MET Exon 14 Splice-Site Mutations Preferentially Activate KRAS Signaling to Drive Tumourigenesis.

Targeted therapies for MET exon 14-skipping (METΔex14)-driven lung cancers have generated some promising results but response rates remain below that seen for other kinase-driven cancers. One strategy for improving treatment outcomes is to employ rational combination therapies to enhance the suppression of tumour growth and delay or prevent the emergence of resistance. To this end, we profiled the transcriptomes of MET-addicted lung tumours and cell lines and identified the RAS-mitogen-activated protein kinase (MAPK) pathway as a critical effector required for METΔex14-dependent growth. Ectopic expression of MET in an isogenic cell line model showed that overexpression of the mutant MET receptor led to higher levels of MAPK phosphorylation and nuclear import, resulting in increased expression and phosphorylation of nuclear MAPK targets. In comparison, other known MET effectors were unaffected. Inhibition of this pathway by KRAS knockdown in MET-addicted cells in vitro led to decreased viability in only the METΔex14-mutant cells. Conversely, decoupling RAS-MAPK axis, but not other effector pathways, from MET activity via the introduction of constitutively active mutants conferred resistance to MET inhibitors in vitro. Our results suggest that aberrant hyperactivity of the MET receptor caused by the exon 14-skipping mutation does not uniformly upregulate all known downstream effectors, rather gaining a predilection for aberrantly activating and subsequently relying on the RAS-MAPK pathway. These findings provide a rationale for the co-targeting of the RAS-MAPK pathway alongside MET to prolong therapeutic response and circumvent resistance to improve patient survival.

Frailty in Parkinson's disease: A systematic review and meta-analysis.

INTRODUCTION: Frailty and Parkinson's disease (PD) are common conditions that increase with age. Independently, frailty and PD lead to increased morbidity and mortality for patients. Few studies report on frailty in patients with PD. We performed a systematic review and meta-analysis of the prevalence, associations and outcomes of frailty in persons with PD. METHODS: We searched four electronic databases and grey literature from inception to May 19, 2020, for articles which reported the prevalence, associations and outcomes of frailty in persons with PD. RESULTS: One-thousand and sixty-three citations were identified, of which 127 articles were reviewed. Thirty studies were included. Twenty-eight studies were observational and the settings varied including 25 community and 5 inpatient studies.The most common frailty screening measures were the frailty phenotype and clinical frailty scale. The prevalence of frailty in PD using the FP was 0.38 (0.24-0.55) with I2 = 92.6% (p < 0.01). Frailty was associated with recurrent falls, cognitive impairment, dementia, orthostatic hypotension, fatigue, hallucinations, nursing home placement, dependency in activities of daily living and in-patient mortality. PD disease duration, motor impairment, non-tremor dominant PD (postural instability/gait difficulty dominant phenotype) and total daily levodopa dose were associated with frailty. CONCLUSION: Frailty is common in PD. There is no agreed upon tool for identifying frailty, however, the importance of its identification is apparent given the high prevalence and the association between frailty and adverse outcomes in persons with PD. Future studies are required to guide clinicians in how best to identify and manage frail patients with PD.