STAT1 contributes to HLA class I upregulation and CTL reactivity after anti-EGFR mAb cetuximab therapy in head and neck cancer patients

Squamous cell carcinoma of head and neck (HNSCC) cells express low HLA class I and antigen processing machinery (APM) components, such as transporter TAP-1/2, which is associated with the reduced sensitivity to cytotoxic T lymphocyte (CTL) mediated lysis. Epidermal growth factor receptor (EGFR) is overexpressed in HNSCC and is associated with the poor prognosis. FDA approved anti-EGFR blockade mAb cetuximab inhibits HNSCC proliferation, and induces EGFR-specific CTL. However, the molecular mechanism(s) underlying the EGFR-specific CTL recognition of HNSCC in the therapeutic efficacy of anti-EGFR mAb is still emerging. We show that cetuximab or EGFR knockdown enhanced expression of HLA class I antigens, which is associated with the EGFR expression level on HNSCC. These findings were validated in a prospective trial of neoadjuvant cetuximab therapy. Interestingly, upregulation of HLA-B/C alleles were more pronounced than HLA-A alleles after cetuximab or EGFR knockdown treatment. EGFR signaling blockade or EGFR depletion also enhanced IFN gamma receptor (IFNAR) on HNSCC and augmented induction of HLA class I and TAP-1/2 caused by IFN gamma treatment. Cetuximab or EGFR knockdown enhanced the level of HLA class I, STAT-1, TAP-1/2 in a STAT-1+/+ cell line but not in STAT-1-/- cell line, documenting the STAT-1 dependence of this effect. We also found that Src homology domain-containing phosphatase 2 (SHP-2), which is downstream of EGFR and also overexpressed in SCCHN, can suppress the immunostimulatory effect of cetuximab treatment on HLA class I/STAT-1 upregulation, and dual targeting of EGFR and SHP-2 co-operates in the most efficient reversal of immune escape phenotype. In addition, cetuximab-based EGFR inhibition and SHP-2 depletion enhanced the recognition of HNSCC cells by EGFR 853-861 specific CTL, and enhanced surface presentation of non-EGFR TA, such as MAGE-3 271-279 , indicating that a broad tumor antigen repertoire is processed and presented by HLA/APM upregulation. These findings elucidate a novel immune escape mechanism associated with EGFR signaling through STAT1 suppression and the reversal with cetuximab, which may provide additional targets for on-going mAb-based immunotherapy

EGFR-mediated tumor immunoescape: The imbalance between phosphorylated STAT1 and phosphorylated STAT3

The epidermal growth factor receptor (EGFR) supports the escape of malignant cells from immunosurveillance by inhibiting the activation of signal transducer and activator of transcription 1 (STAT1) while promoting that of STAT3. We have recently demonstrated that protein tyrosine phosphatase, non-receptor type 11 (PTNP11, best known as SHP2), a phosphatase that operates downstream of EGFR, is responsible for the dephosphorylation of active STAT1 and for the inhibition of the antigen-processing machinery (APM), hence favoring tumor immunoescape. Thus, EGFR signaling may skew the tumor microenvironment to suppress cellular immune responses

A Solitary Neck Nodule as Late Evidence of Recurrent Lobular Breast Carcinoma

Recurrent lobular breast carcinoma manifesting as a cutaneous neck nodule in a woman, 14 years after successful chemotherapy, illustrates the importance of following at-risk patients with a high level of clinical suspicion. This case emphasizes the value of combining clinical findings with appropriate histopathologic and immunohistochemical analysis when evaluating a cutaneous lesion in such a patient

Diversity of Extracellular Vesicles (EV) in Plasma of Cancer Patients

Extracellular vesicles (EVs) are produced by all cells and are found in all body fluids. They function as intercellular messengers that carry and deliver signals regulating cellular interactions in health and disease. EVs are emerging as potential biomarkers of diseases and responses to therapies, and much attention is being devoted to understanding their role in physiological as well as pathological events. EVs are heterogenous in their origin, size, molecular characteristics, genetic content and functions. Isolation of EV subsets from plasma and characterization of their distinct properties have been a limiting factor in ongoing efforts to understand their biological importance. Here, we discuss the immunoaffinity-based strategies that are available for isolating distinct subsets of EVs from plasma and provide a road-map to their successful immunocapture and molecular profiling, with special attention to tumor-derived EVs or TEX

Structural and mutational analyses of the Leptospira interrogans virulence-related heme oxygenase provide insights into its catalytic mechanism

© 2017 Soldano et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Heme oxygenase from Leptospira interrogans is an important virulence factor. During catalysis, redox equivalents are provided to this enzyme by the plastidic-type ferredoxin-NADP+ reductase also found in L. interrogans. This process may have evolved to aid this bacterial pathogen to obtain heme-iron from their host and enable successful colonization. Herein we report the crystal structure of the heme oxygenase-heme complex at 1.73 Å resolution. The structure reveals several distinctive features related to its function. A hydrogen bonded network of structural water molecules that extends from the catalytic site to the protein surface was cleared observed. A depression on the surface appears to be the H+ network entrance from the aqueous environment to the catalytic site for O2 activation, a key step in the heme oxygenase reaction. We have performed a mutational analysis of the F157, located at the above-mentioned depression. The mutant enzymes were unable to carry out the complete degradation of heme to biliverdin since the reaction was arrested at the verdoheme stage. We also observed that the stability of the oxyferrous complex, the efficiency of heme hydroxylation and the subsequent conversion to verdoheme was adversely affected. These findings underscore a long-range communication between the outer fringes of the hydrogen-bonded network of structural waters and the heme active site during catalysis. Finally, by analyzing the crystal structures of ferredoxin-NADP+ reductase and heme oxygenase, we propose a model for the productive association of these proteins

Ultracompact, low-loss directional couplers on InP based on self-imaging by multimode interference

We report extremely compact (494-µm-long 3 dB splitters, including input/output bends), polarization-insensitive, zero-gap directional couplers on InP with a highly multimode interference region that are based on the self-imaging effect. We measured cross-state extinctions better than 28 dB and on-chip insertion losses of 0.5 dB/coupler plus 1 dB/cm guide propagation loss at 1523 nm wavelength

Designing all-graphene nanojunctions by covalent functionalization

We investigated theoretically the effect of covalent edge functionalization, with organic functional groups, on the electronic properties of graphene nanostructures and nano-junctions. Our analysis shows that functionalization can be designed to tune electron affinities and ionization potentials of graphene flakes, and to control the energy alignment of frontier orbitals in nanometer-wide graphene junctions. The stability of the proposed mechanism is discussed with respect to the functional groups, their number as well as the width of graphene nanostructures. The results of our work indicate that different level alignments can be obtained and engineered in order to realize stable all-graphene nanodevices