Variation of ER status between primary and metastatic breast cancer and relationship to p53 expression*

OBJECTIVE

Estrogen-dependent growth of breast cancer can be blocked by anti-estrogens. Estrogen receptor (ER) presence in breast cancer implies responsiveness to endocrine therapy. However, for those patients who ultimately develop resistance to endocrine therapy, the mechanisms remain unclear. The present study attempted to compare the expression status of ER mRNA in a series of primary breast tumors with matched metastases and explored the relation between ER and mutant p53 expression.

METHODS

In situ hybridization using a digoxigenin-labeled estrogen receptor cDNA probe was employed to determine the expression of ER mRNA in 52 cases of primary tumors and their matched axillary lymph node metastases. Immunohistochemical staining using a monoclonal antibody against ER was also performed.

RESULTS

ER expression was observed in 53.8% (28/52) of primary tumors and 48% (25/52) of metastases, while 57.7% (30/52) of primary tumors and 53.8% (28/52) of metastases showed ER mRNA positivity. There were variations in ER status between in situ hybridization and immunohistochemistry measurements and between primary tumors and metastases. Mutant p53 expression was inversely associated with ER-negative, high-grade tumors.

CONCLUSIONS

In situ hybridization may be a more specific and sensitive method for determination of ER status than immunohistochemistry. It is possible that the biologic properties of ER change, and these changes may influence tumor response to endocrine therapy. In view of the ER variation, it was suggested that the ER status of metastatic tumors in addition to primary tumors should be taken into consideration in order to better determine the benefit of clinical endocrine therapy.

[Expression and significance of oncoprotein p53, rasp21 and p185 in carcinomas and polyps of the large intestine]

Seventy eight cases of carcinoma and 14 cases of poly of large intestine were examined to observe the expression of p53, rasp21 and p185 oncoproteins with immunogold silver staining method. The positive expressions for p53, rasp21 and p185 were 53.9%, 46.2% and 51.3% respectively. But only poorly positive expression was found in large intestine polyps for p185 staining. The difference between the carcinomas and polyps for p185 staining was significant (P < 0.01). The normal mucoepithelium near the cancer region expressed positive staining for p53, rasp21 and p185 were 0%, 2.6% and 5.1% respectively. These results were also significantly different when compared to cancer tissue (P < 0.01). In addition, of these 78 cases, 33 cases (42.3%) gave coordinately positive expression for p53 and rasp21 oncoprotein; p53 positive expression was obviously stronger in poorly differentiated carcinoma and mucoadenocarcinoma than in highly and moderately differentiated adenocarcinoma (P < 0.01).

A 54-kDa protein overexpressed by chloroquine-resistant Plasmodium berghei ANKA strain

Using an insoluble chloroquine-adsorbent, a 54-kDa protein (with a range of 50-60 kDa) was extracted from serum of mice infected with chloroquine-resistant (CR) Plasmodium berghei ANKA strain. Immunoblotting assay with antiserum against the 54-kDa protein showed that the content of the protein was higher in serum of mice infected with the CR parasites than that of mice infected with chloroquine-sensitive (CS) P berghei ANKA strain, and that instead of the 54-kDa protein, a set of 15-, 16-, and 23-kDa proteins was found to be highly overexpressed in lysate of purified CR parasites in comparison with that of purified CS parasites, suggesting the 54-kDa protein probably to be composed of 3 subunits. These findings may bear great importance in probing mechanism of chloroquine resistance in malaria parasites.