Dual “mAb” HER family blockade in head and neck cancer human cell lines combined with photon therapy

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DNA double-strand breaks (DSBs) induced by photon irradiation are the most deleterious damage for cancer cells and their efficient repair may contribute to radioresistance, particularly in hypoxic conditions. Carbon ions (C-ions) act independently of the oxygen concentration and trigger complex- and clustered-DSBs difficult to repair. Understanding the interrelation between hypoxia, radiation-type, and DNA-repair is therefore essential for overcoming radioresistance. The DSBs signaling and the contribution of the canonical non-homologous end-joining (NHEJ-c) and homologous-recombination (HR) repair pathways were assessed by immunostaining in two cancer-stem-cell (CSCs) and non-CSCs HNSCC cell lines. Detection and signaling of DSBs were lower in response to C-ions than photons. Hypoxia increased the decay-rate of the detected DSBs (γH2AX) in CSCs after photons and the initiation of DSB repair signaling (P-ATM) in CSCs and non-CSCs after both radiations, but not the choice of DSB repair pathway (53BP1). Additionally, hypoxia increased the NHEJ-c (DNA-PK) and the HR pathway (RAD51) activation only after photons. Furthermore, the involvement of the HR seemed to be higher in CSCs after photons and in non-CSCs after C-ions. Taken together, our results show that C-ions may overcome the radioresistance of HNSCC associated with DNA repair, particularly in CSCs, and independently of a hypoxic microenvironment.

Section: Methodsmentioning

confidence: 99%

Impact of hypoxia on the double-strand break repair after photon and carbon ion irradiation of radioresistant HNSCC cells

Wozny

Alphonse

Cassard

et al. 2020

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“…Trastuzumab binds to domain IV of HER2 which inhibits the homodimerization between HER2 dimers 35 . Pertuzumab binds to domain II of HER2 and interferes with the heterodimerization between HER2 and the other HER family receptors 36 . Further studies were performed to improve the understanding of the mechanism Domain III of HER2 was reported to be involved in the function of HER2 and HER3 interaction 37 .…”

Section: Discussionmentioning

confidence: 99%

A novel anti-HER2 antibody GB235 reverses Trastuzumab resistance in HER2-expressing tumor cells in vitro and in vivo

Shu

Yan

Xu³

et al. 2020

HER2 overexpression is frequently associated with tumor metastasis and poor prognosis of breast cancer. More evidence indicates that HER3 is involved in HER2-resistant therapies. Combination treatments with two or more different monoclonal antibodies are a promising strategy to overcome resistance to HER2 therapies. We presented a novel fully human HER2-targeted monoclonal antibody, GB235, screened from a phage-display library against the HER2 antigen. GB235 in combination with Trastuzumab overcomes resistance in HER2-positive tumors and results in more sustained inhibition of tumor growth over time. The competition binding assay showed that the epitopes of GB235 do not overlap with those of Pertuzumab and Trastuzumab on HER2. Further HER2 mutagenesis results revealed that the binding epitopes of GB235 were located in the domain III of HER2. The mechanism of action of GB235 in blocking HER2-driven tumors is different from the mechanisms of Trastuzumab or Pertuzumab. GB235 does not affect the heterodimerization of HER2 and HER3, whereas the GB235 combined treatment with Trastuzumab significantly inhibited heregulin-induced HER3 phosphorylation and downstream signaling. Moreover, GB235 in combination with Trastuzumab reversed the resistance to heregulin-induced proliferation in HER2-overexpressing cancer cell lines. GB235 combined with Trastuzumab treatment in xenograft models resulted in improved antitumor activity. Complete tumor suppression was observed in the HER2-positive NCI-N87 xenograft model treated with the combination treatment with GB235 and Trastuzumab. In a Trastuzumab-resistant patient-derived tumor xenograft model GA0060, GB235 plus Trastuzumab reversed the resistance to Trastuzumab monotherapy. Because GB235 showed a different working mechanism with Pertuzumab and Trastuzumab, these agents can be considered complementary therapy against HER2 overexpression tumors.www.nature.com/scientificreports www.nature.com/scientificreports/ to HER2 ECD proteins of three different species. GB235 specifically bound to human and rat HER2 ECD, but did not cross-react with the mouse HER2 ECD in the ELISA (Fig. 6C). Moreover, it was observed that 362D, 374Q, 395D, 456 H are phylogenetically conserved in human and rat HER2 ECD d III , but not in mouse HER2 ECD d III . The residues are conserved in the human and rat HER2 but not in the mouse HER2, thus explaining the lack of cross-reaction with mouse HER2. The binding of the full-length human HER2 ECD d I-IV to GB235 was abolished in site-directed mutants of human HER2 (D362N, Q374H and H456N) (Fig. 6D). The residues 362D, 374Q and 456 H in the human HER2 ECD d III were found to be critical for the binding of GB235.

“…Among the four members of this family, HER3 is the only membrane receptor that does not possess a tyrosine kinase cytoplasmic domain and thus requires heterodimerization with HER1 or HER2 35,36 , with these heterodimers being particularly active. Indeed, studies on HNSCC have been published showing increased chemosensitization 37 , radiosensitization 38 and susceptibility to HER1 inhibition (Cetuximab) 36,38,39 after inhibiting the HER3 receptor. Thus, while various HER receptors are found overexpressed or aberrantly activated by mutations, and are responsible for mitogenic signaling, the HER3 receptor is of particular interest.…”

Section: Discussionmentioning

confidence: 99%

SATB1 as oncogenic driver and potential therapeutic target in head & neck squamous cell carcinoma (HNSCC)

Panchal

Wichmann

Grénman

et al. 2020

The Special AT-rich sequence binding protein 1 (SATB1) is a genome organizer protein that controls gene expression of numerous genes by regulating chromatin architecture and targeting chromatinremodeling/-modifying enzymes onto specific chromatin regions. SATB1 is overexpressed in various tumors. In head and neck squamous cell carcinoma (HNSCC), SATB1 upregulation is correlated with TNM classification, metastasis, poor prognosis and reduced overall survival. In this paper, we comprehensively analyze cellular and molecular effects of SATB1 in a large set of primary cell lines from primary HNSCC or metastases, using RNAi-mediated knockdown in vitro and, therapeutically, in tumor xenograft mouse models in vivo. In a series of 15 cell lines, major differences in SATB1 levels are observed. In various 2-D and 3-D assays, growth inhibition upon efficient siRNA-mediated SATB1 knockdown depends on the cell line rather than initial SATB1 levels. Inhibitory effects are found to be based on cell cycle deceleration, apoptosis induction, decreased HER3 and Heregulin A&B expression, and effects on EMT genes. In vivo, systemic treatment of tumor xenograft-bearing mice with siRNAs formulated in polymeric nanoparticles inhibits tumor growth of two HNSCC xenograft models, resulting from therapeutic SATB1 reduction and concomitant decrease of proliferation and induction of apoptosis. In conclusion, SATB1 represents a promising target in HNSCC, affecting crucial cellular processes and molecular pathways.