Grape seed extracts modify the outcome of oxaliplatin in colon cancer cells by interfering with cellular mechanisms of drug cytotoxicity.

Grape seed extracts are commonly utilized as dietary supplements for their antioxidant properties, even from cancer patients. However, whether these natural extracts interfere with chemotherapeutics utilized in colon cancer treatment is still poorly investigated. The cytotoxicity of extracts from Italia and Palieri cultivars either alone or in combination with oxaliplatin was evaluated in colon cancer cells. Grape seed extracts displayed anti-proliferative activity depending on the concentration utilized through apoptosis induction. In combination, they affected the activation of Erk1/2 and counteracted the intrinsic and the extrinsic pathway of apoptosis, the DNA damage and the generation of ROS induced by oxaliplatin. Noteworthy grape seed extracts strongly enhanced the uptake of oxaliplatin into all cells, by affecting the cell transport system of platinum. The addition of these natural extracts to oxaliplatin strongly reduced the cellular response to oxaliplatin and allowed a huge accumulation of platinum into cells. Here, we shed light on the chemical biology underlying the combination of grape seed extracts and oxaliplatin, demonstrating that they might be detrimental to oxaliplatin effectiveness in colon cancer therapy.

Hepatic stellate cells induce hepatocellular carcinoma cell resistance to sorafenib through the laminin-332/α3 integrin axis recovery of focal adhesion kinase ubiquitination.

In patients with hepatocellular carcinoma (HCC) receiving sorafenib, drug resistance is common. HCC develops in a microenvironment enriched with extracellular matrix proteins including laminin (Ln)-332, produced by hepatic stellate cells (HSCs). Ln-332 is the ligand of α3ß1 and α6ß4 integrins, differently expressed on the HCC cell surface, that deliver intracellular pathways. The aim of this study was to investigate the effect of Ln-332 on sorafenib's effectiveness. HCC cells were challenged with sorafenib in the presence of Ln-332 and of HSC conditioned medium (CM). Sorafenib impaired HCC cell proliferation and induced apoptosis. HSC-CM or Ln-332 inhibited sorafenib's effectiveness in HCC cells expressing both α3ß1 and α6ß4. Inhibiting α3 but not α6 integrin subunit using blocking antibodies or small interfering RNA abrogated the protection induced by Ln-332 and HSC-CM. Hep3B cells expressing α6ß4 but lacking the α3 integrin were insensitive to Ln-332 and HSC-CM protective effects. Hep3B α3-positive, but not wild-type and scramble transfected, cells acquired protection by sorafenib when plated on Ln-332-CM or HSCs. Sorafenib dephosphorylated focal adhesion kinase (FAK) and extracellular signal-regulated kinases 1/2, whereas Ln-332 and HSC-CM partially restored the pathways. Silencing FAK, but not extracellular signal-regulated kinases 1/2, abrogated the protection induced by Ln-332 and HSC-CM, suggesting a specific role for FAK. Sorafenib down-regulated total FAK, inducing its proteasomal degradation, while Ln-332 and HSC-CM promoted the escape of FAK from ubiquitination, probably inducing a preferential membrane localization. CONCLUSION: This study unveils a novel mechanism of sorafenib resistance depending on the α3ß1/Ln-332 axis and requiring FAK ubiquitination, providing new insights into personalizing therapy for patients with HCC. (Hepatology 2016;64:2103-2117).

Total and not bevacizumab-bound vascular endothelial growth factor as potential predictive factors to bevacizumab-based chemotherapy in colorectal cancer.

AIM: To identify suitable biomarkers of response to bevacizumab (BV) - it remains an open question. The measurement of serum vascular endothelial growth factor (VEGF) has been proposed as a predictive factor for this drug, even if literature data are contradictory. METHODS: We prospectively evaluated the role of BV, total and not BV-bound VEGF and angiopoietin-2 (Ang-2) serum levels as potential predictive factors of response for BV in combination with an oxaliplatin-based chemotherapy. BV, Ang-2, total and not BV-bound VEGF levels were measured at baseline, before 2(nd) and 5(th) cycle of oxaliplatin-based chemotherapy in 20 consecutive metastatic colorectal cancer patients. RESULTS: Results were correlated to response to treatment. Variability in BV levels have been found, with decreased level in less responding patients. In particular, the concentration of BV increased of 3.96 ± 0.69 folds in serum of responsive patients after 3 more cycles of therapy compared to those with stable or progressive disease with a 0.72 ± 0.25 and 2.10 ± 0.13 fold increase, respectively. The determination of free and total VEGF demonstrated that the ratio between the two values, evaluated immediately before the 2(nd) and the 5(th) cycle of therapy, decreased from 26.65% ± 1.33% to 15.50% ± 3.47% in responsive patients and from 53.41% ± 4.75 to 34.95% ± 2.88% in those with stable disease. Conversely, in those with progression of disease, the ratio showed the opposite behavior coming up from 25.99% ± 5.23% to 51.71% ± 5.28%. The Ang-2 levels did not show any relationship. CONCLUSION: Our data show that the ratio of not BV-bound VEGF to total VEGF serum and BV plasma concentrations for predicting the response to BV plus oxaliplatin-based chemotherapy could be a promising biomarker of response to BV.

Which role for EGFR therapy in breast cancer?

EGFR and HER2 are highly expressed in 15-30% of breast cancer tissues. Therefore, EGFR and its downstream signaling pathways are promising anti-tumour targets. HER2 overexpression is often associated with estrogen receptor (ER) and progesterone receptor (PR) negativity, high histological grade, high rates of cell proliferation and lymph node involvement. Moreover, it is correlated with disease aggressiveness, increased rates of recurrence and poorer survival in node-positive breast cancer patients, whereas the prognostic significance in patients with node-negative tumors remains somewhat controversial. This paper focuses on the therapeutic strategy for treatment of HER2 overexpressing breast cancer in advanced stages of disease, as well as in the adjuvant and neo-adjuvant settings.

The coordinated role of CYP450 enzymes and P-gp in determining cancer resistance to chemotherapy.

The relationship between CYP450 and P-gp occurs at different levels. It is known that certain substrates of P-gp undergo metabolic transformations by various CYP450 isoforms; in addition some of them demonstrated to be activators of both P-gp and CYP450. The majority of such compounds are well-known chemotherapeutics, therefore the purpose of this review is to clarify whether there is a relationship between the simultaneous modulation of CYP450 and P-gp and the onset of drug resistance in tumors treatment. Here, we discuss the biological aspects of the topic in relation to the various tissues distribution of CYP450 and P-gp, the recent findings regarding the ability of some chemotherapeutics in modulating both P-gp and CYP450, whether this modulation is ultimately responsible for the onset of drug resistance in cancer treatment and the promising role of gene polymorphisms in determining the interindividual variability in drug responses in clinical practice.

EGFR tyrosine kinases inhibitors in cancer treatment: in vitro and in vivo evidence.

The increasing understanding of the molecular mechanisms of neoplastic transformation and progression has prompted the search for novel drugs that could interfere with the intracellular targets involved in this process. EGFR is implicated in the development and progression of the majority of the common human epithelial cancer; therefore different agents have been developed to block EGFR activation in cancer cells. This review focuses on EGFR-tyrosine kinase inhibitors in clinical practice that interfere with ATP binding, inhibiting tyrosine kinase activity and subsequently blocking signal transduction from EGFR. We report current knowledge on molecular mechanisms underlying the anticancer activity of EGFR-tyrosine kinase inhibitors in preclinical models, with particular attention to EGFR downstream effectors responsible for treatment efficacy or resistance.

Anti-EGFR monoclonal antibody in cancer treatment: in vitro and in vivo evidence

The complexity of EGFR signaling network suggests that the receptor could be promising targets for new personalised therapy. In clinical practice two strategies targeting the receptor are available; they utilise monoclonal antibodies, directed towards the extracellular domain of EGFR, and small molecule tyrosine kinase inhibitors, which bind the catalytic kinase domain of the receptor. In this review, we summarise currently known pre-clinical data on the antitumor effects of monoclonal antibodies, which bind to EGFR in its inactive configuration, competing for ligand binding and thereby blocking ligand-induced EGFR tyrosine kinase activation. As a consequence of treatment, key EGFR-dependent intracellular signals in cancer cells are affected. Data explaining the mechanisms of action of anti-EGFR monoclonal antibodies, currently used in clinical setting and under development for the treatment of solid tumors, are revised with the aim to provide an overview of the most important preclinical studies showing the impact of this class of EGFR targeted agents on tumor biology.