Figure 1: The effects of designed peptides on metastasis of xenograft of SW620 tumours.

(a) Sequences of three different peptides used in our study. (b) The mRNA levels of human cytokeratin-18 (CK-18) in the spleen extracts of tumour-bearing mice that were treated by different peptides (indicated) 1.5 mg kg⁻¹ i.p. were analysed by quantitative RT–PCR (upper) or end point RT–PCR (bottom). The numbers represent individual mouse in each treatment group. The CK-18 mRNA levels were presented as relative levels of CK-18 mRNA by define the level of β-actin mRNA in the same mouse as 1. The mRNA levels of mouse β-actin in the spleen extracts are loading controls. The levels of the CK-18 mRNA in the extracts prepared from the harvested spleen (without tumour implantation) with direct injection of 100 SW620 cells were used as a reference (10² cells per spleen). (c) Metastatsis rates of the SW620 xenograft tumours in each treatment group. Tumour metastasis was judged by the CK-18 mRNA levels in the qRT–PCR using that of the 10² cells per spleen as the cutoff value. (d) Pictures (left) and weight (right) of harvested SW620 tumours after 28 days growth with 14 days treatment using the indicated peptides. The P-values between ‘buffer’ and ‘pepIQ’ (P=0.46658) are calculated using pairwise Student’s t-test. (e) Tumour growth was monitored by measuring tumour volumes every three days and the tumour volumes were calculated by formula; tumour volume=π/6 × (width) 2 × length. (f) Representative tissue sections were prepared from the harvested tumours and immune fluorescence stained with antibodies against Ki67 (IF: Ki67, red). The blue is 4′,6-diamidino-2-phenylindole stain of cell nucleus. (g) Cell proliferation of SW620 cells that were treated by indicated peptides were measured using a commercial 5-bromodeoxyuridine (BrdU) cell proliferation kit. The proliferation rates are presented as fold changes of BrdU incorporation of the same cultured cells before and after 48 h culturing by defining the initial BrdU incorporation measurement as 1. Scale bars, 1 cm (for d) and 100 μm (for f).