Programmed Death Cells

Imagine treating cancer by simply flipping a switch. In this instance, that biological switch activates therapeutic antitumor immunity by blocking immune checkpoints in our bodies that exist to prevent our immune system from attacking the body’s own cells. Sounds great, right? There is only one major problem. Many tumor cells escape anti-tumor immunity because they express increased amounts of a certain protein known as Programmed Death-Ligand 1 (PD-L1 or B7-H1). When PD-L1 interacts with Programmed Death protein 1 (PD-1) on cancer-fighting white blood cells called T cells, it decreases their effectiveness. With no natural enemies left to stop tumor cells, they proliferate and lead to tumors that can even adapt to various treatments to evade immunity. When that occurs the cancer becomes more severe.¹

AlphaLISA^® Assay Technology

Studies done using human tumor cell lines by PerkinElmer Application Scientist Jeanine Hinterneder have contributed to our understanding of how tumor cells develop the ability to evade the immune response. In recent research involving basal-like breast cancer, Dr. Hinterneder demonstrated the utility and benefits of using PerkinElmer’s AlphaLISA assay technology for identifying and characterizing endogenous PD-L1 expression in cells. “We showed that PD-L1 was expressed and highly induced by Interferon gamma in a basal B breast cancer cell line,” she says. In addition, her research confirmed that the JAK/STAT pathway, which is the principal signaling mechanism within cells for a wide array of biological substances such as interferon, interleukin, and growth factors, plays a major role in this induction of PD-L1.

So how does AlphaLISA technology work? Using antibody-coated Donor and Acceptor beads, human PD-L1 is sandwiched, which brings the Donor and Acceptor beads into close proximity of each other. Upon excitation the beads emit a sharp peak of light. This light emission can be detected on an Alpha-enabled reader such as the PerkinElmer EnVision^® multimode plate reader.

The Results, Please

Dr. Hinterneder’s research confirms that PD-L1 protein expression levels in human cells can be quickly and accurately assessed with the AlphaLISA human PD-L1 assay. “The data further illustrate that treatment of two breast cancer cell lines with Interferon gamma is sufficient for inducing PD-L1 biomarker expression and that AlphaLISA technology can be used to assess differences in expression between cells from different tumor origins,” she says.

Equally important, Dr. Hinterneder’s research shows that PD-L1 upregulation via Interferon signaling is controlled through the JAK1/2 pathway and implicates downstream signaling through a transcription factor known as STAT1.

“AlphaLISA assays provide a fast, powerful, homogeneous platform for screening potential inhibitors of PD-L1 expression in human cells,” Dr. Hinterneder concludes. “The technology has a number of distinct advantages including high signal to background, wide dynamic range, and an extremely simple, straight-forward protocol.”

Reference:

1. Jeanine Hinterneder, “Measuring PD-L1 Expression in Breast Cancer Cell Lines With Alpha LISA,” PerkinElmer Application Note, 2017, September 3, 2017.