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Identification of virus resistant tumor cell subpopulations in three-dimensional uveal melanoma cultures
K Valyi-Nagy1, S Dosa, S K Kovacs
1Department of Pathology, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612, USA.
Abstract:
To better understand melanoma resistance to herpes simplex virus type 1 (HSV-1)-mediated oncolysis, traditional two-dimensional (2D) cultures and extracellular matrix (ECM) containing three-dimensional (3D) cultures of OCM1 and C918 uveal melanoma cells were infected with an HSV-1 strain that expresses the green fluorescent protein (GFP) marker during replication. Although 2D cultures were completely destroyed within a few days of HSV-1 inoculation, viable GFP-negative tumor cells remained detectable in 3D cultures for several weeks. Tumor cells with increased resistance to HSV-1 included cells that formed vasculogenic mimicry patterns and multicellular spheroids and cells that invaded Matrigel individually. Mechanisms of tumor resistance against HSV-1 in the 3D environment included impaired virus spread in the ECM and ECM-mediated inhibition of viral replication after viral entry into tumor cells. Observations also suggested that HSV-1 established quiescent infection in some tumor cells present in multicellular spheroids and that this could revert to productive viral infection when the tumor growth pattern changed. These findings indicate that 3D tumor cell cultures can be used to identify distinct tumor cell populations with increased resistance to HSV-1 and to explore mechanisms of ECM-mediated tumor resistance to oncolytic virotherapy.
Insights
Three-dimensional (3D) melanoma cultures reveal resistance to herpes simplex virus type 1 (HSV-1) oncolysis, unlike 2D cultures. The extracellular matrix (ECM) in 3D models hinders virus spread and replication, offering insights into oncolytic virotherapy resistance.
Area of Science:
- Oncolytic virotherapy
- Cancer biology
- Virology
Background:
- Melanoma resistance to herpes simplex virus type 1 (HSV-1)-mediated oncolysis is not fully understood.
- Traditional 2D cell cultures may not accurately reflect in vivo tumor microenvironments.
Purpose of the Study:
- To investigate melanoma resistance mechanisms to HSV-1 oncolysis using 3D cultures.
- To compare HSV-1 efficacy in 2D versus 3D melanoma models.
- To identify factors contributing to tumor cell resistance in a 3D extracellular matrix (ECM) environment.
Main Methods:
- Infection of 2D and 3D uveal melanoma cell cultures (OCM1, C918) with GFP-expressing HSV-1.
- Observation of tumor cell viability and viral replication.
- Analysis of tumor cell invasion and spheroid formation within Matrigel and ECM.
Main Results:
- Viable melanoma cells persisted in 3D cultures for weeks, unlike complete destruction in 2D cultures.
- Resistant cells exhibited vasculogenic mimicry, formed multicellular spheroids, or invaded Matrigel.
- The ECM impaired HSV-1 spread and inhibited viral replication post-entry.
- Quiescent HSV-1 infections were observed in spheroids, with potential for reactivation.
Conclusions:
- 3D tumor models are crucial for identifying distinct, resistant tumor cell populations.
- The ECM plays a significant role in mediating resistance to HSV-1 oncolysis.
- Understanding ECM-mediated resistance is vital for improving oncolytic virotherapy strategies.
