Table 1.
ST binding parameters and activation of guanylyl cyclase in membranes from normal human intestine and primary and metastatic colorectal tumors
| n | High affinity ST
binding
|
Low affinity ST binding
|
Guanylyl cyclase, fold | |||
|---|---|---|---|---|---|---|
| Bmax | KD, pM | Bmax | KD, nM | |||
| Normal | ||||||
| Small intestine | 9 | 38 ± 22.1 | 23.8 ± 13.4 | 320 ± 77 | 1.7 ± 0.8 | 2.11 ± 0.21 |
| Cecum | 3 | 25 ± 14.3 | 26.2 ± 10.1 | 300 ± 82 | 2.0 ± 0.7 | 1.95 ± 0.12 |
| Colon | 46 | 20 ± 12.2 | 34.4 ± 11.8 | 220 ± 49 | 2.7 ± 1.1 | 1.57 ± 0.22 |
| Rectum | 4 | 12 ± 10.1 | 47.0 ± 14.1 | 125 ± 34 | 2.5 ± 1.5 | 1.39 ± 0.08 |
| Primary CRC | ||||||
| Cecum | 7 | 20 ± 9.91 | 19.3 ± 9.2 | 260 ± 66 | 2.6 ± 0.2 | 1.81 ± 0.09 |
| Colon | 60 | 16 ± 11.4 | 28.3 ± 6.1 | 180 ± 36 | 3.1 ± 0.4 | 1.69 ± 0.10 |
| Rectum | 6 | 10 ± 7.72 | 31.0 ± 4.2 | 95 ± 44 | 4.9 ± 0.3 | 1.35 ± 0.12 |
| Metastatic CRC | ||||||
| Liver | 12 | 10 ± 4.45 | 28.1 ± 6.10 | 110 ± 19 | 2.1 ± 0.3 | 1.81 ± 0.27 |
| Lung | 5 | 15 ± 8.50 | 19.4 ± 4.12 | 195 ± 80 | 5.8 ± 0.1 | 1.92 ± 0.23 |
| Lymph node | 8 | 10 ± 5.21 | 29.3 ± 9.20 | 138 ± 27 | 4.8 ± 1.0 | 1.55 ± 0.26 |
| Ovary | 3 | 12 ± 4.82 | 44.7 ± 12.1 | 160 ± 38 | 6.9 ± 3.3 | 1.38 ± 0.21 |
| Peritoneum | 7 | 18 ± 7.86 | 35.5 ± 6.01 | 209 ± 17 | 5.6 ± 0.2 | 1.44 ± 0.19 |
| Mesentery | 1 | 27 ± 16.1 | 36.2 ± 6.10 | 295 ± 33 | 3.1 ± 1.2 | 1.41 ± 0.20 |
| Stomach | 1 | 17 ± 10.2 | 20.1 ± 9.21 | 100 ± 25 | 1.7 ± 0.4 | 1.50 ± 0.21 |
Equilibrium binding was conducted as described, and activation of guanylyl cyclase was quantified employing 1 μM ST as described. n = number of tissue specimens; Bmax = fmol of ST bound per mg of protein; fold = (cGMP produced in the presence of 1 μM ST) (cGMP produced in the absence of ST). For tissues where n = 1, the SEM reflects at least three determinations using the same tissue. For all other tissues, the SEM reflects results obtained with n tissues. CRC, colorectal cancer.