Heterogeneity in non-invasive detection of apoptosis among human tumor cell lines using annexin-V tagged with EGFP or Qdot-705

Abstract

The ability to measure apoptosis in vivo and in vitro provides an invaluable tool to assess the effects of anti-cancer agents. The annexin-V binding assay has been used extensively, including in the clinic as a Technetium conjugate to assess response to chemo- or radio-therapy. Our results reveal that not all tumor cell lines are amenable to this assay. We investigated ten different human cancer cell lines for their staining patterns with annexin-V during apoptosis. In six human tumor cell lines (HCT116, Jurkat, FADU, PA1, SkBr3, and Saos2) annexin-V staining correlated well with another measurement of apoptosis (APOSTAIN). Four cell lines (SW480, H460, MCF7, and DLD1) showed annexin-V staining which could not be interpreted, where APOSTAIN demonstrated a clear apoptotic population. The poor annexin-V staining of some tumor cells undergoing apoptosis was not correlated with detachment procedures or choice of apoptosis-inducing agent. Use of annexin-V tagged with EGFP or Qdot-705 can reliably detect apoptosis in some but not all human tumors undergoing apoptosis in response to chemotherapy or TRAIL.