The Hedgehog (Hh) pathway has emerged as a new target in cancer treatment, since it is hyperactivated in cancer stem cells (CSCs) in several tumors. The major issues in Hh-antagonist development are drug-resistant Smo mutations and Gli1 hyperactivation. The clinical development of Smo antagonists has often failed because of different issues including pharmacokinetics, low selectivity on CSCs or drug resistance. The development of new modulators of Hh pathway has emerged as a more promising approach to cancer therapy. The in silico screening of an in house library toward the Smo and Gli1 proteins identified several potential Hh-inhibitors, among which, glabrescione B and vismione E showed the best activity in vitro tests, but we focused on the former, since the latter displayed chemical instability. The objective of this proposal is the development and optimization of new Smo and/or Gli-antagonists by the rational structure-based design and synthesis of several derivatives of the two lead compounds. A multidisciplinary research team which owns expertise in organic synthesis, computational chemistry, molecular and structural biology, will identify new Hh-modulators by a computational approach: these compounds will be later synthetized mainly through organometallic catalysis, and then evaluated in vitro. The discovery and development of new green, atom-economic or high efficient chemical reactions is a priority, in order to optimize the synthetic process and minimize the wastes. Potency, specificity and pharmaceutical properties of selected candidates will be optimized by computational design, organic chemistry and biopharmaceutical studies. Most promising compounds will be tested in vitro and in vivo for their efficacy against the Hh-dependent tumors. The subsequent step will be the development of new formulation platforms that are suitable for permitting the drug delivery to the brain, a crucial issue in the administration of drugs for the treatment of brain tumors.
The project brings together three research teams and partners across different technologies and disciplines, with strong experience in their specific fields of research. Hh pathway is crucial for embryonic development, stem cell biology, and tumorigenesis. Aberrant activation of the Hh signalling has been linked to different aspects of cancer development, from initiation to metastasis, in the maintenance and regulation of CSCs in several types of tumors. For all these reasons, Hh pathway has emerged as a druggable target for anticancer therapy. A critical goal in Hh-dependent tumor biology is the discovery of novel antagonists blocking the pathway both at upstream and downstream level. The current development of new Smo antagonists associated with Hh pathway activation represents a major challenge for cancer therapy, because most clinical data have been discouraging. Moreover, transcription factors are generally considered interesting targets in drug discovery and Gli factors are among the most promising targets for the development of new anticancer therapies. The results expected from this proposal will have a remarkable impact on human health and on the progress of clinical treatments of a variety of malignancies with bad prognosis. One of the most detrimental effects of conventional chemotherapy is represented by the systemic toxicity of available anticancer drugs, which is ascribable to off-target distribution and unspecific activity in healthy cells. On the contrary, the bioactive molecules we intend to identify and synthesize in this proposal are endowed with very specific inhibition activity on cellular mechanisms that are activated only in cancer cells. Thus, the toxicity is expected to be negligible, yielding more efficient therapies and higher patient acceptability. These novel drugs targeting Gli proteins, the final and the most powerful effectors of the Hh pathway, would be beneficial for a wide spectrum of patients, whose tumors have either high Gli activity with an intact Ptch/Smo axis or with mutations at different critical points of the pathway. Hence, the identification of novel Smo/Gli1 inhibitors, acting individually or in a combined fashion, could represent a newsworthy strategy for targeting Hh-dependent tumors and CSCs, increasing drug selectivity and lowering adverse side effects. Furthermore, we have planned the administration of these bioactive molecules with dedicated nanovehicles that should further enhance their site-activity in the tumor. From the translational point of view the new knowledge, the technology and therapeutic tools expected from this project will find their potential application in: i) design and sustainable synthesis of natural compounds; ii) identification of novel Smo and Gli antagonists targeting CSCs and able to overcome the resistance to conventional Hh antagonists; iii) development of new therapeutic strategies in the treatment of Hh-driven tumors including smart nanocarriers that are designed to enhance the drug biodistribution to the tumor tissue. In addition, the synthesis of NCE through sustainable chemistry represents an important scientific and technologic progress for the environment, through green chemistry. Moreover, the use of low-molecular-weight phenols as starting materials for the production of molecules of pharmaceutical interest is particularly attractive in consideration that they can be exctacted from natural sources, including agro-industrial wastes such as olive mill waste-waters, chestnut and pomegranate by-products. The recovery of these compounds could allow the conversion of useless wastes into high added-value products with environmental and economic benefits. The project possesses strong potential for translation to clinical development of novel therapeutic approaches for MB and other cancers. In fact, while this project holds a basic research profile, the outcomes we will generate can have high intellectual properties content that can provide a number of patent applications, including novel selective drugs for cancer treatment, novel synthetic procedures for drug production and novel formulation approaches. Furthermore, the project has a remarkable impact on public health that stems from the unmet need to provide efficient and reliable therapeutic approaches to a disease that has, to date, no efficient and definitive treatment.