Tatsuo Akitaya

Matrilysin is associated with progression of colorectal tumor

Matrilysin and gelatinase A, B mRNA expressions were examined in colorectal tumors. Matrilysin mRNA was observed exclusively in tumors, while the others were also found in normal mucosa surrounding tumors. Further analysis revealed that colorectal adenomas with severe dysplasia, not with mild dysplasia, expressed matrilysin with lower levels than cancers. The level of matrilysin mRNA expression increased with the advancement of stages of colorectal cancers, consequently a relatively higher expression was observed in liver metastatic tumors than primary tumors. These results suggest that matrilysin mRNA expression was correlated with the progression of colorectal tumors, and this enzyme may also play a role in developing metastatic tumors in liver.

DETECTION OF REGIONAL LYMPH NODE METASTASES IN COLON CANCER BY USING RT-PCR FOR MATRIX METALLOPROTEINASE 7, MATRILYSIN

Lymph node metastasis is the most important prognostic factor in colon cancer. However, more accurate screening for metastasis than that afforded by conventional pathology remains elusive. We have employed a reverse transcriptase-polymerase chain reaction (RT-PCR) assay for a matrix metalloproteinase (MMP), ‘matrilysin’, because this gene is epithelial-specific and consistently expressed in colorectal cancer cells. The sensitivity of this assay was examined with the matrilysin-producing rectal cancer cell line ‘CaR-1’. Matrilysin mRNA was detected in this system when more than 10 matrilysin-positive cells existed in a lymph node of ordinary size. Fourteen of 15 (93%) primary colon cancers and none of the surrounding normal tissues expressed matrilysin. All 10 histologically-positive lymph nodes were positive for matrilysin, while of 60 histologically-negative lymph nodes, eight were positive for matrilysin. When the additional sequential sectioning and histological re-examinati on was performed on five of these eight ‘matrilysin-positive, but histologically-negative’ lymph nodes, micrometastases were detected in three. Only one of the lymph nodes that were histologically-positive, but negative by matrilysin assay was from a patient with colon cancer in which matrilysin was not detected. In conclusion, RT-PCR assay for matrilysin is a sensitive method for detecting occult metastases in patients with colon cancer, and may complement histologic examination.

Improvement of latex piezoelectric immunoassay : detection of rheumatoid factor

Latex piezoelectric immunoassay is a method for detection of agglutination of antibody- or antigen-bearing latex by immunoreaction using a piezoelectric quartz crystal; the agglutination decreases the oscillation frequency of the crystal. This is advantageous in that coating the surface of the crystal followed by fixation of antibody or antigen is unnecessary. There is, however, a drawback, and to improve this, we designed a micro-cell in which only one side of the crystal is exposed to the solution. A method for regenerating the crystal was also devised. Measurement was carried out using a calibration curve of the frequency change against rheumatoid factor activity. The improvement made it possible to use one crystal repeatedly and reproducibility was satisfactory. The calibration curve became almost independent of the crystal used.

Amyloid β protein substituent peptides do not interact with the substance P receptor expressed in cultured cells

The amyloid beta protein (ABP) has been shown to interact with the substance P (SP) receptor in a cell culture model that may mimic the pathogenesis of Alzheimers disease. In the present study, however, 4 fragments of ABP (beta 1-42, beta 1-16, beta 17-28, and beta 25-35) failed to interact with SP-induced Ca2+ mobilization in SP receptor-expressing cultured cells. Therefore, the action of these ABP-related peptides in our cultured cells is unrelated to the SP receptor.