Clinical and histological evaluation of microneedle fractional radiofrequency treatment on facial fine lines and skin laxity in Koreans.

BACKGROUND: Facial wrinkles and sagging are the most visible signs of aging and can cause profound distress. Microneedle fractional radiofrequency (MFR) is a minimally invasive procedure, which utilizes both microneedling and radiofrequency energy to rejuvenate the skin. OBJECTIVE: To describe the safety and efficacy of a temperature-controlled MFR device on facial fine lines and laxity. PATIENTS AND METHODS: A retrospective chart & histology review was performed on individuals who received bipolar MFR for facial rejuvenation. A total of 15 Koreans with a median age of 46 years were included. All participants underwent a single treatment session. The results were assessed objectively using serial photography and subjectively based on the participants' satisfaction scores. Histologic changes before, immediately after MFR and at 4 months follow-up was examined. Complications were also recorded. RESULTS: Partially denatured collagen fibers and dermal shrinkage was observed immediately after MFR whereas an increase in elastin and collagen was noted at 4 months follow-up. 86.7% of recipients considered the results satisfactory. Consensus ratings by two independent dermatologists on the objective outcomes at 4-month follow-up were very much improved (53.3%), much improved (26.7%) and improved (20%). Treatment was well tolerated and did not cause any significant long-lasting discomfort. CONCLUSION: Temperature-controlled bipolar MFR is a minimally invasive treatment option to consider for facial fine lines and laxity via neo-collagenesis and neo-elastogenesis. The procedure was safe and clinically effective.

Can a radiofrequency device reduce the pore size?

A facial pore is an empty funnel-shaped structure filled with cornified cylindrical plugs that can be cosmetically bothersome to some patients. In the previous report, the new unipolar radiofrequency (RF) device with a vacuum showed excellent skin tightening and patient satisfaction with improved pores. This study aims to confirm the treatment's efficacy with the new unipolar RF device on facial dilated pores by measuring quantitative sebum production differences and doing a histologic examination of pore size. Twelve patients who visited the dermatologic clinic without other underlying inflammatory facial skin diseases were included, regardless of the patient's age or sex. All patients received five successive treatments at 2-week intervals. We assessed all changes in sebum production levels, melanin index, erythema index before and after treatment, along with overall improvement (reduction of pore size, skin tone, skin texture, and skin laxity). In the five patients who agreed in advance, a biopsy of the pore lesion was taken before and 1 month after the last treatment with hematoxylin and eosin (H&E) staining, Masson's trichrome (M-T) staining, and Victoria blue staining. We observed a significant reduction of sebum production and melanin index after using the new unipolar RF device with a vacuum (sebum production, p = 0.011; MI, p = 0.004). In evaluating patient satisfaction for four categories, the patients showed a moderate to the excellent improvement of more than 50% in their condition except for skin tones. The average pore size decreased by 41.7% in the histological examination, from 64.98 to 37.86 µm. Additionally, we observed an overall decreased sebaceous gland in the dermis and the proliferation of dermal collagen fiber. The number of elastic bundles in the D-E junction was increased after treatment. The nonablative unipolar RF devices with a vacuum can improve dilated pores with a dual mechanism (collagen regeneration and reduction of sebum production), with much less pain than other RF devices.

Mitochondrial nucleoid remodeling and biogenesis are regulated by the p53-p21WAF1-PKCζ pathway in p16INK4a-silenced cells.

Mitochondrial dysfunction is linked to age-related senescence phenotypes. We report here the pathway increasing nucleoid remodeling and biogenesis in mitochondria during the senescence of foreskin human diploid fibroblasts (fs-HDF) and WI-38 cells. Replicative senescence in fs-HDF cells increased mitochondrial nucleoid remodeling as indicated by 5-bromo-2'-deoxyuridine (BrdU) incorporation and mitochondrial transcription factor A (TFAM) expression in enlarged and fused mitochondria. Mitochondrial nucleoid remodeling was accompanied by mitochondrial biogenesis in old cells, and the expression levels of OXPHOS complex-I, -IV and -V subunits, PGC-1α and NRF1 were greatly increased compared to young cells. Activated protein kinase C zeta (PKCζ) increased mitochondrial activity and expressed phenotypes of delayed senescence in fs-HDF cells, but not in WI-38 cells. The findings were reproduced in the doxorubicin-induced senescence of young fs-HDF and WI-38 cells via the PKCζ-LKB1-AMPK signaling pathway, which was regulated by the p53-p21WAF1 pathway when p16INK4a was silenced. The signaling enhanced PGC-1α-NRF1-TFAM axis in mitochondria, which was demonstrated by Ingenuity Pathway Analysis of young and old fs-HDF cells. Activation of the p53-p21WAF1 pathway and silencing of p16INK4a are responsible for mitochondrial reprogramming in senescent cells, which may be a compensatory mechanism to promote cell survival under senescence stress.

Superficial intense focused ultrasound on periorbital wrinkle.

The periorbital wrinkles are easily perceived evidence of aging, so become a major concern for many patients. Various treatments have been attempted to improve periorbital wrinkles, but the need for new treatments that are less invasive and more effective is still high. In this study, we evaluated the safety, clinical and histological effects of intense focused ultrasound using only a 1.5 mm transducer in the management of periorbital wrinkles. Ten adult Korean females were enrolled. The treatment effect and safety profile were evaluated up to 3 months after 1 session of IFUS treatment on the periorbital wrinkles. The mean subjective satisfaction score was 3.2 ± 0.79 (mean ± standard deviation) by 5- point scale. The mean objective clinical improvement score was highest in the fine wrinkle on the crow's feet area and lowest in the deep wrinkles of the infraorbital and crow's feet area. Histometrically, increase of collagen and elastic fiber density was observed in the all layers of dermis. No serious side effects occurred after the treatment. In conclusion, intense focused ultrasound treatment using a 1.5-mm transducer alone can significantly improve periocular wrinkles after a single treatment with a good safety profile.

TIS21/BTG2 inhibits breast cancer growth and progression by differential regulation of mTORc1 and mTORc2-AKT1-NFAT1-PHLPP2 signaling axis.

PURPOSE: It has been reported that PI3K/AKT pathway is altered in various cancers and AKT isoforms specifically regulate cell growth and metastasis of cancer cells; AKT1, but not AKT2, reduces invasion of cancer cells but maintains cancer growth. We propose here a novel mechanism of the tumor suppresser, TIS21/BTG2, that inhibits both growth and invasion of triple negative breast cancer cells via AKT1 activation by differential regulation of mTORc1 and mTORc2 activity. METHODS: Transduction of adenovirus carrying TIS21/BTG2 gene and transfection of short interfering RNAs were employed to regulate TIS21/BTG2 gene expression in various cell lines. Treatment of mTOR inhibitors and mTOR kinase assays can evaluate the role of mTORc in the regulation of AKT phosphorylation at S473 residue by TIS21/BTG2 in breast cancer cells. Open data and immunohistochemical analysis were performed to confirm the role of TIS21/BTG2 expression in various human breast cancer tissues. RESULTS: We observed that TIS21/BTG2 inhibited mTORc1 activity by reducing Raptor-mTOR interaction along with upregulation of tsc1 expression, which lead to significant reduction of p70S6K activation as opposed to AKT1S473, but not AKT2, phosphorylation via downregulating PHLPP2 (AKT1-specific phosphatase) in breast cancers. TIS21/BTG2-induced pAKTS473 required Rictor-bound mTOR kinase, indicating activation of mTORc2 by TIS21/BTG2 gene. Additionally, the TIS21/BTG2-induced pAKTS473 could reduce expression of NFAT1 (nuclear factor of activated T cells) and its target genes, which regulate cancer microenvironment. CONCLUSIONS: TIS21/BTG2 significantly lost in the infiltrating ductal carcinoma, but it can inhibit cancer growth via the TIS21/BTG2-tsc1/2-mTORc1-p70S6K axis and downregulate cancer progression via the TIS21/BTG2-mTORc2-AKT1-NFAT1-PHLPP2 pathway.

Inhibition of TNFα-interacting protein α (Tipα)-associated gastric carcinogenesis by BTG2/TIS21 via downregulating cytoplasmic nucleolin expression.

To understand the regulation of Helicobacter pylori (H. pylori)-associated gastric carcinogenesis, we examined the effect of B-cell translocation gene 2 (BTG2) expression on the biological activity of Tipα, an oncoprotein secreted from H. pylori. BTG2, the human ortholog of mouse TIS21 (BTG2/TIS21), has been reported to be a primary response gene that is transiently expressed in response to various stimulations. Here, we report that BTG2 is constitutively expressed in the mucous epithelium and parietal cells of the gastric gland in the stomach. Expression was increased in the mucous epithelium following H. pylori infection in contrast to its loss in human gastric adenocarcinoma. Indeed, adenoviral transduction of BTG2/TIS21 significantly inhibited Tipα activity in MKN-1 and MGT-40, human and mouse gastric cancer cells, respectively, thereby downregulating tumor necrosis factor-α (TNFα) expression and Erk1/2 phosphorylation by reducing expression of nucleolin, a Tipα receptor. Chromatin immunoprecipitation proved that BTG2/TIS21 inhibited Sp1 expression and its binding to the promoter of the nucleolin gene. In addition, BTG2/TIS21 expression significantly reduced membrane-localized nucleolin expression in cancer cells, and the loss of BTG2/TIS21 expression induced cytoplasmic nucleolin availability in gastric cancer tissues, as evidenced by immunoblotting and immunohistochemistry. Higher expression of BTG2 and lower expression of nucleolin were accompanied with better overall survival of poorly differentiated gastric cancer patients. This is the first report showing that BTG2/TIS21 inhibits nucleolin expression via Sp1 binding, which might be associated with the inhibition of H. pylori-induced carcinogenesis. We suggest that BTG2/TIS21 is a potential inhibitor of nucleolin in the cytoplasm, leading to inhibition of carcinogenesis after H. pylori infection.

Clinical efficacy and safety evaluation of a novel fractional unipolar radiofrequency device on facial tightening: A preliminary report.

BACKGROUND: Previous studies have shown that radiofrequency (RF) energy is safe and effective for improving skin laxity. Unlike monopolar and bipolar devices, little has been studied with the unipolar hand piece. OBJECTIVES: We sought to evaluate the safety and efficacy of a novel fractional unipolar RF device on facial tightening. PATIENTS AND METHODS: This was a retrospective, single-center study of 14 subjects with age-related facial laxity who underwent five sessions of fractional unipolar RF at an interval of 2 weeks, and then followed-up for 3 months. Standardized photos were taken at baseline and at 3-months follow-up, and were assessed by two independent dermatologists using a 4-point scale (0=no improvement, 1=mild improvement, 2=moderate improvement, 3=significant improvement). Punch biopsies (2 mm) were performed and a questionnaire was used to evaluate the patient's satisfaction and the incidence of adverse reactions. RESULTS: Fourteen subjects with mild to moderate age-related facial laxity were included in the study. The mean age of the subjects was 49.7 years (range 32-80). 35.7% of the subjects showed significant improvement, 50% moderate improvement, and 14.3% slight improvement of facial laxity in their follow-up photos. About 85.7% of the patients replied that they were either greatly satisfied or satisfied with the results at 3-months follow-up. Skin biopsies revealed an increase in collagen in the dermis. None of the subjects experienced any serious adverse events during or after the procedure. CONCLUSION: Our findings suggest that fractional Unipolar RF can be safely performed on the face and is effective in skin tightening. It has a great advantage over other forms of RF by being entirely painless.

Intense focused ultrasound (IFUS) with a modified parameter on facial tightening: A study on its safety and efficacy.

BACKGROUND: Intense focused ultrasound (IFUS) is a novel treatment modality for skin laxity. The delivery of thermal energy to the deeper tissue layers effectively tightens the skin but can also cause significant fat atrophy, limiting its use in patients with a lean face. OBJECTIVES: We sought to evaluate the safety and efficacy of modified IFUS on facial rejuvenation. PATIENTS AND METHODS: This was a retrospective, single-center study of 28 subjects with age-related facial laxity who underwent 3 sessions of IFUS (UltraskinTM, WONTECH Co., Daejeon, Korea) at an interval of four weeks, and then followed up for three months. IFUS was first applied using a 4-MHZ, 4.5-mm transducer followed by a 7-MHZ, 3-mm transducer. Approximately 200-300 treatment lines were applied to the face during each session. Standardized photographs were taken at baseline and follow-ups and were assessed by two independent dermatologists. A questionnaire was used to evaluate patient satisfaction and the incidence of adverse reactions. RESULTS: Twenty-eight subjects with mild-to-moderate age-related facial laxity were included in the study. The mean age of the subjects was 48 (range 29-74) years. About 32.1% of the subjects showed significant improvement and 57.1% showed improvement of facial laxity in their follow-up photographs. All of them (100%) replied that they were either greatly satisfied or satisfied with the results at three-month follow-up. None of the subjects experienced any serious adverse events including fat atrophy after the procedure. CONCLUSION: Modified IFUS (three sessions, four weeks apart, 200-300 treatment lines per session) can be safely performed with good clinical results.

Dermal Remodeling of Burn Scar by Fractional CO2 Laser.

BACKGROUND: Ablative CO2 fractional lasers have recently been introduced for burn scar treatment because of pronounced clinical outcomes with fewer treatment sessions than nonablative fractional laser. OBJECTIVE: This study was conducted to observe clinical as well as histologic changes of burn scars after treatment with CO2 fractional laser. MATERIALS AND METHODS: Eleven patients (one female and 10 males, aged 31-59 years) with skin phototypes III to V with burn scars received 10 sessions of fractional CO2 laser treatments (UltraPulse(®) Encore; Lumenis, Santa Clara, CA, USA) over an average 5-week interval. Two passes were performed using the following parameters: deep FX mode, 12.5-30 mJ, with a density setting of 5-10 %. Clinical evaluations by three blinded dermatologists were obtained at baseline and at 6 months after the final treatment via photographs using the Vancouver scar scale (VSS). Skin biopsies were done on four patients before and after treatment. RESULTS: All patients showed clinical improvement in their scars with significant decrease in VSS. Histologic findings showed the changes in the upper dermis with newly formed dermal papilla. This characteristic upper dermis change was presented as improvement in surface smoothness and skin tension clinically. Postinflammatory hyperpigmentation and itching sensation were the most common adverse effects. CONCLUSION: Burn scar treatment by fractional CO2 laser is effective by forming new collagen fibers mainly in the upper dermis. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The efficacy and safety of subcision using CO2 gas combined with fractional laser for acne scars: Clinical and microscopic evaluation.

BACKGROUND: Various modalities have been used to treat acne scars. CO2 fractional laser is an effective and commonly used treatment. CO2 gas injection into the dermis by needle with high pressure can cause fibrotic collagen breakage, producing the effects of subcision. CO2 also stimulates collagen synthesis by increasing neovascularization and releasing oxygen. OBJECTIVE: This study evaluated the efficacy and the safety of the combined treatment with CO2 gas subcision and CO2 fractional laser for acne scars. METHODS AND MATERIALS: Fourteen patients with acne scars were treated with three sessions of CO2 gas subcision at 2-week intervals and two sessions of fractional laser at 4-week interval. The clinical improvement was assessed using a 4-point scale. For histologic analysis, punch biopsy was performed before and after treatment in 10 patients. RESULTS: All patients experienced clinical improvements. Excellent, marked, moderate, and mild response was achieved in 1 (7%), 8 (57%), 4 (29%), and 1 patient (7%), respectively. Histologic evaluation of the biopsy specimens showed increased dermal collagen with dermal thickening and elastic fiber straightening in the reticular dermis after the treatment. CONCLUSION: The combination therapy with CO2 gas subcision and fractional laser was satisfactory and safe for treating acne scars. Abbreviation and acronym: CO2: Carbon dioxide GAS: Global assessment scale H&E: hematoxylin and eosin; SD: standard deviation.

Regulations of Reversal of Senescence by PKC Isozymes in Response to 12-O-Tetradecanoylphorbol-13-Acetate via Nuclear Translocation of pErk1/2.

The mechanism by which 12-O-tetradecanoylphorbol-13-acetate (TPA) bypasses cellular senescence was investigated using human diploid fibroblast (HDF) cell replicative senescence as a model. Upon TPA treatment, protein kinase C (PKC) α and PKCß1 exerted differential effects on the nuclear translocation of cytoplasmic pErk1/2, a protein which maintains senescence. PKCα accompanied pErk1/2 to the nucleus after freeing it from PEA-15pS(104) via PKCß1 and then was rapidly ubiquitinated and degraded within the nucleus. Mitogen-activated protein kinase docking motif and kinase activity of PKCα were both required for pErk1/2 transport to the nucleus. Repetitive exposure of mouse skin to TPA downregulated PKCα expression and increased epidermal and hair follicle cell proliferation. Thus, PKCα downregulation is accompanied by in vivo cell proliferation, as evidenced in 7, 12-dimethylbenz(a)anthracene (DMBA)-TPA-mediated carcinogenesis. The ability of TPA to reverse senescence was further demonstrated in old HDF cells using RNA-sequencing analyses in which TPA-induced nuclear PKCα degradation freed nuclear pErk1/2 to induce cell proliferation and facilitated the recovery of mitochondrial energy metabolism. Our data indicate that TPA-induced senescence reversal and carcinogenesis promotion share the same molecular pathway. Loss of PKCα expression following TPA treatment reduces pErk1/2-activated SP1 biding to the p21(WAF1) gene promoter, thus preventing senescence onset and overcoming G1/S cell cycle arrest in senescent cells.

Treatment of dilated pores with 1410-nm fractional erbium-doped fiber laser.

Dilated pores can be an early sign of skin aging and are a significant cosmetic concern. The 1410-nm wavelength is optimal for superficial dermal treatments up to 650 µm deep. The aim of the present study was to evaluate the clinical effectiveness and safety of the fractional erbium-doped fiber 1410-nm laser in the treatment of dilated pores. Fifteen patients with dilated facial pores underwent three laser treatments at 3-week intervals. Posttreatment skin responses and side effects were assessed at treatment and follow-up visits by study physicians. Clinical effectiveness of treatment was assessed by both study physicians and patients 3 months after the final laser treatment using a quartile grading scale. Histological examination was performed using biopsy samples taken at baseline (pretreatment) and 3 months after the last treatment. This study showed that greater than 51 % improvement in dilated pores was demonstrated in 14 of 15 patients after three sessions of laser treatments. Improvements in skin texture, tone, and smoothness were reported in all patients. Treatment was well tolerated in all patients, with no unanticipated side effects. This study demonstrates that the 1410-nm fractional erbium fiber laser is effective and safe for treatment of dilated facial pores in Fitzpatrick skin types III-IV.

Comparative histometric analysis of the effects of high-intensity focused ultrasound and radiofrequency on skin.

INTRODUCTION: High-intensity focused ultrasound (HIFU) and radiofrequency (RF) are used for non-invasive skin tightening. Neocollagenesis and neoelastogenesis have been reported to have a mechanism of controlled thermal injury. OBJECTIVE: To compare neocollagenesis and neoelastogenesis in each layer of the dermis after each session of HIFU and monopolar RF. METHODS: We analyzed the area fraction of collagen and elastic fibers using the Masson's Trichrome and Victoria blue special stains, respectively, before and after 2 months of treatments. Histometric analyses were performed in each layer of the dermis, including the papillary dermis, and upper, mid, and deep reticular dermis. RESULTS: Monopolar RF led to neocollagenesis in the papillary dermis, and upper, mid, and deep reticular dermis, and neoelastogenesis in the papillary dermis, and upper and mid reticular dermis. HIFU led to neocollagenesis in the mid and deep reticular dermis and neoelastogenesis in the deep reticular dermis. Among these treatment methods, HIFU showed the highest level of neocollagenesis and neoelastogenesis in the deep reticular dermis. CONCLUSIONS: HIFU affects deep tissues and impacts focal regions. Monopolar RF also affects deep tissues, but impacts diffuse regions. We believe these data provide further insight into effective skin tightening.

Berberine regulates melanin synthesis by activating PI3K/AKT, ERK and GSK3ß in B16F10 melanoma cells.

Berberine, an isoquinoline alkaloid, has a wide range of beneficial properties, including anti-bacterial, anti-inflammatory, anti-cancer, and cholesterol-lowering effects. Recently findings suggest that berberine improves glucose and lipid metabolism disorders. In the present study, we examined the mechanism underlying the inhibitory effect of berberine on α-melanocyte-stimulating hormone (α-MSH)-stimulated B16F10 melanoma cells. The results showed that berberine attenuated α-MSH induction of the microphthalmia-associated transcription factor (MITF) and tyrosinase in a dose-dependent manner. To elucidate the mechanism underlying the inhibitory effect of berberine, we examined the effect of α-MSH-stimulated phosphorylation of PI3K/AKT, ERK, and GSK3ß. The results showed that treatment with berberine resulted in a reduction in the phosphorylation of PI3K/AKT, ERK, and GSK3ß. Taken together, the results suggested that berberine inhibits melanin synthesis and tyrosinase activity by downregulating the expression of MITF and tyrosinase. Thus, these findings may contribute to the potential application of berberine in the prevention and treatment of skin pigmentation disorders.

Intense focused ultrasound for facial tightening: histologic changes in 11 Patients.

INTRODUCTION: Intense focused ultrasound (IFUS) is a novel modality for treating skin laxity that produces thermal effects at various depths while sparing the overlying tissue. This study assessed histologic changes and the safety and efficacy of intense focused ultrasound (Doublo(TM), HIRONIC Co., Sungnam, Korea) for tightening of facial skin in Asian patients. METHODS: Eleven patients with facial laxity were treated with IFUS and evaluated before and after treatment. Mean age was 46 years (range, 35-64 years). Two available hand-pieces with different focal depths (3 mm and 4.5 mm) were used with three to five passes 1-2 mm apart. Outcome assessment included photographic evaluation by two blinded investigators, skin biopsies before and two months after treatment, and patient satisfaction. RESULTS: Subjective and objective analyses showed 63.6% and 72.7% improvement at the two-month evaluation, respectively. Histologic evaluation by hematoxylin and eosin (H&E) and Masson's trichrome staining showed increased collagen fibers in the lower dermis and between fat layers. DISCUSSION AND CONCLUSIONS: Intense focused ultrasound can be used as a non-invasive skin tightening technique in Asian patients. It induced collagen generation in the dermis and fat layers and was effective and safe in our study population.

Accumulation of cytolytic CD8+ T cells in B16-melanoma and proliferation of mature T cells in TIS21-knockout mice after T cell receptor stimulation.

In vivo and in vitro effects of TIS21 gene on the mature T cell activation and antitumor activities were explored by employing MO5 melanoma orthograft and splenocytes isolated from the TIS21-knockout (KO)(2) mice. Proliferation and survival of mature T cells were significantly increased in the KO than the wild type (WT3)e cells, indicating that TIS21 inhibits the rate of mature T cell proliferation and its survival. In MO5 melanoma orthograft model, the KO mice recruited much more CD8(+) T cells into the tumors at around day 14 after tumor cell injection along with reduced tumor volumes compared with the WT. The increased frequency of granzyme B+ CD8+ T cells in splenocytes of the KO mice compared with the WT may account for antitumor-immunity of TIS21 gene in the melanoma orthograft. In contrast, reduced frequencies of CD107a+ CD8+ T cells in the splenocytes of KO mice may affect the loss of CD8+ T cell infiltration in the orthograft at around day 19. These results indicate that TIS21 exhibits antiproliferative and proapoptotic effects in mature T cells, and differentially affects the frequencies of granzyme B+ CD8+ T-cells and CD107a+ CD8+ T-cells, thus transiently regulating in vivo anti-tumor immunity.

HNF4α contributes to glucose formation in aged rat hepatocytes.

Aging-dependent physiological conditions are attributed to parenchymal structural changes to cellular functions in aged organisms. Compared to the young animals, the primary hepatocytes from old rats showed a higher glucose output and a higher expression of the key gluconeogenesis-regulating enzyme, phosphoenol pyruvate carboxykinase (PEPCK). The primary hepatocytes from old rats showed a higher glucose output and a higher expression of the key gluconeogenesis-regulating enzyme, phosphoenol pyruvate carboxykinase (PEPCK), compared with those from the young animals. The in situ hybridization study showed increased PEPCK mRNA expression in the aged liver tissues. The livers from old rats showed loosened hexagonal hepatic lobular structures, increased collagen accumulation, and high expression of the hypoxia marker hypoxia-inducible factor 1α (HIF1α). Hypoxia increased the PEPCK mRNA and protein expression levels in accordance with the HIF1α expression. PEPCK promoter luciferase reporter assay showed that hypoxia increased PEPCK through transcriptional activation. Furthermore, the hepatocyte nuclear factor α (HNF4α) protein, but not the HNF4α mRNA level, increased in parallel with the PEPCK mRNA expression under hypoxic conditions. Glucose production increased under hypoxic conditions, but this increment diminished by HNF4α siRNA in young hepatocytes. Moreover, increased glucose production from old rat hepatocytes was reversed by the down-regulation of HNF4α through a specific siRNA. This study suggests that the mild hypoxic conditions in response to aging-dependent hepatic structural changes may contribute to the induction of the gluconeogenic enzyme PEPCK through HNF4α protein stabilization.