Protein kinase Cι (PKCι) is an oncogene in lung and ovarian cancers. PKCι is an attractive therapeutic target for treatment of lung cancer, particularly those whose tumors express elevated PKCι. However, it is unknown whether PKCι is a viable therapeutic target in the ovary, and virtually nothing is known about the mechanism by which PKCι drives ovarian tumorigenesis. Here, we demonstrate that PKCι maintains a tumor-initiating cell (TIC) phenotype that drives ovarian tumorigenesis. A highly tumorigenic population of cells from human ovarian cancer cell lines exhibit properties of cancer stem-like TICs including self-renewal, clonal expansion, expression of stem-related genes, enhanced transformed growth in vitro, and aggressive tumor-initiating activity in vivo. Genetic disruption of PKCι inhibits the proliferation, clonal expansion, anchorage-independent growth and enhanced tumorigenic properties of ovarian TICs. Biochemical analysis demonstrates that PKCι acts through its oncogenic partner Ect2 to activate a Mek-Erk signaling axis that drives the ovarian TIC phenotype. Genomic analysis reveals that PRKCI and ECT2 are coordinately amplified and overexpressed in the majority of primary ovarian serous tumors, and these tumors exhibit evidence of an active PKCι-Ect2 signaling axis in vivo. Finally, we demonstrate that auranofin is a potent and selective inhibitor of oncogenic PKCι signaling that inhibits the tumorigenic properties of ovarian TIC cells in vitro and in vivo. Our data demonstrate that PKCι is required for a TIC phenotype in ovarian cancer, and that auranofin is an attractive therapeutic strategy to target deadly ovarian TICs in ovarian cancer patients.

Protein kinase C alpha (PKCα) can activate both pro- and anti-tumorigenic signaling depending upon cellular context. Here, we investigated the role of PKCα in lung tumorigenesis in vivo. Gene expression data sets revealed that primary human non-small lung cancers (NSCLC) express significantly decreased PKCα levels, indicating that loss of PKCα expression is a recurrent event in NSCLC. We evaluated the functional relevance of PKCα loss during lung tumorigenesis in three murine lung adenocarcinoma models (LSL-Kras, LA2-Kras and urethane exposure). Genetic deletion of PKCα resulted in a significant increase in lung tumor number, size, burden and grade, bypass of oncogene-induced senescence, progression from adenoma to carcinoma and a significant decrease in survival in vivo. The tumor promoting effect of PKCα loss was reflected in enhanced Kras-mediated expansion of bronchio-alveolar stem cells (BASCs), putative tumor-initiating cells, both in vitro and in vivo. LSL-Kras/Prkca−/− mice exhibited a decrease in phospho-p38 MAPK in BASCs in vitro and in tumors in vivo, and treatment of LSL-Kras BASCs with a p38 inhibitor resulted in increased colony size indistinguishable from that observed in LSL-Kras/Prkca−/− BASCs. In addition, LSL-Kras/Prkca−/− BASCs exhibited a modest but reproducible increase in TGFβ1 mRNA, and addition of exogenous TGFβ1 to LSL-Kras BASCs results in enhanced growth similar to untreated BASCs from LSL-Kras/Prkca−/− mice. Conversely, a TGFβR1 inhibitor reversed the effects of PKCα loss in LSL-Kras/Prkca−/−BASCs. Finally, we identified the inhibitors of DNA binding (Id) Id1–3 and the Wilm’s Tumor 1 as potential downstream targets of PKCα-dependent tumor suppressor activity in vitro and in vivo. We conclude that PKCα suppresses tumor initiation and progression, at least in part, through a PKCα-p38MAPK-TGFβ signaling axis that regulates tumor cell proliferation and Kras-induced senescence. Our results provide the first direct evidence that PKCα exhibits tumor suppressor activity in the lung in vivo.

Transgenic insect‐resistant crops produced by combining two or more insect‐control traits through conventional breeding are increasingly common in commercial cultivation. In some countries, cultivation of crops with combined insect‐control traits may require additional regulatory risk assessments, even though all component traits are approved for cultivation, which requires, among other things, a demonstration that cultivation of the crop poses negligible ecological risk; that is, there is a low probability of harm to non‐target organisms. In such situations, cultivation of a crop with the combined traits will also pose negligible ecological risk, provided two hypotheses hold: the potency of the proteins when combined is not greater than when separate; and the exposure of non‐target organisms to the proteins is not greater when the traits are combined than when they are separate. The ecological risk assessment for combined traits may be based on tests of these hypotheses, comprising tests for synergism between the proteins in species sensitive to the proteins, and comparisons of protein production in plants with the combined traits and plants with the separate component traits. Tests of these hypotheses are illustrated using Bt11 × MIR604 maize, which produces the insecticidal proteins Cry1Ab and mCry3A. Results from synergism studies using European corn borer and Colorado potato beetle, and from comparisons of the concentrations of Cry1Ab and mCry3A in Bt11 × MIR604, Event Bt11 and Event MIR604 maize, indicate that risks to non‐target organisms from the cultivation of Bt11 × MIR604 maize are no greater than from the cultivation of Event Bt11 or Event MIR604 maize.

Melanoma is one of the most highly mutated cancer types. To identify functional drivers of melanoma, we searched for cross-species conserved mutations utilizing a mouse melanoma model driven by loss of PTEN and CDKN2A, and identified mutations in Kras, Erbb3, and Ptpn11. PTPN11 encodes the SHP2 protein tyrosine phosphatase that activates the RAS/RAF/MAPK pathway. Although PTPN11 is an oncogene in leukemia, lung, and breast cancers, its roles in melanoma are not clear. In this study, we found that PTPN11 is frequently activated in human melanoma specimens and cell lines and is required for full RAS/RAF/MAPK signaling activation in BRAF wild-type (either NRAS mutant or wild-type) melanoma cells. PTPN11 played oncogenic roles in melanoma by driving anchorage-independent colony formation and tumor growth. In Pten-and Cdkn2a-null mice, tet-inducible and melanocytespecific PTPN11 E76K expression significantly enhanced mela-noma tumorigenesis. Melanoma cells derived from this mouse model showed doxycycline-dependent tumor growth in nude mice. Silencing PTPN11 E76K expression by doxycycline withdrawal caused regression of established tumors by induction of apoptosis and senescence, and suppression of proliferation. Moreover, the PTPN11 inhibitor (SHP099) also caused regression of NRAS Q61K -mutant melanoma. Using a quantitative tyrosine phosphoproteomics approach, we identified GSK3a/ b as one of the key substrates that were differentially tyrosinephosphorylated in these experiments modulating PTPN11. This study demonstrates that PTPN11 plays oncogenic roles in melanoma and regulates RAS and GSK3b signaling pathways.Implications: This study identifies PTPN11 as an oncogenic driver and a novel and actionable therapeutic target for BRAF wild-type melanoma.