Cancer Biology

Natural killer (NK) cells are the major effectors of the innate immune system when activated resulting in modulation of immune response of the host defense through target cell lysis and secretion of cytokines. Precise functions of NK cells are essential for the treatment outcome of different virus infections and malignant diseases. NK cells impart cytotoxic effect to the target cells lacking MHC class I molecules and thus the final readout of the activity is death of target cells. The NK cell function is evaluated by the ⁵¹Cr-release and/or flow cytometry-based assays. In the present protocol, we have determined the activation of NK cells by the liberation of IL-10 and IFNγ, and subsequently its function by enumerating the number of dead tumor cells originally isolated from the ascitic fluid of ovarian cancer patients. The entire assay is based on cells of the healthy donors and patients. Besides determining function, this method is able to demarcate between NK-cell sensitive and insensitive tumor cells. This technique enables researchers to study NK cell functions in healthy donors or in patients to reveal their impact on different malignancies and to further discover new therapeutic strategies.

Autophagy is a recycling pathway, in which intracellular cargoes including protein aggregates and bacteria are engulfed by autophagosomes and subsequently degraded after fusion with lysosomes. Dysregulation of this process is involved in several human diseases such as cancer or neurodegeneration. Hence, advancing our understanding of how autophagy is regulated provides an opportunity to explore druggable targets and subsequently develop treatment strategies for these diseases. To identify novel autophagy regulators, we developed an image-based phenotypic RNAi screening approach using autophagic marker proteins at endogenous levels (Jung et al., 2017). In contrast to previously performed autophagy screens, this approach does not use overexpressed, tagged autophagy marker proteins but rather detects autophagic structures at endogenous levels. Furthermore, we monitored early and late phases of autophagy in parallel while other screens employed only a single autophagosome marker mostly GFP-LC3B. Here, we describe this multiplex screening protocol in detail and discuss general considerations about how to establish image-based siRNA screens.

Accumulating evidence is revealing the essential role of immune system in cancer treatment. Certain chemotherapeutic drugs can potently induce the release of ‘cell death associated molecular patterns’ (CDAMPs), which accompanies cancer cell demise. CDAMPs can engage corresponding receptors on immune cells and stimulate immune responses to achieve long-term tumor control (Ma et al., 2013; Ma et al., 2014; Yang et al., 2015). Among reported CDAMPs, calreticulin (CALR), ATP and HMGB1 are well known for their immune-stimulatory effect. Here we describe the assays that we applied to measure cell death and these CDAMPs. Briefly, cell death can be analyzed by co-staining of 4’,6-diamidino-2-phenylindole (DAPI) with 3,3’-Dihexyloxacarbocyanine Iodide [DiOC6(3)] or Annexin V. CALR exposure on the cell membrane can be detected by flow cytometry. ATP and HMGB1 release can be quantified by luminescence assay and ELISA assay respectively.