Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor that is a clinical target of major interest in cancer. Mutations and rearrangements in ALK trigger the activation of the encoded receptor and its downstream signaling pathways. ALK mutations have been identified in both familial and sporadic neuroblastoma cases as well as in 30 to 40% of relapses, which makes ALK a bona fide target in neuroblastoma therapy. Tyrosine kinase inhibitors (TKIs) that target ALK are currently in clinical use for the treatment of patients with ALK-positive non–small cell lung cancer. However, monotherapy with the ALK inhibitor crizotinib has been less encouraging in neuroblastoma patients with ALK alterations, raising the question of whether combinatorial therapy would be more effective. In this study, we established both phosphoproteomic and gene expression profiles of ALK activity in neuroblastoma cells exposed to first- and third-generation ALK TKIs, to identify the underlying molecular mechanisms and identify relevant biomarkers, signaling networks, and new therapeutic targets. This analysis has unveiled various important leads for novel combinatorial treatment strategies for patients with neuroblastoma and an increased understanding of ALK signaling involved in this disease.

The development of cancer begins with cells transitioning from their multicellular nature to a state akin to unicellular organisms. This shift leads to a breakdown in the crucial regulators inherent to multicellularity, resulting in the emergence of diverse cancer cell subpopulations that have enhanced adaptability. The presence of different cell subpopulations within a tumour, known as intratumoural heterogeneity (ITH), poses challenges for cancer treatment. In this review, we delve into the dynamics of the shift from multicellularity to unicellularity during cancer onset and progression. We highlight the role of genetic and non-genetic factors, as well as tumour microenvironment, in promoting ITH and cancer evolution. Additionally, we shed light on the latest advancements in omics technologies that allow for in-depth analysis of tumours at the single-cell level and their spatial organization within the tissue. Obtaining such detailed information is crucial for deepening our understanding of the diverse evolutionary paths of cancer, allowing for the development of effective therapies targeting the key drivers of cancer evolution.

Exposure to toxic metals and metalloids such as cadmium and arsenic results in widespread misfolding and aggregation of cellular proteins. How these protein aggregates are formed in vivo , the mechanisms by which they affect cells, and how cells prevent their accumulation during environmental stress is not fully understood. To find components involved in these processes, we performed a genome-wide imaging screen and identified yeast deletion mutants with either enhanced or reduced protein aggregation levels during arsenite exposure. Mutants with reduced aggregation levels were enriched for functions related to protein biosynthesis and transcription, whilst functions related to cellular signalling, metabolism, and protein folding and degradation were overrepresented among mutants with enhanced aggregation levels. On a genome-wide scale, protein aggregation correlated with arsenite resistance and sensitivity, indicating that many of the identified factors are crucial to safeguard protein homeostasis (proteostasis) and to protect against arsenite toxicity. Dedicated follow-up experiments indicated that intracellular arsenic is a direct cause of protein aggregation and that accurate transcriptional and translational control are crucial for proteostasis during arsenite stress. Specifically, we provide evidence that global transcription affects protein aggregation levels, that loss of transcriptional control impacts proteostasis through distinct mechanisms, and that translational repression is central to control protein aggregation and cell viability. Some of the identified factors are associated with pathological conditions suggesting that arsenite-induced protein aggregation may impact disease processes. The broad network of cellular systems that impinge on proteostasis during arsenic stress provides a valuable resource and a framework for further elucidation of the mechanistic details of metalloid toxicity and pathogenesis. AUTHOR SUMMARY: Human exposure to poisonous metals is increasing in many parts of the world and chronic exposure is associated with certain protein folding-associated disorders such as Alzheimer’s disease and Parkinson’s disease. While the toxicity of many metals is undisputed, their molecular modes of action have remained unclear. Recent studies revealed that toxic metals such as arsenic and cadmium profoundly affect the correct folding of proteins, resulting in the accumulation of toxic protein aggregates. In this study, we used high-content microscopy to identify a broad network of cellular systems that impinge on protein homeostasis and cell viability during arsenite stress. Follow-up experiments highlight the importance of accurate transcriptional and translational control for mitigating arsenite-induced protein aggregation and toxicity. Some of the identified factors are associated with pathological conditions suggesting that arsenite-induced protein aggregation may impact disease processes. The broad network of cellular systems that impinge on proteostasis during arsenic stress provides a valuable resource and a framework for further elucidation of the mechanistic details of metal toxicity and pathogenesis.