Dataset Information

Mapping the anti-cancer activity of alpha-connexin carboxyl-terminal (aCT1) peptide in resistant HER2+ breast cancer

ABSTRACT: Connexin 43 (Cx43) is a protein encoded by the GJA1 gene and is a component of cell membrane structures called gap junctions, which facilitate intercellular communication. Prior evidence indicates that elevated GJA1 expression in the HER2-positive (HER2+) subtype of breast cancer is associated with poor prognosis. Prior evidence also suggests that HER2+ breast cancers that have become refractory to HER2 targeted agents have a loss of Cx43 gap junction intercellular communication (GJIC). In this study, a Cx43 targeted agent called alpha-connexin carboxyl-terminal peptide (aCT1) is examined to determine whether GJIC can be rescued in refractory HER2+ breast cancer cells. A proposed mechanism of action for aCT1 is binding to the tight junction protein Zonal Occludens-1 (ZO-1). However, the true scope of activity for aCT1 has not been explored. In this study, proteomic analysis is used to determine the breadth of aCT1 interacting proteins. The NanoString nCounter Breast Cancer 360 panel was also used to examine the effect of aCT1 on cancer signaling in HER2+ breast cancer cells. Findings from this study show a dynamic range of binding partners for aCT1, many of which regulate gene expression and RNA biology. nCounter analysis shows that a number of pathways are significantly impacted by aCT1 including upregulation of apoptotic factors, leading to the prediction and demonstration that aCT1 can boost the cell death effects of cisplatin and lapatinib in HER2+ breast cancer cells that have become resistant to HER2 targeted agents.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Amber L. Mosley

PROVIDER: MSV000093550 | MassIVE | Fri Dec 01 08:18:00 GMT 2023

SECONDARY ACCESSION(S): PXD047448

REPOSITORIES: MassIVE

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Mapping the Anti-Cancer Activity of α-Connexin Carboxyl-Terminal (aCT1) Peptide in Resistant HER2+ Breast Cancer.

Baker Kimberly M KM Abt Melissa M Doud Emma H EH Oblak Adrian L AL Yeh Elizabeth S ES

Cancers 20240119 2

Connexin 43 (Cx43) is a protein encoded by the <i>GJA1</i> gene and is a component of cell membrane structures called gap junctions, which facilitate intercellular communication. Prior evidence indicates that elevated <i>GJA1</i> expression in the HER2-positive (HER2+) subtype of breast cancer is associated with poor prognosis. Prior evidence also suggests that HER2+ breast cancers that have become refractory to HER2-targeted agents have a loss of Cx43 gap junction intercellular communication (G ...[more]

PMID: 38275864

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Project description:Gene expression data of HER2+ breast tumor samples Increasing evidence indicates that a subset of patients with HER2-positive breast cancer may achieve significant clinical benefit with anti-HER2 targeted therapy without chemotherapy. Thus, identification of biomarkers of long-term benefit from anti-HER2 agents is needed, especially in the metastatic setting. In the HERLAP study (NCT00842998), patients with HER2-positive metastatic breast cancer were randomized to trastuzumab or lapatinib as first-line therapy. Patients showing radiological signs of tumor regression after 8 weeks of treatment were allowed to continue on single agent anti-HER2 therapy until disease progression. Chemotherapy was added to anti-HER-2 therapy in patients failing to achieve tumor regression at the 8-week evaluation and those progressing at any time. Expression analysis of 105 selected genes was performed from formalin-fixed paraffin-embedded in 17 primary tumor samples. The research-based PAM50 intrinsic subtypes were also identified. The association of the expression of each biomarker with clinical outcome endpoints was evaluated. Nineteen patients were enrolled. In 4 patients (21.1%) we observed disease control lasting longer than 12 months with single agent anti-HER2 therapy (range 14.9-38.8 months). High expression of 17q12-21 amplicon genes HER2 and GRB7, and the PAM50 HER2-enriched intrinsic profile, were found significantly associated with 8-week overall response rate and with the duration of disease control during single agent anti-HER2 therapy. Conversely, high expression of luminal-related genes such as PGR, MDM2 or PIK3CA, or the PAM50 luminal intrinsic profile, was found associated with reduced benefit from single agent anti-HER2 therapy. Conclusions: Our data indicate that gene expression-based biomarkers can identify patients with HER2-positive metastatic breast cancer that benefit substantially from single agent chemo-free anti-HER2 targeted therapy. In the study presented here, a well-defined cohort of 21 breast cancer cases from the HERLAP trial, was used to acquire expression profiles of a total of 105 unique genes