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HIF1alpha isoforms in benign and malignant prostate tissue and their correlation to neuroendocrine differentiation.

Monsef N, Soller M, Panagopoulos I, Abrahamsson PA - BMC Cancer (2010)

Bottom Line: HIF1alpha and HIF1beta are two subunits of HIF1, a transcription factor important for angiogenesis.The aim of this study was to elucidate whether the cytoplasmic stabilization of HIF1alpha in androgen independent NE differentiated prostate cancer is due to the presence of certain HIF1alpha isoforms.Co-localization of this isoform with HIF1beta indicates that the HIF1alpha1.2 isoform might sequester HIF1beta in the cytoplasm.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Laboratory Medicine, Division of Pathology, Lund University Hospital, Sweden. Nastaran.Monsef@gmail.com

ABSTRACT

Background: Neuroendocrine (NE) differentiation in prostate cancer has been correlated with a poor prognosis and hormone refractory disease. In a previous report, we demonstrated the presence of immunoreactive cytoplasmic hypoxia inducible factor 1alpha (HIF1alpha), in both benign and malignant NE prostate cells. HIF1alpha and HIF1beta are two subunits of HIF1, a transcription factor important for angiogenesis. The aim of this study was to elucidate whether the cytoplasmic stabilization of HIF1alpha in androgen independent NE differentiated prostate cancer is due to the presence of certain HIF1alpha isoforms.

Methods: We studied the HIF1alpha isoforms present in 8 cases of benign prostate hyperplasia (BPH) and 43 cases of prostate cancer with and without NE differentiation using RT-PCR, sequencing analysis, immunohistochemistry and in situ hybridization.

Results: We identified multiple isoforms in both benign and malignant prostate tissues. One of these isoforms, HIF1alpha1.2, which was previously reported to be testis specific, was found in 86% of NE-differentiated prostate tumors, 92% of HIF1alpha immunoreactive prostate tumors and 100% of cases of benign prostate hyperplasia. Immunohistochemistry and in situ hybridization results showed that this isoform corresponds to the cytoplasmic HIF1alpha present in androgen-independent NE cells of benign and malignant prostate tissue and co-localizes with immunoreactive cytoplasmic HIF1beta.

Conclusion: Our results indicate that the cytoplasmic stabilization of HIF1alpha in NE-differentiated cells in benign and malignant prostate tissue is due to presence of an HIF1alpha isoform, HIF1alpha1.2. Co-localization of this isoform with HIF1beta indicates that the HIF1alpha1.2 isoform might sequester HIF1beta in the cytoplasm.

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Results of in situ hybridization and immunohistochemistry on thin adjacent section to detect expression of HIF-1α1.2 mRNA and HIF1α protein in malignant and benign prostate tissue. In situ hybridization (antisense probe, Fig. 3a) and immunostaining with HIF1α Ab2 (Fig. 3c) on thin adjacent sections of NE-differentiated prostate adenocarcinoma showed co-localization of HIF1α1.2 transcript and HIF-1α protein. Incubation with sense probe did not generate any detectable hybridization signals (Fig. 3b). Both In situ hybridization (Fig. 3d antisense) and HIF-1α Ab2 immunostaining (Fig. 3f) were negative in non-NE-differentiated prostate adenocarcinoma. In situ hybridization with sense probe performed on non-NE-differentiated prostate cancer (Fig. 3e) was negative. In situ hybridizering on benign prostate tissue showed HIF1α1.2 transcript in NE-like cells of benign prostate tissue (Fig. 3g, ↗). The sense probe on thin adjacent section generated no signals (Fig. 3h,↗). Furthermore, co-localization of HIF1α1.2 transcript (Fig. 3i,↗,◢,↖) and HIF1α protein, detected with HIF1αAb3 (Fig. 3j,↗,◢,↖) was also shown in NE-like cells of benign prostate tissue. Panels a, b, c, d, e, f, g, h, i, j: 40× objective.
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Figure 3: Results of in situ hybridization and immunohistochemistry on thin adjacent section to detect expression of HIF-1α1.2 mRNA and HIF1α protein in malignant and benign prostate tissue. In situ hybridization (antisense probe, Fig. 3a) and immunostaining with HIF1α Ab2 (Fig. 3c) on thin adjacent sections of NE-differentiated prostate adenocarcinoma showed co-localization of HIF1α1.2 transcript and HIF-1α protein. Incubation with sense probe did not generate any detectable hybridization signals (Fig. 3b). Both In situ hybridization (Fig. 3d antisense) and HIF-1α Ab2 immunostaining (Fig. 3f) were negative in non-NE-differentiated prostate adenocarcinoma. In situ hybridization with sense probe performed on non-NE-differentiated prostate cancer (Fig. 3e) was negative. In situ hybridizering on benign prostate tissue showed HIF1α1.2 transcript in NE-like cells of benign prostate tissue (Fig. 3g, ↗). The sense probe on thin adjacent section generated no signals (Fig. 3h,↗). Furthermore, co-localization of HIF1α1.2 transcript (Fig. 3i,↗,◢,↖) and HIF1α protein, detected with HIF1αAb3 (Fig. 3j,↗,◢,↖) was also shown in NE-like cells of benign prostate tissue. Panels a, b, c, d, e, f, g, h, i, j: 40× objective.

Mentions: In situ hybridization was performed on serially cut paraffin sections from two cases of benign and four cases of malignant prostate cancer. Two cases of adenocarcinomas were previously shown to contain cells with cytoplasmic HIF1α and NE marker, chromogranin. The other two cases were negative for cytoplasmic HIF1α and NE marker. In adjacent sections, the majority of HIF1α positive cells in both benign and malignant cells (93% versus 89%) also displayed increased HIF1α1.2 specific mRNA levels (Figs. 3a,c, g, i, j). Fifty cells were counted in the benign cases, and 300 cells were counted in the malignant tissue. The HIF1α-negative cells had low or no detectable mRNA levels of HIF1α (Figs. 3e and 3f). These findings suggest that HIF1α1.2 corresponds to the isoform encoding cytoplasmic HIF1α in both benign and malignant prostate tissues.


HIF1alpha isoforms in benign and malignant prostate tissue and their correlation to neuroendocrine differentiation.

Monsef N, Soller M, Panagopoulos I, Abrahamsson PA - BMC Cancer (2010)

Results of in situ hybridization and immunohistochemistry on thin adjacent section to detect expression of HIF-1α1.2 mRNA and HIF1α protein in malignant and benign prostate tissue. In situ hybridization (antisense probe, Fig. 3a) and immunostaining with HIF1α Ab2 (Fig. 3c) on thin adjacent sections of NE-differentiated prostate adenocarcinoma showed co-localization of HIF1α1.2 transcript and HIF-1α protein. Incubation with sense probe did not generate any detectable hybridization signals (Fig. 3b). Both In situ hybridization (Fig. 3d antisense) and HIF-1α Ab2 immunostaining (Fig. 3f) were negative in non-NE-differentiated prostate adenocarcinoma. In situ hybridization with sense probe performed on non-NE-differentiated prostate cancer (Fig. 3e) was negative. In situ hybridizering on benign prostate tissue showed HIF1α1.2 transcript in NE-like cells of benign prostate tissue (Fig. 3g, ↗). The sense probe on thin adjacent section generated no signals (Fig. 3h,↗). Furthermore, co-localization of HIF1α1.2 transcript (Fig. 3i,↗,◢,↖) and HIF1α protein, detected with HIF1αAb3 (Fig. 3j,↗,◢,↖) was also shown in NE-like cells of benign prostate tissue. Panels a, b, c, d, e, f, g, h, i, j: 40× objective.
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Figure 3: Results of in situ hybridization and immunohistochemistry on thin adjacent section to detect expression of HIF-1α1.2 mRNA and HIF1α protein in malignant and benign prostate tissue. In situ hybridization (antisense probe, Fig. 3a) and immunostaining with HIF1α Ab2 (Fig. 3c) on thin adjacent sections of NE-differentiated prostate adenocarcinoma showed co-localization of HIF1α1.2 transcript and HIF-1α protein. Incubation with sense probe did not generate any detectable hybridization signals (Fig. 3b). Both In situ hybridization (Fig. 3d antisense) and HIF-1α Ab2 immunostaining (Fig. 3f) were negative in non-NE-differentiated prostate adenocarcinoma. In situ hybridization with sense probe performed on non-NE-differentiated prostate cancer (Fig. 3e) was negative. In situ hybridizering on benign prostate tissue showed HIF1α1.2 transcript in NE-like cells of benign prostate tissue (Fig. 3g, ↗). The sense probe on thin adjacent section generated no signals (Fig. 3h,↗). Furthermore, co-localization of HIF1α1.2 transcript (Fig. 3i,↗,◢,↖) and HIF1α protein, detected with HIF1αAb3 (Fig. 3j,↗,◢,↖) was also shown in NE-like cells of benign prostate tissue. Panels a, b, c, d, e, f, g, h, i, j: 40× objective.
Mentions: In situ hybridization was performed on serially cut paraffin sections from two cases of benign and four cases of malignant prostate cancer. Two cases of adenocarcinomas were previously shown to contain cells with cytoplasmic HIF1α and NE marker, chromogranin. The other two cases were negative for cytoplasmic HIF1α and NE marker. In adjacent sections, the majority of HIF1α positive cells in both benign and malignant cells (93% versus 89%) also displayed increased HIF1α1.2 specific mRNA levels (Figs. 3a,c, g, i, j). Fifty cells were counted in the benign cases, and 300 cells were counted in the malignant tissue. The HIF1α-negative cells had low or no detectable mRNA levels of HIF1α (Figs. 3e and 3f). These findings suggest that HIF1α1.2 corresponds to the isoform encoding cytoplasmic HIF1α in both benign and malignant prostate tissues.

Bottom Line: HIF1alpha and HIF1beta are two subunits of HIF1, a transcription factor important for angiogenesis.The aim of this study was to elucidate whether the cytoplasmic stabilization of HIF1alpha in androgen independent NE differentiated prostate cancer is due to the presence of certain HIF1alpha isoforms.Co-localization of this isoform with HIF1beta indicates that the HIF1alpha1.2 isoform might sequester HIF1beta in the cytoplasm.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Laboratory Medicine, Division of Pathology, Lund University Hospital, Sweden. Nastaran.Monsef@gmail.com

ABSTRACT

Background: Neuroendocrine (NE) differentiation in prostate cancer has been correlated with a poor prognosis and hormone refractory disease. In a previous report, we demonstrated the presence of immunoreactive cytoplasmic hypoxia inducible factor 1alpha (HIF1alpha), in both benign and malignant NE prostate cells. HIF1alpha and HIF1beta are two subunits of HIF1, a transcription factor important for angiogenesis. The aim of this study was to elucidate whether the cytoplasmic stabilization of HIF1alpha in androgen independent NE differentiated prostate cancer is due to the presence of certain HIF1alpha isoforms.

Methods: We studied the HIF1alpha isoforms present in 8 cases of benign prostate hyperplasia (BPH) and 43 cases of prostate cancer with and without NE differentiation using RT-PCR, sequencing analysis, immunohistochemistry and in situ hybridization.

Results: We identified multiple isoforms in both benign and malignant prostate tissues. One of these isoforms, HIF1alpha1.2, which was previously reported to be testis specific, was found in 86% of NE-differentiated prostate tumors, 92% of HIF1alpha immunoreactive prostate tumors and 100% of cases of benign prostate hyperplasia. Immunohistochemistry and in situ hybridization results showed that this isoform corresponds to the cytoplasmic HIF1alpha present in androgen-independent NE cells of benign and malignant prostate tissue and co-localizes with immunoreactive cytoplasmic HIF1beta.

Conclusion: Our results indicate that the cytoplasmic stabilization of HIF1alpha in NE-differentiated cells in benign and malignant prostate tissue is due to presence of an HIF1alpha isoform, HIF1alpha1.2. Co-localization of this isoform with HIF1beta indicates that the HIF1alpha1.2 isoform might sequester HIF1beta in the cytoplasm.

Show MeSH
Related in: MedlinePlus