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Sunlight exposure is a significant risk factor for UV-induced deteriorating transformations of epidermal homeostasis leading to skin carcinogenesis. The ability of UVB radiation to cause melanoma, as well as basal and squamous cell carcinomas, makes UVB the most harmful among the three known UV ranges. UVB-induced DNA mutations and dysregulation of signaling pathways contribute to skin cancer formation. Among various signaling pathways modulated by UVB, tyrosine phosphorylation signaling which is mediated by the action of protein tyrosine kinases (PTKs) on specific tyrosine residues is highly implicated in photocarcinogenesis. Following UVB irradiation, PTKs get activated and their downstream signaling pathways contribute to photocarcinogenesis by promoting the survival of damaged keratinocytes and increasing cell proliferation. While UVB activates oncogenic signaling pathways, it can also activate tumor suppressive signaling pathways as initial protective mechanisms to maintain epidermal homeostasis. Tyrosine dephosphorylation is one of the protective mechanisms and is mediated by the action of protein tyrosine phosphatases (PTPs). PTP can counteract UVB-mediated PTK activation and downregulate oncogenic signaling pathways. However, PTPs have not been studied extensively in photocarcinogenesis with previous studies regarding their inactivation induced by UVB. This current review will summarize the recent progress in the protective function of PTPs in epidermal photocarcinogenesis.

Supplementary Table 1 from (3-Chloroacetyl)-indole, a Novel Allosteric AKT Inhibitor, Suppresses Colon Cancer Growth In Vitro and In Vivo

Ornithine decarboxylase (ODC) is a rate-limiting enzyme in the first step of polyamine biosynthesis that is associated with cell growth and tumor formation. Existing catalytic inhibitors of ODC have lacked efficacy in clinical testing or displayed unacceptable toxicity. In this study, we report the identification of an effective and nontoxic allosteric inhibitor of ODC. Using computer docking simulation and an in vitro ODC enzyme assay, we identified herbacetin, a natural compound found in flax and other plants, as a novel ODC inhibitor. Mechanistic investigations defined aspartate 44 in ODC as critical for binding. Herbacetin exhibited potent anticancer activity in colon cancer cell lines expressing high levels of ODC. Intraperitoneal or oral administration of herbacetin effectively suppressed HCT116 xenograft tumor growth and also reduced the number and size of polyps in a mouse model of APC-driven colon cancer (ApcMin/+). Unlike the well-established ODC inhibitor DFMO, herbacetin treatment was not associated with hearing loss. Taken together, our findings defined the natural product herbacetin as an allosteric inhibitor of ODC with chemopreventive and antitumor activity in preclinical models of colon cancer, prompting its further investigation in clinical trials. Cancer Res; 76(5); 1146–57. ©2015 AACR.

Supplementary Figures 1-3 from Ribosomal S6 Kinase 2 Is a Key Regulator in Tumor Promoter–Induced Cell Transformation

PDF file - 309K, The protein phosphorylation spectrum activated by UVA, UVB or SUV irradiation. N/TERT-1 cells were irradiated with UVA (60 kJ/m2), UVB (3.6 kJ/m2) or SUV (60 kJ UVA/m2/3.6 kJ UVB/m2). Protein extracts (500 μg) were used for phospho-kinase protein array analysis. Array spots were visualized by ECL kit. The density of the each duplicated array spot in Figure 3A was measured as described in Materials and Methods. The table shows the fold change in SUV-induced phosphorylation of all 46 kinases and transcription factors compared to untreated control (i.e., value of 1). Data are shown as an average of duplicate samples.

Supplementary Figure 1 from Phosphorylation of H2AX at Ser139 and a New Phosphorylation Site Ser16 by RSK2 Decreases H2AX Ubiquitination and Inhibits Cell Transformation

Supplementary Methods from Transient Receptor Potential Type Vanilloid 1 Suppresses Skin Carcinogenesis

Supplementary Figure 1 from Extracellular Signal-Regulated Kinase 8–Mediated c-Jun Phosphorylation Increases Tumorigenesis of Human Colon Cancer

Supplementary Figure Legend from Extracellular Signal-Regulated Kinase 8–Mediated c-Jun Phosphorylation Increases Tumorigenesis of Human Colon Cancer

Supplementary Figure 2 from Cyclin-Dependent Kinase 3–Mediated Activating Transcription Factor 1 Phosphorylation Enhances Cell Transformation

The effect of herbacetin or DFMO on hearing in C57BL/6 mice as measured by PPI. Vehicle, herbacetin (100 mg/kg B.W. p.o. or 2 mg/kg B.W. i.p.) or DFMO (1 g/kg B.W. p.o.) was administered by gavage or intraperitoneal injection 5 times per week for 5 weeks. (A) DFMO significantly decreased hearing (measured as prepulse inhibition or PPI) on day 35. Hearing as measured by PPI was not affected by oral administration (B) or intraperitoneal injection (C) of herbacetin. Data are shown as mean values {plus minus} S.E. The asterisk (*) indicates a significant decrease (p < 0.05) in hearing in DFMO-treated mice compared to the vehicle-treated group.

Supplemental Materials and Methods

Supplementary Methods from Phosphorylation of H2AX at Ser139 and a New Phosphorylation Site Ser16 by RSK2 Decreases H2AX Ubiquitination and Inhibits Cell Transformation

PDF file - 45K, Identification of transgenic mice. The transgenic mice were identified by the tail test method. The tail (1 cm) was cut when the mouse was 12 d old. The genomic DNA was extracted using lysis buffer (100 mM Tris-HCl pH 8.5, 5 mM EDTA, 0.2% SDS, and 200 mM NaCl) with Proteinase K. K14 forward and reverse primers were used for PCR and ras was amplified as a control.

The effect of herbacetin on AP-1 upstream proteins. Colon cancer cells were treated with herbacetin for 48 h and expression of total and phosphorylated ERKs and RSK and total ODC was determined by Western blotting. Beta-Actin was used as a loading control. Similar results were obtained from 3 independent experiments and representative blots are shown.

Supplementary Figure 2 from Resveratrol, a Red Wine Polyphenol, Suppresses Pancreatic Cancer by Inhibiting Leukotriene A4 Hydrolase

PDF file - 148K, Screening of HI-TOPK compounds for inhibition of TOPK kinase activity.

PDF file - 304K, The protein phosphorylation spectrum activated by SUV irradiation at various time points. N/TERT-1 cells were irradiated with SUV (60 kJ UVA/m2/3.6 kJ UVB/m2) and harvested at various times to produce a time course. Protein extracts (500 μg) were used for phospho-kinase array analysis. Array spots were visualized by ECL kit. The density of the each duplicated array spot in Figure 4A was measured as described in Materials and Methods. The table shows the fold change in SUV-induced phosphorylation of all 46 kinases and transcription factors compared to untreated control. Data are shown as an average of duplicate samples.

Supplementary Figure 1 from A Regulatory Mechanism for RSK2 NH2-Terminal Kinase Activity

Supplementary Table 1 from A Regulatory Mechanism for RSK2 NH2-Terminal Kinase Activity

Supplementary Figure 3 from Cyclin-Dependent Kinase-3–Mediated c-Jun Phosphorylation at Ser63 and Ser73 Enhances Cell Transformation

Supplemental Figure Legend

Supplementary Figure 3 from Resveratrol, a Red Wine Polyphenol, Suppresses Pancreatic Cancer by Inhibiting Leukotriene A4 Hydrolase

Supplementary Figure 2 from Cyclin-Dependent Kinase-3–Mediated c-Jun Phosphorylation at Ser63 and Ser73 Enhances Cell Transformation

Blockade of the transient receptor potential channel vanilloid subfamily 1 (TRPV1) is suggested as a therapeutic approach to pain relief. However, TRPV1 is a widely expressed protein whose function might be critical in various nonneuronal physiologic conditions. The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is overexpressed in many human epithelial cancers and is a potential target for anticancer drugs. Here, we show that TRPV1 interacts with EGFR, leading to EGFR degradation. Notably, the absence of TRPV1 in mice results in a striking increase in skin carcinogenesis. The TRPV1 is the first membrane receptor shown to have a tumor-suppressing effect associated with the down-regulation of another membrane receptor. The data suggest that, although a great deal of interest has focused on TRPV1 as a target for pain relief, the chronic blockade of this pain receptor might increase the risk for cancer development. [Cancer Res 2009;69(3):905–13]

Supplementary Figure Legends 1-2 from Phosphorylation of H2AX at Ser139 and a New Phosphorylation Site Ser16 by RSK2 Decreases H2AX Ubiquitination and Inhibits Cell Transformation

Effect of herbacetin on activity of various kinases. Herbacetin has no effect on (A) CHK1, (B) EGFR, (C) GSK3beta, (D) JNK1, (E) JNK2, (F) ERK1, (G) ERK2, (H) MEK1, (I) AKT1, (J) AKT2, (K) RSK2, (L) p38 or (M) PI3-K kinase activity or on (N) AdoMetDC activity. The effect of herbacetin on kinase or enzyme activity was determined by using an in vitro kinase or enzyme assay. All data are represented as mean values {plus minus} S.D. of values from duplicates experiments.

PDF file - 105K, Chemical structure of 36 HI-TOPK compounds.

Supplementary Figure 2 from Transient Receptor Potential Type Vanilloid 1 Suppresses Skin Carcinogenesis

Supplementary Data 1 from [6]-Gingerol Suppresses Colon Cancer Growth by Targeting Leukotriene A4 Hydrolase

Supplementary Figure 3 from Nuclear Factor of Activated T3 Is a Negative Regulator of Ras-JNK1/2-AP-1–Induced Cell Transformation

Supplementary Figure 3 from Transient Receptor Potential Type Vanilloid 1 Suppresses Skin Carcinogenesis

PDF file - 63K, Effect of HI-TOPK-032 on AP1, NF-kB or COX2 reporter activity in colon cancer cells.

The effect of herbacetin on cell cycle. The effect of herbacetin or DFMO on cell cycle was determined using HCT116, DLD1 or HT29 colon cancer cells. Cells were treated with herbacetin or DFMO for 48 h in medium supplemented with 10% FBS and then cells were serum starved for 24 h in medium supplemented with 0.5% FBS. Cells were stained with propidium iodide (PI) and cell cycle was analyzed by Fluorescence Activated Cell Sorting (FACS). All data are represented as mean values {plus minus} S.D. of triplicate values from 3 independent experiments. The asterisk (*) indicates a significant effect (p < 0.05) of herbacetin or DFMO compared to untreated control.

Supplementary Figure 1 from Resveratrol, a Red Wine Polyphenol, Suppresses Pancreatic Cancer by Inhibiting Leukotriene A4 Hydrolase

PDF file - 51K, Representative photographs of tumor-bearing athymic nude mouse treated or not treated with HI-TOPK-032.