Marta Castiglia

New findings on primary and acquired resistance to anti-EGFR therapy in metastatic colorectal cancer: do all roads lead to RAS?

Anti-epidermal growth factor receptor therapy with the monoclonal antibodies cetuximab and panitumumab is the main targeted treatment to combine with standard chemotherapy for metastatic colorectal cancer. Many clinical studies have shown the benefit of the addition of these agents for patients without mutations in the EGFR pathway. Many biomarkers, including KRAS and NRAS mutations, BRAF mutations, PIK3CA mutations, PTEN loss, AREG and EREG expression, and HER-2 amplification have already been identified to select responders to anti-EGFR agents. Among these alterations KRAS and NRAS mutations are currently recognized as the best predictive factors for primary resistance. Liquid biopsy, which helps to isolate circulating tumor DNA, is an innovative method to study both primary and acquired resistance to anti-EGFR monoclonal antibodies. However, high-sensitivity techniques should be used to enable the identification of a wide set of gene mutations related to resistance.

Stabilizing versus destabilizing the microtubules: A double-edge sword for an effective cancer treatment option?

Microtubules are dynamic and structural cellular components involved in several cell functions, including cell shape, motility, and intracellular trafficking. In proliferating cells, they are essential components in the division process through the formation of the mitotic spindle. As a result of these functions, tubulin and microtubules are targets for anticancer agents. Microtubule-targeting agents can be divided into two groups: microtubule-stabilizing, and microtubule-destabilizing agents. The former bind to the tubulin polymer and stabilize microtubules, while the latter bind to the tubulin dimers and destabilize microtubules. Alteration of tubulin-microtubule equilibrium determines the disruption of the mitotic spindle, halting the cell cycle at the metaphase-anaphase transition and, eventually, resulting in cell death. Clinical application of earlier microtubule inhibitors, however, unfortunately showed several limits, such as neurological and bone marrow toxicity and the emergence of drug-resistant tumor cells. Here we review several natural and synthetic microtubule-targeting agents, which showed antitumor activity and increased efficacy in comparison to traditional drugs in various preclinical and clinical studies. Cryptophycins, combretastatins, ombrabulin, soblidotin, D-24851, epothilones and discodermolide were used in clinical trials. Some of them showed antiangiogenic and antivascular activity and others showed the ability to overcome multidrug resistance, supporting their possible use in chemotherapy.

Exosomes isolation and characterization in serum is feasible in non-small cell lung cancer patients: critical analysis of evidence and potential role in clinical practice

Exosomes are nano-sized vesicles of endolysosomal origin, released by several cytotypes in physiological and pathological conditions. Tumor derived exosomes, interacting with other cells of the tumor microenvironment, modulate tumor progression, angiogenic switch, metastasis, and immune escape. Recently, extracellular vesicles were proposed as excellent biomarkers for disease monitoring and prognosis in cancer patients. Non-small cell lung cancer (NSCLC) has a poor 5-year survival rate due to the delay in the detection of the disease. The majority of patients are diagnosed in an advanced disease stage. Exosomes might be promising beneficial tools as biomarker candidates in the scenario of NSCLC, since they contain both, proteins and miRNAs. The clinical case reported in this manuscript is a proof of concept revealing that NSCLC exosomes and sorted miRNAs might constitute, in a near future, novel biomarkers. This review summarizes the role of exosomes in NSCLC, focusing on the importance of exosomal microRNAs in lung cancer diagnosis and prognosis.

Triple negative breast cancer: shedding light onto the role of pi3k/akt/mtor pathway

Breast cancer is one of the most widespread carcinoma and one of the main causes of cancer-related death worldwide, especially in women aged between 35 and 75 years. Among the different subtypes, triple negative breast cancer (TNBC) is characterized by the total absence of the estrogen-receptor (ER) and progesteron-receptor (PR) expression as well as the lack of human epidermal growth factor receptor 2 (HER2) overexpression or gene amplification. These biological characteristics confer to TNBC a higher aggressiveness and relapse risk along with poorer prognosis compared to other subtypes. Indeed, 5-years survival rate is still low and almost all patients die, despite any adjuvant treatment which at moment represents the heading pharmacological approach. To date, several clinical trials have been designed to investigate the potential role of some molecular markers, such as VEGF, EGFR, Src and mTOR, for targeted treatments in TNBC. In fact, many inhibitors of the PI3K/AKT/mTOR pathway, frequently de-regulated in TNBC, are acquiring a growing interest and several inhibitors are in preclinical development or already in early phase clinical trials. In this Review, we investigated the role of the PI3K/AKT/mTOR pathway in TNBC patients, by summarizing the molecular features that led to the distinction of different histotypes of TNBC. Furthermore, we provided an overview of the inhibition mechanisms of the mTOR and PI3K/AKT signaling pathways, highlighting the importance of integrating biological and clinical data for the development of mTOR inhibitors in order to implement targeted therapies for TNBC patients.

Immunotherapy: is a minor god yet in the pantheon of treatments for lung cancer?

Immunotherapy has been studied for many years in lung cancer without significant results, making the majority of oncologists quite skeptical about its possible application for non-small cell lung cancer treatment. However, the recent knowledge about immune escape and subsequent ‘cancer immunoediting’ has yielded the development of new strategies of cancer immunotherapy, heralding a new era of lung cancer treatment. Cancer vaccines, including both whole-cell and peptide vaccines have been tested both in early and advanced stages of non-small cell lung cancer. New immunomodulatory agents, including anti-CTLA4, anti-PD1/PDL1 monoclonal antibodies, have been investigated as monotherapy in metastatic lung cancer. To date, these treatments have shown impressive results of efficacy and tolerability in early clinical trials, leading to testing in several large, randomized Phase III trials. As these results will be confirmed, these drugs will be available in the near future, offering new exciting therapeutic options for lung cancer treatment.

HIF-1 is involved in the negative regulation of AURKA expression in breast cancer cell lines under hypoxic conditions

AbstractNumerous microarray-based gene expression studies performed on several types of solid tumors revealed significant changes in key genes involved in progression and regulation of the cell cycle, including AURKA that is known to be overexpressed in many types of human malignancies. Tumor hypoxia is associated with poor prognosis in several cancer types, including breast cancer (BC). Since hypoxia is a condition that influences the expression of many genes involved in tumorigenesis, proliferation, and cell cycle regulation, we performed a microarray-based gene expression analysis in order to identify differentially expressed genes in BC cell lines exposed to hypoxia. This analysis showed that hypoxia induces a down-regulation of AURKA expression. Although hypoxia is a tumor feature, the molecular mechanisms that regulate AURKA expression in response to hypoxia in BC are still unknown. For the first time, we demonstrated that HIF-1 activation downstream of hypoxia could drive AURKA down-regulation in BC cells. In fact, we found that siRNA-mediated knockdown of HIF-1α significantly reduces the AURKA down-regulation in BC cells under hypoxia. The aim of our study was to obtain new insights into AURKA transcriptional regulation in hypoxic conditions. Luciferase reporter assays showed a reduction of AURKA promoter activity in hypoxia. Unlike the previous findings, we hypothesize a new possible mechanism where HIF-1, rather than inducing transcriptional activation, could promote the AURKA down-regulation via its binding to hypoxia-responsive elements into the proximal region of the AURKA promoter. The present study shows that hypoxia directly links HIF-1 with AURKA expression, suggesting a possible pathophysiological role of this new pathway in BC and confirming HIF-1 as an important player linking an environmental signal to the AURKA promoter. Since AURKA down-regulation overrides the estrogen-mediated growth and chemoresistance in BC cells, these findings could be important for the development of new possible therapies against BC.

Prognostic and predictive biomarkers for targeted therapy in NSCLC: for whom the bell tolls?

Introduction: The discovery of molecular biomarkers and the advent of targeted therapies have led to a radical change in the treatment of several tumors, including NSCLC. In the last few years, the number of molecular biomarkers has rapidly increased, and a growing interest has been recently focused on their potential prognostic and predictive value in clinical settings. Areas covered: This review describes all the molecular biomarkers with prognostic and predictive value in NSCLC, including both clinically approved biomarkers, and emerging biomarkers under investigation in clinical trials. Liquid biopsy and applications of circulating biomarkers are also described. Expert opinion: The oncological research is currently focusing on the discovery and validation of molecular biomarkers in order to promote even more personalized treatment strategies. This paradigm of care will expand quickly thanks to the advent of new genotyping technologies, such as next-generation sequencing, making it possible to create a molecular-genomic profile of every patient’s tumor. Liquid biopsy and the use of circulating-biomarkers represent the new challenge of oncological research, with very promising implications in the management of patients.

Cancer and the microbiome: potential applications as new tumor biomarker

Microbial communities that colonize in humans are collectively described as microbiome. According to conservative estimates, about 15% of all types of neoplasms are related to different infective agents. However, current knowledge is not sufficient to explain how the microbiome contributes to the growth and development of cancers. Large and thorough studies involving colonized, diverse and complex microbiome entities are required to identify microbiome as a potential cancer marker and to understand how the immune system is involved in response to pathogens. This article reviews the existing evidence supporting the enigmatic association of transformed microbiome with the development of cancer through the immunological modification. Ascertaining the connection between microbiome and immunological responses with risk of cancer may direct to explaining significant advances in the etiology of cancer, potentially disclosing a novel paradigm of research for the management and prevention of cancer.

Hypoxia and Human Genome Stability: Downregulation of BRCA2 Expression in Breast Cancer Cell Lines

Previously, it has been reported that hypoxia causes increased mutagenesis and alteration in DNA repair mechanisms. In 2005, an interesting study showed that hypoxia-induced decreases in BRCA1 expression and the consequent suppression of homologous recombination may lead to genetic instability. However, nothing is yet known about the involvement of BRCA2 in hypoxic conditions in breast cancer. Initially, a cell proliferation assay allowed us to hypothesize that hypoxia could negatively regulate the breast cancer cell growth in short term in vitro studies. Subsequently, we analyzed gene expression in breast cancer cell lines exposed to hypoxic condition by microarray analysis. Interestingly, genes involved in DNA damage repair pathways such as mismatch repair, nucleotide excision repair, nonhomologous end-joining and homologous recombination repair were downregulated. In particular, we focused on the BRCA2 downregulation which was confirmed at mRNA and protein level. In addition, breast cancer cells were treated with dimethyloxalylglycine (DMOG), a cell-permeable inhibitor of both proline and asparaginyl hydroxylases able to induce HIF-1α stabilization in normoxia, providing results comparable to those previously described. These findings may provide new insights into the mechanisms underlying genetic instability mediated by hypoxia and BRCA involvement in sporadic breast cancers.

Analysis of tissue and circulating microRNA expression during metaplastic transformation of the esophagus

Genetic changes involved in the metaplastic progression from squamous esophageal mucosa toward Barretts metaplasia and adenocarcinoma are almost unknown. Several evidences suggest that some miRNAs are differentially expressed in Barretts esophagus (BE) and esophageal adenocarcinoma. Among these, miR-143, miR-145, miR-194, miR-203, miR-205, miR-215 appear to have a key role in metaplasia and neoplastic progression. The aim of this study was to analyze deregulated miRNAs in serum and esophageal mucosal tissue biopsies to identify new biomarkers that could be associated with different stages of esophageal disease. Esophageal mucosal tissue biopsies and blood samples were collected and analyzed for BE diagnosis. Quantitative Real-time PCR was used to compare miRNA expression levels in serum and 60 disease/normal-paired tissues from 30 patients diagnosed with esophagitis, columnar-lined oesophagus (CLO) or BE. MiRNA expression analysis showed that miR-143, miR-145, miR-194 and miR-215 levels were significantly higher, while miR-203 and miR-205 were lower in BE tissues compared with their corresponding normal tissues. Esophageal mucosa analysis of patients with CLO and esophagitis showed that these miRNAs were similarly deregulated but to a lesser extent keeping the same trend and CLO appeared as intermediate step between esophagitis and BE. Analysis on circulating miRNA levels confirmed that miR-194 and miR-215 were significantly upregulated in both BE and CLO compared to esophagitis, while miR-143 was significantly upregulated only in the Barrett group. These findings suggest that miRNAs may be involved in neoplastic/metaplastic progression and miRNA analysis might be useful for progression risk prediction as well as for monitoring of BE/CLO patients.