Current Cancer Drug Targets - Volume 18, Issue 7, 2018

Background: There is emerging data suggesting that the non-coding RNA (microRNA 193a or miR-193a) plays key roles in different types of cancers. Objective: This review aims to investigate the functional significance of miR-193a in different cancers according to the information of literature. Method: All the literature concerning miR-193a in cancer in PubMed are analysed. Results: Several studies proved the association of miR-193a expression patterns with cancer's stages, grades, response to the chemotherapy and even patient survival. Also, miR-193a can be used to differentiate some types of cancer. In cancer, miR-193a can act as a tumour suppressor gene or as an oncogene. Till now, several genetic factors (MAX, RXR α, XB130, P63, P73, AEG-1, HIFs, EGFR, Drosha, DGCR8, Dicer) and epigenetic factors (DNA methylation and long non-coding RNAs) were predicted to control miR-193a expression. They have fundamental effects on its biological behaviour in different types of cancers. Conclusion: miR-193a has significant roles in cancer and can be targeted in the future for cancer therapy by better understanding of the factors that control its biological behaviour.

One of the crucial reasons of breast cancer therapy failure is an impairment of mechanisms responsible for metabolism and cellular homeostasis, which makes it difficult to foresee the response to the treatment. Targeted therapy in breast cancer is dictated by the expression of specific molecules such as growth factor or hormone receptors. Many types of breast cancer exhibit different abnormalities in the apoptotic pathway, which confer the resistance to many forms of chemotherapy. Because of the fundamental importance of autophagy in the development and progression of cancer and its ability to affect treatment response, there has been an immense research on molecular regulation and signal transduction mechanisms that control this process. Here, we summarize the present knowledge concerning different breast cancer treatment strategies using drugs approved for the treatment of different breast cancer molecular subtypes with targeting pathways and factors associated with autophagy modulation/ regulation.

A growing body of evidence suggests that phytochemicals are potentially able to affect a variety of cellular processes, including proliferation, apoptosis, cell-cycle control, angiogenesis, inflammation, and DNA repair. Phytochemicals may typically play pleiotropic regulatory roles in cancer cells. Chemoprevention, which can be achieved by using these natural agents, has emerged as a helpful strategy to manage a variety of malignancies. With regard to cancer-associated chemopreventive mechanisms, phytochemicals can act by modulating microRNAs (miRNAs) and their target genes. This review aims to present an overview of recent findings on the effects of some wellcharacterized bioactive phytochemicals on miRNA regulation in different cancer types. The potential use of these phytochemicals for the chemoprevention and treatment of cancer is also discussed.

Prostate cancer is the most common carcinoma among aged males in western countries and more aggressive and lethal castration resistant prostate cancer often occurs after androgen deprivation therapy. The high expression of androgens and androgen receptor is closely related to prostate cancer. Efficient androgen receptor antagonists, such as enzalutamide and ARN-509, could be employed as potent anti-prostate cancer agents. Nevertheless, recent studies have revealed that F876L mutation in androgen receptor converts the action of enzalutamide and ARN-509 from an antagonist to agonist, so that novel strategies are urgent to address this resistance mechanism. In this review, we focus on the discussion about some novel strategies, which targets androgen receptor mainly through the degrading pathway as potential treatments for prostate cancer.

Background: Despite prolonged disease-free survival and overall survival rates in Estrogen Receptor (ER)-positive patients undergoing adjuvant treatment, Tamoxifen therapy tends to fail due to eventual acquisition of resistance. Objective: Although numerous studies have emphasized the Role of Receptor Tyrosine Kinases (RTKs) in the development of Tamoxifen resistance, inadequate clinical evidence is available regarding the alteration of biomarker expression during acquired resistance, thus undermining the validity of the findings. Results: Results of two meta-analyses investigating the effect of HER2 status on the prognosis of Tamoxifen-receiving patients have demonstrated that despite HER2-negative patients having longer disease-free survival; there is no difference in overhaul survival between the two groups. Furthermore, due to the intricate molecular interactions among estrogen receptors including ERα36, ERα66, and also RTKs, it is not surprising that RTK suppression does not restore Tamoxifen sensitivity. In considering such a complex network, we speculate that by the time HER2/EGFR is suppressed via targeted therapies, activation of ERα66 and ERα36 initiate molecular signaling pathways downstream of RTKs, thereby enhancing cell proliferation even in the presence of both Tamoxifen and RTK inhibitors. Conclusion: Although clinical findings regarding the molecular pathways downstream of RTKs have been thoroughly discussed in this review, further clinical studies are required in determining a consistency between preclinical and clinical findings. Discovering the best targets in preventing tumor progression requires thorough comprehension of estrogen-dependent and estrogen-independent pathways during Tamoxifen resistance development. Indeed, exploring additional clinically-proven targets would allow for better characterized treatments being available for breast cancer patients.

Background: The ultimate emergence of multidrug resistance remains a severe limitation of chemotherapy treatment for patients with cancer. The best-characterized cause of drug resistance involves the overexpression of P-glycoprotein (Pgp), which decreases the intracellular accumulation of chemotherapeutic agents in drug-resistant cancer cells. Thus, Pgp has become an attractive potential target for treating chemotherapy-resistant cancer, but the outcomes of using chemotherapy in combination with Pgp inhibitors in clinical trials to date have been disappointing. Objective: We herein examine the relationship between Pgp and drug resistance and update the strategies for overcoming drug resistance by targeting Pgp, with a special focus on the recent progress in the area of preventing the development of drug resistance by targeting Pgp both in vitro and in vivo. Given the essential roles of drug-resistant cancer models in these investigations, commonly used approaches for establishing drug-resistant models in the laboratory are also addressed. Conclusion: Considering the roles of Pgp in normal physiological conditions and its appreciated roles in detoxification, the currently available Pgp inhibitors undoubtedly cannot be used to reverse drug resistance in the clinic. Although agents that target Pgp to prevent and/or reverse drug resistance are not beneficial at the doses used in the laboratory when administered to patients with cancer who are enrolled in clinical trials, compounds targeting Pgp are widely acknowledged to be promising for circumventing drug resistance.

Background: Recent studies evaluated the diagnostic accuracy of circulating tumor DNA (ctDNA) analysis in the detection of epidermal growth factor receptor (EGFR) mutations from plasma of NSCLC patients, overall showing a high concordance as compared to standard tissue genotyping. However it is less clear if the location of metastatic site may influence the ability to identify EGFR mutations. Objective: This pooled analysis aims to evaluate the association between the metastatic site location and the sensitivity of ctDNA analysis in detecting EGFR mutations in NSCLC patients. Methods: Data from all published studies, evaluating the sensitivity of plasma-based EGFRmutation testing, stratified by metastatic site location (extrathoracic (M1b) vs intrathoracic (M1a)) were collected by searching in PubMed, Cochrane Library, American Society of Clinical Oncology, and World Conference of Lung Cancer, meeting proceedings. Pooled Odds ratio (OR) and 95% confidence intervals (95% CIs) were calculated for the ctDNA analysis sensitivity, according to metastatic site location. Results: A total of ten studies, with 1425 patients, were eligible. Pooled analysis showed that the sensitivity of ctDNA-based EGFR-mutation testing is significantly higher in patients with M1b vs M1a disease (OR: 5.09; 95% CIs: 2.93 – 8.84). A significant association was observed for both EGFR-activating (OR: 4.30, 95% CI: 2.35-7.88) and resistant T790M mutations (OR: 11.89, 95% CI: 1.45-97.22), regardless of the use of digital-PCR (OR: 5.85, 95% CI: 3.56-9.60) or non-digital PCR technologies (OR: 2.96, 95% CI: 2.24-3.91). Conclusions: These data suggest that the location of metastatic sites significantly influences the diagnostic accuracy of ctDNA analysis in detecting EGFR mutations in NSCLC patients.

Background: Stilbenes, 1,2-diphenylethen derivatives, including resveratrol and combretastatins, show anticancer features especially against tumor angiogenesis. Fosbretabulin, CA-4, in combination with carboplatin, is in the last stages of clinical tests as an inhibitor of thyroid cancer. The mode of action of these compounds involves suppression of angiogenesis through interfering with tubulin (de)polymerization. Objective: We have previously synthesized five E-2-hydroxystilbenes and seven dibenzo [b,f]oxepins in Z configuration, with methyl or nitro groups at varied positions. The aim of the present work was to evaluate the anticancer activity and molecular mechanism(s) of action of these compounds. Results: Two healthy, EUFA30 and HEK293, and two cancerous, HeLa and U87, cell lines were treated with four newly synthetized stilbenes and seven oxepins. Two of these compounds, JJR5 and JJR6, showed the strongest cytotoxic effect against cancerous cells tested and these two were selected for further investigations. They induced apoptosis with sub-G1 or S cell cycle arrest and PARP cleavage, with no visible activation of caspases 3 and 7. Proteomic differential analysis of stilbene-treated cells led to the identification of proteins involved almost exclusively in cell cycle management, apoptosis, DNA repair and stress response, e.g. oxidative stress. Conclusion: Among the newly synthesized stilbene derivatives, we selected two as potent anticancer compounds triggering late apoptosis/necrosis in cancerous cells through sub-G1 phase cell cycle arrest. They changed cyclin expression, induced DNA repair mechanisms, enzymes involved in apoptosis and oxidative stress response. Compounds JJR5 and JJR6 can be a base for structure modification(s) to obtain even more active derivatives.