Coexpression patterns of EGFR, HER2, HER3 and HER4 in non-melanoma skin cancer

Revolutionizing non-melanoma skin cancer treatment: Receptor tyrosine kinase inhibitors take the stage

BACKGROUND

Innovative treatments for non-melanoma skin cancers (NMSCs) are required to enhance patient outcomes.

AIMS

This review examines the effectiveness and safety of receptor tyrosine kinase inhibitors (RTKIs).

METHODS

A comprehensive review was conducted on the treatment potential of several RTKIs, namely cetuximab, erlotinib, gefitinib, panitumumab, and lapatinib.

RESULTS

The findings indicate that these targeted therapies hold great promise for the treatment of NMSCs. However, it is crucial to consider relapse rates and possible adverse effects. Further research is needed to improve treatment strategies, identify patient groups that would benefit the most, and assess the long-term efficacy and safety, despite the favorable results reported in previous studies. Furthermore, it is crucial to investigate the potential benefits of integrating RTKIs with immunotherapy and other treatment modalities to enhance the overall efficacy of therapy for individuals with NMSC.

CONCLUSIONS

Targeted therapies for NMSCs may be possible with the use of RTKIs. The majority of studies focused on utilizing epidermal growth factor receptor inhibitors as the primary class of RTKIs for the treatment of NMSC. Other RTKIs were only employed in experimental investigations. Research indicates that RTKIs could potentially serve as a suitable alternative for elderly patients who are unable to undergo chemotherapy and radiotherapy.

EGFR and HER-2 oncogenes expression in an experimental model of two-stage chemically induced carcinogenesis in mouse skin

The aim of the study was to investigate the expression of EGFR and HER-2 oncogenes using an experimental two stage chemically induced carcinogenesis protocol on the dorsal skin in FVB/N mice. Forty female FVB/N mice 4 weeks old, were grouped into one control (n = 8) and two experimental groups (Group A: n = 16, Group B: n = 16) following a randomization process. Two-stage carcinogenesis protocol, was implicated, including an initial treatment with 97.4 nmol DMBA on their shaved dorsal skin and subsequent treatments of 32.4 nmol TPA applications after 13 weeks for Group A and after 20 weeks for Group B. The control group C, received no treatment. Skin was examined weekly for tumor development. Post-experiment, animals were euthanized for tissue analysis. The histological status of the skin lesions in the experimental groups corresponded well with tumour advancement (from dysplasia to poorly-differentiated carcinoma). Tumour sections were evaluated histologically and immunohistochemically. EGFR expression was found significantly higher in precancerous and malignant tumours (p = 042 and p = 008 respectively), while tended to be higher in benign tumours (p = 079), compared to normal histology. Moreover, mean percentage of EGFR positive expression in malignant tumours was significantly higher than in benign tumours (p < 001). HER-2 expression was found significantly higher in precancerous and malignant tumours (p = 042 and p = 015 respectively), while tended to be higher in benign tumours (p = 085), compared to normal histology. Furthermore, mean percentage of HER-2 positive expression in malignant tumours was significantly higher than in benign tumours (p = 005). The study demonstrated that in FVB/N mice subjected to a two-stage chemically induced carcinogenesis protocol, there was a significant increase in the expression of EGFR and HER-2 oncogenes in precancerous and malignant skin lesions compared to normal tissue. This suggests a potentially early role of these oncogenes in the progression of skin tumours in this model.

Site-Specific 68Ga Radiolabeling of Trastuzumab Fab via Methionine for ImmunoPET Imaging

Bioconjugates of antibodies and their derivatives radiolabeled with β+-emitting radionuclides can be utilized for diagnostic PET imaging. Site-specific attachment of radioactive cargo to antibody delivery vectors provides homogeneous, well-defined immunoconjugates. Recent studies have demonstrated the utility of oxaziridine chemistry for site-specific labeling of methionine residues. Herein, we applied this approach to site-specifically radiolabel trastuzumab-derived Fab immunoconjugates with 68Ga, which can be used for in vivo PET imaging of HER2-positive breast cancer tumors. Initially, a reactive azide was introduced to a single solvent-accessible methionine residue in both the wild-type Fab and an engineered derivative containing methionine residue M74, utilizing the principles of oxaziridine chemistry. Subsequently, these conjugates were functionalized with a modified DFO chelator incorporating dibenzocyclooctyne. The resulting DFO-WT and DFO-M74 conjugates were radiolabeled with generator-produced [68Ga]Ga3+, to yield the novel PET radiotracers, [68Ga]Ga-DFO-WT and [68Ga]Ga-DFO-M74. In vitro and in vivo studies demonstrated that [68Ga]Ga-DFO-M74 exhibited a higher affinity for HER2 receptors. Biodistribution studies in mice bearing orthotopic HER2-positive breast tumors revealed a higher uptake of [68Ga]Ga-DFO-M74 in the tumor tissue, accompanied by rapid renal clearance, enabling clear delineation of tumors using PET imaging. Conversely, [68Ga]Ga-DFO-WT exhibited lower uptake and inferior image contrast compared to [68Ga]Ga-DFO-M74. Overall, the results demonstrate that the highly facile methionine-oxaziridine modification approach can be simply applied to the synthesis of stable and site-specifically modified radiolabeled antibody-chelator conjugates with favorable pharmacokinetics for PET imaging.

Nutraceutical strategies for alleviation of UVB phototoxicity

Ultraviolet B exposure to keratinocytes promotes carcinogenesis by inducing pyrimidine dimer lesions in DNA, suppressing the nucleotide excision repair mechanism required to fix them, inhibiting the apoptosis required for the elimination of initiated cells, and driving cellular proliferation. Certain nutraceuticals - most prominently spirulina, soy isoflavones, long-chain omega-3 fatty acids, the green tea catechin epigallocatechin gallate (EGCG) and Polypodium leucotomos extract - have been shown to oppose photocarcinogenesis, as well as sunburn and photoaging, in UVB-exposed hairless mice. It is proposed that spirulina provides protection in this regard via phycocyanobilin-mediated inhibition of Nox1-dependent NADPH oxidase; that soy isoflavones do so by opposing NF-κB transcriptional activity via oestrogen receptor-beta; that the benefit of eicosapentaenoic acid reflects decreased production of prostaglandin E2; and that EGCG counters UVB-mediated phototoxicity via inhibition of the epidermal growth factor receptor. The prospects for practical nutraceutical down-regulation of photocarcinogenesis, sunburn, and photoaging appear favourable.

Targeting EGFR in melanoma - The sea of possibilities to overcome drug resistance

Melanoma is considered one of the most aggressive skin cancers. It spreads and metastasizes quickly and is intrinsically resistant to most conventional chemotherapeutics, thereby presenting a challenge to researchers and clinicians searching for effective therapeutic strategies to treat patients with melanoma. The use of inhibitors of mutated serine/threonine-protein kinase B-RAF (BRAF), e.g., vemurafenib and dabrafenib, has revolutionized melanoma chemotherapy. Unfortunately, the response to these drugs lasts a limited time due to the development of acquired resistance. One of the proteins responsible for this process is epidermal growth factor receptor (EGFR). In this review, we summarize the role of EGFR signaling in the multidrug resistance of melanomas and discuss possible applications of EGFR inhibitors to overcome the development of drug resistance in melanoma cells during therapy.

Loss of Tpl2 activates compensatory signaling and resistance to EGFR/MET dual inhibition in v-RAS transduced keratinocytes

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer in the United States, affecting one million people per year. Patients with aggressive disease have limited treatment options and high mortality, highlighting the need to identify new biomarkers linked to poor clinical outcome. HRAS mutations are found in skin papillomas and cSCCs and increase in frequency when MAP3K family members are inhibited, suggesting a link between blockade of mitogen-activated protein kinase (MAPK) signaling and initiation of RAS-primed cells. Tpl2, a MAP3K gene, can serve as a tumor suppressor gene in cSCC. We have previously shown that upon Tpl2 ablation, mice have heightened sensitivity to aberrant RAS signaling. Tpl2-/- mice display significantly higher numbers of papillomas and cSCCs in two-stage chemical carcinogenesis studies and increased tumorigenicity of keratinocytes expressing oncogenic v-rasHa in nude mouse skin grafts. In part, this is mediated through increased mesenchymal-epithelial transition factor (MET) receptor activity. Epidermal Growth Factor Receptor (EGFR) is reported to be an essential factor for MET-driven carcinogenesis and MET activation may confer resistance to EGFR therapies, suggesting that the concurrent use of both an EGFR inhibitor and a MET inhibitor may show promise in advanced cSCCs. In this study we assessed whether normal or Ras-transformed Tpl2-/- keratinocytes have aberrant EGFR signaling and whether concomitant treatment with EGFR/MET tyrosine kinase inhibitors was more effective than single agents in reducing growth and angiogenic potential of Ras-transformed keratinocytes. Tpl2-/- keratinocytes exhibited increased HER-2 and STAT-3 under basal conditions and elevated p-MET and p-EGFR when transduced with oncogenic RAS. Inhibition of MET by Capmatinib increased p-EGFR in Tpl2-/- keratinocytes and papillomas, and inhibition of EGFR by Gefitinib increased HER2 and HER3 signaling in both genotypes. Treatment of keratinocytes with EGFR and MET inhibitors, in combination, significantly enhanced endothelial tube formation, MMP-9 activity and activation of other RTKs, with more pronounced effects when Tpl2 was ablated. These data indicate that Tpl2 cross-talks with both EGFR and MET signaling pathways. Upon inhibition of EGFR/MET signaling, a myriad of escape mechanisms exists in keratinocytes to overcome targeted drug effects.

Identification of key proteins in the signaling crossroads between wound healing and cancer hallmark phenotypes

Wound healing (WH) and cancer seem to share common cellular and molecular processes that could work in a tight balance to maintain tissue homeostasis or, when unregulated, drive tumor progression. The "Cancer Hallmarks" comprise crucial biological properties that mediate the advancement of the disease and affect patient prognosis. These hallmarks have been proposed to overlap with essential features of the WH process. However, common hallmarks and proteins actively participating in both processes have yet to be described. In this work we identify 21 WH proteins strongly linked with solid tumors by integrated TCGA Pan-Cancer and multi-omics analyses. These proteins were associated with eight of the ten described cancer hallmarks, especially avoiding immune destruction. These results show that WH and cancer's common proteins are involved in the microenvironment modification of solid tissues and immune system regulation. This set of proteins, between WH and cancer, could represent key targets for developing therapies.

New Bifunctional Chelators Incorporating Dibromomaleimide Groups for Radiolabeling of Antibodies with Positron Emission Tomography Imaging Radioisotopes

Positron Emission Tomography (PET) imaging with antibody-based contrast agents frequently uses the radioisotopes [64Cu]Cu2+ and [89Zr]Zr4+. The macrobicyclic chelator commonly known as sarcophagine (sar) is ideal for labeling receptor-targeted biomolecules with [64Cu]Cu2+. The siderophore chelator, desferrioxamine-B (dfo), has been widely used to incorporate [89Zr]Zr4+ into antibodies. Here, we describe new bifunctional chelators of sar and dfo: these chelators have been functionalized with dibromomaleimides (dbm), that enable site-specific and highly stable attachment of molecular cargoes to reduced, solvent-accessible, interstrand native disulfide groups. The new sar-dbm and dfo-dbm derivatives can be easily conjugated with the IgG antibody trastuzumab via reaction with reduced interstrand disulfide groups to give site-specifically modified dithiomaleamic acid (dtm) conjugates, sar-dtm-trastuzumab and dfo-dtm-trastuzumab, in which interstrand disulfides are rebridged covalently with a small molecule linker. Both sar- and dfo-dtm-trastuzumab conjugates have been radiolabeled with [64Cu]Cu2+ and [89Zr]Zr4+, respectively, in near quantitative radiochemical yield (>99%). Serum stability studies, in vivo PET imaging, and biodistribution analyses using these radiolabeled immunoconjugates demonstrate that both [64Cu]Cu-sar-dtm-trastuzumab and [89Zr]Zr-dfo-dtm-trastuzumab possess high stability in biological milieu. Dibromomaleimide technology can be easily applied to enable stable, site-specific attachment of radiolabeled chelators, such as sar and dfo, to native interstrand disulfide regions of antibodies, enabling tracking of antibodies with PET imaging.

Extravasation of an antibody-drug conjugate: A case report of epidermal necrosis after trastuzumab-emtansine extravasation

WHAT IS KNOWN AND OBJECTIVE

Trastuzumab-emtansine is an antibody-drug conjugate developed to decrease off-target toxicity. According to the product label, reactions secondary to extravasation are mild or moderate.

CASE SUMMARY

We report on a 51-year-old woman who developed epidermal necrosis after extravasation of trastuzumab-emtansine, which required surgical intervention. Six weeks later, the lesions were healed with residual hyperpigmentation.

WHAT IS NEW AND CONCLUSION

We describe the course of a case of severe toxicity following trastuzumab-emtansine extravasation. We provide treatment recommendations and recommend amending the information on the product label on extravasation.

The secretome of skin cancer cells activates the mTOR/MYC pathway in healthy keratinocytes and induces tumorigenic properties

Cutaneous squamous cell carcinoma (cSCC) is the most prominent tumor of non-melanoma skin cancers and the most aggressive tumor among keratinocyte carcinoma of the skin, showing a high potential for local invasion and metastasis. The cSCC incidences increased dramatically in recent years and the disease occurs more commonly than any other malignancy. The secretome of cancer cells is currently the focus of many studies in order to identify new marker proteins for different types of cancer and to investigate its influence on the tumor microenvironment. In our study we evaluated whether the secretome of cSCC cells has an impact on keratinocytes, the surrounding tissue cells of cSCC. Therefore, we analyzed and compared the secretome of human A431 cancer cells and of HaCaT keratinocytes by mass spectrometry. In a second experiment, keratinocytes were exposed to the secretome of A431 cells and vice versa and the transcriptome was analyzed by next-generation sequencing. HaCaT cells incubated with A431 conditioned medium revealed a significantly activated mammalian target of rapamycin pathway with a concomitant increase in proliferation and migration. In conclusion, our data demonstrate the impact of the secretome of cancer cells on the transcription machinery of the cells surrounding the tumor, leading to a tumorigenic cell fate.

PD-L1 Expression in Unresectable Locally Advanced or Metastatic Skin Squamous Cell Carcinoma Treated with Anti-Epidermal Growth Factor Receptor Agents

BACKGROUND

Recurrent or metastatic (R/M) skin squamous cell carcinoma (sSCC) not amenable of surgery or irradiation may benefit from systemic therapies. Epidermal growth factor receptor (EGFR) inhibitors and, more recently, immune checkpoint blockers (ICBs) showed activity in R/M sSCC. In this study, we aimed at exploring the possible role of PD-L1 expression in predicting response to anti-EGFR agents.

METHODS

Patients affected by R/M sSCC, treated with pan-HER inhibitor dacomitinib or with platinum-based chemotherapy with cetuximab (CT-cet) from 2010 to 2016, were considered. PD-L1 expression was assessed with immunohistochemistry on tumor cells (TCs) and on microenvironment (TC and tumor-infiltrating lymphocyte [IC] scores, respectively). Prognostic role of PD-L1 and the correlation with response to EGFR inhibitors and survival were analyzed.

RESULTS

Twenty-eight R/M sSCCs were analyzed (19 treated with dacomitinib, 9 with CT-cet). TC and IC were negative in 82 and 45% of cases, respectively; 15% sSCCs were both TC and IC positive. Progression-free survival (PFS) was longer in IC-positive cases (median 7.5 months vs. 2.1 in IC0, p = 0.02). No statistically significant differences were observed between PD-L1 expression and both overall survival and response rates.

CONCLUSION

PD-L1 expression in microenvironment predicted better PFS. The combination of EGFR inhibitors and ICB could help deepening the knowledge about the interrelations between the EGFR and PD-1/PD-L1 pathways.

Advanced basal cell cancer: concise review of molecular characteristics and novel targeted and immune therapeutics

Metastatic basal cell carcinoma is an ultra-rare manifestation of a common disease, appearing in 0.0028%-0.5% of basal cell carcinomas. Initial therapeutic efforts focused on cytotoxic chemotherapy administration. However, it is now known that the Hedgehog signaling pathway is crucial for basal cell proliferation and Hedgehog pathway mutations may lead to tumorigenesis; thus, small-molecule inhibitors of alterations in the components of this pathway, including smoothened (SMO) and GLI, have been the focus of recent therapeutic developments. Indeed, the European Medicines Agency and the Food and Drug Administration have approved the SMO inhibitors, vismodegib and sonidegib, with additional GLI inhibitors currently in clinical trials. Molecular profiling of these tumors has revealed other potential targets for therapy, including high tumor mutational burden and PD-L1 amplification, which predict response to immune checkpoint blockade (PD-1 and PD-L1 inhibitors). An illustrative patient with a giant, advanced, unresectable basal cell carcinoma who obtained an ongoing complete remission after treatment with a combination of an immune checkpoint inhibitor (due to the tumor's high mutational burden) and the Hedgehog inhibitor vismodegib is described. A fuller understanding of the genomic portfolio of these patients can assist in developing novel, rational therapeutic approaches that should continue to improve responses and outcomes.

The HER3 pathway as a potential target for inhibition in patients with biliary tract cancers

INTRODUCTION

Expression of human epidermal growth factor receptor (HER)2 and HER3 have been investigated in small BTC studies using variable scoring systems.

METHODS

HER2 and HER3 overexpression/amplification were explored following internationally agreed guidelines using immunohistochemistry (IHC) and fluorescent in-situ hybridisation (FISH), respectively. Logistic regression and survival analysis (Kaplan Meier, Log rank test and Cox Regression) were used for statistical analysis.

RESULTS

Sixty-seven eligible patients with Stage I/II (31.3%) or III/IV (68.7%) disease at diagnosis were included. Membrane HER2 overexpression/amplification was identified in 1 patient (1%). HER3 overexpression was predominantly cytoplasmic; the rate of overexpression/amplification of HER3 in membrane and cytoplasm was 16% [ampullary cancer (AMP) (1/13; 8%), gallbladder cancer (GBC) (1/10; 10%), intra-hepatic cholangiocarcinoma (ICC) (6/26; 23%), extra-hepatic cholangiocarcinoma (ECC) (3/18; 17%)] and 24% [AMP (1/13; 8%), GBC (1/10; 10%), ICC (10/26; 38%), ECC (4/18; 22%)], respectively.

CONCLUSIONS

A significant subset of patients with BTC expressed HER3. Inhibition of HER3 warrants further investigation. A better understanding of the downstream effects of HER3 in BTC requires further mechanistic investigations to identify new biomarkers and improve patient selection for future clinical trials.

Metastatic squamous cell carcinoma of the skin with clinical response to lapatinib

Background

Lapatinib is a tyrosine kinase inhibitor that blocks the HER2 receptor and is typically used in the setting of metastatic breast cancer. Both ERBB2 (HER2) and ERBB3 (HER3) belong to the same family of receptor tyrosine kinases. Dimerization of these receptors leads to activation of cell proliferation and survival pathways, granting oncogenic potential to dysregulated ERBB/HER receptors. Next generation sequencing (NGS) of tumors has ushered in a new era of personalized oncology therapy and has the ability to detect mutations in ERBB receptors.

Case presentation

We present a patient with metastatic cutaneous squamous cell carcinoma who failed surgery, radiation, and anti-PD1 therapy, but showed clinical response to a drug targeting an ERBB3 mutation identified with NGS. Following initiation of the drug lapatinib, this patient exhibited dramatic tumor regression in the skin, soft tissue, bone and nerves.

Conclusions

Cutaneous squamous cell carcinoma is the 2nd most common skin cancer in humans and future investigation of ERBB2 targeted therapies may provide an effective treatment strategy for patients with mutations in the ERBB2/3 pathway.

Efficacy and safety of single-agent pan-human epidermal growth factor receptor (HER) inhibitor dacomitinib in locally advanced unresectable or metastatic skin squamous cell cancer

BACKGROUND

In recurrent or metastatic (R/M) skin squamous cell cancer (sSCC) not amenable to radiotherapy (RT) or surgery, chemotherapy (CT) has a palliative intent and limited clinical responses. The role of oral pan-HER inhibitor dacomitinib in this setting was investigated within a clinical trial.

METHODS

Patients with diagnosis of R/M sSCC were treated. Dacomitinib was started at a dose of 30 mg daily (QD) for 15 d, followed by 45 mg QD. Primary end-point was response rate (RR). Tumour samples were analysed through next-generation sequencing using a custom panel targeting 36 genes associated with sSCC.

RESULTS

Forty-two patients (33 men; median age 77 years) were treated. Most (86%) received previous treatments consisting in surgery (86%), RT (50%) and CT (14%). RR was 28% (2% complete response; 26% partial response), disease control rate was 86%. Median progression-free survival and overall survival were 6 and 11 months, respectively. Most patients (93%) experienced at least one adverse event (AE): diarrhoea, skin rash (71% each), fatigue (36%) and mucositis (31%); AEs grade 3-4 occurred in 36% of pts. In 16% of cases, treatment was discontinued because of drug-related toxicity. TP53, NOTCH1/2, KMT2C/D, FAT1 and HER4 were the most frequently mutated genes. BRAF, NRAS and HRAS mutations were more frequent in non-responders, and KMT2C and CASP8 mutations were restricted to this subgroup.

CONCLUSIONS

In sSCC, dacomitinib showed activity similar to what was observed with anti-epidermal growth factor receptor agents, and durable clinical benefit was observed. Safety profile was comparable to previous experiences in other cancers. Molecular pt selection could improve therapeutic ratio.

The receptor tyrosine kinase ERBB4 is expressed in skin keratinocytes and influences epidermal proliferation

BACKGROUND

The epidermal growth factor receptor (EGFR) and associated receptors ERBB2 and ERBB3 are important for skin development and homeostasis. To date, ERBB4 could not be unambiguously identified in the epidermis. The aim of this study was to analyze the ERBB-receptor family with a special focus on ERBB4 in vitro in human keratinocytes and in vivo in human and murine epidermis.

METHODS

We compared the transcript levels of all ERBB-receptors and the seven EGFR-ligands in HaCaT and A431 cells. ERBB-receptor activity was analyzed after epidermal growth factor (EGF) stimulation by Western blot analysis. The location of the receptors was investigated by immunofluorescence in human keratinocytes and skin. Finally, we investigated the function of ERBB4 in the epidermis of skin-specific ERBB4-knockout mice.

RESULTS

After EGF stimulation, all ligands were upregulated except for epigen. Expression levels of EGFR were unchanged, but all other ERBB-receptors were down-regulated after EGF stimulation, although all ERBB-receptors were phosphorylated. We detected ERBB4 at mRNA and protein levels in both human epidermal cell lines and in the basal layer of human and murine epidermis. Skin-specific ERBB4-knockout mice revealed a significantly reduced epidermal thickness with a decreased proliferation rate.

CONCLUSIONS

ERBB4 is expressed in the basal layer of human epidermis and cultured keratinocytes as well as in murine epidermis. Moreover, ERBB4 is phosphorylated in HaCaT cells due to EGF stimulation, and its deletion in murine epidermis affects skin thickness by decreasing proliferation.

GENERAL SIGNIFICANCE

ERBB4 is expressed in human keratinocytes and plays a role in murine skin homeostasis.

Surrogate Predictive Biomarkers for Response to Anti-EGFR Agents: State of the Art and Challenges

The epidermal growth factor receptor (EGFR) plays a key role in cancer development and progression in several human malignancies including non-small cell lung cancer (NSCLC). Several strategies aimed at inhibiting the EGFR have been investigated in the last years, including the use of small tyrosine kinase inhibitors (TKIs) directed against the intracellular domain of the receptor and monoclonal antibodies targeting its extracellular portion. Subgroups of patients who are more likely to respond to TKIs have been identified based on both clincal and biological features. Never-smoking history has emerged as the most relevant clinical characteristic predictive of response to TKIs in NSCLC, while presence of drug-sensitive EGFR mutations and EGFR gene gain represent critical biological variables associated with an improved outcome for patients exposed to these agents. Recent studies have highlighted the existence of biological factors involved in intrinsic and acquired resistance to TKIs, including k-ras, HER-2 and EGFR exon 20 mutations. Increasing knowledge of EGFR biology and drug-receptor interactions will allow to identify individuals who are likely to derive a clinical benefit from the proposed targeted therapy, sparing refractory patients expensive and potentially toxic treatment.

Induction of Tyrosine Phosphorylation of UV-Activated EGFR by the Beta-Human Papillomavirus Type 8 E6 Leads to Papillomatosis

Epidemiological evidence is accumulating that beta-human papillomaviruses (HPV) synergize with UV-light in the development of precancerous actinic keratosis, and cutaneous squamous cell carcinomas (cSCC), one of the most common cancers in the Caucasian population. We previously demonstrated the tumorigenic activity of beta-HPV type 8 (HPV8) in the skin of transgenic mice and its cooperation with UV-light. Analysis of underlying mechanisms now showed that in keratinocytes expressing the HPV8E6 protein a transient increase of tyrosine phosphorylated epidermal growth factor receptor (EGFR) in response to UV-irradiation occurred, while EGFR tyrosine phosphorylation, i.e., receptor tyrosine kinase (RTK)-activity was hardly affected in empty vector control cells. FACS and immunofluorescences revealed that the EGFR was internalized into early endosomes in response to UV-exposure in both, HPV8E6 positive and in control cells, yet with a higher rate in the presence of HPV8E6. Moreover, only in HPV8E6 expressing keratinocytes the EGFR was further sorted into CD63+ intraluminal vesicles, indicative for trafficking to late endosomes. The latter requires the ubiquitination of the EGFR, and in correlation, we could show that only in HPV8E6 positive keratinocytes the EGFR was ubiquitinated upon UV-exposure. HPV8E6 and tyrosine phosphorylated EGFR directly interacted which was enhanced by UV-irradiation. The treatment of K14-HPV8E6 transgenic mice with Canertinib, an inhibitor of the RTK-activity of the EGFR, suppressed skin papilloma growth in response to UV-irradiation. This confirms the crucial role of the RTK-activity of the EGFR in HPV8E6 and UV-mediated papillomatosis in transgenic mice. Taken together, our results demonstrate that HPV8E6 alters the signaling of the UV-activated EGFR and this is a critical step in papilloma formation in response to UV-light in transgenic mice. Our results provide a molecular basis how a beta-HPV type may support early steps of skin tumor formation in cooperation with UV-light.

Updates on the Management of Non-Melanoma Skin Cancer (NMSC)

Non-melanoma skin cancers (NMSCs) are the most common malignancy worldwide, of which 99% are basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) of skin. NMSCs are generally considered a curable diseases, yet they currently pose an increasing global healthcare problem due to rising incidence. This has led to a shift in emphasis on prevention of NMSCs with development of various skin cancer prevention programs worldwide. This article aims to summarize the most recent changes and advances made in NMSC management with a focus on prevention, screening, diagnosis, and staging.

Synthesis and evaluation of MR probes for targeted-reporter imaging

Visualizing disease heterogeneity remains a challenging task since most imaging agents are targeted to a single receptor. We describe the development of an MR platform able to report on multiple molecular events. Enzyme activation and enhanced cellular uptake of this modular probe make it suitable for subsequent targeted-reporter imaging applications.

Non-melanoma skin cancer: new and future synthetic drug treatments

INTRODUCTION

Non-melanoma skin cancers (NMSC) mainly comprise two different entities: basal cell carcinoma (BCC) and squamous cell carcinoma (SCC); beneath these two entities, Merkel cell carcinoma, adnexal tumors, dermatofibrosarcoma protuberans, angiosarcoma, and cutaneous lymphoma belong to NMSC. These rare skin tumors are not the topic of this review. BCC and SCC are the most common cancers diagnosed in humans. The preferred treatment is surgery, which in most cases is curative. Although a high recurrence rate is seen, these cancers rarely metastasize. Therefore, systemic treatments were not a priority for these patients. It is long known that the abnormal activation of Hedgehog and epidermal growth factor receptor pathways were involved in BCC and SCC. In the last decade, metastatic disease became an important area of research, mostly because new therapies that targeted components of these two pathways became available. Areas covered: Here we cover the available therapeutic options for patients diagnosed with BCC and SCC, focus on systemic and targeted therapies. Expert opinion: BCC and SCC are common cancers, with good prognosis. More than the metastatic disease, advanced local disease and recurrent disease pose clinicians a great challenge. Albeit there are promising results with targeted therapies, resistance development has already been described.

ERBB2 Is Essential for the Growth of Chemically Induced Skin Tumors in Mice

Although the epidermal growth factor receptor has established roles in skin carcinogenesis, inflammation, and wound healing, the functions of the structurally related receptor ERBB2 in this tissue remain poorly explored. To assess the functions of ERBB2 in skin homeostasis, tumorigenesis, and wound healing, we employed keratin 5-directed, cre recombinase-mediated targeting of Erbb2 alleles in mice. Erbb2^del mice, lacking ERBB2 specifically in keratinocytes, showed no noticeable spontaneous skin abnormalities. During early wound healing, the thickness and the number and proliferation rate of keratinocytes in the wound epithelium of Erbb2^del mice were significantly reduced. Compared with control littermates, Erbb2^del mice remained free of papillomas for a longer time and had significantly reduced tumor burden after application of the 7,12-dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate multistage chemical carcinogenesis protocol. Furthermore, tumor cell proliferation was substantially reduced in Erbb2^del mice, and loss of ERBB2 also decreased keratinocyte proliferation after 12-O-tetradecanoylphorbol-13-acetate application. Thus, ERBB2 is dispensable for the development and homeostasis of the epidermis and its appendages. However, reflecting its pro-proliferative role, ERBB2 is required for the normal healing of skin wounds and for the progression of tumors during skin chemical carcinogenesis in mice. Thus, ERBB2 may be a promising target for inhibiting human nonmelanoma skin cancer progression.

Telangiectasia and Pulmonary Arterial Hypertension Following Treatment With Trastuzumab Emtansine: A Case Report

Trastuzumab emtansine (T-DM1) is a Food and Drug Administration-approved novel agent for the treatment of HER-2 positive advanced breast cancer. We report a case of pulmonary arterial hypertension (PAH) that we attribute to the use of T-DM1. A 43-year-old woman with stage IV breast cancer presented with dyspnea on exertion. After excluding other secondary causes of pulmonary hypertension, a diagnosis of moderately severe PAH was made based on right heart catheterization. History revealed that the patient had been on T-DM1 before presentation. During T-DM1 treatment, the patient experienced hereditary hemorrhagic telangiectasia-like symptoms consisting of spider angiomata-skin lesions, epistaxis, and hematochezia, which resolved with discontinuation of T-DM1. Temporal associations of T-DM1 use with the development of PAH in the patient, and the reported association between hereditary hemorrhagic telangiectasia and PAH via genetic linkage, led us to suspect T-DM1 as the cause of PAH.

AKT1 Activation is Obligatory for Spontaneous BCC Tumor Growth in a Murine Model that Mimics Some Features of Basal Cell Nevus Syndrome

Patients with basal cell nevus syndrome (BCNS), also known as Gorlin syndrome, develop numerous basal cell carcinomas (BCC) due to germline mutations in the tumor suppressor PTCH1 and aberrant activation of Hedgehog (Hh) signaling. Therapies targeted at components of the Hh pathway, including the smoothened (SMO) inhibitor vismodegib, can ablate these tumors clinically, but tumors recur upon drug discontinuation. Using SKH1-Ptch1^+/- as a model that closely mimics the spontaneous and accelerated growth pattern of BCCs in patients with BCNS, we show that AKT1, a serine/threonine protein kinase, is intrinsically activated in keratinocytes derived from the skin of newborn Ptch1^+/- mice in the absence of carcinogenic stimuli. Introducing Akt1 haplodeficiency in Ptch1^+/- mice (Akt1^+/- Ptch1^+/-) significantly abrogated BCC growth. Similarly, pharmacological inhibition of AKT with perifosine, an alkyl phospholipid AKT inhibitor, diminished the growth of spontaneous and UV-induced BCCs. Our data demonstrate an obligatory role for AKT1 in BCC growth, and targeting AKT may help reduce BCC tumor burden in BCNS patients. Cancer Prev Res; 9(10); 794-802. ©2016 AACR.

Recurrent squamous cell carcinoma of the skin treated successfully with single agent cetuximab therapy

Recurrent squamous cell carcinoma of the skin is a rare but difficult to treat condition. Frequently, the disease presents itself in elderly patients with poor performance status and bearing many comorbidities, thus the decision to administer systemic chemotherapy becomes difficult to make. In addition, current chemotherapeutic protocols response rates are far from satisfactory. Recently cetuximab, a chimeric antibody against epidermal growth factor receptor, is increasingly being reported as an alternative treatment. We therefore report this case of a recurrent squamous cell carcinoma of the skin in an elderly woman with poor performance status and who had an excellent clinical response to single agent cetuximab therapy with complete resolution of the disease and minimal toxicity during the course of the treatment to provide evidence for future prospective clinical trials.

Nonmelanoma Cutaneous Head and Neck Cancer and Merkel Cell Carcinoma: Current Concepts, Advances, and Controversies

Nonmelanoma skin cancer (NMSC) is the most common cancer worldwide and the most frequently observed malignancy in whites. Approximately 75% to 80% are basal cell carcinomas and 20% to 25% are squamous cell carcinomas. Incidence is increasing, partly reflecting an ageing population, and NMSC is more commonly seen in men. The predominant causative agent is ultraviolet solar radiation exposure, with the majority of cases occurring on the head and neck. Surgical excision is typically the treatment of choice, providing histopathologic information, high cure rates, and acceptable cosmetic and functional outcomes. Radiation therapy is reserved for cases where surgery is not the preferred choice or for high-risk cases where adjuvant therapy is recommended. Although overall mortality rates are low, patients with complex cases such as those with immunosuppression should be considered for management within multidisciplinary tumor boards. In contrast, Merkel cell carcinoma is a rare and aggressive malignancy, frequently arising on the head and neck in older whites, with a poorer prognosis. This article focuses on the current evidence guiding practice, recent advances, and areas of controversy in NMSC and Merkel cell carcinoma of the head and neck.

ERBB3 is required for tumor promotion in a mouse model of skin carcinogenesis

The epidermal growth factor receptor (EGFR) plays a key role in skin inflammation, wound healing, and carcinogenesis. Less is known about the functions of the structurally related receptor ERBB3 (HER3) in the skin. We assessed the requirement of ERBB3 for skin homeostasis, wound healing, and tumorigenesis by crossing mice carrying a conditional Erbb3 allele with animals expressing cre under the control of the keratin 5 promoter. Erbb3(del) mice, lacking ERBB3 specifically in keratinocytes, showed no obvious abnormalities. The EGFR was upregulated in Erbb3(del) skin, possibly compensating the loss of ERBB3. Nonetheless, healing of full-thickness excisional wounds was negatively affected by ERBB3 deficiency. To analyze the function of ERBB3 during tumorigenesis, we employed the established DMBA/TPA multi-stage chemical carcinogenesis protocol. Erbb3(del) mice remained free of papillomas for a longer time and had significantly reduced tumor burden compared to control littermates. Tumor cell proliferation was considerably reduced in Erbb3(del) mice, and loss of ERBB3 also impaired keratinocyte proliferation after a single application of TPA. In human skin tumor samples, upregulated ERBB3 expression was observed in squamous cell carcinoma, condyloma, and malignant melanoma. Thus, we conclude that ERBB3, while dispensable for the development and the homeostasis of the epidermis and its appendages, is required for proper wound healing and for the progression of skin tumors during multi-stage chemical carcinogenesis in mice. ERBB3 may also be important for human skin cancer progression. The latter effects most probably reflect a key role for ERBB3 in increasing cell proliferation after stimuli as wounding or carcinogenesis.

Squamous Cell Carcinoma - Similarities and Differences among Anatomical Sites

Squamous cell carcinoma (SCC) is an epithelial malignancy involving many anatomical sites and is the most common cancer capable of metastatic spread. Development of early diagnosis methods and novel therapeutics are important for prevention and mortality reduction. In this effort, numerous molecular alterations have been described in SCCs. SCCs share many phenotypic and molecular characteristics, but they have not been extensively compared. This article reviews SCC as a disease, including: epidemiology, pathology, risk factors, molecular characteristics, prognostic markers, targeted therapy, and a new approach to studying SCCs. Through this comparison, several themes are apparent. For example, HPV infection is a common risk factor among the four major SCCs (NMSC, HNSC, ESCC, and NSCLC) and molecular abnormalities in cell-cycle regulation and signal transduction predominate. These data reveal that the molecular insights, new markers, and drug targets discovered in individual SCCs may shed light on this type of cancer as a whole.

Bispecific anti-CD3 x anti-HER2 antibody mediates T cell cytolytic activity to HER2-positive colorectal cancer in vitro and in vivo

Targeting HER2 overexpressed breast cancer cells with anti‑HER2 monoclonal antibodies inhibits tumor growth. Here we investigated whether HER2 can serve as a target for T cell-mediated immunotherapy of human colorectal carcinoma. Specific cytolytic activity of activated T cells (ATCs) armed with anti‑CD3 x anti‑HER2 bispecific antibody (HER2Bi-Ab) against HER2+ tumor cells was evaluated by bioluminescent signal generated by luciferase reporter on tumor cells in vitro and in vivo. In contrast to unarmed ATCs, increased cytotoxic activity of HER2Bi-armed ATCs against HER2+ tumor cells was observed. Moreover, HER2Bi-armed ATCs expressed higher level of activation marker CD69 and secreted significantly higher levels of IFN-γ than the unarmed ATC counterpart. In addition, compared with anti‑HER2 mAb (Herceptin®) or unarmed ATC, HER2Bi-armed ATCs showed significant suppression against colorectal carcinoma cells. In colorectal tumor cell xenograft mice, infusion of HER2Bi-armed ATCs successfully inhibited the growth of Colo205-luc cells. The HER2Bi-armed ATCs with anti-tumor effects may provide a promising immunotherapy for colorectal carcinoma in the future.

Ado-trastuzumab emtansine-associated telangiectasias in metastatic breast cancer: a case series

Treatment of HER2-positive metastatic breast cancer with ado-trastuzumab emtansine (T-DM1), a novel antibody-drug conjugate, has resulted in both improved progression-free and overall survival. Recognition and treatment of diverse adverse events related to T-DM1 is critical for safety and tolerability. The most frequent adverse events with T-DM1 include fatigue, diarrhea, anemia, elevated transaminases, and mild-to-moderate hemorrhagic events, which are thought to be related to induced thrombocytopenia. Here, we present five case series of cutaneous and mucosal telangiectasias, definitely related to T-DM1. The development of telangiectasias represents a newly recognized adverse effect of T-DM1. We provide description and timing of the telangiectasias and review the mechanisms that may explain the formation of these vascular lesions in association with T-DM1. Further, we describe associated bleeding events and propose that induced telangiectasias could represent an additional cause of T-DM1-associated hemorrhage.

Vismodegib: the proof of concept in Basal cell carcinoma

Although basal cell carcinoma (BCC) is the most common cancer worldwide, its metastatic dissemination is exceptional. Before 2012, we had a few treatment options available for metastatic or locally advanced cases. Management of these patients was complicated due to the lack of scientific data, the deterioration of a patient’s general status, the patient’s advanced age, and the presence of multiple comorbidities. The hedgehog signaling pathway is dysregulated in BCC. The exploration of this signaling pathway yielded to a major milestone in the treatment of advanced BCC. Vismodegib (GDC-0449), an oral small-molecule agent that targets the Hedgehog signaling pathway, demonstrates high levels of activity in clinical trials. It was approved in January 2012 for the treatment of locally advanced or metastatic BCC. Vismodegib confirms, once again, the interest in exploring the signal transduction pathways in cancers.

Emerging drugs and combination strategies for basal cell carcinoma

INTRODUCTION

Basal cell carcinoma (BCC) is a malignancy that is driven by an activated Hedgehog (Hh) pathway. Smoothened inhibitors are a new promising treatment option for patients with locally advanced or metastatic BCC or basal cell nevus syndrome. But long-term data are still limited, the optimal treatment duration is not yet defined and there are already documented cases with acquired resistance.

AREAS COVERED

Treatment modalities with Hh inhibitors, side effects and potential pharmacological combination options are discussed. The current literature, including PubMed, Cochrane database and registered trials on ClinicalTrials.gov, was searched.

EXPERT OPINION

BCCs typically regress during therapy with Hh inhibitors. Muscle toxicity, dysgeusia and hair loss can be considered as on target adverse reactions. Muscle toxicity is the dose-limiting toxicity of sonidegib. It was not seen with vismodegib because of its high binding to plasma protein α-1-acid glycoprotein. Sonidegib is different and shows a clear dose-toxicity relationship, which allows to address the question of whether there is a dose dependency of regression rate, cure rate and progression-free survival. In addition, basic research has offered strategies to enhance efficacy by the combination with other molecules, such as EGFR inhibitors, MEK inhibitors or immunotherapy.

Treatment of advanced cutaneous squamous cell carcinomas with epidermal growth factor receptor inhibitors

In advanced cutaneous squamous cell carcinoma (cSCC), efficient medical treatment options are limited in case surgery and radiotherapy failed, particularly since most patients are of higher age and suffer from comorbidities. In many tumor entities, the epidermal growth factor receptor (EGFR) has been established as an important therapeutic target, and blockade of EGFR signaling by monoclonal antibodies or small molecules achieves a therapeutic benefit. EGFR expression is also often dysregulated in cSCC. We report here two patients with advanced cSCC treated with the EGFR inhibitor cetuximab and summarize the current published experience with the use of EGFR inhibitors in cSCC.

Cetuximab in refractory skin cancer treatment

Objectives: Non-melanoma skin cancer is the most common malignancy in US, with an annual incidence of in excess of 1.5 million cases. In the majority of cases, locoregional treatment is curative and systemic therapy is not indicated. Platinum-based chemotherapy regimens have been used most commonly in refractory cases. The use of cetuximab, a monoclonal antibody targeting epidermal growth factor receptor [EGFR], has been reported for skin cancer treatment. This current study evaluated eight cases of locally advanced and refractory basal cell or squamous cell cancers which were treated with cetuximab.

Methods: This is a retrospective study on eight patients who had received cetuximab for treatment of cutaneous carcinoma since 2007 at Southern Illinois University School of Medicine (SIU-SOM) Medical Oncology clinic.

Results: Three of the four patients with basal cell carcinoma and two of the four patients with squamous cell carcinoma maintained remission on treatment.. The main side effect was acneiform rash which required termination of treatment for one patient and dose reduction in another.

Conclusion: The study indicates that cetuximab may have a beneficial role for patients with non-melanoma cutaneous carcinomas that are refractory to standard therapy.

Cell-specific aptamers as emerging therapeutics

Aptamers are short nucleic acids that bind to defined targets with high affinity and specificity. The first aptamers have been selected about two decades ago by an in vitro process named SELEX (systematic evolution of ligands by exponential enrichment). Since then, numerous aptamers with specificities for a variety of targets from small molecules to proteins or even whole cells have been selected. Their applications range from biosensing and diagnostics to therapy and target-oriented drug delivery. More recently, selections using complex targets such as live cells have become feasible. This paper summarizes progress in cell-SELEX techniques and highlights recent developments, particularly in the field of medically relevant aptamers with a focus on therapeutic and drug-delivery applications.

Prognostic and risk factors in patients with locally advanced cutaneous squamous cell carcinoma of the trunk and extremities

55 patients with advanced cutaneous squamous cell carcinoma (CSCC) of the trunk and extremities were studied. A Tissue Microarray was constructed using immunohistochemistry to quantify expression of the HER family, E-cadherins, and podoplanin. Clinical and histopathological factors related to lymph node metastasis and prognosis were also established. Primary tumor positivity was 25.5% for EGFR, 87.3% for HER-3, and 48.1% for HER-4. Metastases were positive for EGFR in 41.7%, for HER-3 in 83.3%, and HER-4 in 43.5%. HER-2 was negative in all samples. Membrane E-cadherin and cytoplasmic E-cadherin were positive in 47.3% and 30.2% of primary tumors and 45.5% and 27.3% of metastases, respectively. Podoplanin was positive in 41.8% of primary tumors and 41.7% of metastases. Intratumoral lymphocytic infiltrate was associated with lymph node metastasis. Patients with T3 tumors had better cancer-specific survival (CSS) than those with T4 tumors; patients with no lymph node involvement had better CSS than patients with N1 tumors. Undifferentiated tumors and hyperexpression of podoplanin were negative prognostic indicators on multivariate analysis.

Systemic therapy for disseminated basal cell carcinoma: an uncommon manifestation of a common cancer

While basal cell carcinoma (BCC) is the most common human malignancy, distant metastases from this are rare. Current therapy for disseminated BCC is based on anecdotal reports in the absence of clinical trials to guide management. For many years, platinum based cytotoxic chemotherapy was the mainstay of treatment. Advances in the understanding of the biology of BCC have led to the development of targeted therapies (e.g. inhibitors of the hedgehog and the epidermal growth factor receptor pathways) that are currently being investigated in this disease. This review summarizes the available data on the epidemiology and management of disseminated BCC.

Dual inhibition of both the epidermal growth factor receptor and erbB2 effectively inhibits the promotion of skin tumors during two-stage carcinogenesis

The erbB family of receptor tyrosine kinases are known to play important roles in normal epithelial development and epithelial neoplasia. Considerable evidence also suggests that signaling through the epidermal growth factor receptor (EGFR) plays an important role in multistage skin carcinogenesis in mice; however, less is known about the role of erbB2. In this study, to further examine the role of both erbB2 and EGFR in epithelial carcinogenesis, we examined the effect of a dual erbB2/EGFR tyrosine kinase inhibitor, GW2974, given in the diet on skin tumor promotion during two-stage carcinogenesis in wild-type and BK5.erbB2 mice. In BK5.erbB2 mice, erbB2 is overexpressed in the basal layer of epidermis and leads to heightened sensitivity to skin tumor development. GW2974 effectively inhibited skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate in wild-type and BK5.erbB2 mice, although a more marked effect was seen in BK5.erbB2 mice. In addition, this inhibitory effect was reversible when GW2974 treatment was withdrawn. GW2974 inhibited 12-O-tetradecanoylphorbol-13-acetate-induced epidermal hyperproliferation, which correlated with reduced activation of both the EGFR and erbB2. These results support the hypothesis that both the EGFR and erbB2 play an important role in the development of skin tumors during two-stage skin carcinogenesis, especially during the tumor promotion stage. Furthermore, the marked sensitivity of BK5.erbB2 mice to the inhibitory effects of GW2974 during tumor promotion suggest greater efficacy for this compound when erbB2 is overexpressed or amplified as an early event in the carcinogenic process.

Re-epithelialization from human skin explant cultures is promoted by ligand-activated HER3 receptor

BACKGROUND

Ligand-stimulated epidermal growth factor receptor (EGFR/HER1) plays a fundamental role in skin biology as potent transducer of mitotic and anti-apoptotic stimuli in keratinocytes. In human epidermis, at least two additional EGFR family members--HER2 and HER3--are expressed but their biological functions in normal and diseased human skin remain obscure.

OBJECTIVE

Here, we studied the expression and biological impact of HER3 in regenerating human epidermis formed from skin explants adhered to acellular dermis.

METHODS

Neoepidermal HER3 expression was examined by quantitative real-time reverse transcriptase polymerase chain reaction, immunohistochemistry and Western blot analysis. The dynamic effect of HER3 receptor stimulation by recombinant heregulin (HRG)-beta1 was assessed by fluorescence imaging of re-epithelialization.

RESULTS

In the neoepidermis, HER3 mRNA and protein were detected with activated receptors being immunolocalized at basal and low suprabasal levels. Exogenous HRG-beta1 at 10-20 ng/ml increased the outgrowth rate corresponding to approximately 30% the response of exogenous EGF. The growth-promoting effect of HRG-beta1 was associated with enhanced HER3 phosphorylation, keratinocyte proliferation and thickening of viable neoepidermis whereas blockade of ligand-binding to HER3 delayed the outgrowth process and inhibited both constitutive and ligand-induced HER3 phosphorylation. HER2 antagonism using an anti-dimerization antibody, pertuzumab, impeded the re-epithelialization rate. In addition, a selective HER2 kinase inhibitor, CP654577, downregulated phospho-HER3 expression suggesting that transactivation of kinase-deficient HER3 was accomplished through dimerization with HER2.

CONCLUSION

The study emphasizes the central role of EGFR in epidermal renewal and demonstrates that HRG-activated HER3 contributes to the outgrowth process of epidermis in vitro.

Expanding the utility of beta-galactosidase complementation: piece by piece

The ability to image and quantify multiple biomarkers in disease necessitates the development of split reporter fragment platforms. We have divided the beta-galactosidase enzyme into unique, independent polypeptides that are able to reassemble and complement enzymatic activity in bacteria and in mammalian cells. We created two sets of complementing pairs that individually have no enzymatic activity. However, when brought into close geometric proximity, the complementing pairs associated resulting in detectable enzymatic activity. We then constructed a stable ligand complex composed of reporter fragment, linker, and targeting moiety. The targeting moiety, in this case a ligand, allowed cell surface receptor targeting in vitro. Further, we were able to simultaneously visualize two cell surface receptors implicated in cancer development, epidermal growth factor receptor and transferrin receptor, using complementing pairs of the ligand-reporter fragment complex.

Erbb2 suppresses DNA damage-induced checkpoint activation and UV-induced mouse skin tumorigenesis

The Erbb2 receptor is activated by UV irradiation, the primary cause of non-melanoma skin cancer. We hypothesized that Erbb2 activation contributes to UV-induced skin tumorigenesis by suppressing cell cycle arrest. Consistent with this hypothesis, inhibition of Erbb2 in v-ras(Ha) transgenic mice before UV exposure resulted in both 56% fewer skin tumors and tumors that were 70% smaller. Inhibition of the UV-induced activation of Erbb2 also resulted in milder epidermal hyperplasia, S-phase accumulation, and decreased levels of the cell cycle regulator Cdc25a, suggesting altered cell cycle regulation on inhibition of Erbb2. Further investigation using inhibition or genetic deletion of Erbb2 in vitro revealed reduced Cdc25a levels and increased S-phase arrest in UV-irradiated cells lacking Erbb2 activity. Ectopic expression of Cdc25a prevented UV-induced S-phase arrest in keratinocytes lacking Erbb2 activity, demonstrating that maintenance of Cdc25a by Erbb2 suppresses cell cycle arrest. Examination of checkpoint pathway activation upstream of Cdc25a revealed Erbb2 activation did not alter Ataxia Telangiectasia and Rad3-related/Ataxia Telangiectasia Mutated activity but increased inhibitory phosphorylation of Chk1-Ser(280). Since Akt phosphorylates Chk1-Ser(280), the effect of Erbb2 on phosphatidyl inositol-3-kinase (PI3K)/Akt signaling during UV-induced cell cycle arrest was determined. Erbb2 ablation reduced the UV-induced activation of PI3K while inhibition of PI3K/Akt increased UV-induced S-phase arrest. Thus, UV-induced Erbb2 activation increases skin tumorigenesis through inhibitory phosphorylation of Chk1, Cdc25a maintenance, and suppression of S-phase arrest via a PI3K/Akt-dependent mechanism.

UV-induced EGFR signal transactivation is dependent on proligand shedding by activated metalloproteases in skin cancer cell lines

Exposure to extensive ultraviolet (UV) rays is a major cause of skin cancer, which is thought to be initiated by DNA mutations. Members of the epidermal growth factor receptor (EGFR) family are important in various pathophysiologic processes like cancer and are shown to be phosphorylated upon UV exposure. Here we show that EGFR phosphorylation by modest UV doses is dependent on metalloprotease activity and resultant epidermal growth factor (EGF) family proligand shedding. This proligand cleavage releases the mature ligand, which then binds to and activates EGFR. We show that UV induced EGFR phosphorylation in transformed cell lines of melanocyte and keratinocyte origin, which was reduced upon preincubation with a broad-spectrum metalloprotease inhibitor, BB94. UV also activated EGFR downstream signaling via Erk and Akt pathways in a BB94-sensitive manner. Furthermore, using neutralizing antibodies we found that proligand amphiregulin was required for UV-induced EGFR activation in SCC-9 cells. Using RNAi this EGFR activation was further shown to depend on the metalloproteases ADAM9 and ADAM17 in SCC-9 cells. cDNA array hybridization and RT-PCR analysis showed overexpression of a Disintegrin and a Metalloproteases (ADAMs) and EGF family proligands in melanoma cell lines. Additionally, blocking EGFR signal transactivation by BB94 led to increased apoptosis in UV-irradiated cells. EGFR signal transactivation also led to increased stability of the DNA repair protein, PARP, under UV stress. Thus, both antiapoptotic and DNA repair pathways are activated simultaneously by EGFR signal transactivation. Together, our data provide novel insights into the mechanism of UV-induced EGFR activation, suggesting broad relevance of the UV-ADAM-proligand-EGFR-Erk/Akt pathway and its significance in skin cancer.

EGFR mutations and HER2/3 protein expression and clinical outcome in Chinese advanced non-small cell lung cancer patients treated with gefitinib

BACKGROUND

To assess the role of various epidermal growth factor receptor (EGFR) mutations and HER2/3 protein expression as predictive markers of responsiveness to gefitinib therapy in Chinese patients with advanced non-small cell lung cancer (NSCLC).

METHODS

A total of 106 Chinese NSCLC patients who had failed at least one chemotherapy regimen received gefitinib 250 mg once daily. All the 106 tumors from these patients were screened for mutations in the EGFR exons 18-24, and 84 tumors were studied by immunohistochemistry for HER2/3 expression and correlated with clinical treatment outcome.

RESULTS

Patients with EGFR mutations had a significantly higher overall response rate (ORR), longer time to progression (TTP) and overall survival (OS) compared with those with wild-type receptor. No difference in ORR was observed between patients with exon 19 deletion and patients with other EGFR mutations. ORR in HER2-positive patients was significantly higher than in the HER2-negative group, irrespective of EGFR mutational status, and a trend for better ORR was observed for HER3-positive patients. HER2 and HER3 expression levels were not associated with any difference in terms of TTP and OS. Nevertheless, when considering the subgroups of non-responders to gefitinib, median TTP in patients with mutated EGFR was significantly longer than in those with no mutations (8.0 vs. 3.0 months, P = 0.0065). EGFR-mutated patients had no significant difference in ORR, TTP and OS according to HER2 and/or HER3 expression.

CONCLUSIONS

EGFR mutations are effective predictors for gefitinib efficacy in Chinese patients with advanced NSCLC. HER2 and HER3 expression does not provide any additional information for selecting patients most likely to benefit from gefitinib treatment.

Aneuploidy, but not Ki-67 or EGFR expression, is associated with recurrences in basal cell carcinoma

BACKGROUND

Basal cell carcinoma (BCC), the most common skin cancer, has an overall excellent prognosis, but recurrences are frequent. The value of classical clinical and histological prognostic factors to predict recurrences remain limited.

METHODS

In order to evaluate the prognostic value of Epidermal Growth Factor Receptor (EGFR) expression, Ki-67 antigen expression and DNA ploidy, we compared primary tumors in 20 patients who had subsequent local recurrences and 20 matched controls without recurrences. DNA ploidy was determined by image cytometry, and EGFR and Ki-67 expression were studied by immunohistochemistry.

RESULTS

Statistical analysis of the intensity and the percentage of EGFR expression and Ki-67 antigen expression did not show any significant difference between the two groups. In contrast, we found that 78% of primary BCC in patients who experienced recurrences vs. 32% in the control group were aneuploid (p = 0.005).

CONCLUSIONS

Aneuploidy is a risk factor for recurrences. This factor should be useful in clinical practice and require evaluation in further studies.