Clinical significance of quantitative analysis of carcinoembryonic antigen assessed by flow cytometry in fresh human gastric cancer cells

Clinical application of omental bursa wash detection in gastric carcinoma

AIM: To evaluate the application value of omental bursa wash detection in gastric carcinoma.

METHODS: Omental bursa washes from 78 patients with gastric carcinoma were collected. The expression of carcino-embryonic antigen (CEA) in omental bursa washes was detected by flow cytometry (FCM). Peritoneal lavage cytology (PLC) examinations were also carried out.

RESULTS: The FCM and PLC positive rates of omental bursa washes were 37.1% (29/78) and 11.5% (9/78), respectively, which had a significant difference (P = 0.001). The positive rate of omental bursa washes correlated well with the width of tumor, location of lesion, and depth of invasion (P < 0.05). The age, gender, differentiation, vessel carcinoma embolus, and area of invasion were not relevant to omental bursa wash detection.

CONCLUSION: FCM can be well used to detect omental bursa washes. The best use of omental bursa wash detection is to assess tumor progression and to predict the emergence of gastric carcinoma micrometastases.

Characterization of gastric adenocarcinoma cell lines established from CEA424/SV40 T antigen-transgenic mice with or without a human CEA transgene

Background

Gastric carcinoma is one of the most frequent cancers worldwide. Patients with gastric cancer at an advanced disease stage have a poor prognosis, due to the limited efficacy of available therapies. Therefore, the development of new therapies, like immunotherapy for the treatment of gastric cancer is of utmost importance. Since the usability of existing preclinical models for the evaluation of immunotherapies for gastric adenocarcinomas is limited, the goal of the present study was to establish murine in vivo models which allow the stepwise improvement of immunotherapies for gastric cancer.

Methods

Since no murine gastric adenocarcinoma cell lines are available we established four cell lines (424GC, mGC3, mGC5, mGC8) from spontaneously developing tumors of CEA424/SV40 T antigen (CEA424/Tag) mice and three cell lines derived from double-transgenic offsprings of CEA424/Tag mice mated with human carcinoembryonic antigen (CEA)-transgenic (CEA424/Tag-CEA) mice (mGC2^CEA, mGC4^CEA, mGC11^CEA). CEA424/Tag is a transgenic C57BL/6 mouse strain harboring the Tag under the control of a -424/-8 bp CEA gene promoter which leads to the development of invasive adenocarcinoma in the glandular stomach. Tumor cell lines established from CEA424/Tag-CEA mice express the well defined tumor antigen CEA under the control of its natural regulatory elements.

Results

The epithelial origin of the tumor cells was proven by morphological criteria including the presence of mucin within the cells and the expression of the cell adhesion molecules EpCAM and CEACAM1. All cell lines consistently express the transgenes CEA and/or Tag and MHC class I molecules leading to their susceptibility to lysis by Tag-specific CTL in vitro. Despite the presentation of CTL-epitopes derived from the transgene products the tumor cell lines were tumorigenic when grafted into C57BL/6, CEA424/Tag or CEA424/Tag-CEA-transgenic hosts and no significant differences in tumor take and tumor growth were observed in the different hosts. Although no spontaneous tumor rejection was observed, vaccination of C57BL/6 mice with lysates from gastric carcinoma cell lines protected C57BL/6 mice from tumor challenge, demonstrating the tumorigenicity of the tumor cell lines in nontransgenic mice of the H-2^b haplotype.

Conclusion

These tumor cell lines grafted in different syngeneic hosts should prove to be very useful to optimize immunotherapy regimens to be finally tested in transgenic animals developing primary gastric carcinomas.

P-glycoprotein-expressing tumor cells are resistant to anticancer drugs in human gastrointestinal cancer

The resistance to doxorubicin (DOX) by some tumor cells is mainly due to the effect of P-glycoprotein encoded by the multidrug resistance-1 (mdr1) gene. We tried to prove the correlations between P-glycoprotein expression and the sensitivity for anticancer drugs including DOX and other cytotoxic drugs that are currently used for gastrointestinal cancer patients. We quantified the P-glycoprotein expression by flow cytometry techniques, and the sensitivity for anticancer drugs using a tetrazolium salt, 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), assay in highly purified fresh human tumor cells obtained from 25 cancer patients. The inhibition rates were the lowest in DOX and mitomycin C (MMC), compared with other drugs. The most significant correlation between DOX and MMC was seen in the inhibition rates. A significant correlation was also seen between the inhibition rates for DOX and P-glycoprotein expression, whereas only a slight correlation between the sensitivity for MMC and P-glycoprotein expression was observed. We should therefore pay close attention to the effect of P-glycoprotein when treating cancer patients, especially if both the inhibition rates of DOX and MMC are low based on the findings of an MTT assay.