Networks of signal transducers determine the conversion of environmental cues into cellular actions. Among the main players in these networks are protein kinases, which can acutely and reversibly modify protein functions to influence cellular events. One group of kinases, the protein kinase C (PKC) family, have been increasingly implicated in the organization of signal propagation, particularly in the spatial distribution of signals. Examples of where and how various PKC isoforms direct this tier of signal organization are becoming more evident.
Soft-tissue sarcoma (STS) is a rare and heterogeneous group of tumours that comprise approximately 1% of all adult cancers, and encompass over 50 different subtypes. These tumours exhibit a wide range of differing behaviours and underlying molecular pathologies, and can arise anywhere in the body. Surgical resection is critical to the management of locoregional disease. In the locally advanced or metastatic disease settings, systemic therapy has an important role in the multidisciplinary management of sarcoma. Cytotoxic therapy that usually consists of doxorubicin and ifosfamide has been the mainstay of treatment for many years. However recent advances in molecular pathogenesis, the development of novel targeted therapies, changes in clinical trial design and increased international collaboration have led to the development of histology-driven therapy. Furthermore, genomic profiling has highlighted that some STS are driven by translocation, mutation or amplification and others have more complex and chaotic karyotypes. In this Review, we aim to describe the current gold standard treatment for specific STS subtypes as well as outline future promising therapies in the pipeline.
Bladder cancer is a heterogeneous group of tumours with at least 40 histological subgroups that leads to ~165,000 deaths worldwide each year 1. Patients with localized disease can be cured with surgical resection or radiotherapy, but such curative options are limited in the setting of recurrent disease or distant spread, in which case systemic therapy is used to control disease and palliate symptoms. Cytotoxic chemotherapy has been the mainstay of treatment for advanced bladder cancer, but high-quality evidence is lacking to inform the management of rare subgroups that are often excluded from studies. Advances in molecular pathology, the development of targeted therapies, and the resurgence of immunotherapy has led to the reclassification of bladder cancer subgroups and rigorous efforts to define predictive biomarkers for cancer therapies. In this Review, we present the current evidence for the management of conventional, variant, and divergent urothelial cancer subtypes, as well as nonurothelial bladder cancers, and discuss how the integration of genomic, transcriptomic and proteomic characterisation of bladder cancer could guide future therapies.
Protein kinase inhibitors represent a major class of targeted therapeutics that has made a positive impact on treatment of cancer and other disease indications. Among the promising kinase targets for further therapeutic development are members of the Protein Kinase C (PKC) family.The PKCs are central components of many signaling pathways that regulate diverse cellular functions including proliferation, cell cycle, differentiation, survival, cell migration, and polarity. Genetic manipulation of individual PKC isozymes has demonstrated that they often fulfill distinct, nonredundant cellular functions.11 Participation of PKC members in different intracellular signaling pathways reflects responses to varying extracellular stimuli, intracellular localization, tissue distribution, phosphorylation status, and intermolecular interactions. PKC activity, localization, phosphorylation, and/or expression are often altered in human tumors, and PKC isozymes have been implicated in various aspects of transformation, including uncontrolled proliferation, migration, invasion, metastasis, angiogenesis, and resistance to apoptosis. Despite the strong relationship between PKC isozymes and cancer, to date only atypical PKCiota has been shown to function as a bona fide oncogene, and as such is a particularly attractive therapeutic target for cancer treatment. In this review, we discuss the role of PKCiota in transformation and describe mechanism-based approaches to therapeutically target oncogenic PKCiota signaling in cancer.
The protein kinase TOR (target of rapamycin) is a key regulator of cell growth and metabolism with significant clinical relevance. In mammals, TOR signals through two distinct multi-protein complexes, mTORC1 and mTORC2 (mammalian TOR complex 1 and 2 respectively), the subunits of which appear to define the operational pathways. Rapamycin selectively targets mTORC1 function, and the emergence of specific ATP-competitive kinase inhibitors has enabled assessment of dual mTORC1 and mTORC2 blockade. Little is known, however, of the molecular action of mTORC2 components or the relative importance of targeting this pathway. In the present study, we have identified the mTORC2 subunit Sin1 as a direct binding partner of the PKC (protein kinase C) ε kinase domain and map the interaction to the central highly conserved region of Sin1. Exploiting the conformational dependence for PKC phosphorylation, we demonstrate that mTORC2 is essential for acute priming of PKC. Inducible expression of Sin1 mutants, lacking the PKC-interaction domain, displaces endogenous Sin1 from mTORC2 and disrupts PKC phosphorylation. PKB (protein kinase B)/Akt phosphorylation is also suppressed by these Sin1 mutants, but not the mTORC1 substrate p70(S6K) (S6 kinase), providing evidence that Sin1 serves as a selectivity adaptor for the recruitment of mTORC2 targets. This inducible selective mTORC2 intervention is used to demonstrate a key role for mTORC2 in cell proliferation in three-dimensional culture.
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