Imaging the recruitment of cancer-associated fibroblasts by liver-metastatic colon cancer

The tumor microenvironment (TME) is critical for tumor growth and progression. However, the formation of the TME is largely unknown. This report demonstrates a color-coded imaging model in which the development of the TME can be visualized. In order to image the TME, a green fluorescent protein (GFP)-expressing mouse was used as the host which expresses GFP in all organs but not the parenchymal cells of the liver. Non-colored HCT-116 human colon cancer cells were injected in the spleen of GFP nude mice which led to the formation of experimental liver metastasis. TME formation resulting from the liver metastasis was observed using the Olympus OV100 small animal fluorescence imaging system. HCT-116 cells formed tumor colonies in the liver 28 days after cell transplantation to the spleen. GFP-expressing host cells were recruited by the metastatic tumors as visualized by fluorescence imaging. A desmin positive area increased around and within the liver metastasis over time, suggesting cancer-associated fibroblasts (CAFs) were recruited by the liver metastasis which have a role in tumor progression. The color-coded model of the TME enables its formation to be visualized at the cellular level in vivo, in real-time. This imaging model of the TME should lead to new visual targets in the TME.     

Comparison of efficacy of Salmonella typhimurium A1-R and chemotherapy on stem-like and non-stem human pancreatic cancer cells

The XPA1 human pancreatic cancer cell line is dimorphic, with spindle stem-like cells and round non-stem cells. We report here the in vitro IC₅₀ values of stem-like and non-stem XPA1 human pancreatic cells cells for: (1) 5-fluorouracil (5-FU), (2) cisplatinum (CDDP), (3) gemcitabine (GEM), and (4) tumor-targeting Salmonella typhimurium A1-R (A1-R). IC₅₀ values of stem-like XPA1 cells were significantly higher than those of non-stem XPA1 cells for 5-FU (P = 0.007) and CDDP (P = 0.012). In contrast, there was no difference between the efficacy of A1-R on stem-like and non-stem XPA1 cells. In vivo, 5-FU and A1-R significantly reduced the tumor weight of non-stem XPA1 cells (5-FU; P = 0.028; A1-R; P = 0.011). In contrast, only A1-R significantly reduced tumor weight of stem-like XPA1 cells (P = 0.012). The combination A1-R with 5-FU improved the antitumor efficacy compared with 5-FU monotherapy on the stem-like cells (P = 0.004). The results of the present report indicate A1-R is a promising therapy for chemo-resistant pancreatic cancer stem-like cells.     

Simultaneous color‐coded imaging to distinguish cancer “stem‐like” and non‐stem cells in the same tumor

In this study, we demonstrate that the differential behavior, including malignancy and chemosensitivity, of cancer stem‐like and non‐stem cells can be simultaneously distinguished in the same tumor in real time by color‐coded imaging. CD133⁺ Huh‐7 human hepatocellular carcinoma (HCC) cells were considered as cancer stem‐like cells (CSCs), and CD133^? Huh‐7 cells were considered as non‐stem cancer cells (NSCCs). CD133⁺ cells were isolated by magnetic bead sorting after Huh‐7 cells were genetically labeled with green fluorescent protein (GFP) or red fluorescent protein (RFP). In this scheme, CD133⁺ cells were labeled with GFP and CD133^? cells were labeled with RFP. CSCs had higher proliferative potential compared to NSCCs in vitro. The same number of GFP CSCs and the RFP NSCCs were mixed and injected subcutaneously or in the spleen of nude mice. CSCs were highly tumorigenic and metastatic as well as highly resistant to chemotherapy in vivo compared to NSCCs. The ability to specifically distinguish stem‐like cancer cells in vivo in real time provides a visual target for prevention of metastasis and drug resistance. J. Cell. Biochem. 111: 1035–1041, 2010. © 2010 Wiley‐Liss, Inc.