Structure/function analysis of ErbB2

Amplification and overexpression of ErbB2 strongly correlates with low rates of apoptosis, resistance to chemotherapies and a poor clinical prognosis. A deeper understanding of pathways downstream of ErbB2 signaling that promotes transformation of mammary epithelial cells and confers resistance to chemotherapeutic drugs is likely to identify novel strategies for therapeutic intervention in breast cancer. Using a controlled dimerization system to activate ErbB2 within three-dimensional epithelial acini-like structures derived from MCF 10A cells, I investigated pathways used by ErbB2 to transform normal human breast epithelial cells. I found that while ErbB2 uses multiple pathways to induce cell proliferation and disrupt 3D epithelial organization, it preferentially uses pathways downstream of Tyr 1201 to disrupt apical basal polarity and pathways downstream of Tyr 1226/7 to inhibit cell death in 3D acini and during Taxol treatment. The autophosphorylation site 1226/7 interacts with the scaffolding molecule Shc, and is known to activate the Ras/Erk pathway. However, inhibition of cell death did not correlate with activation Erk or Akt pathways, but was dependent on Shc expression suggesting the presence of Shc dependent pathway that controls ErbB2 induced inhibition of cell death. These results provide a new paradigm for treatment of ErbB2 driven tumors. Pathways responsible for inhibiting apoptosis are more attractive than pathways that target cell proliferation to design therapeutic intervention to treat ErbB2 positive tumors

Immune Dysregulation in Patients Persistently Infected with Human Papillomaviruses 6 and 11

Human Papillomaviruses (HPVs) 6 and 11 are part of a large family of small DNA viruses, some of which are commensal. Although much of the population can contain or clear infection with these viruses, there is a subset of individuals who develop persistent infection that can cause significant morbidity and on occasion mortality. Depending on the site of infection, patients chronically infected with these viruses develop either recurrent, and on occasion, severe genital warts or recurrent respiratory papillomas that can obstruct the upper airway. The HPV-induced diseases described are likely the result of a complex and localized immune suppressive milieu that is characteristic of patients with persistent HPV infection. We review data that documents impaired Langerhans cell responses and maturation, describes the polarized adaptive T-cell immune responses made to these viruses, and the expression of class select II MHC and KIR genes that associate with severe HPV6 and 11 induced disease. Finally, we review evidence that documents the polarization of functional TH2 and T-regulatory T-cells in tissues persistently infected with HPV6 and 11, and we review evidence that there is suppression of natural killer cell function. Together, these altered innate and adaptive immune responses contribute to the cellular and humoral microenvironment that supports HPV 6 and 11-induced disease

Constitutive Overexpression of the Oncogene Rac1 in the Airway of Recurrent Respiratory Papillomatosis Patients Is a Targetable Host-Susceptibility Factor

Recurrent respiratory papillomatosis (RRP) is caused by human papillomaviruses (HPVs), primarily types 6 and 11. The disease is characterized by multiple recurrences of airway papillomas, resulting in high levels of morbidity and significant mortality. The prevalence of latent HPV in the larynx of the general population is much greater than the prevalence of RRP, suggesting a host-susceptibility factor for disease. We report that the oncogene Rac1 and its downstream product cyclooxygenase-2 (COX-2) are both constitutively expressed at high levels throughout the airway of these patients, independent of active HPV infection. Use of the COX-2 inhibitor celecoxib in primary papilloma cell culture resulted in the downregulation of HPV transcription. Furthermore, a proof-of-principle study treating three patients with severe RRP with celecoxib resulted in remission of disease in all cases. Therefore, we have identified the first pharmacologically targetable host-susceptibility pathway that contributes to RRP recurrence

Decreased Langerhans Cell Responses to IL-36γ: Altered Innate Immunity in Patients with Recurrent Respiratory Papillomatosis

Recurrent respiratory papillomatosis (RRP) is a rare, chronic disease caused by human papillomaviruses (HPVs) types 6 and 11 that is characterized by the polarization of adaptive immune responses that support persistent HPV infection. Respiratory papillomas express elevated mRNA levels of IL-36γ, a proinflammatory cytokine in comparison to autologous clinically normal laryngeal tissues; however there is no evidence of inflammation in these lesions. Consistent with this, respiratory papillomas do not contain T(H)1-like CD4(+) T-cells or cytotoxic CD8(+) T-cells, but instead contain a predominance of T(H)2-like and T regulatory cells (Tregs). In addition, papillomas also are infiltrated with immature Langerhans cells (iLCs). In this study, we show that papilloma cells express IL-36γ protein, and that human keratinocytes transduced with HPV11 have reduced IL-36γ secretion. We now provide the first evidence that peripheral blood-derived iLCs respond to IL-36γ by expressing inflammatory cytokines and chemokines. When stimulated with IL-36γ, iLCs from patients with RRP had lower expression levels of the T(H)2-like chemokine CCL-20 as compared with controls. Patients’ iLCs also had decreased steady state levels of CCL-1, which is a proinflammatory chemokine. Moreover, CCL-1 levels in iLCs inversely correlated with the severity of RRP. The combined decrease of T(H)1- and a T(H)2-like chemokines by iLCs from patients could have consequences in the priming of IFN-γ expression by CD8(+) T-cells. Taken together, our results suggest that, in RRP, there is a defect in the proinflammatory innate immune responses made by iLCs in response to IL-36γ. The consequence of this defect may lead to persistent HPV infection by failing to support an effective HPV-specific, T(H)1-like and/or T(c)1-like adaptive response, thus resulting in the predominant T(H)2-like and/or Treg micromilieu present in papillomas