TAS2940, a novel brain-penetrable pan-ERBB inhibitor, for tumors with HER2 and EGFR aberrations.

Genetic alterations in human epidermal growth factor receptor type 2 (HER2)/epidermal growth factor receptor (EGFR) are commonly associated with breast and lung cancers and glioblastomas. Cancers with avian erythroblastosis oncogene B (ERBB) deregulation are highly metastatic and can cause primary brain tumors. Currently, no pan-ERBB inhibitor with remarkable brain penetration is available. Here, TAS2940, a novel irreversible pan-ERBB inhibitor with improved brain penetrability, was evaluated for its efficacy against several ERBB aberrant cancer models. The selectivity of TAS2940 was evaluated by enzymatic kinase assays. The inhibitory effects of TAS2940 against ERBB genetic alterations were examined using MCF10A cells expressing various HER2 or EGFR mutations and other generic cell lines harboring deregulated ERBB expression. In vivo efficacy of TAS2940 was examined following oral treatment in subcutaneous or intracranial xenograft cancer models. TAS2940 was highly potent against cells harboring HER2/EGFR alterations. TAS2940 could selectively inhibit phosphorylation of targets and the growth of cancer cells with ERBB aberrations in vitro. TAS2940 also inhibited tumor growth in xenograft mouse models with ERBB aberrations: HER2 amplification, HER2/EGFR exon 20 insertions, and EGFR vIII mutation. TAS2940 was effective in the intracranial xenograft models of HER2/EGFR cancers and improved the survival of these mice. TAS2940 has promising therapeutic effects in preclinical study against cancers harboring HER2/EGFR mutations, especially metastatic and primary brain tumors. Our results highlight potential novel strategies against lung cancers with brain metastases harboring HER2/EGFR exon 20 insertions and glioblastomas with EGFR aberrations.

Age-related nitration/dysfunction of myogenic stem cell activator HGF.

Mechanical perturbation triggers activation of resident myogenic stem cells to enter the cell cycle through a cascade of events including hepatocyte growth factor (HGF) release from its extracellular tethering and the subsequent presentation to signaling-receptor c-met. Here, we show that with aging, extracellular HGF undergoes tyrosine-residue (Y) nitration and loses c-met binding, thereby disturbing muscle homeostasis. Biochemical studies demonstrated that nitration/dysfunction is specific to HGF among other major growth factors and is characterized by its locations at Y198 and Y250 in c-met-binding domains. Direct-immunofluorescence microscopy of lower hind limb muscles from three age groups of rat, provided direct in vivo evidence for age-related increases in nitration of ECM-bound HGF, preferentially stained for anti-nitrated Y198 and Y250-HGF mAbs (raised in-house) in fast IIa and IIx myofibers. Overall, findings highlight inhibitory impacts of HGF nitration on myogenic stem cell dynamics, pioneering a cogent discussion for better understanding age-related muscle atrophy and impaired regeneration with fibrosis (including sarcopenia and frailty).

A pilot study on nitration/dysfunction of NK1 segment of myogenic stem cell activator HGF.

Protein tyrosine residue (Y) nitration, a post-translational chemical-modification mode, has been associated with changes in protein activity and function; hence the accumulation of specific nitrated proteins in tissues may be used to monitor the onset and progression of pathological disorders. To verify the possible impact of nitration on postnatal muscle growth and regeneration, a pilot study was designed to examine the nitration/dysfunction of hepatocyte growth factor (HGF), a key ligand that is released from the extracellular tethering and activates myogenic stem satellite cells to enter the cell cycle upon muscle stretch and injury. Exposure of recombinant HGF (a hetero-dimer of α- and ß-chains) to peroxynitrite induces Y nitration in HGF α-chain under physiological conditions. Physiological significance of this finding was emphasized by Western blotting that showed the NK1 segment of HGF (including a K1 domain critical for signaling-receptor c-met binding) undergoes nitration with a primary target of Y198. Peroxynitrite treatment abolished HGF-agonistic activity of the NK1 segment, as revealed by in vitro c-met binding and bromodeoxyuridine-incorporation assays. Importantly, direct-immunofluorescence microscopy of rat lower hind-limb muscles from two aged-groups (2-month-old "young" and 12-month-old "retired/adult") provided in vivo evidence for age-related nitration of extracellular HGF (Y198). Overall, findings provide the insight that HGF/NK1 nitration/dysfunction perturbs myogenic stem cell dynamics and homeostasis; hence NK1 nitration may stimulate progression of muscular disorders and diseases including sarcopenia.