Antitumor Activity of the Xanthonoside XGAc in Triple-Negative Breast, Ovarian and Pancreatic Cancer by Inhibiting DNA Repair

Dysregulation of the DNA damage response may contribute to the sensitization of cancer cells to DNA-targeting agents by impelling cell death. In fact, the inhibition of the DNA repair pathway is considered a promising anticancer therapeutic strategy, particularly in combination with standard-of-care agents. The xanthonoside XGAc was previously described as a potent inhibitor of cancer cell growth. Herein, we explored its antitumor activity against triple-negative breast cancer (TNBC), ovarian cancer and pancreatic ductal adenocarcinoma (PDAC) cells as a single agent and in combination with the poly(ADP-ribose) polymerase inhibitor (PARPi) olaparib. We demonstrated that XGAc inhibited the growth of TNBC, ovarian and PDAC cells by inducing cell cycle arrest and apoptosis. XGAc also induced genotoxicity, inhibiting the expression of DNA repair proteins particularly involved in homologous recombination, including BRCA1, BRCA2 and RAD51. Moreover, it displayed potent synergistic effects with olaparib in TNBC, ovarian cancer and PDAC cells. Importantly, this growth inhibitory activity of XGAc was further reinforced in a TNBC spheroid model and in patient-derived ovarian cancer cells. Also, drug-resistant cancer cells showed no cross-resistance to XGAc. Additionally, the ability of XGAc to prevent cancer cell migration was evidenced in TNBC, ovarian cancer and PDAC cells. Altogether, these results highlight the great potential of acetylated xanthonosides such as XGAc as promising anticancer agents against hard-to-treat cancers.

Overcoming therapeutic resistance in pancreatic cancer: Emerging opportunities by targeting BRCAs and p53

Pancreatic cancer (PC) is characterized by (epi)genetic and microenvironmental alterations that negatively impact the treatment outcomes. New targeted therapies have been pursued to counteract the therapeutic resistance in PC. Aiming to seek for new therapeutic options for PC, several attempts have been undertaken to exploit BRCA1/2 and TP53 deficiencies as promising actionable targets. The elucidation of the pathogenesis of PC highlighted the high prevalence of p53 mutations and their connection with the aggressiveness and therapeutic resistance of PC. Additionally, PC is associated with dysfunctions in several DNA repair-related genes, including BRCA1/2, which sensitize tumours to DNA-damaging agents. In this context, poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) were approved for mutant BRCA1/2 PC patients. However, acquired drug resistance has become a major drawback of PARPi. This review emphasizes the importance of targeting defective BRCAs and p53 pathways for advancing personalized PC therapy, with particular focus on how this approach may provide an opportunity to tackle PC resistance.

Exploiting DNA Damage Repair in Precision Cancer Therapy: BRCA1 as a Prime Therapeutic Target

Simple Summary

Chemical inhibition of central DNA damage repair (DDR) proteins has become a promising approach in precision cancer therapy. In particular, BRCA1 and its DDR-associated proteins constitute important targets for developing DNA repair inhibiting drugs. This review provides relevant insights on DDR biology and pharmacology, aiming to boost the development of more effective DDR targeted therapies.

Abstract

Precision medicine aims to identify specific molecular alterations, such as driver mutations, allowing tailored and effective anticancer therapies. Poly(ADP)-ribose polymerase inhibitors (PARPi) are the prototypical example of targeted therapy, exploiting the inability of cancer cells to repair DNA damage. Following the concept of synthetic lethality, PARPi have gained great relevance, particularly in BRCA1 dysfunctional cancer cells. In fact, BRCA1 mutations culminate in DNA repair defects that can render cancer cells more vulnerable to therapy. However, the efficacy of these drugs has been greatly affected by the occurrence of resistance due to multi-connected DNA repair pathways that may compensate for each other. Hence, the search for additional effective agents targeting DNA damage repair (DDR) is of crucial importance. In this context, BRCA1 has assumed a central role in developing drugs aimed at inhibiting DNA repair activity. Collectively, this review provides an in-depth understanding of the biology and regulatory mechanisms of DDR pathways, highlighting the potential of DDR-associated molecules, particularly BRCA1 and its interconnected partners, in precision cancer medicine. It also affords an overview about what we have achieved and a reflection on how much remains to be done in this field, further addressing encouraging clues for the advance of DDR targeted therapy.

PERCUTANEOUS TRANSAXILLARY TRANSCATHETER AORTIC VALVE IMPLANTATION

The transaxillary (TAX) approach for transcatheter aortic valve implantation (TAVI) results in comparable short and long-term clinical results compared to the transfemoral (TF) approach. However, adequate closure of the axillary artery is the most critical issue when performing the percutaneous approach. Compared to surgical transaxillary approach, the percutaneous approach was used only in selected cases due to this closure limitation. In the present paper, we aim to demonstrate the feasibility of implanting the CoreValve Evolut Pro transcatheter heart valve via percutaneous transaxillary approach and make a literature review of procedure particularities and outcome. We describe the case of a patient with severe aortic stenosis in the presence of small calibre and severely calcified femoral arteries. A CoreValve Evolut Pro 26 was successfully implanted percutaneously through the left axillary artery. Percutaneous transaxillary transcatheter aortic valve implantation is a feasible and safe alternative in patients who have suboptimal iliofemoral vessels.

BBIT20 inhibits homologous DNA repair with disruption of the BRCA1-BARD1 interaction in breast and ovarian cancer

BACKGROUND AND PURPOSE

Advances in the treatment of triple-negative breast and ovarian cancer remain challenging. In particular, resistance to the available therapy, by restoring or overexpressing the DNA repair machinery, has often been reported. New strategies to improve the therapeutic outcomes of these cancers are needed. Herein, we disclose the dregamine 5-bromo-pyridin-2-ylhydrazone (BBIT20), a natural monoterpene indole alkaloid derivative, as an inhibitor of homologous DNA repair.

EXPERIMENTAL APPROACH

To unveil BBIT20 antitumour activity and underlying molecular mechanism of action, two-dimensional (2D) and three-dimensional (3D) cell cultures, patient-derived cell lines and xenograft mouse models were used.

KEY RESULTS

BBIT20 disrupted the BRCA1-BARD1 interaction, triggering nuclear-to-cytoplasmic BRCA1 translocation, cell cycle arrest and downregulation of homologous DNA repair-related genes and proteins, with subsequent enhancement of DNA damage, reactive oxygen species generation and apoptosis, in triple-negative breast and ovarian cancer cells. BBIT20 also displayed pronounced antitumour activity in patient-derived cells and xenograft mouse models of ovarian cancer, with low toxicity in non-malignant cells and undetectable side effects in mice. Additionally, it did not induce resistance in triple-negative breast and ovarian cancer and displayed marked synergistic effects with cisplatin and olaparib (a poly [ADP-ribose] polymerase inhibitor), on 2D and 3D models of these cancer cells.

CONCLUSION AND IMPLICATIONS

These findings add an inhibitor of the BRCA1-BARD1 interaction to the list of DNA-damaging agents. Importantly, either as a single agent or in combination therapy, BBIT20 reveals great potential in the personalized treatment of aggressive and resistant cancers, particularly triple-negative breast and advanced ovarian cancer.

A selective p53 activator and anticancer agent to improve colorectal cancer therapy

Impairment of the p53 pathway is a critical event in cancer. Therefore, reestablishing p53 activity has become one of the most appealing anticancer therapeutic strategies. Here, we disclose the p53-activating anticancer drug (3S)-6,7-bis(hydroxymethyl)-5-methyl-3-phenyl-1H,3H-pyrrolo[1,2-c]thiazole (MANIO). MANIO demonstrates a notable selectivity to the p53 pathway, activating wild-type (WT)p53 and restoring WT-like function to mutant (mut)p53 in human cancer cells. MANIO directly binds to the WT/mutp53 DNA-binding domain, enhancing the protein thermal stability, DNA-binding ability, and transcriptional activity. The high efficacy of MANIO as an anticancer agent toward cancers harboring WT/mutp53 is further demonstrated in patient-derived cells and xenograft mouse models of colorectal cancer (CRC), with no signs of undesirable side effects. MANIO synergizes with conventional chemotherapeutic drugs, and in vitro and in vivo studies predict its adequate drug-likeness and pharmacokinetic properties for a clinical candidate. As a single agent or in combination, MANIO will advance anticancer-targeted therapy, particularly benefiting CRC patients harboring distinct p53 status.

Effectiveness of different supralottic airways during resuscitation manoeuvres. A systematic review

INTRODUCTION

Supraglottic airways, which are easily inserted and minimize interruptions in cardiopulmonary resuscitation manoeuvres, are now widely used in pre- and in-hospital emergencies. However, most studies in these devices do not specify whether they ensure good ventilation during CPR. This systematic review aims to determine whether there is evidence that supraglotic airways enable effective ventilation during resuscitation.

METHODS

The MEDLINE and COCHRANE databases were searched for studies published in English up to 30 November 2018. Eligible studies were all those that objectively evaluated tidal volume during resuscitation maneuvers in patients over 18 years of age using various supraglottic airways.

RESULTS

A total of 3734 articles were identified, of which 252 were duplicates. Only 1 objectively evaluated ventilation during resuscitation maneuvers and presented data relevant to this review. The study included 470 patients, 51 of which underwent spirometry. Only 4.48% of patients survived to hospital discharge; however, the correlation with ventilation effectiveness was not assessed.

CONCLUSION

There is no scientific evidence that supraglottic airways provide effective ventilation during resuscitation maneuvers. Evaluation by spirometry, chest impedance and ultrasound may help to determine the ventilatory efficacy of supraglottic airways during CPR, and clarify whether this factor contributes to the difficulties experienced in reversing cardiorespiratory arrest.

BRCA1/P53: Two strengths in cancer chemoprevention

Increasing emphasis has been given to prevention as a feasible approach to reduce the cancer burden. However, for its clinical success, further advances are required to identify effective chemopreventive agents. This review affords a critical and up-to-date discussion of issues related to cancer prevention, including an in-depth knowledge on BRCA1 and p53 tumor suppressor proteins as key molecular players. Indeed, it compiles the most recent advances on the topic, highlighting the unique potential of BRCA1 and p53 germline mutations as molecular biomarkers for risk assessment and targets for chemoprevention. Relevant evidences are herein provided supporting the effectiveness of distinct pharmacological agents in cancer prevention, by targeting BRCA1 and p53. Moreover, the rationale for using germline mutant BRCA1- or p53-related cancer syndromes as model systems to investigate effective chemopreventive agents is also addressed. Altogether, this work provides an innovative conception about the dependence on p53 and BRCA1 co-inactivation in tumor formation and development, emphasizing the relationship between these two proteins as an encouraging direction for future personalized pharmacological interventions in cancer prevention.

Carcinoembryonic antigen carrying SLeX as a new biomarker of more aggressive gastric carcinomas

Malignant transformation of gastric cells is accompanied by the deregulated expression of glycosyltransferases leading to the biosynthesis of tumor-associated glycans such as the sialyl-Lewis X antigen (SLe^x). SLe^x presence on cell surface glycoconjugates increases the invasive capacity of gastric cancer cells and is associated with tumor metastasis. ST3Gal IV enzyme is involved in the synthesis of SLe^x antigen and overexpressed in gastric carcinomas. Herein, we identified the glycoproteins carrying SLe^x in gastric cancer cells overexpressing ST3Gal IV enzyme and evaluated their biomarker potential for gastric carcinoma.

Methods: SLe^x modified glycoproteins were identified applying western blot and mass spectrometry. Immunoprecipitation, proximity ligation assay (PLA), E-selectin binding assay and CRISPR/cas9 knockout experiments were performed to characterize the presence of SLe^x on the identified glycoprotein. Protein N-glycans of the SLe^x protein carrier were in deep analyzed by porous-graphitized-carbon liquid-chromatography and tandem mass spectrometry glycomics. In silico expression analysis of α2-3 sialyltransferase ST3Gal IV and SLe^x protein carrier was performed and the conjoint expression of the SLe^x modified glycoproteins evaluated by immunohistochemistry and PLA in a series of gastric carcinomas.

Results: Carcinoembryonic antigen (CEA; CEACAM5) was identified and validated by different methodologies as a major carrier of SLe^x. N-glycomics of CEA revealed that complex N-glycans are capped with α2-3 linked sialic acid (Neu5Acα2-3Galβ1-4GlcNAc). Data set analysis of ST3Gal IV and CEA showed that ST3Gal IV expression was associated with patient´s poor survival, whereas CEA did not show any prognostic value. The co-expression of both CEA and SLe^X was observed in 86,3% of gastric carcinoma cases and 74,5% of the total cases displayed the conjoint CEA+SLe^xin situ PLA expression. This expression was associated with clinicopathological features of the tumors, including infiltrative pattern of tumor growth, presence of venous invasion and patient's poor survival. CEA immunoprecipitation from gastric carcinoma tissues also confirmed the presence of SLe^x.

Conclusion: CEA is the major glycoprotein carrying SLe^x in gastric carcinoma and the conjoint detection of CEA-SLe^x is associated with aggressive tumor features highlighting its PLA detection as a biomarker of gastric cancer patient prognosis for theranostic applications.

Chronic utilization of agents acting on the renin-angiotensin system and intraoperative arterial pressure

BACKGROUND

There has been concern that taking agents acting on the renin-angiotensin system (ARAS) in surgery day, may predispose patients to higher risk of intraoperative hypotension during surgery. Therefore, the European Society of Cardiology and the European Society of Anesthesiology recommend transient discontinuation of ARAS before non-cardiac surgery in hypertensive patients. As the existent evidence is limited, this recommendation remains debated.

AIM

The objectives of the study were to evaluate the effects of ARAS chronic utilization on intraoperative arterial pressure.

PATIENTS AND METHODS

This historical cohort consisted in recruitment of surgery patients over 12 months, at "Cova da Beira Hospital Center". The data were gathered from an interview to the patient and by postoperative review of the medical record.

RESULTS

The study consisted of 756 patients. Of those, 589 did not take antihypertensive medication and 176 were taking chronic ARAS. In univariate analysis, only the appearance of intraoperative hypertension was significantly greater in ARAS group. In logistic regression analysis, age, diabetes mellitus and taking ARAS were the only significant risk factors to the appearance of intraoperative hypertension. In ARAS group, 123 patients stopped the ARA before surgery and 53 continued it until the surgery day. The frequency of the two outcomes did not differ between the two groups.

CONCLUSIONS

In our study hypotension episodes during non-cardiac surgery could not be attributed to ARAS chronic utilization and taking ARAS on surgery morning when compared with withdrawal was not associated with hypotension episodes.

[Children and lead exposure. Preliminary study]

Lead poisoning is one of the most common and preventable childhood illness. The authors believe that the present study is the first evaluation of this problem in Portugal.

OBJECTIVES

a) to characterize blood lead levels in children aged 1 to 6 years living in the Oporto area; b) to identify risk groups and develop screening strategies.

MATERIAL AND METHODS

The authors studied an opportunistic sample of children that were observed at the Hospital Maria Pia and the Instituto Nacional de Saúde Dr. Ricardo Jorge (Porto) to whom blood testing was requested. All children with neurological or digestive symptoms were excluded (October-December 1991; n = 113).

RESULTS

One child had a blood lead level of 46.6 micrograms/dl (class-IV, CDC); 32% (n = 36) were between 20 e 44 micrograms/dl (class-III), while only four children (3.2%) presented values < = 9 micrograms/dl (class-I). Class II included the remainder (n = 73). The results clearly point out that lead poisoning is a real problem among Portuguese children, since the proportion of children not considered to be lead-poisoned is very small. Children in the other classes are at risk of developing acute and chronic toxicity.