Zachary S. Morris

NK Cell-Mediated Antibody-Dependent Cellular Cytotoxicity in Cancer Immunotherapy

Natural killer (NK) cells play a major role in cancer immunotherapies that involve tumor-antigen targeting by monoclonal antibodies (mAbs). NK cells express a variety of activating and inhibitory receptors that serve to regulate the function and activity of the cells. In the context of targeting cells, NK cells can be “specifically activated” through certain Fc receptors that are expressed on their cell surface. NK cells can express FcγRIIIA and/or FcγRIIC, which can bind to the Fc portion of immunoglobulins, transmitting activating signals within NK cells. Once activated through Fc receptors by antibodies bound to target cells, NK cells are able to lyse target cells without priming, and secrete cytokines like interferon gamma to recruit adaptive immune cells. This antibody-dependent cell-mediated cytotoxicity (ADCC) of tumor cells is utilized in the treatment of various cancers overexpressing unique antigens, such as neuroblastoma, breast cancer, B cell lymphoma, and others. NK cells also express a family of receptors called killer immunoglobulin-like receptors (KIRs), which regulate the function and response of NK cells toward target cells through their interaction with their cognate ligands that are expressed on tumor cells. Genetic polymorphisms in KIR and KIR-ligands, as well as FcγRs may influence NK cell responsiveness in conjunction with mAb immunotherapies. This review focuses on current therapeutic mAbs, different strategies to augment the anti-tumor efficacy of ADCC, and genotypic factors that may influence patient responses to antibody-dependent immunotherapies.

Aberrant epithelial morphology and persistent epidermal growth factor receptor signaling in a mouse model of renal carcinoma

The epidermal growth factor receptor (EGFR) has frequently been implicated in hyperproliferative diseases of renal tubule epithelia. We have shown that the NF2 tumor suppressor Merlin inhibits EGFR internalization and signaling in a cell contact–dependent manner. Interestingly, despite the paucity of recurring mutations in human renal cell carcinoma (RCC), homozygous mutation of the NF2 gene is found in ≈2% of RCC patient samples in the Sanger COSMIC database. To examine the roles of Merlin and EGFR in kidney tumorigenesis, we generated mice with a targeted deletion of Nf2 in the proximal convoluted epithelium using a Villin-Cre transgene. All of these mice developed intratubular neoplasia by 3 months, which progressed to invasive carcinoma by 6–10 months. Kidneys from these mice demonstrated marked hyperproliferation and a concomitant increase in label-retaining putative progenitor cells. Early lumen-filling lesions in this model exhibited hyperactivation of EGFR signaling, altered solubility of adherens junctions components, and loss of epithelial polarity. Renal cortical epithelial cells derived from either early or late lesions were dependent on EGF for in vitro proliferation and were arrested by pharmacologic inhibition of EGFR or re-expression of Nf2. These cells formed malignant tumors upon s.c. injection into immunocompromised mice before in vitro passage. Treatment of Vil-Cre;Nf2lox/lox mice with the EGFR inhibitor erlotinib halted the proliferation of tumor cells. These studies give added credence to the role of EGFR signaling and perhaps Nf2 deficiency in RCC and describe a rare and valuable mouse model for exploring the molecular basis of this disease.

Interaction of Radiation Therapy With Molecular Targeted Agents

The development of molecular targeted therapeutics in oncology builds on many years of scientific investigation into the cellular mechanics of malignant transformation and progression. The past two decades have brought an accelerating pace to the clinical investigation of new molecular targeted agents, particularly in the setting of metastatic disease. The integration of molecular targeted agents into phase III clinical trial design has lagged in the curative treatment setting, particularly in combination with established therapeutic modalities such as radiation. In this review, we discuss the interaction of radiation and molecular targeted therapeutics. The dynamics of cellular and tumor response to radiation offer unique opportunities for beneficial interplay with molecular targeted agents that may go unrecognized with conventional screening and monotherapy clinical testing of novel agents. By using epidermal growth factor receptor (EGFR) as a primary example, we discuss recent clinical studies that illustrate the potential synergy of molecular targeted agents with radiation and highlight the clinical value of such interactions. For various molecular targeted agents, their greatest clinical impact may rest in combination with radiation, and efforts to facilitate systematic investigation of this approach appear highly warranted.

A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history

The avian beak is a key evolutionary innovation whose flexibility has permitted birds to diversify into a range of disparate ecological niches. We approached the problem of the mechanism behind this innovation using an approach bridging paleontology, comparative anatomy, and experimental developmental biology. First, we used fossil and extant data to show the beak is distinctive in consisting of fused premaxillae that are geometrically distinct from those of ancestral archosaurs. To elucidate underlying developmental mechanisms, we examined candidate gene expression domains in the embryonic face: the earlier frontonasal ectodermal zone (FEZ) and the later midfacial WNT‐responsive region, in birds and several reptiles. This permitted the identification of an autapomorphic median gene expression region in Aves. To test the mechanism, we used inhibitors of both pathways to replicate in chicken the ancestral amniote expression. Altering the FEZ altered later WNT responsiveness to the ancestral pattern. Skeletal phenotypes from both types of experiments had premaxillae that clustered geometrically with ancestral fossil forms instead of beaked birds. The palatal region was also altered to a more ancestral phenotype. This is consistent with the fossil record and with the tight functional association of avian premaxillae and palate in forming a kinetic beak.

The skull roof tracks the brain during the evolution and development of reptiles including birds

Major transformations in brain size and proportions, such as the enlargement of the brain during the evolution of birds, are accompanied by profound modifications to the skull roof. However, the hypothesis of concerted evolution of shape between brain and skull roof over major phylogenetic transitions, and in particular of an ontogenetic relationship between specific regions of the brain and the skull roof, has never been formally tested. We performed 3D morphometric analyses to examine the deep history of brain and skull-roof morphology in Reptilia, focusing on changes during the well-documented transition from early reptiles through archosauromorphs, including nonavian dinosaurs, to birds. Non-avialan taxa cluster tightly together in morphospace, whereas Archaeopteryx and crown birds occupy a separate region. There is a one-to-one correspondence between the forebrain and frontal bone and the midbrain and parietal bone. Furthermore, the position of the forebrain–midbrain boundary correlates significantly with the position of the frontoparietal suture across the phylogenetic breadth of Reptilia and during the ontogeny of individual taxa. Conservation of position and identity in the skull roof is apparent, and there is no support for previous hypotheses that the avian parietal is a transformed postparietal. The correlation and apparent developmental link between regions of the brain and bony skull elements are likely to be ancestral to Tetrapoda and may be fundamental to all of Osteichthyes, coeval with the origin of the dermatocranium.Brain and skull development are intimately related across tetrapods. Here, the authors show a close relationship between brain and skull roof across evolutionary transitions and ontogenetic stages of reptiles.

NF2/Merlin mediates contact-dependent inhibition of EGFR mobility and internalization via cortical actomyosin

Merlin and Ezrin are central to a mechanism whereby mechanical forces transduced across the apical actomyosin cytoskeleton from cell junctions control the mobility and internalization of EGFR, providing novel insight into how cells inhibit mitogenic signaling in response to cell contact.

In situ tumor vaccination by combining local radiation and tumor-specific antibody or immunocytokine treatments

Interest in combining radiotherapy and immune checkpoint therapy is growing rapidly. In this study, we explored a novel combination of this type to augment antitumor immune responses in preclinical murine models of melanoma, neuroblastoma, and head and neck squamous cell carcinoma. Cooperative effects were observed with local radiotherapy and intratumoral injection of tumor-specific antibodies, arising in part from enhanced antibody-dependent cell-mediated cytotoxicity (ADCC). We could improve this response by combining radiation with intratumoral injection of an IL2-linked tumor-specific antibody (termed here an immunocytokine), resulting in complete regression of established tumors in most animals associated with a tumor-specific memory T-cell response. Given the T-cell response elicited by combined local radiation and intratumoral immunocytokine, we tested the potential benefit of adding this treatment to immune checkpoint blockade. In mice bearing large primary tumors or disseminated metastases, the triple-combination of intratumoral immunocytokine, radiation, and systemic anti-CTLA-4 improved primary tumor response and animal survival compared with combinations of any two of these three interventions. Taken together, our results show how combining radiation and intratumoral immunocytokine in murine tumor models can eradicate large tumors and metastases, eliciting an in situ vaccination effect that can be leveraged further by T-cell checkpoint blockade, with immediate implications for clinical evaluation. Cancer Res; 76(13); 3929-41. ©2016 AACR.

Increased tumor response to neoadjuvant therapy among rectal cancer patients taking angiotensin-converting enzyme inhibitors or angiotensin receptor blockers

Angiotensin‐converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are commonly used antihypertensive medications that have been reported to affect aberrant angiogenesis and the dysregulated inflammatory response. Because of such mechanisms, it was hypothesized that these medications might affect the tumor response to neoadjuvant radiation in patients with rectal cancer.

Pan-HER Inhibitor Augments Radiation Response in Human Lung and Head and Neck Cancer Models

Purpose: Aberrant regulation of the EGF receptor family (EGFR, HER2, HER3, HER4) contributes to tumorigenesis and metastasis in epithelial cancers. Pan-HER represents a novel molecular targeted therapeutic composed of a mixture of six monoclonal antibodies against EGFR, HER2, and HER3. Experimental Design: In the current study, we examine the capacity of Pan-HER to augment radiation response across a series of human lung and head and neck cancers, including EGFR inhibitor–resistant cell lines and xenografts. Results: Pan-HER demonstrates superior antiproliferative and radiosensitizing impact when compared with cetuximab. The mechanisms underlying these effects appear to involve attenuation of DNA damage repair, enhancement of programmed cell death, cell-cycle redistribution, and induction of cellular senescence. Combined treatment of Pan-HER with single or fractionated radiation in human tumor xenografts reveals a potent antitumor and regrowth delay impact compared with Pan-HER or radiation treatment alone. Conclusions: These data highlight the capacity of Pan-HER to augment radiation response in lung and head and neck cancer models and support investigation of Pan-HER combined with radiation as a promising clinical therapeutic strategy. Clin Cancer Res; 22(3); 633–43. ©2015 AACR.

Thyroid-specific knockout of the tumor suppressor mitogen-inducible gene 6 activates epidermal growth factor receptor signaling pathways and suppresses nuclear factor-κB activity

BACKGROUND Mitogen-inducible gene 6 (Mig-6) is a putative tumor suppressor gene and prognostic biomarker in papillary thyroid cancer. We hypothesized that Mig-6 knockout would activate pro-oncogenic signaling in mouse thyrocytes. METHODS We performed a thyroid-specific knockout using the Cre/loxP recombinase system. RESULTS Four knockout and 4 control mouse thyroids were harvested at 2 months of age. Immunoblotting confirmed Mig-6 ablation in knockout mice thyrocytes. Epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase (ERK) phosphorylation levels were increased in Mig-6 knockout compared to wild-type mice. Total EGFR levels were similar in knockout and wild-type mice. However, EGFR was absent in the caveolae-containing membrane fraction of knockout mice, indicating that Mig-6 depletion is associated with a change in the membrane distribution of EGFR. Although p65 localized to the nucleus in wild-type mice, it was distributed in both cytoplasm and nucleus in knockouts, suggesting that Mig-6 loss decreases p65 activity. CONCLUSION Our results confirm the feasibility of targeted, thyroid-specific gene knockout as a strategy for studying the relevance of specific genes in thyroid oncogenesis. We suggest that the loss of Mig-6 alters the membrane distribution of EGFR, which may limit receptor degradation and activate this oncogenic signaling pathway.