Expression of cDNA fragment encoding MGr1-Ag1 detected by MDR related antibody MGr1 in gastric cancer

Tamoxifen can reverse multidrug resistance of colorectal carcinoma in vivo

AIM: To investigate the effect of tamoxifen (TAM) on multidrug resistance (MDR) of colorectal carcinoma in vivo and its relationship with estrogen receptor (ER).

METHODS: Multidrug resistance was determined by means of semi-quantitative retro-transcription polymerase chain reaction (RT-PCR) to test mdr1 gene mRNA and ER expression was studied by immunohistochemistry. Tumor tissues from three cases of human colon carcinoma, which had mdr1(+)/ER(+), mdr1(+)/ER(-), mdr1(-) expressions, were planted subcutaneously in the neck of nude mice to establish three xenograft models. These models were subdivided into four subgroups randomly: Doxorubicin (DOX)-treated group, TAM-treated group, DOX and TAM group and control group. The dimensions of these xenografts were measured after each course of treatment and the xenografts were removed at the end of the experiments for measurements of weight and the variation of mdr1 mRNA level with RT-PCR. In each course, TAM [15 mg/(kg/d)] was administrated orally per day in the first seven days and DOX (3.6 mg/kg) was injected peritoneally on the first day. Data was evaluated by q and t tests.

RESULTS: In the animal models with mdr1(-) tumor, the weights and volumes of the planted tumor in DOX group [(39.1±2.29) mg, (31.44±1.61) mm³] and TAM and DOX group [(38.72±2.56) mg, (31.31±1.74) mm³], which were lesser than that of control group [(45.48±3.92) mg, (36.42±2.77) mm³, P = 0.037, P = 0.016 respectively] significantly. In the animal models with mdr1(+)/ER(+) tumor, the weights and volumes of planted tumor were not affected by DOX or TAM treatment; however, in TAM and DOX group [(425.5±28.58) mg, (340.35±22.28) mm³], they were significantly less than that of control group [(634.23±119.41) mg, (507.45±93.34) mm³, P = 0.022, P = 0.045 respectively], which are similar to that in the models with mdr1(+)/ER(-) tumor. No significant changes were found in the expressive level of mdr1 mRNA following these treatments.

CONCLUSION: The expression of mdr1 gene corresponds to the sensitivity of colon cancer to anti-tumor drugs in vivo. TAM can reverse the MDR of colorectal carcinoma in nude mice, which is independent of the expression of ER; however, no change was observed in the expressive level of mdr1 mRNA.

Loss of fragile histidine triad protein expression and its clinicopathological significance in gastric cancer

AIM: To investigate the expression of fragile histidine triad protein, Fhit and the possible relationship between its expression and clinicopathological indices in gastric carcinoma.

METHODS: Fhit protein expression was detected in 76 cases of gastric carcinoma, 58 dysplasia and 10 normal mucosae by immunohistochemical method to analyse its relationship to histological grade, clinical stage, metastatic status and prognosis.

RESULTS: The loss of Fhit protein expression was detected in 48/76 (63.2%) cases of cancer tissue, 36/58 (62.1%)cases of adjacent dysplastic tissue and 0/10 cases of normal gastric mucosa. There was a significant difference in the expression of Fhit protein between cancer or adjacent dysplastic tissue and normal gastric mucosa (P=0.000). It was also showed that loss of Fhit protein expression was found first in 35.7% (10/28) of grade I-II, and in 79.2% (38/48) of grade III (P = 0.000); second in 43.8% (14/32)of stage I-II, whereas in 77.3% (34/44) of stage III-IV (P = 0.004); and last in 36.4% (8/22) of tumors without metastasis but in 74.1% (40/54) of those with metastasis (P = 0.003). The significant difference in the loss of expression of Fhit was found between cancers on different histological grade, clinical stage and metastatic status, respectively. Follow-up data showed that there was a significant difference in median survival time between carcinomas with loss of Fhit (33 mos) and those without (71 mos) (Log rank = 20.78; P = 0.000).

CONCLUSION: Fhit protein is an important tumor suppressor protein. Loss of Fhit protein expression may be associated with carcinogenesis, invasion, metastasis and prognosis in gastric carcinoma.