was to assess the potential of tan-IIA as a therapeutic agent against psoriasis. Network pharmacology was employed to ascertain the active constituents and potential pathways associated with SMXYD and psoriasis. We conducted CCK-8, qRT-PCR, and western blotting to assess the proliferation of HaCaT keratinocytes and the expression of IL-17/IL-23 and PTGS2/NF-κB/AP-1 pathways. Additionally, we used H&E staining, western blotting, and ELISA to evaluate the therapeutic effects and signaling pathways of tan-IIA in psoriasis-like mice induced by imiquimod (IMQ). Network pharmacology analysis identified eight hub compounds. The Th17/IL-17 signaling was found to be a potential therapeutic pathway of SMXYD against psoriasis, with JUN (AP-1) as the core molecule. Next, PTGS2 was selected as the target of tan-IIA against psoriasis using network pharmacology analysis. Molecular docking showed a high affinity between PTGS2 and tan-IIA. Tan-IIA treatment attenuated M-5-induced hyperproliferation and inflammation in HaCaT keratinocytes. Additionally, Tan-IIA downregulated the PTGS2/NF-κB/AP-1 pathway in HaCaT keratinocytes. In the IMQ-induced psoriasis-like mouse, tan-IIA significantly reduced the severity of skin lesions and downregulated the PTGS2/NF-κB/AP-1 pathway. Moreover, the combination of methotrexate (MTX) and tan-IIA further inhibited the IL-17/IL-23 and PTGS2/NF-κB/AP-1 pathways. The administration of tan-IIA has shown a positive effect on psoriasis by inhibiting the IL-17/IL-23 and PTGS2/NF-κB/AP-1 pathways. The findings suggest that it has promising qualities that make it a potential candidate for the development of future anti-psoriatic agents.

Analysis of Bulk Transcriptome Sequencing Data and in vitro Experiments Reveal SIN3A as a Potential Target for Diabetic Foot Ulcer.

Diabetic foot ulcers (DFUs) represent a severe complication of diabetes associated with reduced quality of life, lower limb amputations, hospitalizations, increased incidence, and mortality. Importantly, a significant number of pathogenic genes remain unexplored in DFUs. A series of bioinformatics analyses were performed on publicly available bulk transcriptome sequencing datasets GSE134431 and GSE80178 to explore the transcriptomic changes in DFUs and select core genes for in vitro functional validation. In a focused examination, the differential expression analysis unveiled distinctions in gene expression patterns between DFUs and non-ulcerated diabetic skin tissues. Enriched functional annotations of differentially expressed genes were explored using the DAVID online tool. Protein-protein interaction analysis was conducted to investigate interactions among differentially expressed genes and select core genes. Knockdown or overexpression of core genes in HaCaT keratinocytes was performed to assess their impact on cell proliferation and migration. Ten core genes were identified. Cell Counting Kit-8 (CCK-8) and scratch assays demonstrated that downregulation of the core gene SIN3A significantly inhibited the migration and proliferation of HaCaT keratinocytes, while overexpression of SIN3A reversed the high-glucose-induced suppression of HaCaT cell viability and migration. SIN3A expression is downregulated in DFUs. In vitro, SIN3A promotes the proliferation and migration of HaCaT keratinocytes, suggesting it may be a potential therapeutic target for DFUs.

Liquiritin targeting Th17 cells differentiation and abnormal proliferation of keratinocytes alleviates psoriasis via NF-κB and AP-1 pathway.

Psoriasis is a common immune-mediated inflammatory skin disease, caused by disturbed interactions between keratinocytes and immune cells. Chinese medicine shows potential clinical application for its treatment. Liquiritin is a flavone compound extracted from licorice and shows potential antitussive, antioxidant and antiinflammatory effects, and therefore may have potential as a psoriasis therapeutic. The aim of this work was to examine the possible roles that liquiritin may have in treating psoriasis. HaCaT cells were stimulated by TNF-α with or without liquiritin, harvested for analysis by western blots and RT-qPCR, and the cellular supernatants were collected and analyzed by ELISA for cytokines. In addition, 4 groups of mice were examined: Normal, Vehicle, LQ-L and LQ-H. The mice were sacrificed after 6 days and analyzed using IHC, ELISA, RT-qPCR and flow cytometry. The results showed that liquiritin could significantly inhibit the progression of psoriasis both in vitro and in vivo. Liquiritin strongly suppressed the proliferation of HaCaT keratinocytes but did not affect cell viability. Moreover, liquiritin alleviated imiquimod-induced psoriasis-like skin inflammation and accumulation of Th17 cells and DCs in vivo. In TNF-α-induced HaCaT keratinocytes, both protein and mRNA expression levels of inflammatory cytokines were sharply decreased. In imiquimod-induced mice, the activation of NF-κB and AP-1 was reduced after treatment with liquiritin. Collectively, our results show that liquiritin might act as a pivotal regulator of psoriasis via modulating NF-κB and AP-1 signal pathways.

Gentiopicroside-Loaded Chitosan Nanoparticles Inhibit TNF-α-Induced Proliferation and Inflammatory Response in HaCaT Keratinocytes and Ameliorate Imiquimod-Induced Dermatitis Lesions in Mice.

In this study, we aimed to report the biological characteristics of the first successful synthesis of gentiopicroside-loaded chitosan nanoparticles and to evaluate the therapeutic effects and preliminary mechanisms of gentiopicrin-loaded chitosan on psoriasis-like cell and mouse models. Gentiopicroside-loaded chitosan nanoparticles (CHI-GEN) were prepared, and their biological characteristics were evaluated. HaCaT keratinocytes were stimulated with TNF-α to establish a psoriatic keratinocyte model. MTT assay and flow cytometry were used to measure cell viability and apoptosis, respectively. mRNA levels of K17, VEGF A, and IL-6 and IL-23A were detected using qRT-PCR. These tests were used to preliminarily assess the effects of CHI-GEN on keratinocyte proliferation and inflammation. Imiquimod was used to construct a psoriasis-like mice model. The severity of psoriasis was scored based on the psoriasis area severity index (PASI), H&E staining was used to observe the histological changes and the level of inflammation and cell proliferation of skin lesions was evaluated by measuring the mRNA levels of K17, IL-23A, and IL-17A using qRT-PCR. The average particle size of CHI-GEN nanoparticles was approximately 100 nm, and the zeta potential was 2.69 ± 0.87 mV. The cumulative release was 67.2% in solutions of pH 5.5 at 24 h. GEN reduced TNF-α-induced excessive proliferation of HaCaT keratinocytes and downregulated mRNA levels of K17, VEGF A, and inflammatory cytokines IL-6 and IL-23A, which was more obvious in the CHI-GEN treatment group. Additionally, CHI-GEN significantly improved the severity of skin lesions in psoriasis-like mice and downregulated the mRNA expressions of IL-6, IL-23A, and IL-17A in mice skin lesions. In conclusion, we successfully prepared gentiopicrin-chitosan nanoparticles. Our results show that these nanoparticles have anti-psoriasis activity, inhibits keratinocyte proliferation and improves symptoms in psoriasis model mice and can be used to develop an effective strategy for the treatment of psoriasis.

BCL11B Is Involved in Stress-Induced Differentiation of Keratinocytes and Has A Potential Role in Psoriasis Pathogenesis.

Psoriasis is a common, auto-immune skin disease characterized by abnormal proliferation and differentiation of keratinocytes. Studies revealed the role of stress stimulators in the pathogenesis of psoriasis. Oxidative stress and heat shock are two important stress factors tuning differentiation and proliferation of keratinocytes, regarding to psoriasis disease. BCL11B is a transcription factor with critical role in embryonic keratinocyte differentiation and proliferation. Given this, in keratinocytes we have investigated potential role of BCL11B in stress-induced differentiation. Furthermore, we searched for a potential intercommunication between BCL11B expression and psoriasis-related keratinocyte stress factors. In this experimental study, data sets of psoriatic and healthy skin samples were downloaded in silico and BCL11B was chosen as a potential transcription factor to analyze. Next, a synchronized in vitro model was designed for keratinocyte proliferation and differentiation. Oxidative stress and heat shock treatments were employed on HaCaT keratinocytes in culture, and BCL11B expression level was measured. Cell proliferation rate and differentiation were analyzed by synchronized procedure test. Flow cytometry was done to analyze cell cycle alterations due to the oxidative stress. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) data revealed a significant upregulation of BCL11B expression in keratinocytes, by 24 hours after initiating differentiation. However, it was followed by a significant down-regulation in almost all the experiments, including the synchronized model. Flow cytometer data demonstrated a G1 cell cycle arrest in the treated cells. Results indicated a remarkable role of BCL11B in differentiation and proliferation of HaCaT keratinocytes. This data along with the results of flow cytometer suggested a probable role for BCL11B in stress-induced differentiation, which is similar to what is happening during initiation and progression of normal differentiation.

MiR‐221 promotes keratinocyte proliferation and migration by targeting SOCS7 and is regulated by YB‐1

Proliferation and migration of keratinocytes are vital processes for the successful epithelization specifically after wounding. MiR‐221 has been identified to play a potential role in promoting wound regeneration by inducing blood vessel formation. However, little is known about the role of miR‐221 in the keratinocyte proliferation and migration during wound healing. An in vivo mice wound‐healing model was generated; the expression levels of miR‐221 were assessed by qRT‐PCR and fluorescence in situ hybridization. Initially, we found that miR‐221 was upregulated in the proliferative phase of wound healing. Further, in an in vivo wound‐healing mice model, targeted delivery of miR‐221 mimics accelerated wound healing. Contrastingly, inhibition of miR‐221 delayed healing. Additionally, we observed that overexpression of miR‐221 promoted cell proliferation and migration, while inhibition of miR‐221 had the opposite effects. Moreover, we identified SOCS7 as a direct target of miR‐221 in keratinocytes and overexpression of SOCS7 reversed the effects of miR‐221 in HaCaT keratinocytes. Finally, we identified that YB‐1 regulates the expression of miR‐221 in HaCaT keratinocytes. Overall, our experiments suggest that miR‐221 is regulated by YB‐1 in HaCaT keratinocytes and acts on SOCS7, thereby playing an important role in HaCaT keratinocyte proliferation and migration during wound healing.

Adhesion and proliferation properties of type I collagen-derived peptide for possible use in skin tissue engineering application.

The surface properties of three-dimensional scaffolds are improved by coating or covalently linking certain adhesion-promoting proteins or peptides. In the present study, the effect of type I collagen-derived peptide (GKNGDDGEA) on adhesion and proliferation of HaCaT keratinocytes and NIH3T3 murine fibroblast cell lines was studied to assess its suitability for possible skin tissue engineering applications. Cell adhesion and proliferation of HaCaT and NIH3T3 were found to be enhanced by peptide coating. The optimum peptide coating densities to obtain the best cell adhesion and proliferation were found to be 0.827 µmoles/cm2 and 0.62 µmoles/cm2 for HaCaT and NIH3T3, respectively. Cell adhesion, in the presence of anti-integrin α1 antibody, inhibited attachment of NIH3T3 cells indicating the involvement of integrin α1 receptor. However, the attachment of HaCaT cells was not affected by anti-integrin treatment. The higher expression of paxillin confirmed the effect of the peptide in mediating focal adhesion kinases (FAKs) in cell adhesion and proliferation. Gene expression analysis was performed on cell migration proteins like Rho, Rac, Cdc42, integrin receptor α1, and β1, and the extracellular matrix modulating proteins like MMP2, TIMP, and COL1A1 to validate their role on the peptide-mediated cell proliferation. Immunofluorescence analysis showed the distribution and localisation of phospho-FAKon cells cultured on the peptide-coated surfaces. Results support the role of peptides in enhancing cell adhesion and proliferation properties.

Anoctamin1 Induces Hyperproliferation of HaCaT Keratinocytes and Triggers Imiquimod-Induced Psoriasis-Like Skin Injury in Mice.

Psoriasis, a long-lasting and multifactorial skin disease, is related to comorbidities such as metabolic disease, depression, and psoriatic arthritis. Psoriasis occurs due to a variety of factors including keratinocyte hyperproliferation, inflammation, and abnormal differentiation. Proinflammatory cytokines upregulated by increased activation of keratinocytes and immune cells in the skin trigger progression of psoriasis. This study aimed to investigate the effects of anoctamin1 (ANO1) on psoriasis development in vitro and in vivo. We analyzed the proliferation of HaCaT keratinocytes and ANO1-related ERK and AKT signaling pathways after ANO1 inhibitor (T16Ainh-A01 and Ani9) treatment and knock-down of ANO1. Furthermore, after applying imiquimod (IMQ) cream or coapplying IMQ cream and T16Ainh-A01 on mouse ears, we not only observed psoriatic symptoms, including ear thickening, but also quantified the effects of treatment on ERK and AKT signaling-involved proteins and proinflammatory cytokines. Inhibition of ANO1 attenuated the proliferation of HaCaT cells and induced reduction of pERK1/2. Coapplication of IMQ and T16Ainh-A01 on ears of mice reduced not only symptoms of IMQ-induced psoriasis such as thickening and erythema, but also expression of ANO1 and pERK1/2 compared to that of application of IMQ alone. In addition, the expression levels of IL-17A, IL-17F, IL-22, IL-23, IL-6, IL-1β, and TNF-α increased after applying IMQ and were significantly reduced by coapplying IMQ and T16Ainh-A01. These results aid in understanding the underlying mechanisms of ANO1 in epidermal layer keratinocyte hyperproliferation and suggest the potential of ANO1 as a target to treat psoriasis.

Isolation, characterization and evaluation of anti-proliferative properties of andrographolide isolated from Andrographis paniculata on cultured HaCaT cells

Summary Introduction: Psoriasis is an inflammatory skin disease characterized by hyper-proliferation, abnormal epidermal keratinocytes and inflammatory infiltration. It affects approximately 4% of the population globally. Herbal extracts have better results with less toxic effects than the synthetic drugs in the treatment of psoriasis. Objective: Present study was aimed to access the anti-psoriatic effect of andrographolide extracted from Andrographis paniculate (A. paniculata). Method: We extracted, characterized, and screened the extracted andrographolide for anti-proliferative characteristics using cultured cell model of human HaCaT keratinocyte. Results: Andrographolide at 31.25 µg/mL (90 µM) demonstrated significant inhibitory effect on human HaCaT keratinocytes proliferation in cell culture. To our best knowledge, we reported the anti-proliferative potency of andrographolide extracted from A. paniculata for the first time. Conclusion: The results suggest that the andrographolide extracted from A. paniculata plant may have potential to be used in the management of psoriasis.

IL28RA inhibits human epidermal keratinocyte proliferation by inhibiting cell cycle progression.

Interleukin (IL) 28 receptor α (IL28RA) is a well-known candidate for psoriasis susceptibility based on previous genome-wide association study (GWAS) analysis. However, the function of IL28RA in psoriasis has not been elucidated. In the present study, the expression of IL28RA was significantly decreased in lesional tissues from patients with plaque psoriasis when compared with the expression observed in adjacent non-lesional tissues. In vitro studies further demonstrated that in the presence of IL-29, HaCaT keratinocytes with IL28RA knockdown exhibited a faster rate of proliferation than control cells, and an enhanced ratio of cells in the S and G2/M phase. By contrast, IL28RA overexpression inhibited the proliferation of HaCaT keratinocytes and caused cell cycle arrest at the G0/G1 phases. Western blot analysis revealed that knockdown of IL28RA upregulated cyclinB1 expression and downregulated cyclinE expression; the opposite results were observed in the IL28RA-overexpressing HaCaT cells. Finally, a mechanistic study revealed that IL28RA functions through the activation of the Janus kinase-signal transducer and activator of transcription signaling pathway to exert its anti-proliferative effect. These results suggested that weak expression of IL28RA may contribute to the pathogenesis of psoriasis and that IL28RA may be an effective drug target for the treatment of psoriasis. However, further in vivo studies are required.

Knockdown of lncRNA MIR31HG inhibits cell proliferation in human HaCaT keratinocytes

BackgroundPsoriasis is a complex, chronic inflammatory skin disease with substantial negative effects on patient quality of life. Long non-coding RNAs (lncRNAs) are able to be involved in multitudes of cellular processes in diverse human diseases. This study aimed to investigate the potential involvement of lncRNA MIR31HG in HaCaT keratinocytes proliferation.ResultsThe study showed that MIR31HG was significantly elevated in the lesional psoriatic skin compared with normal individuals’ skin. Knockdown of MIR31HG inhibited HaCaT keratinocytes proliferation. Flow cytometry analysis showed that siRNA-mediated MIR31HG depletion induced cell cycle arrest in the G2/M phase. In addition, MIR31HG expression was found to be dependent on NF-κB activation.ConclusionsNF-κB activation mediated MIR31HG upregulation plays an important role in the regulation of HaCaT keratinocytes proliferation. It could be a potential diagnostic biomarker and therapeutic target for psoriasis.

Epidermal YAP activity drives canonical WNT16/β-catenin signaling to promote keratinocyte proliferation in vitro and in the murine skin

The skin constantly self-renews throughout adult life. Wnt/β-catenin signaling plays a key role in promoting keratinocyte proliferation in the hair follicles and in the interfollicular epidermis. A recent report demonstrated that epidermal YAP activity drives β-catenin activation to promote keratinocyte proliferation in the murine skin. However, it remains unclear whether this is caused by paracrine activation of canonical Wnt signaling or through other YAP/β-catenin regulatory interactions. In the present study, we found that XAV939-inhibition of canonical WNT signaling in skin of YAP2-5SA-ΔC mice resulted in diminished β-catenin activation, reduced keratinocyte proliferation, and a mitigation of the hyperplastic abnormalities in the interfollicular epidermis, signifying a canonical WNT ligand-dependent mechanism. Our subsequent analyses determined that WNT16 is produced in response to YAP activity in keratinocytes both in vitro and in vivo, and that WNT16 drives HaCaT keratinocyte proliferation via canonical WNT16/β-catenin signaling. We conclude that under normal physiological conditions WNT16 is the paracrine WNT ligand secreted in response to epidermal YAP activity that promotes cell proliferation in the interfollicular epidermis. This study delineates a fundamental YAP-driven mechanism that controls normal skin regeneration, and that may be perturbed in human regenerative disease displaying increased YAP and WNT signaling activity.

Wound Healing potential of Grandiflorenic Acid Isolated from Wedelia trilobata Linn.

The ethyl acetate fraction from ethanolic extract of Wedelia trilobata (L.) leaves displayed wound healing properties. The ethyl acetate fraction was further subjected to bioassay-guided fractionation which afforded isolation of grandiflorenic acid which requires further investigation to prove its wound healing potential. The grandiflorenic acid from leaves of Wedelia trilobata was assessed for its possible activity on BJ human fibroblast and HaCaT keratinocytes proliferation, and effect on in vitro scratch assay, collagen content, TGF-2 levels, and nitric oxide, TNF- and IL-1 determination using Raw 264.7 cells. Grandiflorenic acid (2.5µg/mL) produced percentage viability of BJ human fibroblast, and HaCaT keratinocytes 116, and 106% respectively. Grandiflorenic acid (2.5 µg/mL) induced a 100% migration rate in the in vitro scratch assay and the collagen content was increased to 171.2 µg/mL compared to the control (61.1µg/mL) with BJ human fibroblast. Grandiflorenic acid (2.5µg/mL) neither produced any significant increase in TGF-2 levels of HaCaT keratinocytes cells nor induced migration of HaCaT cells in the in vitro scratch assay. The present study provides scientific evidence that grandiflorenic acid has potential wound healing activity due to combination of fibroblast stimulation and inhibiting prolonging inflammatory phase of wound healing evident by reduced levels of inflammatory cytokines from macrophage Raw 264.7 cells.

TLR4 as a negative regulator of keratinocyte proliferation.

TLR4 is an innate immune receptor with expression in human skin, keratinocytes as well as squamous cell carcinoma (SCC) of the skin. In the present study we investigate the role of TLR4 as a negative regulator of keratinocyte proliferation. We present here that the expression of TLR4 increased with the differentiation of cultured keratinocytes in a passage-dependent manner or under calcium-rich conditions. Moreover, the down-regulation of TLR4 by specific knockdown increased the proliferation of HaCaT keratinocytes in vitro. In addition, subcutaneously injected HaCaT keratinocytes with shTLR4 formed growing tumors in nude mice. In contrast, we observed lower proliferation and increased migration in vitro of the SCC13 cell line stably overexpressing TLR4 in comparison to SCC13 TLR4 negative cells. In vivo, SCC13 TLR4-overexpressing tumors showed delayed growth in comparison to TLR4 negative tumors. The overexpression of TLR4 in SCC13 tumor cells was followed by phosphorylation of ERK1/2 and JNK and increased expression of ATF3. In gene expression arrays, the overexpression of TLR4 in tumor cells correlated with gene expression of ATF-3, IL-6, CDH13, CXCL-1 and TFPI. In summary, TLR4 negatively regulates the proliferation of keratinocytes and its overexpression reduces tumor growth of SCC cells.

MiR-26a inhibits proliferation and migration of HaCaT keratinocytes through regulating PTEN expression

MicroRNAs (miRNAs) have been shown to be associated with differentiation, migration and apoptosis in keratinocyte. Although it has been reported that microRNA-26a (miR-26a) plays important roles in tumor cells, its biological functions in keratinocytes are still not well elucidated. In this study, we confirmed expression of miR-26a in human keratinocytes using RT-PCR and further studied the role of miR-26a in cell proliferation and cell migration. Ectopic expression of MiR-26a mimic or inhibitor increased or decreased miR-26a expression respectively in HaCaT cells. Proliferation of HaCaT keratinocyte can be suppressed or promoted by overexpression or down-expression of miR-26a. In scratch wound-healing assay and Boyden chamber cell migration assay, upregulating miR-26a expression blocked cell migration, while downregulating miR-26a expression enhanced the migration. Using quantitative RT-PCR (qRT-PCR) and western blot, we further discovered that both mRNA and protein level of phosphatase and tensin homolog deleted from chromosome 10(PTEN) were regulated by miR-26a in HaCaT cells. Meanwhile the level of active form of AKT was also regulated by the miR-26a. In rescue experiment, knockdown of PTEN in the miR-26a mimic transduced cells recovered the migration ability of HaCaT cells. Together these results suggest that miR-26a modulates the proliferation and migration of keratinocytes via regulating PTEN/AKT signaling pathway.

YAC tripeptide of epidermal growth factor promotes the proliferation of HaCaT keratinocytes through activation of EGFR.

Epidermal growth factor (EGF) is known to play key roles in skin regeneration and wound-healing. Here, we demonstrate that Pep2-YAC, a tripeptide covering residues 29-31 in the B loop of EGF, promotes the proliferation of HaCaT keratinocytes with activity comparable to EGF. The treatment of HaCaT cells with Pep2-YAC induced phosphorylation, internalization, and degradation of EGFR and organization of signaling complexes, which consist of Grb2, Gab1, SHP2, and PI3K. In addition, it sti mulated the phosphorylation of ERK1/2 at Thr 202/Tyr 204 and of Akt1 at Ser 473 and the nuclear translocation of EGFR, STAT3, c-Jun, and c-Fos. These results suggest that Pep2-YAC may be useful as a therapeutic agent for skin regeneration and wound-healing as an EGFR agonist. [BMB Reports 2014; 47(10): 581-586]

Persea americanaMill. Seed: Fractionation, Characterization, and Effects on Human Keratinocytes and Fibroblasts

Methanolic avocado (Persea americana Mill., Lauraceae) seed extracts were separated by preparative HSCCC. Partition and HSCCC fractions were principally characterized by LC-ESI-MS/MS analysis. Their in vitro influence was investigated on proliferation, differentiation, cell viability, and gene expression on HaCaT and normal human epidermal keratinocytes (NHEK) and normal human dermal fibroblasts (NHDF). The methanol-water partition (M) from avocado seeds and HSCCC fraction 3 (M.3) were mostly composed of chlorogenic acid and its isomers. Both reduced NHDF but enhanced HaCaT keratinocytes proliferation. HSCCC fraction M.2 composed of quinic acid among chlorogenic acid and its isomers inhibited proliferation and directly induced differentiation of keratinocytes as observed on gene and protein level. Furthermore, M.2 increased NHDF proliferation via upregulation of growth factor receptors. Salidrosides and ABA derivatives present in HSCCC fraction M.6 increased NHDF and keratinocyte proliferation that resulted in differentiation. The residual solvent fraction M.7 contained among low concentrations of ABA derivatives high amounts of proanthocyanidins B1 and B2 as well as an A-type trimer and stimulated proliferation of normal cells and inhibited the proliferation of immortalized HaCaT keratinocytes.