Targeting the Structural Maturation Pathway of HIV-1 Reverse Transcriptase.

Formation of active HIV-1 reverse transcriptase (RT) proceeds via a structural maturation process that involves subdomain rearrangements and formation of an asymmetric p66/p66' homodimer. These studies were undertaken to evaluate whether the information about this maturation process can be used to identify small molecule ligands that retard or interfere with the steps involved. We utilized the isolated polymerase domain, p51, rather than p66, since the initial subdomain rearrangements are largely limited to this domain. Target sites at subdomain interfaces were identified and computational analysis used to obtain an initial set of ligands for screening. Chromatographic evaluations of the p51 homodimer/monomer ratio support the feasibility of this approach. Ligands that bind near the interfaces and a ligand that binds directly to a region of the fingers subdomain involved in subunit interface formation were identified, and the interactions were further characterized by NMR spectroscopy and X-ray crystallography. Although these ligands were found to reduce dimer formation, further efforts will be required to obtain ligands with higher binding affinity. In contrast with previous ligand identification studies performed on the RT heterodimer, subunit interface surfaces are solvent-accessible in the p51 and p66 monomers, making these constructs preferable for identification of ligands that directly interfere with dimerization.

Structure-activity relationship study of DEL-22379: ERK dimerization inhibitors with increased safety.

Aberrant activation of ERK signaling pathway usually leads to oncogenesis, and small molecular agents targeting this pathway are impeded by the emergence of drug resistance due to reactivation of ERK signaling. Compound DEL-22379 has been reported to inhibit ERK dimerization which was unaffected by drug-resistant mechanism reactivating the ERK signaling. Here, we discussed a structure-activity relationship study of DEL-22379. Forty-seven analogues were designed and synthesized. Each synthesized compound was biologically evaluated for their inhibitory rates on several tumor cell lines and compounds with high inhibitory rates were further evaluated for IC50 values. The structure-activity relationship of idolin-2-one scaffold and the impact of Z/E configuration on potency were discussed. Potential safety of two synthesized analogues was investigated and in silico docking study of five compounds was performed to understand the structural basis of ERK dimerization inhibition.

Tumors topple when ERKs uncouple.

Current antitumor therapies targeting the RAS-ERK pathway have been mostly aimed at inhibiting the activity of the kinases that populate the route. A small-molecule inhibitor of ERK dimerization effectively prevents the progression of tumors harboring oncogenic RAS and BRAF, demonstrating that targeting regulatory protein-protein interactions can be a valid strategy for treating RAS-ERK pathway-driven neoplasia.

Changes in signal transducer and activator of transcription 3 (STAT3) dynamics induced by complexation with pharmacological inhibitors of Src homology 2 (SH2) domain dimerization.

The activity of the transcription factor signal transducer and activator of transcription 3 (STAT3) is dysregulated in a number of hematological and solid malignancies. Development of pharmacological STAT3 Src homology 2 (SH2) domain interaction inhibitors holds great promise for cancer therapy, and a novel class of salicylic acid-based STAT3 dimerization inhibitors that includes orally bioavailable drug candidates has been recently developed. The compounds SF-1-066 and BP-1-102 are predicted to bind to the STAT3 SH2 domain. However, given the highly unstructured and dynamic nature of the SH2 domain, experimental confirmation of this prediction was elusive. We have interrogated the protein-ligand interaction of STAT3 with these small molecule inhibitors by means of time-resolved electrospray ionization hydrogen-deuterium exchange mass spectrometry. Analysis of site-specific evolution of deuterium uptake induced by the complexation of STAT3 with SF-1-066 or BP-1-102 under physiological conditions enabled the mapping of the in silico predicted inhibitor binding site to the STAT3 SH2 domain. The binding of both inhibitors to the SH2 domain resulted in significant local decreases in dynamics, consistent with solvent exclusion at the inhibitor binding site and increased rigidity of the inhibitor-complexed SH2 domain. Interestingly, inhibitor binding induced hot spots of allosteric perturbations outside of the SH2 domain, manifesting mainly as increased deuterium uptake, in regions of STAT3 important for DNA binding and nuclear localization.

Molecular insights into dimerization inhibition of c-Maf transcription factor.

The Maf protein family belongs to the activator protein 1 (AP-1) superfamily of transcription factors that bind specific DNA target sequences through a basic region and exploit a leucine zipper (LZ) motif for protein-protein interactions leading to homo- or hetero-dimerization. Mafs unique DNA-binding domain contains a highly conserved extended homology region (EHR) that allows to recognize longer DNA sequences than other basic leucine zipper (bZIP) transcription factors. Inspired by the fact that overexpression of Mafs is observed in about 50% of cases of multiple myeloma, a hematological malignant disorder, we undertook a peptide inhibitor approach. The LZ domain of c-Maf, one of large Mafs, was produced by solid phase peptide synthesis. We characterized its secondary structure and dimerization properties, and found that dimerization and folding events are strictly coupled. Moreover, potential peptidic c-Maf dimerization inhibitors were computationally designed and synthesized. These compounds were demonstrated by circular dichroism (CD) spectroscopy and MALDI-TOF mass spectrometry to bind to c-Maf LZ monomers, to drive folding of their partially disordered structure and to efficiently compete with dimerization, suggesting a way for interfering with the function of c-Maf and, more generally, of intrinsically disordered proteins, till now considered undruggable targets.

Pertuzumab for the treatment of breast cancer.

HER2-targeted therapies have revolutionized the outcome of patients with HER2-positive breast cancer. Pertuzumab is the first in a new class of monoclonal antibodies that target the extracellular dimerization domain of HER2 receptors, also known as HER dimerization inhibitors. The development of pertuzumab and preclinical and clinical data in breast cancer are reviewed. Regulatory affairs related to pertuzumab and the recent accelerated approval granted by the FDA for the treatment of breast cancer in the neoadjuvant setting are also covered. This process opens doors for further approvals which could considerably shorten the time between initial drug development and availability.

Pertuzumab, primer inhibidor de la dimerización HER / Pertuzumab, first HER dimerization inhibitor

Entre un 15 y un 20% de pacientes con cáncer de mama presentan amplificación o sobre expresión de HER2, lo que le confiere un comportamiento más agresivo. Pese a que el advenimiento del trastuzumab, primer agente dirigido contra HER2, mejoró significativamente el pronóstico de este grupo de pacientes, el 50% de ellas aún progresa dentro del año de tratamiento. Pertuzumab, el primer inhibidor de la dimerización de HER2, muestra un mecanismo de acción complementario a trastuzumab, logrando mejores resultados clínicos en pacientes tratadas con ambos agentes anti-HER2 y quimioterapia. El presente trabajo repasa las propiedades de pertuzumab y su desarrollo clínico.

Approximately 15 to 20% of breast cancers present amplificationor overexpression of HER2, and these tumoursshow a more aggressive behavior. Trastuzumab, the firsttargeted agent against HER2, significantly improved prognosisfor these patients, but still around 50% shows diseaseprogression within the first year of treatment. Pertuzumab,the first HER2 dimerization inhibitor, has a mechanismof action that is complementary to that of trastuzumab,achieving enhanced efficacy for patients treated with bothanti-HER2 agents and chemotepapy. This work reviews themain aspects of pertuzumab and its clinical development.