Dataset Information

Reciprocal regulation of annexin A2 and EGFR with Her-2 in Her-2 negative and herceptin-resistant breast cancer.

ABSTRACT: Alternative survival pathways are commonly seen to be upregulated upon inhibition of receptor tyrosine kinases (RTK), including Her-2. It is established that treatment with Herceptin leads to selective overexpression and activation of epidermal growth factor receptor (EGFR) and Src which further contributes to oncogenesis in Herceptin resistant and triple negative breast cancer (TNBC) patients. Here, we show a co-regulated upregulation in the expression of Annexin A2 (AnxA2), a known substrate of Src and one of the regulators of EGFR receptor endocytosis, in Herceptin resistant and Her-2 negative breast cancer. Immunohistochemical expression analysis revealed a reciprocal regulation between Her-2 and AnxA2 in breast cancer clinical samples as well as in cell lines as confirmed by protein and RNA analysis. The siRNA and Herceptin mediated downregulation/inhibition of Her-2 in Her-2 amplified cells induced AnxA2 expression and membrane translocation. In this study we report a possible involvement of AnxA2 in maintaining constitutively activated EGFR downstream signaling intermediates and hence in cell proliferation, migration and viability. This effect was consistent in Herceptin resistant JIMT-1 cells as well as in Her-2 negative breast cancer. The siRNA mediated AnxA2 downregulation leads to increased apoptosis, decreased cell viability and migration. Our studies further indicate the role of AnxA2 in EGFR-Src membrane bound signaling complex and ligand induced activation of downstream signaling pathways. Targeting this AnxA2 dependent positive regulation of EGFR signaling cascade may be of therapeutic value in Her-2 negative breast cancer.

SUBMITTER: Shetty PK

PROVIDER: S-EPMC3434131 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Reciprocal regulation of annexin A2 and EGFR with Her-2 in Her-2 negative and herceptin-resistant breast cancer.

Shetty Praveenkumar K PK Thamake Sanjay I SI Biswas Swati S Johansson Sonny L SL Vishwanatha Jamboor K JK

PloS one 20120905 9

Alternative survival pathways are commonly seen to be upregulated upon inhibition of receptor tyrosine kinases (RTK), including Her-2. It is established that treatment with Herceptin leads to selective overexpression and activation of epidermal growth factor receptor (EGFR) and Src which further contributes to oncogenesis in Herceptin resistant and triple negative breast cancer (TNBC) patients. Here, we show a co-regulated upregulation in the expression of Annexin A2 (AnxA2), a known substrate o ...[more]

PMID: 22957061

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Project description:BACKGROUND:Limited information is available on biomarker(s) for triple-negative breast cancer (TNBC) that can address the higher incidence and aggressiveness of TNBC in African-American (AA) women. Our previous studies have demonstrated annexin A2 (AnxA2) association with exosomes which promotes angiogenesis and metastasis. Therefore, our goal was to examine the expression and function of exosomal-annexin A2 (exo-AnxA2) derived from the serum samples of breast cancer patients. METHODS:The expression of serum exo-AnxA2 and its association with clinicopathological features of the breast cancer patients were determined. The role of serum exo-AnxA2 to promote angiogenesis was determined by an in vivo Matrigel plug assay. RESULTS:Our results show that the expression of serum exo-AnxA2 in breast cancer patients (n?=?169; 83.33?±?2.040?ng/mL, P?<?0.0001) is high compared to non-cancer females (n?=?68; 34.21?±?2.238?ng/mL). High expression of exo-AnxA2 levels in breast cancer was significantly associated with tumor grade (P?<?0.0001), poor overall survival (hazard ratio (HR) 2.802; 95% confidence intervals (CI)?=?1.030-7.620; P?=?0.0353), and poor disease-free survival (HR 7.934; 95% CI?=?1.778-35.398; P?=?0.0301). The expression of serum exo-AnxA2 levels was significantly elevated in TNBC (n?=?68; 109.1?±?2.905?ng/mL; P?<?0.0001) in comparison to ER+ (n?=?50; 57.35?±?1.545?ng/mL), HER2+ (n?=?59; 78.25?±?1.146?ng/mL), and non-cancer females (n?=?68; 34.21?±?2.238?ng/mL). Exo-AnxA2 showed diagnostic values with a maximum AUC as 1.000 for TNBC, 0.8304 for ER+, and 0.9958 for HER2+ compared to non-cancer females. The expression of serum exo-AnxA2 was significantly elevated in AA women with TNBC (n?=?29; 118.9?±?4.086?ng/mL, P?<?0.0001) in comparison to Caucasian-American TNBC (n?=?27; 97.60?±?3.298?ng/mL) patients. Our in vivo results suggest a role of serum exo-AnxA2 in angiogenesis and its association with aggressiveness of TNBC in AA women. CONCLUSIONS:Our results demonstrated that the expression of serum exo-AnxA2 is high in AA women with TNBC and promotes angiogenesis. These findings suggest that exo-AnxA2 holds promise as a potential prognosticator of TNBC and may lead to an effective therapeutic option.

Project description:Exosomes are carriers of intercellular information that regulate the tumor microenvironment, and they have an essential role in drug resistance through various mechanisms such as transporting RNA molecules and proteins. Nevertheless, their effects on gemcitabine resistance in triple-negative breast cancer (TNBC) are unclear. In the present study, we examined the effects of exosomes on TNBC cell viability, colony formation, apoptosis, and annexin A6 (ANXA6)/EGFR expression. We addressed their roles in gemcitabine resistance and the underlying mechanism. Our results revealed that exosomes derived from resistant cancer cells improved cell viability and colony formation and inhibited apoptosis in sensitive cancer cells. The underlying mechanism included the transfer of exosomal ANXA6 from resistant cancer cells to sensitive cancer cells. Isobaric peptide labeling-liquid chromatography-tandem mass spectrometry and western blotting revealed that ANXA6 was upregulated in resistant cancer cells and their derived exosomes. Sensitive cancer cells exhibited resistance with increased viability and colony formation and decreased apoptosis when ANXA6 was stably overexpressed. On the contrary, knockdown ANXA6 restored the sensitivity of cells to gemcitabine. Co-immunoprecipitation expression and GST pulldown assay demonstrated that exosomal ANXA6 and EGFR could interact with each other and exosomal ANXA6 was associated with the suppression of EGFR ubiquitination and downregulation. While adding lapatinib reversed gemcitabine resistance induced by exosomal ANXA6. Moreover, ANXA6 and EGFR protein expression was correlated in TNBC tissues, and exosomal ANXA6 levels at baseline were lower in patients with highly sensitive TNBC than those with resistant TNBC when treated with first-line gemcitabine-based chemotherapy. In conclusion, resistant cancer cell-derived exosomes induced gemcitabine resistance via exosomal ANXA6, which was associated with the inhibition of EGFR ubiquitination and degradation. Exosomal ANXA6 levels in the serum of patients with TNBC might be predictive of the response to gemcitabine-based chemotherapy.

Dataset Information

Reciprocal regulation of annexin A2 and EGFR with Her-2 in Her-2 negative and herceptin-resistant breast cancer.

Publications

Reciprocal regulation of annexin A2 and EGFR with Her-2 in Her-2 negative and herceptin-resistant breast cancer.

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