Dissecting phenotypic transitions in metastatic disease via photoconversion-based isolation

Targeted Single-cell Isolation of Spontaneously Escaping Live Melanoma Cells for Comparative Transcriptomics

Solid cancer cells escape the primary tumor mass by transitioning from an epithelial-like state to an invasive migratory state. As they escape, metastatic cancer cells employ interchangeable modes of invasion, transitioning between fibroblast-like mesenchymal movement to amoeboid migration, where cells display a rounded morphology and navigate the extracellular matrix in a protease-independent manner. However, the gene transcripts that orchestrate the switch between epithelial, mesenchymal, and amoeboid states remain incompletely mapped, mainly due to a lack of methodologies that allow the direct comparison of the transcriptomes of spontaneously invasive cancer cells in distinct migratory states. Here, we report a novel single-cell isolation technique that provides detailed three-dimensional data on melanoma growth and invasion, and enables the isolation of live, spontaneously invasive cancer cells with distinct morphologies and invasion parameters. Via the expression of a photoconvertible fluorescent protein, compact epithelial-like cells at the periphery of a melanoma mass, elongated cells in the process of leaving the mass, and rounded amoeboid cells invading away from the mass were tagged, isolated, and subjected to single-cell RNA sequencing. A total of 462 differentially expressed genes were identified, from which two candidate proteins were selected for further pharmacologic perturbation, yielding striking effects on tumor escape and invasion, in line with the predictions from the transcriptomics data. This work describes a novel, adaptable, and readily implementable method for the analysis of the earliest phases of tumor escape and metastasis, and its application to the identification of genes underpinning the invasiveness of malignant melanoma.

Significance

This work describes a readily implementable method that allows for the isolation of individual live tumor cells of interest for downstream analyses, and provides the single-cell transcriptomes of melanoma cells at distinct invasive states, both of which open avenues for in-depth investigations into the transcriptional regulation of the earliest phases of metastasis.

Application of CRISPR screen in mechanistic studies of tumor development, tumor drug resistance, and tumor immunotherapy

Tumor is one of the biggest threats to human health. Though tumor therapy has been dramatically advanced by the progress of technology and research in recent decades, it is still far from expectations. Thus, it is of great significance to explore the mechanisms of tumor growth, metastasis, and resistance. Screen based on Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR-associated protein (Cas) 9 gene editing technology are powerful tools for exploring the abovementioned facets. This review summarizes the recent screen performed in cancer cells and immune cells in the tumor microenvironment. The screens in cancer cells mainly focus on exploring the mechanisms underlying cancer cells' growth, metastasis, and how cancer cells escape from the FDA approved drugs or immunotherapy. And the studies in tumor-associated immune cells are primarily aimed at identifying signaling pathways that can enhance the anti-tumor function of cytotoxic T lymphocytes (CTLs), CAR-T cells, and macrophages. Moreover, we discuss the limitations, merits of the CRISPR screen, and further its future application in tumor studies. Importantly, recent advances in high throughput tumor related CRISPR screen have deeply contributed to new concepts and mechanisms underlying tumor development, tumor drug resistance, and tumor immune therapy, all of which will eventually potentiate the clinical therapy for tumor patients.

Targeting lung cancer brain metastases: a narrative review of emerging insights for anaplastic lymphoma kinase (ALK)-positive disease

Background and Objective

Lung cancer is commonly associated with brain metastasis formation, and certain subtypes, such as anaplastic lymphoma kinase (ALK) rearranged disease, have an especially high propensity for early and frequent central nervous system (CNS) involvement for which treatment can be challenging. Historical management has centered on surgery and radiation therapy (RT), which persist as mainstays of treatment for large, symptomatic lesions and widespread CNS disease. To date, sustained disease control remains elusive, and the role for effective systemic adjunctive therapies is clear. Here we discuss the epidemiology, genomics, pathophysiology, identification, and management of lung cancer brain metastases with a particular emphasis on systemic treatment of ALK-positive disease according to the best available evidence.

Methods

Review of PubMed and Google Scholar databases as well as ClinicalTrials.gov provided background and seminal trials for the local and systemic management of ALK rearranged lung cancer brain metastases.

Key Content and Findings

The development of effective, CNS-penetrant systemic agents-including alectinib, brigatinib, ceritinib, and lorlatinib-has dramatically changed the management and prevention of ALK rearranged brain metastases. Most notably, there is a burgeoning role for upfront systemic therapy for both symptomatic and incidentally discovered lesions.

Conclusions

Novel targeted therapies offer patients a pathway to delay, obviate, or supplement traditional local therapies while minimizing neurologic sequelae of treatment and may reduce the risk of brain metastasis formation. However, the selection of patients to whom local and targeted treatments is offered is not trivial, and the risks and benefits of both must be weighed carefully. More work is needed to establish treatment regimens that yield durable intra- and extracranial disease control.

Redox Regulation in Cancer Cells during Metastasis

Metastasis is an inefficient process in which the vast majority of cancer cells are fated to die, partly because they experience oxidative stress. Metastasizing cancer cells migrate through diverse environments that differ dramatically from their tumor of origin, leading to redox imbalances. The rare metastasizing cells that survive undergo reversible metabolic changes that confer oxidative stress resistance. We review the changes in redox regulation that cancer cells undergo during metastasis. By better understanding these mechanisms, it may be possible to develop pro-oxidant therapies that block disease progression by exacerbating oxidative stress in cancer cells. SIGNIFICANCE: Oxidative stress often limits cancer cell survival during metastasis, raising the possibility of inhibiting cancer progression with pro-oxidant therapies. This is the opposite strategy of treating patients with antioxidants, an approach that worsened outcomes in large clinical trials.