The cell surface receptor encoded by the proto-oncogene KIT and its ligand

c-Kit proto-oncogene expression in endometrial hyperplasia and endometrial cancer

PURPOSE

To evaluate the expression of c-kit (CD117) in endometrial hyperplasia and endometrial cancer.

METHODS

Expression of c-kit in 10 normal endometrium, 18 simple endometrial hyperplasia, 16 complex endometrial hyperplasia (10 cases with atypia and 6 cases without atypia), and 6 endometrial cancer were investigated by immunohistochemistry.

RESULTS

c-Kit expression decreased as the lesion progressed to endometrial cancer. Immunostaining was mostly focal and weak in the normal endometrium and was mostly diffuse and strong in the simple and complex endometrial hyperplasia.

CONCLUSIONS

Simple and complex hyperplastic endometrial tissues express diffuse cytoplasmic staining for c-kit and the expression decreases with the progression of the lesion.

Endometrium from women with and without endometriosis, and peritoneal, ovarian and bowel endometriosis, show different c-kit protein expression

BACKGROUND

Endometriosis is defined by the presence of endometrium outside the uterus. Changes in the expression of the proto-oncogene c-kit are associated with aggressive behaviour of both benign and malignant tumours, but there are few data on its c-kit expression in endometriosis. Here we examined c-kit expression in endometrium and endometriotic tissue.

METHODS

Immunohistochemistry was used for qualitative and semi-quantitative (mean+/-S.D. positive cells) analysis of c-kit expression in endometrium from women with (n=9) and without endometriosis (n=18), and in peritoneal (n=20), ovarian (n=20) and colorectal endometriosis (n=20).

RESULTS

Semi-quantitative c-kit expression was higher in endometrial glandular cells from women with endometriosis than from women without endometriosis (15.0+/-14.6% versus 3.9+/-7.4%, p=0.01). No difference in c-kit expression was found in qualitative analysis and according to the phase of the menstrual cycle. C-kit expression values in peritoneal, ovarian and colorectal endometriosis were 2.0+/-3.8%, 2.0+/-4.1% and 21.7+/-18.4%, respectively. Qualitative and semi-quantitative c-kit expression was higher in colorectal endometriosis than in peritoneal and ovarian endometriosis (p<0.001); no difference was found between ovarian and peritoneal endometriosis. No c-kit expression was detected in stromal cells of either endometrium or endometriotic tissue.

CONCLUSION

These results suggest that the c-kit/stem cell factor axis is involved in the pathogenesis of endometriosis. Strong c-kit protein expression was associated with invasive endometriotic lesions.

The proto-oncogene c-kit is expressed in leiomyosarcomas of the uterus

OBJECTIVE

The proto-oncogene c-kit encodes for a 145-kDa transmembrane tyrosine kinase receptor. Interaction with its ligand, stem cell factor, is essential in the development of hematopoietic stem cells, mast cells, gametocytes, melanocytes, and interstitial cells of Cajal. C-kit expression has been identified in a number of different neoplasms that includes mastocytosis/mast cell leukemia, acute myeloblastic leukemia, seminoma/dysgerminoma, and gastrointestinal stromal tumors. This study examines c-kit expression in uterine endometrial stromal sarcomas, leiomyomas, and leiomyosarcomas using immunohistochemistry.

METHODS

Archival tissue from 38 patients with the uterine mesenchymal tumors (16 leiomyosarcomas, 8 leiomyomas, 11 low-grade endometrial stromal sarcomas, and 3 high-grade endometrial stromal sarcomas) was stained with polyclonal antibody for c-kit. Modified avidin biotin (ABC) immunoperoxidase method was employed for antibody detection. Individual tumors were considered positive if more than 10% of the cells comprising the neoplasm displayed immunoreactive staining. Staining intensity was graded 1+ to 3+ and distribution graded as focal (10-30% of the cells), intermediate (30-60% of the cells), or diffuse (>60% of the cells).

RESULTS

C-kit was positive in 12 (75%) of the 16 leiomyosarcomas. The staining was 3+ and diffuse in the majority of the positive tumors. C-kit expression was not detected in any of the 8 leiomyomas. Two of the 3 high-grade endometrial stromal sarcomas displayed c-kit positivity. Staining was diffuse and 3+ in both of these tumors. Expression of c-kit was observed in only 3 of the 11 low-grade endometrial stromal sarcomas.

CONCLUSIONS

C-kit is expressed in uterine leiomyosarcomas and endometrial stromal sarcomas. Adjunctive diagnostic studies using c-kit may be useful in distinguishing leiomyosarcomas from benign leiomyomas in uterine tumors that offer uncharacteristic features. Furthermore, studies should investigate the prospect of treating these malignant tumors with tyrosine kinase inhibitors.

Expression of c-kit (CD117) in benign and malignant human endometrial epithelium

BACKGROUND

The proto-oncogene c-kit encodes a tyrosine kinase receptor (CD117) with a molecular weight of 145 kd. Previous studies, predominantly utilizing immunohistochemistry, have led to contradictory findings regarding the expression of CD117 in the endometrium. To help resolve this issue, we analyzed a series of benign and malignant endometrial tissues using both immunohistochemistry and Western blot analysis.

OBJECTIVE

To examine the expression of CD117 in benign and malignant human endometrial tissues.

METHODS

The expression of CD117 in 35 benign endometrial tissues (7 hyperplastic, 14 proliferative, 14 secretory) and 10 endometrioid carcinomas was investigated by immunohistochemistry (clone K45 monoclonal antibody). Immunoprecipitation (clone K69 monoclonal antibody) followed by Western blotting (clone K45 monoclonal antibody and clone 1.D9.3D6 monoclonal antibody) was performed to confirm CD117 expression.

RESULTS

Fifty-seven percent of the hyperplasias, 93% of proliferative endometria, and 79% of secretory endometria immunostained positively for CD117. In benign endometria, epithelial staining tended to be more intense in the hyperplastic and proliferative endometria as compared to the secretory endometria, whereas endometrial stromal cells were not immunoreactive. Of the 10 frozen endometrial tissues analyzed by immunohistochemistry, 4 of 9 endometrioid carcinomas and a single case of an endometrioid polyp developing in association with a carcinoma expressed CD117. Immunoprecipitation followed by Western blot analysis confirmed expression of full-length CD117 in an endometrial polyp and carcinoma, and revealed a correlation between levels of immunoprecipitated CD117 and immunohistochemical staining intensity.

CONCLUSIONS

Benign and malignant endometrial tissues express CD117. Our data suggest (a) a possible relationship between estrogen and CD117 expression in benign endometrium and (b) potential involvement of this growth factor receptor in endometrial carcinogenesis.