Expression of hypoxia-inducible factor-1alpha and cell cycle proteins in invasive breast cancer are estrogen receptor related

c-Jun activation is associated with proliferation and angiogenesis in invasive breast cancer

c-Jun is a component of the transcription factor activator protein 1 (AP-1), which binds and activates transcription at TRE/AP-1 elements. Extra- or intracellular signals, including growth factors, transforming oncoproteins, and UV irradiation, stimulate phosphorylation of c-Jun at serine 63/73 and activate c-Jun-dependent transcription. Therefore, activated c-Jun potentially plays an important role in carcinogenesis and cancer progression. To evaluate expression patterns of activated c-Jun in breast cancer in relation to angiogenesis and proliferation, we performed immunohistochemistry on 103 cases of invasive breast cancer with an antibody recognizing phosphorylated c-Jun at serine 73. Activated c-Jun showed a predominantly nuclear expression at the invasive front in 38% of invasive breast cancer cases. Furthermore, expression of activated c-Jun was seen in mitotic cells of the invasive front in 50% of cases. Occasionally, fibroblasts, endothelial cells, and benign breast cells showed nuclear expression. Activated nuclear c-Jun expression showed positive correlations with expression of hyperphosphorylated pRb, vascular endothelial growth factor, and with microvessel density. Mitotic c-Jun expression was associated with pRb and microvessel density. Stromal c-Jun expression showed positive relations with microvessel density. In survival analysis, no significant relation was found with activated c-Jun expression and survival, although a trend with poor survival was found for mitotic cells overexpressing activated c-Jun (P = .09). Our results show that activated c-Jun is predominantly expressed at the invasive front in breast cancer and is associated with proliferation and angiogenesis. Earlier studies have established a functional, in vitro link between activated c-Jun and tumor angiogenesis. Our present results in breast cancer patients confirm this relation in vivo for the first time. Therefore, c-Jun/AP-1 targeting may provide new ways to block tumor angiogenesis.

Hypoxic activation of unoccupied estrogen-receptor-alpha is mediated by hypoxia-inducible factor-1 alpha

The estrogen receptor (ER) plays an important role in breast cancer development and progression. Hypoxia has been shown to modulate the level of ERalpha expression, which is intimately associated with the biology of breast carcinomas. However, the effect of hypoxia on ERalpha-mediated transactivation is largely unknown. In this report, we have examined ligand-independent transcriptional activation of ERalpha by hypoxia. The hypoxia-induced ERalpha-mediated transcriptional response was inhibited by the ER antagonist ICI 182,780 as determined by transient expression of ERalpha and ER-responsive reporter plasmids in the HEK 293 cells. Hypoxic activation of ERalpha was dependent on the increased expression of hypoxia-inducible factor-1alpha (HIF-1alpha), as examined in HEK 293 cells under conditions of normoxia. These results indicate that hypoxia activates ERalpha in a ligand-independent manner, possibly through the interaction between HIF-1alpha and ERalpha.

Hypoxia inducible factor-1alpha is a prognostic marker in premenopausal patients with intermediate to highly differentiated breast cancer but not a predictive marker for tamoxifen response

Hypoxia is common in many solid tumours, including breast cancer. Hypoxia triggers the expression of hypoxia inducible factor-1alpha (HIF-1alpha), and HIF-1alpha has been associated with an impaired prognosis in breast cancer and down-regulation of the oestrogen receptor (ER), potentially affecting the treatment efficiency of antioestrogens. The role of HIF-1alpha regarding prognostic and treatment predictive information in breast cancer has not been established and we therefore analyzed HIF-1alpha using immunohistochemistry in a cohort of 377 premenopausal stage II breast cancers arranged in a tissue microarray. The patients were included in a randomized trial with either 2 years of tamoxifen or no adjuvant treatment. The tamoxifen treatment effect could be studied in subgroups of breast cancer and pure prognostic information could be scrutinized for untreated control patients. HIF-1alpha was scored as positive in 24% of the tumours and correlated positively to tumour size, Nottingham histological grade (NHG), Ki-67, Her2 and cyclin E expression and negatively to lymph node status, cyclin D1, ER and PR (progesterone receptor) expression. Surprisingly, there was no difference in tamoxifen response for patients with high or low HIF-1alpha expressing tumours. In lymph node-positive patients as well as NHG 1/2 tumours, high HIF-1alpha protein expression was significantly associated with an impaired recurrence-free survival (p=0.014, 0.018). When analyzing the subgroup of NHG 1/2 tumours, a high HIF-1alpha expression was the only independent significant prognostic marker in multivariate analysis, including standard prognostic markers, suggesting that HIF-1alpha might be a useful prognostic marker in this subgroup of breast cancer, with a rather good but diverse prognosis.

Changes in electric charge and phospholipids composition in human colorectal cancer cells

Cancer cells perform their malicious activities through own cell membranes that screen and transmit inhibitory and stimulatory signals out of the cells and into them. This work is focused on changes of phospholipids content (PI-phosphatidylinositol, PS-phosphatidylserine, PE-phosphatidylethanolamine, PC-phosphatidylcholine) and electric charge that occur in cell membranes of colorectal cancer of pT 3 stage, various grades (G2, G3) and without/with metastasis. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC (high-performance liquid chromatography). The surface charge density of colorectal cancer cell membranes was measured using electrophoresis. The measurements were carried out at various pH of solution. It was shown that the process of cancer transformation was accompanied by an increase in total amount of phospholipids as well as an increase in total positive charge at low pH and total negative charge at high pH. A malignant neoplasm cells with metastases are characterized by a higher PC/PE ratio than malignant neoplasm cells without metastases.

Intermittent hypoxia induces proteasome-dependent down-regulation of estrogen receptor alpha in human breast carcinoma

PURPOSE

Hypoxia may influence gene expression to promote malignancy, and acute hypoxia has been shown to transiently repress estrogen receptor (ER)-alpha expression in breast cell lines. However, the effect of intermittent hypoxia, which is likely more prevalent in breast cancers, remains to be determined.

EXPERIMENTAL DESIGN

ER-alpha expression was assessed by Western blot and immunohistochemistry in a selected cohort of 51 ER-alpha-positive breast carcinomas, in relation to markers of hypoxia. The effect of acute and intermittent hypoxia on ER-alpha expression was also determined in MCF7 and ZR-75 breast cell lines, together with the role of proteasome function with the proteasome inhibitor bortezomib.

RESULTS

Regional loss of ER-alpha expression occurs in breast tumors and is consistently present in hypoxic regions defined by the proximity of necrosis and induction of hypoxia-induced genes carbonic anhydrase IX (CA-IX) and glucose transporter 1 (Glut-1), in both in situ (n = 29; P < 0.0001) and invasive (n = 20; P = 0.0001) carcinomas. In MCF7 and ZR-75 cells, ER-alpha is transiently down-regulated by acute hypoxia and rapidly restored by reoxygenation. However, intermittent, acute hypoxia can cause a similar down-regulation of ER-alpha that is not attributable to decreased mRNA and persists in MCF7 cells despite reoxygenation for up to 14 days. This effect occurs with no change in cell viability but a corresponding reduction in growth response to estradiol. However, ER-alpha expression can be restored by bortezomib.

CONCLUSIONS

Intermittent hypoxia can cause persistent changes in proteasome function that may contribute to reduced ER-alpha expression in breast tumors and consequently to diminished response and development of resistance to endocrine therapy.

Prognostic and predictive molecular markers in DCIS: a review

Eighteen percent of all new breast cancers detected on screening mammography are ductal carcinoma in situ (DCIS), a preinvasive lesion that is highly curable. However, some women with DCIS will develop life-threatening invasive breast cancer. Because the determinants of invasive recurrence are unknown, all women with DCIS require the same treatment (usually with surgery and radiation). Therefore, there is a need to identify biologic markers and create a profile that will provide prognostic information that is more accurate than the currently used van Nuys Index to predict invasive recurrence. In the present review, we examined the many biologic markers studied in breast cancer, describe their main biologic role and their expression in DCIS, and review the various studies regarding their ability to serve as prognostic factors in breast cancer with an emphasis on predicting invasive recurrence in patients with DCIS. This review covers established markers, namely, ER, PR and HER2/neu, that are used routinely to make treatment decisions as well as investigative biologic factors involved in cell proliferation, cell cycle regulation, extracellular molecules, factors involved in extracellular matrix degradation, and angiogenesis. However, controversies exist regarding the value of these prognostic factors, their interrelationship, and their advantages over morphologic evaluation.