Figure 9

Connexin 43 facilitates tumor cell attachment to lung endothelium. (A) Hematoxylin-eosin staining of mouse lung sections 12 hours after tail vein injection with 4T1-GFP control cells or cells expressing connexin-43 (Cx43) variants C61S, G138R, or Cx43OE. Panel '4T1': a vessel containing red blood cells and dark nuclei of adherent 4T1-GFP control cells within it. Panel 'C61S': C61S expressing tumor cells show a comparable density of tumor cell nuclei in blood vessels. Panel 'G138R': dominant-negative G138R expressing tumor cells show a decreased number of tumor cells inside vessels. In contrast, tumor cells overexpressing Cx43 appear to populate the vessels in much larger number (see panel 'Cx43OE'). (B) Quantification of the tumor cell numbers adhering to the lung endothelium showing that dominant-negative expression Cx43 reduced the number of the tumor cells within the vessels in the lung (red bar), while overexpressing wild-type Cx43 resulted in more tumor cells within the lung vasculature (black bar). *P < 0.05 versus 4T1. The results represent three lungs for each condition, four slides per lung, and 20 contiguous picture frames per slide.