(100CAP032-2) Prevention of Metastasis after Radiotherapy by Targeting Galectins and/or Its Associated Ligands (I)

The incidence of colorectal cancer is increasing in Taiwan, with ten thousand new cases each year. Radiotherapy is the one of the major treatments in adjuvant therapy for rectal cancer. Local recurrence and distant metastasis are patterns of treatment failure following radiotherapy. We recently found that Gal-1 mediates radioresistance of cervical cancer in vivo and in vitro. Hence, we aim to investigate the functions of targeting Gal-1 or Gal-3 in conjunction with radiotherapy to prevent local recurrence or distant metastasis. We will use truncated galectin-3 binding protein (Gal-3BP) linked with human Fc portion (Fc-tGal-3BP) to scavenge extracellular Gal-1 and/or Gal-3, and use truncated Gal-1 and/or Gal-3 linked to EGF peptide (EGF-Gal-3C) to deliver the competitors of Gal-3 and/or Gal-1 via the EGF receptor (EGFR). The specific aims of this study are: (1) to screen most radioresistant cells and correlate the radioresistance to Gal-1 and/or Gal-3 expression in vitro and in vivo; (2) to investigate the effects of simultaneous targeting of extracellular and intracellular Gal-1 and/or Gal-3 expression in preventing cancer cell invasiveness and promoting radiosensitivity in vitro; and (3) to investigate the effects of simultaneous targeting of extracellular and intracellular Gal-1 and/or Gal-3 expression in preventing cancer cell invasiveness and promoting radiosensitivity in vivo. This study will be completed in 2 years and attempt to optimize conditions for creating targeting fusion proteins that are more suitable for in vivo drug stability and functions by the third year. Materials and methods: For Specific Aim 1, eight colon cancer cell lines will be tested for radiosensitivity and Gal-1/ Gal-3/Gal-3 BP expression on cell surfaces, and inside cells (mRNA and protein) and supernatants. We will correlate the expressing profiles of Gal-1/Gal-3/Gal-3 BP to radiosensitivity. In addition, we will either increase or decrease the Gal-1/Gal-3/Gal-3 BP to validate the correlation to cancer invasiveness and radioresistance. In vivo correlation of tissue and serum Gal-1/ Gal-3/Gal-3 BP will be performed in patients undergoing radiotherapy. For Specific Aim 2, we will test how Fc-tGal-3BP and/or EGF-Gal-3C affect radiosensitivity, cancer invasiveness (migration, invasion, epithelial to mesenchymal transition: EMT, cancer stem cell markers), and anti-tumor immune responses of radioresistant cells. For Specific Aim 3, we will use constructed fusion proteins in Specific Aim 2 to test inhibition of cancer progression in vivo. We will perform experimental metastasis in SCID mice and dimethylhydrazine-induced colon cancer in Wistar rats. The incidence and number of liver metastasis, colon tumor size, and normal small-bowel damage will be compared between constructed fusion protein and control treatment after irradiation. Collaboration with other subprojects: The radioresistance of colon cancer cells in vivo and in vitro with and without targeting Gal-1 and/or Gal-3 will be correlated to tumor cell migration performed in Subproject-1, to the cancer stem cell transition demonstrated in Subproject-3, and to the anti-tumor immune responses studied in Subproject-4. Anticipated results and further prospect: Radioresistant cell lines will have higher Gal-1/Gal-3 expression than radiosensitive cell lines, associated with cancer invasiveness and depressed tumor immunity. Simultaneous targeting of extracellular and intracellular Gal-1 and/or Gal-3 expression will suppress cancer cell invasiveness, promote radiosensitivity, and enhance tumor immunity.

Project ID:PC10006-0135
External Project ID:NSC100-2325-B182-004