Soluble Epidermal Growth Factor Receptors (sEGFRs) in Cancer: Biological Aspects and Clinical Relevance.

The identification of molecules that can reliably detect the presence of a tumor or predict its behavior is one of the biggest challenges of research in cancer biology. Biological fluids are intriguing mediums, containing many molecules that express the individual health status and, accordingly, may be useful in establishing the potential risk of cancer, defining differential diagnosis and prognosis, predicting the response to treatment, and monitoring the disease progression. The existence of circulating soluble growth factor receptors (sGFRs) deriving from their membrane counterparts has stimulated the interest of researchers to investigate the use of such molecules as potential cancer biomarkers. But what are the origins of circulating sGFRs? Are they naturally occurring molecules or tumor-derived products? Among these, the epidermal growth factor receptor (EGFR) is a cell-surface molecule significantly involved in cancer development and progression; it can be processed into biological active soluble isoforms (sEGFR). We have carried out an extensive review of the currently available literature on the sEGFRs and their mechanisms of regulation and biological function, with the intent to clarify the role of these molecules in cancer (and other pathological conditions) and, on the basis of the retrieved evidences, speculate about their potential use in the clinical setting.

Tracing Behçet's disease origins along the Silk Road: an anthropological evolutionary genetics perspective.

OBJECTIVES: Behçet's disease is a multifactorial vasculitis that shows its highest prevalence in geographical areas historically involved in the Silk Road, suggesting that it might have originated somewhere along these ancient trade routes. This study aims to provide a first clue towards genetic evidence for this hypothesis by testing it via an anthropological evolutionary genetics approach. METHODS: Behçet's disease variation at ancestry informative mitochondrial DNA control region and haplogroup diagnostic sites was characterised in 185 disease subjects of Italian descent and set into the Eurasian mitochondrial landscape by comparison with nearly 9,000 sequences representative of diversity observable in Italy and along the main Silk Road routes. RESULTS: Dissection of the actual genetic ancestry of disease individuals by means of population structure, spatial autocorrelation and haplogroup analyses revealed their closer relationships with some Middle Eastern and Central Asian groups settled along the Silk Road than with healthy Italians. CONCLUSIONS: These findings support the hypothesis that the Behçet's disease genetic risk has migrated to western Eurasia in parallel with ancestry components typical of Silk Road-related groups. This provided new insights that are useful to improve the understanding of disease origins and diffusion, as well as to inform future association studies aimed at properly accounting for the actual genetic ancestry of the examined Behçet's disease samples in order to minimise the detection of spurious associations and to improve the identification of genetic variants with actual clinical relevance.

Preliminary Evidence on the Diagnostic and Molecular Role of Circulating Soluble EGFR in Non-Small Cell Lung Cancer.

Assessment of biological diagnostic factors providing clinically-relevant information to guide physician decision-making are still needed for diseases with poor outcomes, such as non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) is a promising molecule in the clinical management of NSCLC. While the EGFR transmembrane form has been extensively investigated in large clinical trials, the soluble, circulating EGFR isoform (sEGFR), which may have a potential clinical use, has rarely been considered. This study investigates the use of sEGFR as a potential diagnostic biomarker for NSCLC and also characterizes the biological function of sEGFR to clarify the molecular mechanisms involved in the course of action of this protein. Plasma sEGFR levels from a heterogeneous cohort of 37 non-advanced NSCLC patients and 54 healthy subjects were analyzed by using an enzyme-linked immunosorbent assay. The biological function of sEGFR was analyzed in vitro using NSCLC cell lines, investigating effects on cell proliferation and migration. We found that plasma sEGFR was significantly decreased in the NSCLC patient group as compared to the control group (median value: 48.6 vs. 55.6 ng/mL respectively; p = 0.0002). Moreover, we demonstrated that sEGFR inhibits growth and migration of NSCLC cells in vitro through molecular mechanisms that included perturbation of EGF/EGFR cell signaling and holoreceptor internalization. These data show that sEGFR is a potential circulating biomarker with a physiological protective role, providing a first approach to the functional role of the soluble isoform of EGFR. However, the impact of these data on daily clinical practice needs to be further investigated in larger prospective studies.

Circulating plasma DNA as diagnostic biomarker in non-small cell lung cancer.

OBJECTIVES: The presence of circulating DNA in plasma of patients with malignant neoplasm has been a known fact for over 30 years. Since then, the concentration of free circulating plasma DNA has been studied as well as the genetic alterations and epigenetic alterations of tumour DNA of patients that suffer from various types of tumours. The analysis of circulating plasma DNA may be a useful marker to get an early diagnosis on malignant neoplasms. This study has been specifically designed to validate the quantification of circulating DNA in order to design a test useful for the early identification of non-small cell lung cancer patients and the monitoring of lung cancer progression. A second aim of this work is the sensibility and specificity evaluation of such method for future applications. METHODS: The quantity of plasma DNA was determined using quantitative Real-Time PCR with amplification of the human telomerase reverse transcriptase (hTERT) gene in 151 patients that suffer from lung cancer and 79 healthy controls. The performance of the test was evaluated with a ROC curve. The relationship between the DNA concentration and main demographic, clinical and pathological variables was examined with logistic regression models as well as multiple linear regression models. RESULTS: The concentration of circulating plasma DNA was about four times higher in patients with lung cancer with respect to the controls (12.8 vs 2.9 ng/mL). The area under the ROC curve was 0.79 (95% CI, 0.710-0.83). The concentration of circulating DNA proved to be an important risk factor for the presence of the illness and a prognostic index in the follow-up. CONCLUSIONS: The use of quantitative Real-Time PCR revealed that higher values of circulating DNA can be found in patients with lung neoplasm compared to the healthy controls. This could have practical implications such as the use in screening programs and a possible prognostic significance in the follow-up.

Higher expression of miR-133b is associated with better efficacy of erlotinib as the second or third line in non-small cell lung cancer patients.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (gefitinib, erlotinib and afatinib) are indicated as first-line therapy in patients with non-small cell lung cancer (NSCLC) whose tumors harbor activating mutations in the EGFR gene. Erlotinib is also used in second and third-line therapy for patients whose tumors have wild type EGFR but to date there are no validated biomarkers useful to identify which patients may benefit from this treatment. The expression level of four miRNAs: miR-133b, -146a, -7 and -21 which target EGFR was investigated by real-time PCR in tumor specimens from NSCLC patients treated with erlotinib administered as the second or third line. We found that miR-133b expression level better discriminated responder from non-responder patients to erlotinib. Higher levels of miR-133b in NSCLCs were associated with longer progression-free survival time of patients. Functional analyses on miR-133b through transfection of a miR-133b mimic in A549 and H1299 NSCLC cell lines indicated that increasing miR-133b expression level led to a decreased cell growth and altered morphology but did not affect sensitivity to erlotinib. The detection of miR-133b expression levels in tumors help in the identification of NSCLC patients with a better prognosis and who are likely to benefit from second and third-line therapy with erlotinib.

Biomarkers of cancer angioprevention for clinical studies.

With the great advances made in the treatment and prevention of infectious diseases over the last century, chronic degenerative diseases-cardiovascular, cerebrovascular, and cancer-represent the major causes of death in the developed world. Although massive efforts and investments have been made in cancer therapy, the progress made towards reducing mortality has been more successful for cardiovascular disease than for tumours. This can be attributable largely to an active prevention approach implemented for cardiovascular disease. Cardiologists treat their patients before the overt disease becomes life threatening, performing early interventions in phenotypically healthy patients, by using several markers that predict risk. If the concept of prevention could be applied to cancer in a more extensive way, a significant number of tumours could be avoided through preventive measures. Prevention approaches range from avoiding tobacco exposure to dietary strategies to active pharmacological approaches in higher risk groups. Host targets rather than the tumour cells themselves are attractive for chemoprevention, in particular endothelial and immune cells. Angioprevention i.e. preventing cancer angiogenesis is a key concept that we introduced; yet one of the major current challenges for anti-angiogenesis in therapy and prevention is finding the right biomarkers. Here we discuss the importance of angioprevention and the potential use of VEGF, PlGF, CD31, Ang and Tie, circulating vascular cell precursors, and microRNA as potential biomarkers.

Runx2 isoform I controls a panel of proinvasive genes driving aggressiveness of papillary thyroid carcinomas.

CONTEXT: The ability of tumor cells to invade adjacent tissues is governed by a complicated network of molecular signals, most of which have not yet been identified. In a recent work, we reported that the transcriptional regulator Id1 contributes to thyroid cancer progression by powering the invasion capacity of tumor cells. OBJECTIVE: The intent of this work was to further investigate the biology of invasive thyroid tumors, through the analysis of the molecular interactions existing between Id1 and some of its target genes and through the characterization of the function of these factors in the progression of thyroid tumors. RESULTS: We showed that Id1 controls the expression of the Runx2 isoform I and that this transcription factor plays a central role in mediating the Id1 proinvasive function in thyroid tumor cells. We demonstrated that Runx2 regulates proliferation, migration, and invasiveness by activating a panel of genes involved in matrix degradation and cellular invasion, which we previously identified as Id1 target genes in thyroid tumor cells. Finally, we show that Runx2 is strongly expressed in metastatic human thyroid tumors both at the primary site and in metastases. CONCLUSION: Overall, our experiments demonstrate the existence of a previously unknown molecular axis that controls thyroid tumor invasiveness by altering the ability of tumor cells to interact with the surrounding microenvironment. These factors could prove to be valuable markers that permit early diagnosis of aggressive thyroid tumors.

Soluble epidermal growth factor receptor isoforms in non-small cell lung cancer tissue and in blood.

Epidermal growth factor receptor (EGFR) is implicated in tumor development and is highly expressed in many human tumors. EGFR overexpression has been observed in both premalignant lesions and in malignant lung tumors, as well as in 40-80% of patients with non-small cell lung cancer (NSCLC). EGFR is a 170-kDa transmembrane glycoprotein with an extracellular ligand-binding domain and a cytoplasmic domain with intrinsic tyrosine kinase activity. Soluble forms of EGFR (sEGFR) containing the extracellular domain have been described both in conditioned media from EGFR overexpressing cells as well as in peripheral blood. However, very little is known regarding the molecular function and the biochemical properties of these circulating EGFR isoforms. This study investigates the expression of sEGFR in lung cancer cultured cells and NSCLC patients with the aim of identifying clinically relevant isoforms specifically produced by tumor cells. Proteomic approaches including OFFGEL electrophoresis and Western blotting analysis were used to assess the sEGFR expression pattern in primary lung tumor samples, normal counterparts and matched plasma. We discover that the isoelectric points of sEGFR isoforms in NSCLC biopsy tissue differ from those of the isoforms present in healthy tissue and detected in the plasma of all subjects. These results demonstrate, for the first time, the existence of sEGFR isoforms specifically produced by NSCLC tumor cells which could represent a new potential biomarker for diagnosis and therapy of lung tumors. However, our observations indicate that more highly sensitive and specific quantitative assays are needed in order to reliably detect the tumor-associated sEGFR isoforms in plasma samples.

New biomarkers for lung cancer.

IMPORTANCE OF THE FIELD: Despite many efforts to improve early detection, lung cancer remains the leading cause of cancer deaths. Stage is the main determinant of prognosis and the basis for deciding treatment options. Screening tests for lung cancer have not been successful so far. AREAS COVERED IN THE REVIEW: The article reviews the available literature related to biomarkers in use at present and those that could be used for early diagnosis, staging, prognosis, response to therapy and prediction of recurrence. The single biomarkers are analysed, divided according to the technological methods used and the locations of sampling. WHAT THE READER WILL GAIN: The reader will gain knowledge on biomarkers in use and those now under study. The reader will also gain insights into the difficulties pertaining to the development of biomarkers, results reproducibility and clinical application. TAKE HOME MESSAGE: Although some markers seem to be promising, at present there is no consensus on the proven value of their clinical use in lung cancer. The future lies probably in a panel of biomarkers instead of individual assays, or in predictive models derived from the integration of clinical variables and gene expression profiles.