Cancer Biology


Protocols in Current Issue
Protocols in Past Issues
0 Q&A 584 Views Jan 20, 2024

The blood–brain barrier (BBB) is a major obstacle to the diagnostics and treatment of many central nervous system (CNS) diseases. A prime example of this challenge is seen in glioblastoma (GBM), the most aggressive and malignant primary brain tumor. The BBB in brain tumors, or the blood–brain–tumor barrier (BBTB), prevents the efficient delivery of most therapeutics to brain tumors. Current strategies to overcome the BBB for therapeutic delivery, such as using hyperosmotic agents (mannitol), have impeded progress in clinical translation limited by the lack of spatial resolution, high incidences of complications, and potential for toxicity. Focused ultrasound combined with intravenously administered microbubbles enables the transient disruption of the BBB and has progressed to early-phase clinical trials. However, the poor survival with currently approved treatments for GBM highlights the compelling need to develop and validate treatment strategies as well as the screening for more potent anticancer drugs. In this protocol, we introduce an optical method to open the BBTB (OptoBBTB) for therapeutic delivery via ultrashort pulse laser stimulation of vascular targeting plasmonic gold nanoparticles (AuNPs). Specifically, the protocol includes the synthesis and characterization of vascular-targeting AuNPs and a detailed procedure of optoBBTB. We also report the downstream characterization of the drug delivery and tumor treatment efficacy after BBB modulation. Compared with other barrier modulation methods, our optical approach has advantages in high spatial resolution and minimally invasive access to tissues. Overall, optoBBTB allows for the delivery of a variety of therapeutics into the brain and will accelerate drug delivery and screening for CNS disease treatment.

Key features

• Pulsed laser excitation of vascular-targeting gold nanoparticles non-invasively and reversibly modulates the blood–brain barrier permeability.

• OptoBBTB enhances drug delivery in clinically relevant glioblastoma models.

• OptoBBTB has the potential for drug screening and evaluation for superficial brain tumor treatment.

Graphical overview

0 Q&A 843 Views Aug 5, 2023

Resistance of acute lymphoblastic leukemia (ALL) cells to chemotherapy, whether present at diagnosis or acquired during treatment, is a major cause of treatment failure. Primary ALL cells are accessible for drug sensitivity testing at the time of new diagnosis or at relapse, but there are major limitations with current methods for determining drug sensitivity ex vivo. Here, we describe a functional precision medicine method using a fluorescence imaging platform to test drug sensitivity profiles of primary ALL cells. Leukemia cells are co-cultured with mesenchymal stromal cells and tested with a panel of 40 anti-leukemia drugs to determine individual patterns of drug resistance and sensitivity (“pharmacotype”). This imaging-based pharmacotyping assay addresses the limitations of prior ex vivo drug sensitivity methods by automating data analysis to produce high-throughput data while requiring fewer cells and significantly decreasing the labor-intensive time required to conduct the assay. The integration of drug sensitivity data with genomic profiling provides a basis for rational genomics-guided precision medicine.

Key features

• Analysis of primary acute lymphoblastic leukemia (ALL) blasts obtained at diagnosis from bone marrow aspirate or peripheral blood.

• Experiments are performed ex vivo with mesenchymal stromal cell co-culture and require four days to complete.

• This fluorescence imaging–based protocol enhances previous ex vivo drug sensitivity assays and improves efficiency by requiring fewer primary cells while increasing the number of drugs tested to 40.

• It takes approximately 2–3 h for sample preparation and processing and a 1.5-hour imaging time.

Graphical overview

BM: bone marrow; PB: peripheral blood; ALL: acute lymphoblastic leukemia; MNCs: mononuclear cells, which include leukemia cells when present; MSCs: mesenchymal stromal cells; LC50: drug concentration that kills 50% of the leukemia cells

0 Q&A 4304 Views Aug 5, 2019
Photodynamic therapy (PDT), is a clinically-approved light-based anti-cancer treatment modality in which a photoactivatable photosensitizer is irradiated with an appropriate wavelength of light to generate cytotoxic molecules to kill cancer cells. In this article, we describe an in vitro PDT protocol using a 3-dimensional (3D) model of ovarian cancer that was established on beds of Matrigel. PDT was performed using a liposomal formulation of verteporfin photosensitizer (Visudyne®). The cancer cells were genetically-labeled with the fluorescent protein mCherry to facilitate the evaluation of the treatment response. This protocol is advantageous because the mCherry fluorescence is an indicator of cell viability, eliminating the need for external dyes, which often exhibit limited penetration and diffusion into 3D organoids. Additionally, Visudyne PDT achieves significant tumor-killing efficacy in a 3D model for ovarian cancer.
0 Q&A 12241 Views May 20, 2015
The expression of genes is frequently manipulated in cell lines to study their cellular functions. The use of exogenous small Interfering RNAs (siRNAs) is a very efficient technique to temporarily downregulate the expression of genes of interest [reviewed by Hannon and Rossi (2004)]. A genome-wide siRNA library allows the user to study both the effect of each individual gene on a particular cell phenotype in a high throughput manner and also assess its phenotypic effect relative to all other genes targeted. Several factors that potentially influence the outcome of a screen need to be considered when performing a large siRNA screen (Jiang et al., 2011). Here we present a detailed protocol for a genome-wide screen to identify genes involved in anti-cancer drug resistance using the human siGENOME library from Dharmacon. In this protocol, we focus on resistance to treatment with the Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor (EGFR-TKI) erlotinib in the lung cancer cell line PC9, which is exquisitely sensitive to EGFR-TKIs (de Bruin et al., 2014). This protocol can be used for other cell lines and other drug treatments, as we expand in the Notes below.
0 Q&A 8244 Views Sep 5, 2013
Thymidine Kinase from human Herpes simplex virus type 1 (HSV1-TK) in combination with specific substrate prodrug nucleotide analogue ganciclovir (GCV) has been widely used as suicidal therapeutic gene for cancer gene therapy. HSV1, and its mutant (HSV1-sr39TK) with improved substrate specificity, were used as reporter genes for PET-imaging of various biological functions in small animals, by combining with radiolabeled substrates such as 18F-FHBG and 124I-FIAU. 3H-Penciclovir (PCV) uptake assay is a method of choice used to determine the expression level of HSV1-TK in mammalian cells and tissues. HSV1-TK phosphorylate PCV and result in the formation of penciclovir monophosphate, and its subsequent phopsphorylation by cellular TK lead to the formation of penciclovir triphosphate, which is trapped selectively in cells express HSV-TK. 3H-Penciclovir enables the detection of penciclovir uptake of mammalian cells and tissues by radioactive procedures such as scintillation counting. Here we describe the protocol to carry out 3H-Penciclovir uptakes in mammalian cells.

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