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Overexpression of Eag1 potassium channels in clinical tumours.

Hemmerlein B, Weseloh RM, Mello de Queiroz F, Knötgen H, Sánchez A, Rubio ME, Martin S, Schliephacke T, Jenke M - Mol. Cancer (2006)

Bottom Line: The use of reverse transcription real-time PCR and specifically generated monoclonal anti-Eag1 antibodies showed that expression of the channel is normally limited to specific areas of the brain and to restricted cell populations throughout the body.Inhibition of Eag1 expression in tumour cell lines reduced cell proliferation.Furthermore, as normal cells expressing Eag1 are either protected by the blood-brain barrier or represent the terminal stage of normal differentiation, Eag1 based therapies could produce only minor side effects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, Georg-August University, Göttingen, Germany. hemmer@med.uni-goettingen.de

ABSTRACT

Background: Certain types of potassium channels (known as Eag1, KCNH1, Kv10.1) are associated with the production of tumours in patients and in animals. We have now studied the expression pattern of the Eag1 channel in a large range of normal and tumour tissues from different collections utilising molecular biological and immunohistochemical techniques.

Results: The use of reverse transcription real-time PCR and specifically generated monoclonal anti-Eag1 antibodies showed that expression of the channel is normally limited to specific areas of the brain and to restricted cell populations throughout the body. Tumour samples, however, showed a significant overexpression of the channel with high frequency (up to 80% depending on the tissue source) regardless of the detection method (staining with either one of the antibodies, or detection of Eag1 RNA).

Conclusion: Inhibition of Eag1 expression in tumour cell lines reduced cell proliferation. Eag1 may therefore represent a promising target for the tailored treatment of human tumours. Furthermore, as normal cells expressing Eag1 are either protected by the blood-brain barrier or represent the terminal stage of normal differentiation, Eag1 based therapies could produce only minor side effects.

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Some normal tissues show Eag1 staining in restricted populations. In the female reproductive system, the follicular epithelia (a) do not show Eag1-staining. The surface and gland epithelia of the resting endometrium are also negative (b). However, in proliferating and secretory activated glands, a strong Eag1-expression can be observed (b. Inset). In the healthy mammary gland (c), Eag1 signals are limited to luminal cells in the acini and ducts of the ductulo-lobular unit, while the basal cell layer is negative (arrow). In the testis (d), interstitial cells and spermatogonia within the ducti seminiferi show a weak to intermediate Eag1 expression. (e) The gastric corpus mucosa express little or no Eag1 (white arrow) except in chief cells (black arrow) where very strong signals are observed. In colon (f), the normal mucosa is negative, while mucosa-associated lymphocytes stain positive.
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Figure 3: Some normal tissues show Eag1 staining in restricted populations. In the female reproductive system, the follicular epithelia (a) do not show Eag1-staining. The surface and gland epithelia of the resting endometrium are also negative (b). However, in proliferating and secretory activated glands, a strong Eag1-expression can be observed (b. Inset). In the healthy mammary gland (c), Eag1 signals are limited to luminal cells in the acini and ducts of the ductulo-lobular unit, while the basal cell layer is negative (arrow). In the testis (d), interstitial cells and spermatogonia within the ducti seminiferi show a weak to intermediate Eag1 expression. (e) The gastric corpus mucosa express little or no Eag1 (white arrow) except in chief cells (black arrow) where very strong signals are observed. In colon (f), the normal mucosa is negative, while mucosa-associated lymphocytes stain positive.

Mentions: To determine the cellular distribution of the Eag1 potassium channel we analyzed biopsy specimens by immunohistochemistry using the Eag1.62.mAb. In good agreement with the results obtained by RT-PCR, the overall staining was absent or faint in all organs tested. A closer examination revealed that restricted cell populations with clear Eag1 reactivity do exist as described below and some examples are shown in Fig. 3. In the gastrointestinal tract, gastric gland chief cells and pancreatic acini were the only populations showing positive signals. In the male reproductive system, the spermatogenic cells were positive, in agreement with RNA expression data. In the female reproductive system, epithelial cells in both the endocervix and endometrium were moderately positive, particularly in secretory activated endometrial glands. This contrasts with the surface epithelium, which showed very low signal intensity. In non-transformed breast tissue we found variable staining of the ductular-lobular unit, in contrast to the virtual absence of Eag1 reactivity in the epithelium of the ducts. Since unaltered breast tissue is not biopsied, the tissue available was always from the vicinity of tumours or from fibrocystic proliferating changes within the gland. Bone marrow, spleen, lymph nodes, thymus and tonsil were all negative. However, we did detect positive signals in the germinal centres of lymph follicles in reactive lymph nodes. Interestingly, mast cells and tissular macrophages were found to stain positively, frequently with very strong signals. We found this property useful as a positive control for our stainings, since these cells gave us an internal estimate of the highest staining level possible for that particular preparation. Regarding the endocrine and autonomous nervous system, the anterior pituitary and the adrenal gland were stained with a low intensity both in cortex and medulla, again confirming the RT-PCR data. All cell subsets positively stained correspond to the terminal developmental stages of the respective lineages and therefore to a non-proliferating population.


Overexpression of Eag1 potassium channels in clinical tumours.

Hemmerlein B, Weseloh RM, Mello de Queiroz F, Knötgen H, Sánchez A, Rubio ME, Martin S, Schliephacke T, Jenke M - Mol. Cancer (2006)

Some normal tissues show Eag1 staining in restricted populations. In the female reproductive system, the follicular epithelia (a) do not show Eag1-staining. The surface and gland epithelia of the resting endometrium are also negative (b). However, in proliferating and secretory activated glands, a strong Eag1-expression can be observed (b. Inset). In the healthy mammary gland (c), Eag1 signals are limited to luminal cells in the acini and ducts of the ductulo-lobular unit, while the basal cell layer is negative (arrow). In the testis (d), interstitial cells and spermatogonia within the ducti seminiferi show a weak to intermediate Eag1 expression. (e) The gastric corpus mucosa express little or no Eag1 (white arrow) except in chief cells (black arrow) where very strong signals are observed. In colon (f), the normal mucosa is negative, while mucosa-associated lymphocytes stain positive.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC1621079&req=5

Figure 3: Some normal tissues show Eag1 staining in restricted populations. In the female reproductive system, the follicular epithelia (a) do not show Eag1-staining. The surface and gland epithelia of the resting endometrium are also negative (b). However, in proliferating and secretory activated glands, a strong Eag1-expression can be observed (b. Inset). In the healthy mammary gland (c), Eag1 signals are limited to luminal cells in the acini and ducts of the ductulo-lobular unit, while the basal cell layer is negative (arrow). In the testis (d), interstitial cells and spermatogonia within the ducti seminiferi show a weak to intermediate Eag1 expression. (e) The gastric corpus mucosa express little or no Eag1 (white arrow) except in chief cells (black arrow) where very strong signals are observed. In colon (f), the normal mucosa is negative, while mucosa-associated lymphocytes stain positive.
Mentions: To determine the cellular distribution of the Eag1 potassium channel we analyzed biopsy specimens by immunohistochemistry using the Eag1.62.mAb. In good agreement with the results obtained by RT-PCR, the overall staining was absent or faint in all organs tested. A closer examination revealed that restricted cell populations with clear Eag1 reactivity do exist as described below and some examples are shown in Fig. 3. In the gastrointestinal tract, gastric gland chief cells and pancreatic acini were the only populations showing positive signals. In the male reproductive system, the spermatogenic cells were positive, in agreement with RNA expression data. In the female reproductive system, epithelial cells in both the endocervix and endometrium were moderately positive, particularly in secretory activated endometrial glands. This contrasts with the surface epithelium, which showed very low signal intensity. In non-transformed breast tissue we found variable staining of the ductular-lobular unit, in contrast to the virtual absence of Eag1 reactivity in the epithelium of the ducts. Since unaltered breast tissue is not biopsied, the tissue available was always from the vicinity of tumours or from fibrocystic proliferating changes within the gland. Bone marrow, spleen, lymph nodes, thymus and tonsil were all negative. However, we did detect positive signals in the germinal centres of lymph follicles in reactive lymph nodes. Interestingly, mast cells and tissular macrophages were found to stain positively, frequently with very strong signals. We found this property useful as a positive control for our stainings, since these cells gave us an internal estimate of the highest staining level possible for that particular preparation. Regarding the endocrine and autonomous nervous system, the anterior pituitary and the adrenal gland were stained with a low intensity both in cortex and medulla, again confirming the RT-PCR data. All cell subsets positively stained correspond to the terminal developmental stages of the respective lineages and therefore to a non-proliferating population.

Bottom Line: The use of reverse transcription real-time PCR and specifically generated monoclonal anti-Eag1 antibodies showed that expression of the channel is normally limited to specific areas of the brain and to restricted cell populations throughout the body.Inhibition of Eag1 expression in tumour cell lines reduced cell proliferation.Furthermore, as normal cells expressing Eag1 are either protected by the blood-brain barrier or represent the terminal stage of normal differentiation, Eag1 based therapies could produce only minor side effects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology, Georg-August University, Göttingen, Germany. hemmer@med.uni-goettingen.de

ABSTRACT

Background: Certain types of potassium channels (known as Eag1, KCNH1, Kv10.1) are associated with the production of tumours in patients and in animals. We have now studied the expression pattern of the Eag1 channel in a large range of normal and tumour tissues from different collections utilising molecular biological and immunohistochemical techniques.

Results: The use of reverse transcription real-time PCR and specifically generated monoclonal anti-Eag1 antibodies showed that expression of the channel is normally limited to specific areas of the brain and to restricted cell populations throughout the body. Tumour samples, however, showed a significant overexpression of the channel with high frequency (up to 80% depending on the tissue source) regardless of the detection method (staining with either one of the antibodies, or detection of Eag1 RNA).

Conclusion: Inhibition of Eag1 expression in tumour cell lines reduced cell proliferation. Eag1 may therefore represent a promising target for the tailored treatment of human tumours. Furthermore, as normal cells expressing Eag1 are either protected by the blood-brain barrier or represent the terminal stage of normal differentiation, Eag1 based therapies could produce only minor side effects.

Show MeSH
Related in: MedlinePlus