What is HER2?

In Silico Design of Peptide Inhibitors Targeting HER2 for Lung Cancer Therapy

BACKGROUND/OBJECTIVES

Human epidermal growth factor receptor 2 (HER2) is overexpressed in several malignancies, such as breast, gastric, ovarian, and lung cancers, where it promotes aggressive tumor proliferation and unfavorable prognosis. Targeting HER2 has thus emerged as a crucial therapeutic strategy, particularly for HER2-positive malignancies. The present study focusses on the design and optimization of peptide inhibitors targeting HER2, utilizing machine learning to identify and enhance peptide candidates with elevated binding affinities. The aim is to provide novel therapeutic options for malignancies linked to HER2 overexpression.

METHODS

This study started with the extraction and structural examination of the HER2 protein, succeeded by designing the peptide sequences derived from essential interaction residues. A machine learning technique (XGBRegressor model) was employed to predict binding affinities, identifying the top 20 peptide possibilities. The candidates underwent further screening via the FreeSASA methodology and binding free energy calculations, resulting in the selection of four primary candidates (pep-17, pep-7, pep-2, and pep-15). Density functional theory (DFT) calculations were utilized to evaluate molecular and reactivity characteristics, while molecular dynamics simulations were performed to investigate inhibitory mechanisms and selectivity effects. Advanced computational methods, such as QM/MM simulations, offered more understanding of peptide-protein interactions.

RESULTS

Among the four principal peptides, pep-7 exhibited the most elevated DFT values (-3386.93 kcal/mol) and the maximum dipole moment (10,761.58 Debye), whereas pep-17 had the lowest DFT value (-5788.49 kcal/mol) and the minimal dipole moment (2654.25 Debye). Molecular dynamics simulations indicated that pep-7 had a steady binding free energy of -12.88 kcal/mol and consistently bound inside the HER2 pocket during a 300 ns simulation. The QM/MM simulations showed that the overall total energy of the system, which combines both QM and MM contributions, remained around -79,000 ± 400 kcal/mol, suggesting that the entire protein-peptide complex was in a stable state, with pep-7 maintaining a strong, well-integrated binding.

CONCLUSIONS

Pep-7 emerged as the most promising therapeutic peptide, displaying strong binding stability, favorable binding free energy, and molecular stability in HER2-overexpressing cancer models. These findings suggest pep-7 as a viable therapeutic candidate for HER2-positive cancers, offering a potential novel treatment strategy against HER2-driven malignancies.

Key genes and drug delivery systems to improve the efficiency of chemotherapy

Cancer cells can develop resistance to anticancer drugs, thereby becoming tolerant to treatment through different mechanisms. The biological mechanisms leading to the generation of anticancer treatment resistance include alterations in transmembrane proteins, DNA damage and repair mechanisms, alterations in target molecules, and genetic responses, among others. The most common anti-cancer drugs reported to develop resistance to cancer cells include cisplatin, doxorubicin, paclitaxel, and fluorouracil. These anticancer drugs have different mechanisms of action, and specific cancer types can be affected by different genes. The development of drug resistance is a cellular response which uses differential gene expression, to enable adaptation and survival of the cell to diverse threatening environmental agents. In this review, we briefly look at the key regulatory genes, their expression, as well as the responses and regulation of cancer cells when exposed to anticancer drugs, along with the incorporation of alternative nanocarriers as treatments to overcome anticancer drug resistance.

Cardiovascular Health during and after Cancer Therapy

Certain cancer treatments have been linked to specific cardiovascular toxicities, including (but not limited to) cardiomyopathy, atrial fibrillation, arterial hypertension, and myocarditis. Radiation, anthracyclines, human epidermal growth factor receptor 2 (Her2)-directed therapies, fluoropyrimidines, platinums, tyrosine kinase inhibitors and proteasome inhibitors, immune checkpoint inhibitors, and chimeric antigen-presenting (CAR)-T cell therapy can all cause cardiovascular side effects. Management of cardiovascular dysfunction that occurs during cancer therapy often requires temporary or permanent cessation of the risk-potentiating anti-neoplastic drug as well as optimization of medical management from a cardiovascular standpoint. Stem cell or bone marrow transplant recipients face unique cardiovascular challenges, as do patients at extremes of age.

A single-domain antibody-linked Fab bispecific antibody Her2-S-Fab has potent cytotoxicity against Her2-expressing tumor cells

Her2, which is frequently overexpressed in breast cancer, is one of the most studied tumor-associated antigens for cancer therapy. Anti-HER2 monoclonal antibody, trastuzumab, has achieved significant clinical benefits in metastatic breast cancer. In this study, we describe a novel bispecific antibody Her2-S-Fab targeting Her2 by linking a single domain anti-CD16 VHH to the trastuzumab Fab. The Her2-S-Fab antibody can be efficiently expressed and purified from Escherichia coli, and drive potent cancer cell killing in HER2-overexpressing cancer cells. In xenograft model, the Her2-S-Fab suppresses tumor growth in the presence of human immune cells. Our results suggest that the bispecific Her2-S-Fab may provide a valid alternative to Her2 positive cancer therapy.

Structural identification of an HER2 receptor model binding pocket to optimize lead compounds: a combined experimental and computational approach

In silico methods and experimental data obtained from fluorescence studies allowed the identification of a new binding pocket for the HER2-DIVMP receptor model.

Progression and treatment of HER2-positive breast cancer

PURPOSE

Approximately 20-30% of breast cancer tumors overexpress or amplify human epidermal growth factor receptor 2 (HER2). The role of this receptor in the progression of HER2+ breast cancer and resistance to certain anticancer monotherapies was investigated. The results of several pre-clinical and clinical trials, with the aim of determining the most safe and effective course of treatment for HER2+ breast cancer, were also thoroughly examined.

METHODS

A thorough search of databases including Pubmed, Springer, and The American Society of Clinical Oncology was performed, and pertinent studies were identified. The most relevant studies were preclinical, phase II, and III clinical trials identifying the function of the HER2 receptor in HER2+ breast cancer progression, as well as studies assessing the efficacy of monotherapy and combination therapy in the treatment of this aggressive form of cancer.

RESULTS

The HER2 receptor belongs to a family of receptors that consists of four cell-surface receptors (HER1-4) that share strong homology with the epidermal growth factor receptor (EGFR). All HER receptors interact with specific types of ligands to induce receptor activation, except for HER2, for which no known ligand has yet been identified. HER2 is activated by forming dimers with other HER receptors, and this results in a stronger and more prolonged signal transduction event. When expressed at normal levels, HER2 regulates cell growth, differentiation, and survival. However, under pathological conditions of HER2 overexpression, numerous HER2 heterodimers are formed resulting in aggressive tumor growth. Therefore, the prognosis associated with HER2-positive breast cancer is usually poor. A specific cohort of patients with breast cancer whose tumors test both hormone receptor (estrogen receptor [ER] and progesterone receptor [PR]) and HER2 positive have been found to be resistant to targeted hormone therapy. Studies investigating the etiology of this resistance have found that the cell membrane estrogen receptor communicates with HER2 in promoting the release of ER coactivators that cause the endocrine drug and selective estrogen receptor modulator, tamoxifen, to act as an agonist rather than an antagonist of the hormone estrogen. Thus, research has directed its inquiry toward the development of therapies specifically targeting HER2. The development of trastuzumab, a recombinant monoclonal antibody against HER2, initially proved to be a well-tolerated first line of treatment. However, in the long-term patients, trastuzumab was shown to develop resistance to this monotherapy. Therefore, research on HER2 positive breast cancer has focused on the study of different anti-HER2 combination therapies over the past decade.

CONCLUSIONS

While the development and approval of the HER2-targeted recombinant monoclonal antibody trastuzumab (Herceptin) has been efficacious in slowing HER2 cancer progression, combining this and other anti-HER2 therapy with either chemotherapy or endocrine therapy has proven more effective in improving overall and progression free survival.

The Ras-MAPK signal transduction pathway, cancer and chromatin remodeling

Stimulation of the Ras-mitogen-activated protein kinase (MAPK) signal transduction pathway results in a multitude of events including expression of the immediate-early genes, c-fos and c-myc. Downstream targets of this stimulated pathway are the mitogen- and stress-activated protein kinases (MSK) 1 and 2, which are histone H3 kinases. In chromatin immunoprecipitation assays, it has been shown that the mitogen-induced phosphorylated H3 is associated with the immediate-early genes and that MSK1/2 activity and H3 phosphorylation have roles in chromatin remodeling and transcription of these genes. In oncogene-transformed fibroblasts in which the Ras-MAPK pathway is constitutively active, histone H1 and H3 phosphorylation is increased and the chromatin of these cells has a more relaxed structure than the parental cells. In this review we explore the deregulation of the Ras-MAPK pathway in cancer, with an emphasis on breast cancer. We discuss the features of MSK1 and 2 and the impact of a constitutively activated Ras-MAPK pathway on chromatin remodeling and gene expression.Key words: Ras, mitogen-activated protein kinase signal transduction pathway, histone H3 phosphorylation, MSK1, breast cancer.

Herceptin: increasing survival in metastatic breast cancer

Growth factors and their receptors play an important role in the pathogenesis of human cancer. The human epidermal growth factor receptor-2 (HER2) is overexpressed in approximately 30% of breast cancers and this is associated with poor clinical outcome. Overexpression of HER2 has been demonstrated to play a direct role in oncogenic transformation. Murine monoclonal antibodies (muMAbs) targeting the extracellular domain of the HER2 receptors suppress HER2-positive cancer cell growth, with muMAb 4D5 having particularly potent activity. A humanized form of muMAb 4D5 was generated by converting all but the antigen-binding region of muMAb 4D5 into human IgG consensus sequences. The humanized monoclonal antibody, Herceptin, preferentially targets HER2-overexpressing cells, produces responses in breast cancer patients and is well tolerated. In a pivotal phase III trial, Herceptin administered in combination with chemotherapy (anthracycline/cyclophosphamide or paclitaxel) was compared with chemotherapy alone. The combination was found to produce significant survival benefits in HER2-positive metastatic breast cancer patients. These results have led to the approval of Herceptin for clinical use in the USA and elsewhere.