Qing Yan Li Ge Tang, a Chinese Herbal Formula, Induces Autophagic Cell Death through the PI3K/Akt/mTOR Pathway in Nasopharyngeal Carcinoma Cells In Vitro.

Since a portion of patients with nasopharyngeal carcinoma (NPC) do not benefit much from current standard treatments, it is still needed to discover new therapeutic drugs to improve the prognosis of the patients. Considering that Chinese traditional medicine plays a role in inhibiting tumor progression, in this study, we aimed to investigate whether a Chinese herbal formula, Qing Yan Li Ge Tang (QYLGT), has the anticancer activity in NPC cells and explore the underlying mechanism as well. MTT assay, colony formation assay, immunoblotting assay, and DNA laddering assay were performed to assess cell viability, cell colony formation, protein expression, and DNA fragmentation, respectively. Results show that QYLGT was able to inhibit the cell viability and decrease colony formation ability in NPC cells. QYLGT could also increase the formation of intracellular vacuoles and induce the autophagy-related protein expressions, including Atg3, Atg6, and Atg12-Atg5 conjugate in NPC cells. Treatment with an autophagy inhibitor, 3-methyladenine, could significantly recover QYLGT-inhibited cell viability of NPC cells. In addition, QYLGT did not significantly induce apoptosis in NPC cells. We also found that QYLGT had the ability to activate phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of the rapamycin (mTOR) pathway. Treatment with PI3K inhibitors, LY294002 and wortmannin, or mTOR inhibitors, rapamycin and Torin 1, could not only recover QYLGT-inhibited cell viability of NPC cells but also inhibit Atg3 expression. Taken together, our results demonstrated that QYLGT could induce autophagic cell death in NPC cells through the PI3K/Akt/mTOR pathway.

Role of JNK activation in paclitaxel-induced apoptosis in human head and neck squamous cell carcinoma.

It has been reported that paclitaxel activates cell cycle arrest and increases caspase protein expression to induce apoptosis in head and neck squamous cell carcinoma (HNSCC) cell lines. However, the potential signaling pathway regulating this apoptotic phenomenon remains unclear. The present study used OEC-M1 cells to investigate the underlying molecular mechanism of paclitaxel-induced apoptosis. Following treatment with paclitaxel, cell viability was assessed via the MTT assay. Necrosis, apoptosis, cell cycle and mitochondrial membrane potential (∆Ψm) were analyzed via flow cytometric analyses, respectively. Western blot analysis was performed to detect the expression levels of proteins associated with the MAPK and caspase signaling pathways. The results demonstrated that low-dose paclitaxel (50 nM) induced apoptosis but not necrosis in HNSCC cells. In addition, paclitaxel activated the c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase or p38 mitogen-activated protein kinase. The paclitaxel-activated JNK contributed to paclitaxel-induced apoptosis, activation of caspase-3, -6, -7, -8 and -9, and reduction of ∆Ψm. In addition, caspase-8 and -9 inhibitors, respectively, significantly decreased paclitaxel-induced apoptosis. Notably, Bid was truncated following treatment with paclitaxel. Taken together, the results of the present study suggest that paclitaxel-activated JNK is required for caspase activation and loss of ∆Ψm, which results in apoptosis of HNSCC cells. These results may provide mechanistic basis for designing more effective paclitaxel-combining regimens to treat HNSCC.

Effects of Solanum undatum extract (SR-T100) on photocarcinogenesis and photoaging of actinic keratosis.

SR-T100 gel, containing solamargine extracted from Solanum undatum (synonym: Solanum incanum), had good therapeutic effects on actinic keratosis (AK) in human and ultraviolet B-induced papilloma in mice. This study aimed to investigate the immunohistochemical changes in the human skin after SR-T100 treatment. An immunohistochemical study was performed and the changes in photocarcinogenesis and photoaging markers after 16-week SR-T100 gel treatment were documented. SR-T100 gel treatment for 16 weeks resulted in complete remission in nine AK lesions and partial remission in four AK lesions. SR-T100 gel abolished the expression of mutant p53 and SOX2 and restored the expression of NOTCH1. Additionally, SR-T100 gel improved wrinkling in human skin, while restoring the expression of lamin B1 and increasing synthesis of new elastic fibers. SR-T100 gel had therapeutic effects on photocarcinogenesis and photoaging of photodamaged skin with AK.

EBV Rta-induced IL-6 Promotes Migration of Bystander Tumor Cells Through IL-6R/JAK/STAT3 Pathway In Vitro.

BACKGROUND/AIM: Rta, a transactivator of Epstein-Barr virus, is associated with progression of nasopharyngel carcinoma (NPC); however, its mechanism of contribution to the pathogenesis of NPC remains unclear. Interleukin-6 (IL-6), a tumor promoter, is detected in NPC. This in vitro study examined whether and how Rta promotes NPC progression by up-regulating IL-6. MATERIALS AND METHODS: Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time PCR, ELISA, immunoblotting assays, reporter gene assays, and transwell migration assays were performed. RESULTS: In NPC cells, Rta up-regulated IL-6 expression at the mRNA and protein levels, and the Rta's C-terminus was essential for promoter activation and expression of IL-6. The induction of IL-6 by Rta also required activation of extracellular signal-regulated kinase 1/2 and activator protein-1. Furthermore, IL-6 secreted from Rta-expressing NPC cells promoted migration of Rta-negative NPC cells by activating IL-6 receptor/Janus kinase/signal transducer and activator of transcription 3 pathway. CONCLUSION: Rta contributes to progression of NPC cells through induction of IL-6 in vitro.

Comparison of the effects of insulin and SGLT2 inhibitor on the Renal Renin-Angiotensin system in type 1 diabetes mice.

AIMS: SGLT2 inhibitors have been proposed as an adjunct to insulin therapy for glycemic control in type 1 diabetes (T1D) patients. However, concern has been raised due to an increase in renin-angiotensin-system (RAS) activity reported in a clinical trial in which an SGLT2 inhibitor was added while insulin dose was reduced in T1D patients. We previously reported that insulin inhibits intrarenal angiotensinogen (Agt) gene transcription and RAS activation. We hypothesized that insulin, rather than SGLT2 inhibition might regulate the intrarenal RAS. METHODS: We compared RAS activity in non-diabetic wild type mice, Akita mice (T1D model) and Akita mice treated with insulin or the SGLT2 inhibitor canagliflozin. RESULTS: Treatment of Akita mice with insulin or canagliflozin produced similar reductions in blood glucose, whereas insulin, but not canagliflozin, reduced elevated systolic blood pressure. Akita mice exhibited increased renal Agt mRNA/protein expression, which was attenuated by insulin, but not by canagliflozin. Furthermore, insulin was more effective than canagliflozin in lowering kidney weight and albuminuria. CONCLUSIONS: Insulin, but not canagliflozin, lowers intrarenal RAS activity in Akita mice. Our findings can be of potential clinical importance, especially for T1D patients who are not on RAS inhibitors at the time of adding SGLT2 inhibitors.

High glucose environment induces M1 macrophage polarization that impairs keratinocyte migration via TNF-α: An important mechanism to delay the diabetic wound healing.

BACKGROUND: Macrophages play important roles during wound healing, and delayed healing in diabetics is associated with sustained inflammation. M1 type macrophage is recognized to secrete excessive amount of tumor necrosis factor-alpha (TNF-α) as compared to its M2 counterpart. OBJECTIVES: We hypothesized that macrophage polarization is different between diabetic and normal rats during skin wounding and has direct impact on keratinocyte function in the context of re-epithelialization. METHODS: Skin wounds were created in diabetic and control rats. The phenotypes of infiltrating macrophages, the levels of TNF-α, and the rate of wound closure were determined. Using cell model, the effects of M1 type macrophage on keratinocyte migration were evaluated, and the potential regulatory pathways were determined. RESULTS: The percentage of M1 macrophages and the levels of TNF-α expression were significantly higher in the perilesional area of diabetic rats as compared to control. The condition media (CM) from M1 type macrophage upregulated tissue inhibitor metalloproteinases (TIMP)-1 expression in keratinocytes and significantly reduced keratinocyte migratory capacity. Addition of neutralizing TNF-α antibody to the CM or gene-silencing of TIMP1 in keratinocytes restored the keratinocyte migratory capacity. Treating wounds of diabetic rats with TNF-α antagonist improved the wound healing process. CONCLUSIONS: In summary, high glucose wound environment harbored more M1 macrophages infiltration, an event that created excess TNF-α micro-environment. TNF-α upregulated TIMP1 expression in keratinocytes and resulted in impaired keratinocyte migration. Taken together, these events contributed to impaired wound healing during diabetic condition, and targeting TNF-α is a potential therapeutic option to improve diabetic wound healing.

Downregulated Salt-inducible Kinase 3 Expression Promotes Chemoresistance in Serous Ovarian Cancer via the ATP-binding Cassette Protein ABCG2.

Background: Epithelial ovarian cancer (EOC) has a high tumor-associated mortality rate among gynecological cancers. Although CA125 is a well-studied biomarker for ovarian cancer, it is also elevated under numerous conditions, resulting in decreased specificity. Recently, we identified a novel tumor-associated antigen, salt-inducible kinase 3 (SIK3), during tumorigenesis in ovarian cancer. However, the association between SIK3 expression and patient outcomes in ovarian cancer remains unclear. Materials and Methods: We collected EOC samples from 204 patients and examined tumor SIK3 expression by immunohistochemistry (IHC) and CA125 expression in tumors and serum. The expression levels of SIK3 and CA125 were correlated with patient survival. SIK3 expression was silenced with SIK3-specific shRNAs to investigate the possible mechanisms related to chemoresistance in serous-type ovarian cancer cell lines OVCAR4 and SKOV3. Results: In advanced-stage serous ovarian cancer, patients with low SIK3 expression have poorer overall survival (OS) and progression-free survival (PFS) than patients with high SIK3 expression. Ovarian cancer cells with SIK3 knockdown display increased chemoresistance to Taxol plus cisplatin treatment, which is associated with the upregulation of the ABCG2 transporter. In addition, in serous ovarian cancer, SIK3 expression is inversely correlated to ABCG2 expression, and patients with low SIK3 and high ABCG2 expression have worse prognosis than patients with high SIK3 and low ABCG2 expression. Conclusion: Our results demonstrated that serous EOC patients with low SIK3 expression have poor prognosis, which is associated with chemoresistance mediated by ABCG2 upregulation. SIK3 and ABCG2 expression levels may be potential prognostic markers to predict the outcome in serous EOC patients.

Tension pneumoperitoneum after surgery for endometrial cancer and hernia in a morbidly obese female: a case report.

BACKGROUND: Obesity is a risk factor for the development of endometrial cancer and abdominal wall hernias. We report a case of tension pneumoperitoneum that developed after gynecological surgery and mesh repair of a ventral hernia. CASE PRESENTATION: A 57-year-old Asian Taiwanese woman with a body mass index of 52.9 (kg/m2) underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy due to endometrial cancer, and ventral herniorrhaphy with mesh due to ventral hernia. Tension pneumoperitoneum with severe dyspnea developed on postoperative day 14. Rather than performing emergency laparotomy as in visceral perforation, a transabdominal catheter was inserted to drain the intra-abdominal gas. This approach dramatically relieved the tension pneumoperitoneum and dyspnea. Our patient then recovered smoothly; the catheter was removed on postoperative 24, and she was discharged on postoperative day 28. The clinical course of the endometrial cancer and repaired ventral hernia was well at the 1-year follow-up. CONCLUSIONS: Tension pneumoperitoneum, which may result from the valve effect of unhealed abdominal mesh, could develop after gynecological surgery and hernia mesh repair in obese patients. Under these conditions, emergency drainage of the intra-abdominal gas by catheter insertion is sufficient to relieve the abdominal pressure and correct the conditions, while emergency laparotomy as in visceral perforation is unnecessary and may increase patient morbidities.

Efficacy and safety of topical SR-T100 gel in treating actinic keratosis in Taiwan: A Phase III randomized double-blind vehicle-controlled parallel trial.

BACKGROUND: Currently available topical treatments for actinic keratosis (AK) are associated with substantial side-effects. OBJECTIVES: To evaluate the efficacy and safety of topical SR-T100 gel in treating AK. METHODS: A multicenter, randomized, double-blinded phase III trial was conducted. Patients with at least two clinically visible AK were enrolled and a punch biopsy was performed on one of the AK to confirm the diagnosis. This study consisted of up to 16-week treatment and 8-week post-treatment periods. Medication was applied daily with occlusive dressing. RESULTS: 123 subjects were recruited and 113 were randomized. 76 subjects were in the SR-T100 and 37 in the vehicle arms. In SR-T100 and vehicle groups, 32.39% and 17.14% of subjects achieved complete clearance, respectively. For 75% partial clearance of lesions, 71.83% and 37.1% of subjects achieved this goal in SR-T100 and vehicle group, respectively. When comparing SR-T100 to vehicle, the odds ratio of complete clearance was 2.14 (p = 0.111), and odds ratio of partial clearance was 4.36 (p < 0.001). Severe local reactions were reported by only one subject using SR-T100. CONCLUSION: The imitation of the study was that not all the treated AK lesions were confirmed by histopathology. The diagnostic uncertainty may contribute to the high partial clearance rate in the vehicle group since the clinical-diagnosed AK showed higher clearance rate compared to histopathology-confirmed AK. The use of occlusive dressing was another possible explanation for high placebo effects. The results suggested that topical SR-T100 gel may be an effective and safe treatment for field therapy of AK.

Heterogeneous Nuclear Ribonucleoprotein F Stimulates Sirtuin-1 Gene Expression and Attenuates Nephropathy Progression in Diabetic Mice.

We investigated the mechanism of heterogeneous nuclear ribonucleoprotein F (hnRNP F) renoprotective action in a type 2 diabetes (T2D) mouse model (db/db). Immortalized rat renal proximal tubular cells (IRPTCs) and kidneys from humans with T2D were also studied. The db/db mice developed hyperglycemia, oxidative stress, and nephropathy at age 20 weeks compared with their db/m littermates. These abnormalities, with the exception of hyperglycemia, were attenuated in db/dbhnRNP F-transgenic (Tg) mice specifically overexpressing hnRNP F in their RPTCs. Sirtuin-1, Foxo3α, and catalase expression were significantly decreased in RPTCs from db/db mice and normalized in db/dbhnRNP F-Tg mice. In vitro, hnRNP F overexpression stimulated Sirtuin-1 and Foxo3α with downregulation of acetylated p53 expression and prevented downregulation of Sirtuin-1 and Foxo3α expression in IRPTCs by high glucose plus palmitate. Transfection of Sirtuin-1 small interfering RNA prevented hnRNP F stimulation of Foxo3α and downregulation of acetylated p53 expression. hnRNP F stimulated Sirtuin-1 transcription via hnRNP F-responsive element in the Sirtuin-1 promoter. Human T2D kidneys exhibited more RPTC apoptosis and lower expression of hnRNP F, SIRTUIN-1, and FOXO3α than nondiabetic kidneys. Our results demonstrate that hnRNP F protects kidneys against oxidative stress and nephropathy via stimulation of Sirtuin-1 expression and signaling in diabetes.

Arsenic treatment increase Aurora-A overexpression through E2F1 activation in bladder cells.

BACKGROUND: Arsenic is a widely distributed metalloid compound that has biphasic effects on cultured cells. In large doses, arsenic can be toxic enough to trigger cell death. In smaller amounts, non-toxic doses may promote cell proliferation and induces carcinogenesis. Aberration of chromosome is frequently detected in epithelial cells and lymphocytes of individuals from arsenic contaminated areas. Overexpression of Aurora-A, a mitotic kinase, results in chromosomal instability and cell transformation. We have reported that low concentration (≦1 µM) of arsenic treatment increases Aurora-A expression in immortalized bladder urothelial E7 cells. However, how arsenic induces carcinogenesis through Aurora-A activation remaining unclear. METHODS: Bromodeoxyuridine (BrdU) staining, MTT assay, and flow cytometry assay were conducted to determine cell proliferation. Messenger RNA and protein expression levels of Aurora-A were detected by reverse transcriptional-PCR and Western blotting, respectively. Centrosome of cells was observed by immunofluorescent staining. The transcription factor of Aurora-A was investigated by promoter activity, chromosome immunoprecipitation (ChIP), and small interfering RNA (shRNA) assays. Mouse model was utilized to confirm the relationship between arsenic and Aurora-A. RESULTS: We reveal that low dosage of arsenic treatment increased cell proliferation is associated with accumulated cell population at S phase. We also detected increased Aurora-A expression at mRNA and protein levels in immortalized bladder urothelial E7 cells exposed to low doses of arsenic. Arsenic-treated cells displayed increased multiple centrosome which is resulted from overexpressed Aurora-A. Furthermore, the transcription factor, E2F1, is responsible for Aurora-A overexpression after arsenic treatment. We further disclosed that Aurora-A expression and cell proliferation were increased in bladder and uterus tissues of the BALB/c mice after long-term arsenic (1 mg/L) exposure for 2 months. CONCLUSION: We reveal that low dose of arsenic induced cell proliferation is through Aurora-A overexpression, which is transcriptionally regulated by E2F1 both in vitro and in vivo. Our findings disclose a new possibility that arsenic at low concentration activates Aurora-A to induce carcinogenesis.

Insulin Inhibits Nrf2 Gene Expression via Heterogeneous Nuclear Ribonucleoprotein F/K in Diabetic Mice.

Oxidative stress induces endogenous antioxidants via nuclear factor erythroid 2-related factor 2 (Nrf2), potentially preventing tissue injury. We investigated whether insulin affects renal Nrf2 expression in type 1 diabetes (T1D) and studied its underlying mechanism. Insulin normalized hyperglycemia, hypertension, oxidative stress, and renal injury; inhibited renal Nrf2 and angiotensinogen (Agt) gene expression; and upregulated heterogeneous nuclear ribonucleoprotein F and K (hnRNP F and hnRNP K) expression in Akita mice with T1D. In immortalized rat renal proximal tubular cells, insulin suppressed Nrf2 and Agt but stimulated hnRNP F and hnRNP K gene transcription in high glucose via p44/42 mitogen-activated protein kinase signaling. Transfection with small interfering RNAs of p44/42 MAPK, hnRNP F, or hnRNP K blocked insulin inhibition of Nrf2 gene transcription. Insulin curbed Nrf2 promoter activity via a specific DNA-responsive element that binds hnRNP F/K, and hnRNP F/K overexpression curtailed Nrf2 promoter activity. In hyperinsulinemic-euglycemic mice, renal Nrf2 and Agt expression was downregulated, whereas hnRNP F/K expression was upregulated. Thus, the beneficial actions of insulin in diabetic nephropathy appear to be mediated, in part, by suppressing renal Nrf2 and Agt gene transcription and preventing Nrf2 stimulation of Agt expression via hnRNP F/K. These findings identify hnRNP F/K and Nrf2 as potential therapeutic targets in diabetes.

Irradiance-dependent UVB Photocarcinogenesis.

Ultraviolet B (UVB) radiation from the sun may lead to photocarcinogenesis of the skin. Sunscreens were used to protect the skin by reducing UVB irradiance, but sunscreen use did not reduce sunburn episodes. It was shown that UVB-induced erythema depends on surface exposure but not irradiance of UVB. We previously showed that irradiance plays a critical role in UVB-induced cell differentiation. This study investigated the impact of irradiance on UVB-induced photocarcinogenesis. For hairless mice receiving equivalent exposure of UVB radiation, the low irradiance (LI) UVB treated mice showed more rapid tumor development, larger tumor burden, and more keratinocytes harboring mutant p53 in the epidermis as compared to their high irradiance (HI) UVB treated counterpart. Mechanistically, using cell models, we demonstrated that LI UVB radiation allowed more keratinocytes harboring DNA damages to enter cell cycle via ERK-related signaling as compared to its HI UVB counterpart. These results indicated that at equivalent exposure, UVB radiation at LI has higher photocarcinogenic potential as compared to its HI counterpart. Since erythema is the observed sunburn at moderate doses and use of sunscreen was not found to associate with reduced sunburn episodes, the biological significance of sunburn with or without sunscreen use warrants further investigation.

High-glucose environment increased thrombospondin-1 expression in keratinocytes via DNA hypomethylation.

Diabetes is an important health issue because of its increasing prevalence and association with impaired wound healing. Epidermal keratinocytes with overexpressed antiangiogenic molecule thrombospondin-1 (TSP1) have been shown to impair proper wound healing. This study examined the potential involvement of keratinocyte-derived TSP1 on diabetic wound healing. Cultured human keratinocytes and diabetic rat model were used to evaluate the effect of high-glucose environment on TSP1 expression in epidermal keratinocytes, and the molecular mechanisms involved in the process were also studied. We demonstrated that high-glucose environment increased TSP1 expression in keratinocytes. In addition, increased oxidative stress induced DNA hypomethylation at the TSP1 promoter region in keratinocytes exposed to high-glucose environment. Similar findings were found in our diabetic rat model. Early antioxidant administration normalized TSP1 expression and global DNA methylation status in diabetic rat skin and improved wound healing in vivo. Because oxidative stress contributed to TSP1 DNA hypomethylation, early recognition of diabetic condition and timely administration of antioxidant are logical approaches to reduce complications associated with diabetes as alterations in epigenome may not be reversible by controlling glucose levels during the later stages of disease course.

Human sebum extract induces barrier disruption and cytokine expression in murine epidermis.

BACKGROUND: Previous studies have shown that human sebum may play a role in barrier function but with much debate. OBJECTIVE: To elucidate the effects of human sebum on skin barrier function. METHODS: We used hairless mouse skin to study the functional and morphological alternation of epidermis after the application of human sebum. RESULTS: The results showed a significant increase in transepidermal water loss and erythema value, and a decrease in skin hydration, accompanied by epidermal hyperplasia with parakeratosis following sebum application. Nile red staining together with electron microscopic examination confirmed the underlying mechanisms for sebum-induced barrier disruption are related directly to the interaction of sebum with the intracellular lipid lamellae of the SC, thereby leading to the increase in the fluidity of SC intracellular lipids as demonstrated by ATR-FTIR measurement. An inflammatory reaction characterized by an enhanced cytokine cascade, including up-regulation of TNF-α, IL-1α and IL-6, was also observed. On the other hand, there were insignificant expression of thymic stromal lymphopoietin and unchanged serum levels of IgE, suggesting non-immunogenic stimulation by sebum treatment. CONCLUSION: It may be concluded that inflammation induced by excess amount of sebum is more likely an irritant contact dermatitis rather than an allergic one. Moreover, these findings implicated possible relationships between sebum, irritant contact dermatitis, and seborrheic dermatitis.

Low concentration of arsenic-induced aberrant mitosis in keratinocytes through E2F1 transcriptionally regulated Aurora-A.

Chronic exposure to low-concentration arsenic promotes cell proliferation and carcinogenesis both in vitro and in vivo. Centrosome amplification, the major cause of chromosome instability, occurs frequently in cancers. Aurora-A is a mitotic kinase and causes centrosome amplification and chromosome instability when overexpressed. Our previous study revealed that low-concentration arsenic induces Aurora-A overexpression in immortalized bladder cells. In this study, we hypothesized that low-concentration arsenic induces aberrant mitosis in keratinocytes due to Aurora-A overexpression. The specimen of Bowen's disease (BD) and squamous cell carcinoma obtained from arseniasis-endemic areas in Taiwan showed Aurora-A overexpression. The mRNA/protein levels and kinase activity of Aurora-A were increased in immortalized keratinocyte HaCaT cells after arsenic treatment at low concentration (< 1µM). Aberrant spindles, multiple centrosomes, and multinucleated cells were detected under fluorescent microscopy in HaCaT cells after arsenic treatment. These findings were associated with increased expression of Aurora-A. We further revealed that Aurora-A was regulated by arsenic-induced transcriptional factor E2F1 as demonstrated by chromosome immunoprecipitation, promoter activity, and small interfering RNA assays. Finally, in arsenic-treated HaCaT cells and in BD, a significant increase of dysfunctional p53 was found, and this event correlated with the increase in expression of Aurora-A. Altogether, our data suggest that low concentration of arsenic induces activation of E2F1-Aurora-A axis and results in aberrant mitosis of keratinocytes. Overexpression of Aurora-A and dysfunctional p53 may act synergistically to trigger skin tumor formation. Our findings suggest that Aurora-A may be a potential target for the prevention and treatment of arsenic-related cancers.

Solanum incanum extract (SR-T100) induces human cutaneous squamous cell carcinoma apoptosis through modulating tumor necrosis factor receptor signaling pathway.

BACKGROUND: The Solanum species herbs have been used to treat cancer for centuries; however, the underlying mechanisms and effectiveness in vivo remain unclear. OBJECTIVES: SR-T100, extracted from the Solanum incanum, contains solamargine alkaloid as the main active ingredient. Here, we investigated the apoptosis-inducing effects of SR-T100 for targeting squamous cell carcinoma (SCC) in vitro and in vivo. METHODS: We elucidated the mechanism by which SR-T100 induces apoptosis of human SCCs (A431, SCC4, SCC9, and SCC25) cells. The efficacy and safety issues were addressed regarding topical treatment of SR-T100 on UVB-induced cutaneous SCC of hairless mice and actinic keratoses (AKs) of human. RESULTS: SR-T100 induces apoptosis in human SCCs cell lines by up-regulating the expressions of tumor necrosis factor receptors (TNFRs) and Fas, and downstream adaptors FADD/TRADD of the TNF-α and Fas ligand signaling cascades. SR-T100 also triggered the mitochondrial apoptotic pathway, as up-regulated cytochrome c and Bax, down-regulated Bcl-X(L). Animal experiments showed that all papillomas (35/35) and 27 of 30 UVB-induced microinvasive SCCs in hairless mice disappeared within 10 weeks after once-daily application of topical SR-T100. Furthermore, 13 patients, who suffered with 14 AKs, were treated with once-daily topical SR-T100 gel and 10 AKs cured after 16 weeks, showing negligible discomforts. CONCLUSION: Our studies indicate that SR-T100 induces apoptosis of SCC cells via death receptors and the mitochondrial death pathway. The high efficacy of SR-T100 in our preclinical trial suggests that SR-T100 is a highly promising herb for AKs and related disorders.

Oncogenic Ras-induced morphologic change is through MEK/ERK signaling pathway to downregulate Stat3 at a posttranslational level in NIH3T3 cells.

Ras is a key regulator of the MAP kinase-signaling cascade and may cause morphologic change of Ras-transformed cells. Signal transducer and activator of transcription 3 (Stat3) can be activated by cytokine stimulation. In this study, we unravel that Ha-ras(V12) overexpression can downregulate the expression of Stat3 protein at a posttranslational level in NIH3T3 cells. Furthermore, we demonstrate that Stat3 expression downregulated by Ha-ras(V12) overexpression is through proteosome degradation and not through a mTOR/p70S6K-related signaling pathway. The suppression of Stat3 accompanied by the morphologic change induced by Ha-ras(V12) was through mitogen extracellular kinase (MEK)/extracellular-regulated kinase (ERK) signaling pathway. Microtubule disruption is involved in Ha-ras(V12)-induced morphologic change, which could be reversed by overexpression of Stat3. Taken together, we are the first to demonstrate that Stat3 protein plays a critical role in Ha-ras(V12)-induced morphologic change. Oncogenic Ras-triggered morphologic change is through the activation of MEK/ERK to posttranslationally downregulate Stat3 expression. Our finding may shed light on developing novel therapeutic strategies against Ras-related tumorigenesis.

SUMO-1 overexpression increases RbAp46 protein stability and suppresses cell growth.

The retinoblastoma suppressor (Rb)-associated protein 46 (RbAp46) is a nuclear protein of 46 kDa and contains four repeats that end with Trp-Asp (WD) residues. In this study, we reveal that the RbAp46 protein level upon SUMO-1 expression was increased. The increasing level of RbAp46 protein by SUMO-1 was not regulated at the transcriptional level. SUMO-1 does not affect the degradation of RbAp46. Co-localization of RbAp46 and SUMO-1 in the nuclei of stable NIH/3T3 cells harboring the inducible Ha-ras(Val12) oncogene (pSVlacOras) designated as 7-4, and protein-protein interaction between RbAp46 and SUMO-1 was also detected by co-immunoprecipitation in these cells. However, SUMO-l-related sumoylation was not involved in the modification of RbAp46. It is possibly that SUMO-1 acts through formation of complex with RbAp46 to stabilize RbAp46 protein. Overexpression of RbAp46 protein suppressed the NIH/3T3 cell growth induced by Ha-Ras(V12). SUMO-1 further enhances the suppression of cell growth through stabilization of RbAp46 protein. This is the first report to demonstrate that SUMO-1 can suppress Ras-related cell proliferation through stabilization of RbAp46 protein.