Ji Li

Diethylstilbestrol enhances melanogenesis via cAMP-PKA-mediating up-regulation of tyrosinase and MITF in mouse B16 melanoma cells.

BACKGROUND It is well known that melanin synthesis in melanoma cells is controlled by melanogenic enzymes, which regulate the cAMP-PKA signaling pathway. Estrogen was previously reported to upregulate melanogenesis that is associated with human skin pigmentation. OBJECTIVE To investigate the influence and mechanism of diethylstilbestrol (DES) on melanogenesis in mouse B16 melanoma cells. METHODS The effects of diethylstilbestrol on cell viability, melanin content, tyrosinase activity, cAMP level, expression of the tyrosinase family and microphthalmia related transcription factor (MITF) were measured in B16 melanoma. Estrogen receptor (ER) expression were detected in B16 melanoma and A375 melanoma. Diethylstilbestrol-induced melanin synthesis were evaluated in the presence and absence of H89 (a PKA-specific inhibitor) and ICI182, 780 (a pure ER antagonist). Tyrosinase activity, the mRNA levels of tyrosinase and MITF were evaluated in the presence and absence of H89. RESULTS In B16 cells, diethylstilbestrol increased cell proliferation, melanin synthesis, tyrosinase activity and expression of the tyrosinase family and MITF. ER expression have not difference in human and mouse melanoma. When ER were inhibited by ICI182, 780, DES-induced melanogenesis was significantly reduced. Diethylstilbestrol enhanced the level of cAMP. The upregulation of melanin content and tyrosinase activity stimulated by diethylstilbestrol was significantly attenuated in the presence of H89. Further, diethylstilbestrol-induced upregulation of tyrosinase and MITF were significantly attenuated when the PKA pathway was blocked. CONCLUSIONS Diethylstilbestrol can enhance melanin synthesis in melanoma cells. This effect is associated with activation of the cAMP-PKA pathway and upregulation of expression and activity of the melanogenesis-related enzyme tyrosinase and MITF.

Aquaporin‐3 gene and protein expression in sun‐protected human skin decreases with skin ageing

Backgroud/Objectives:  Aquaporin 3 (AQP3) is a protein implicated in skin hydration. AQP3 null mice have relatively dry skin, reduced skin elasticity, and delayed recovery of barrier function after removal of the stratum corneum which is also present in skin of old people. A feature of skin aging is the change in both water content and barrier function of the skin. We investigated the expression of aquaporin 3 in non sun‐exposed human skin, normal human keratinocytes and fibroblasts from different age groups to further understand the relationship between AQP3 and intrinsic skin aging.

Inhibition of CD147 Gene Expression via RNA Interference Reduces Tumor Cell Proliferation, Activation, Adhesion, and Migration Activity in the Human Jurkat T-Lymphoma Cell Line

CD147, a leukocyte surface molecule over-expressed in T-lymphoma cells, is reportedly associated with lymphocyte activation and proteinase production via interactions with fibroblasts and plays a role in stromal invasion by lymphoma cells. To determine the role of CD147 in the progression of T-lymphoma, we performed siRNA interference-mediated knockdown of CD147 in a CD147-expressing Jurkat T-cell line. CD147 knockdown resulted in the decreased proliferation and migration of Jurkat cells and reduced the adhesion of Jurkat cells to extracelluar matrix fibronectin in vitro. CD147-siRNA inhibited the activation of Jurkat cells via down-regulation of CD25 expression. Our results indicate that CD147 is involved in T-lymphoma progression, a finding useful in efforts to develop targeted therapies to treat patients with T-lymphoma.

RASSF1A suppresses melanoma development by modulating apoptosis and cell-cycle progression.

The tumor suppressor candidate gene Ras association domain family 1, isoform A (RASSF1A) encodes a microtubule‐associated protein that is implicated in the regulation of cell proliferation, migration, and apoptosis. Several studies indicate that down‐regulation of RASSF1A resulting from promoter hypermethylation is a frequent epigenetic abnormality in malignant melanoma. In this study, we report that compared with melanocytes in normal skins or benign skin lesions, RASSF1A is down‐regulated in melanoma tissues as well as cell lines, and its expression negatively correlates with lymph node metastasis. Following ectopic expression in RASSF1A‐deficient melanoma A375 cell line, RASSF1A reduces cell viability, suppresses cell‐cycle progression but enhances apoptotic cell death. In vivo, RASSF1A expression inhibits the tumorigenic potential of A375 cells in nude mice, which also correlates with decreased cell proliferation and increased apoptosis. On the molecular level, ectopic RASSF1A expression leads to differential expression of 209 genes, including 26 down‐regulated and 183 up‐regulated ones. Among different signaling pathways, activation of the apoptosis signal‐regulating kinase 1 (ASK1)/p38 MAP kinase signaling is essential for RASSF1A‐induced mitochondrial apoptosis, and the inhibition of the Akt/p70S6 kinase/eIF4E signaling is also important for RASSF1A‐mediated apoptosis and cell‐cycle arrest. This is the first study exploring the biological functions and the underlying mechanisms of RASSF1A during melanoma development. It also identifies potential targets for further diagnosis and clinical therapy. J. Cell. Physiol. 226: 2360–2369, 2011.

Proteome Analysis of Multidrug Resistance of Human Oral Squamous Carcinoma Cells Using CD147 Silencing

There is a correlation between the multidrug-resistance (MDR) of cancer cells and their enhanced invasive or metastatic potential. We studied the expression of CD147, a plasma membrane glycoprotein that plays a key role in tumor metastasis by stimulating the production of matrix metalloproteinases (MMPs), in sensitive human oral squamous KB and MDR derivative KB/V cells. Reverse transcription-PCR and flow cytometric analysis revealed that KB/V cells expressed CD147 at significantly higher levels than their parental KB cells. Using stable RNA interference, we succeeded in establishing a CD147 knock-down KB/V cell line (KB/VsiCD147). MTT colorimetric assay showed an increase in the chemosensitivity to vincristine (VCR), all transretinoic acid (ATRA), taxol, and 5-fluorouracil (5-Fu) of KB/VsiCD147 cells. Proteome analysis of KB, KB/V, and KB/VsiCD147 cell lines identified 21 differently expressed proteins. The enhanced expression of representative active proteins, GRP75 and CyPA, was confirmed by Western blotting and RT-PCR. In addition, pretreatment of KB/V cells with a CyPA-binding immunosuppressive drug, cyclosporine A (CsA), enhanced their chemosensitivity to VCR and 5-Fu. We document an abundance of molecules that interact with CD147 in the MDR of human oral squamous carcinoma cells. Additional studies are needed to investigate these novel target proteins of CD147.

Comparison of three problem-based learning conditions (real patients, digital and paper) with lecture-based learning in a dermatology course: a prospective randomized study from China.

Background: The precise effect and the quality of different cases used in dermatology problem-based learning (PBL) curricula are yet unclear. Aim: To prospectively compare the impact of real patients, digital, paper PBL (PPBL) and traditional lecture-based learning (LBL) on academic results and student perceptions. Methods: A total of 120 students were randomly allocated into either real-patients PBL (RPBL) group studied via real-patient cases, digital PBL (DPBL) group studied via digital-form cases, PPBL group studied via paper-form cases, or conventional group who received didactic lectures. Academic results were assessed through review of written examination, objective structured clinical examination and student performance scores. A five-point Likert scale questionnaire was used to evaluate student perceptions. Results: Compared to those receiving lectures only, all PBL participants had better results for written examination, clinical examination and overall performance. Students in RPBL group exhibited better overall performance than those in the other two PBL groups. Real-patient cases were more effective in helping develop students’ self-directed learning skills, improving their confidence in future patient encounters and encouraging them to learn more about the discussed condition, compared to digital and paper cases. Conclusion: Both real patient and digital triggers are helpful in improving students’ clinical problem-handling skills. However, real patients provide greater benefits to students.

Differential response of normal human epidermal keratinocytes and HaCaT cells to hydrogen peroxide-induced oxidative stress

Background.  Normal human epidermal keratinocytes (NHEKs) and HaCaT cells are the most common models used to study the effects of various factors on skin cells. These cell lines share some common characteristics, but little is known about their differences in handling hydrogen peroxide (H2O2)‐induced oxidative stress.

Protective role of AQP3 in UVA-induced NHSFs apoptosis via Bcl2 up-regulation

Aquaporin-3 (AQP3), a water/glycerol-transporting protein that facilitates water, urea, and glycerol transport, can inhibit arsenite-induced apoptosis by up-regulating Bcl-2. However, whether it has a protective role in ultraviolet A (UVA)-induced apoptosis in normal human skin fibroblasts is not known. In this study, we demonstrate that mild UVA treatment fails to induce oxidative cell stress and apoptosis in normal human skin fibroblasts (NHSFs) overexpressing AQP3. After severe UVA irradiation, there was an increase in oxidative cell stress and apoptosis when AQP3 levels decreased. We also found that silencing AQP3 sensitized NHSFs to low-dose UVA. Overexpressing AQP3 was protective against high-dose UVA-induced oxidative stress and apoptosis. Besides, we observed that Bcl-2 may be involved in UVA-induced apoptosis. Our findings suggested that the water/glycerol-transporting protein AQP3 plays a role in resistance to UVA-induced apoptosis.

Adverse effects of propranolol treatment for infantile hemangiomas in China

Objectives: The β-blocker propranolol was discovered to be highly effective for the treatment of infantile hemangiomas (IHs), since 2008. Although some side effects have been reported earlier, no serious side effects of its use have been reported so far in Asia, especially in China. To determine the safety of this therapy, the side effects were analyzed in 97 infants who used propranolol (2 mg kg−1·d−1) against hemangioma from 2010 to 2011. Materials and methods: Routine blood and urine tests, hepatic and renal function tests, myocardial enzyme, electrolytes and blood sugar levels at baseline were performed. Electrocardiogram monitoring was performed 48 h after administration of the first dose (2 mg kg−1·d−1). Every patient (n = 97) was required to report to the hospital once a month. Results: The following adverse effects were observed: bronchial hyperactivity (n = 5), cyanosis and cold extremities (n = 1), agranulocytosis (n = 1), and low body temperature (n = 1). These side effects were reported for the first time in Asia. Conclusions: Although propranolol is effective against IHs, its potential side effects should be considered and appropriate monitoring performed. Further studies need to be conducted to determine the optimal dose and duration of propranolol treatment for large and complex hemangiomas.

Depletion of CD147 sensitizes human malignant melanoma cells to hydrogen peroxide-induced oxidative stress.

BACKGROUND Increased sensitivity to reactive oxygen species (ROS) contributes to the effectiveness of therapeutic strategies in patients with malignant melanoma (MM). CD147, a cell surface receptor for cyclophilin A (CypA), is thought to exert antioxidant activities. OBJECTIVE To understand the influences and mechanisms of CD147 on proliferation, apoptosis and redox state of A375 cells under H(2)O(2)-induced oxidative stress. METHODS The effect of CD147 silencing on cell viability, apoptosis, the generation of ROS, superoxide dismutase (SOD) activity, and the malondialdehyde (MDA) level that reflects oxidative damage, was measured in human malignant melanoma cell line A375 treated or untreated with hydrogen peroxide (H(2)O(2)). RESULTS In A375 cells, CD147 silencing increased the H(2)O(2)-induced inhibition of cell viability, H(2)O(2)-induced apoptosis, H(2)O(2)-mediated ROS- and MDA generation, and the H(2)O(2)-triggered decrease in SOD activity. CONCLUSIONS Our results demonstrated that CD147 silencing increased cellular ROS and destroyed the intrinsic antioxidant defenses in A375, indicating that CD147 exerts a cytoprotective effect against H(2)O(2)-induced oxidative damage.