Centrosomes and associated proteins in pathogenesis and treatment of breast cancer.

Breast cancer is the most prevalent malignancy among women worldwide. Despite significant advances in treatment, it remains one of the leading causes of female mortality. The inability to effectively treat advanced and/or treatment-resistant breast cancer demonstrates the need to develop novel treatment strategies and targeted therapies. Centrosomes and their associated proteins have been shown to play key roles in the pathogenesis of breast cancer and thus represent promising targets for drug and biomarker development. Centrosomes are fundamental cellular structures in the mammalian cell that are responsible for error-free execution of cell division. Centrosome amplification and aberrant expression of its associated proteins such as Polo-like kinases (PLKs), Aurora kinases (AURKs) and Cyclin-dependent kinases (CDKs) have been observed in various cancers, including breast cancer. These aberrations in breast cancer are thought to cause improper chromosomal segregation during mitosis, leading to chromosomal instability and uncontrolled cell division, allowing cancer cells to acquire new genetic changes that result in evasion of cell death and the promotion of tumor formation. Various chemical compounds developed against PLKs and AURKs have shown meaningful antitumorigenic effects in breast cancer cells in vitro and in vivo. The mechanism of action of these inhibitors is likely related to exacerbation of numerical genomic instability, such as aneuploidy or polyploidy. Furthermore, growing evidence demonstrates enhanced antitumorigenic effects when inhibitors specific to centrosome-associated proteins are used in combination with either radiation or chemotherapy drugs in breast cancer. This review focuses on the current knowledge regarding the roles of centrosome and centrosome-associated proteins in breast cancer pathogenesis and their utility as novel targets for breast cancer treatment.

PLK4 as a potential target to enhance radiosensitivity in triple-negative breast cancer.

Radioresistance is one of the barriers to developing more effective therapies against the most aggressive, triple-negative, breast cancer (TNBC) subtype. In our previous studies, we showed that inhibition of Polo-like Kinase 4 (PLK4) by a novel drug, CFI-400945 significantly enhances the anticancer effects of radiotherapy (RT) compared to single treatment alone. Here we further investigate the role of PLK4 in enhancing radiation effects in TNBC and explore mechanisms of PLK4 inhibition and radiation combinatorial antiproliferative effects. To assess cellular proliferation in response to treatments, we used colony formation assays in TNBC cell lines and patient-derived organoids (PDOs). Downregulation of PLK4 expression was achieved using siRNA silencing in TNBC cell lines. Immunofluorescence against centrin was used to assess the alteration of centriole amplification in response to treatments. We observed that inhibition of PLK4 by CFI-400945 or Centrinone B or its downregulation by siRNA, when combined with RT, resulted in a significant increase in antiproliferative effect in TNBC cells lines and PDOs compared to untreated or single-treated cells. Anticancer synergy was observed using a response matrix in PDOs treated with CFI-400945 and RT. We show that the overamplification of centrioles might be involved in the combined antiproliferative action of RT and PLK4 inhibition. Our data suggest that PLK4 is a promising target for enhancing the anticancer effects of RT in TNBC that, at least in part, is modulated by the overamplification of centrioles. These results support further mechanistic and translational studies of anti-PLK4 agents and RT as an anticancer combination treatment strategy.

Preclinical Models of Brain Metastases in Breast Cancer.

Breast cancer remains a leading cause of mortality among women worldwide. Brain metastases confer extremely poor prognosis due to a lack of understanding of their specific biology, unique physiologic and anatomic features of the brain, and limited treatment strategies. A major roadblock in advancing the treatment of breast cancer brain metastases (BCBM) is the scarcity of representative experimental preclinical models. Current models are predominantly based on the use of animal xenograft models with immortalized breast cancer cell lines that poorly capture the disease's heterogeneity. Recent years have witnessed the development of patient-derived in vitro and in vivo breast cancer culturing systems that more closely recapitulate the biology from individual patients. These advances led to the development of modern patient-tissue-based experimental models for BCBM. The success of preclinical models is also based on the imaging technologies used to detect metastases. Advances in animal brain imaging, including cellular MRI and multimodality imaging, allow sensitive and specific detection of brain metastases and monitoring treatment responses. These imaging technologies, together with novel translational breast cancer models based on patient-derived cancer tissues, represent a unique opportunity to advance our understanding of brain metastases biology and develop novel treatment approaches. This review discusses the state-of-the-art knowledge in preclinical models of this disease.

Radiotherapy and radiosensitization in breast cancer: Molecular targets and clinical applications.

Relatively poor survival outcomes are observed in advanced or metastatic breast cancer, where local control of the primary or metastatic disease may be achieved by surgical resection, local ablative and radiation therapies. Radioresistance, poses a major challenge in achieving durable oncologic outcomes, mandating development of novel management strategies. Although multimodality approaches that combine radiotherapy with chemotherapy, or systemic agents, are utilized for radiosensitization and treatment of various malignancies, this approach has not yet found its clinical application in breast cancer. Some agents for breast cancer treatment can serve as radiosensitizers, creating an opportunity to enhance effects of radiation while providing systemic disease control. Hence, combination of radiotherapy with radiosensitizing agents have the potential to improve oncologic outcomes in advanced or metastatic breast cancer. This review discusses molecular targets for radiosensitization and novel systemic agents that have potential for clinical use as radiosensitizers in breast cancer.

Anticancer effects of radiation therapy combined with Polo-Like Kinase 4 (PLK4) inhibitor CFI-400945 in triple negative breast cancer.

Development of novel multimodality radiotherapy treatments in metastatic breast cancer, especially in the most aggressive triple negative (TNBC) subtype, is of significant clinical interest. Here we show that a novel inhibitor of Polo-Like Kinase 4 (PLK4), CFI-400945, in combination with radiation, exhibits a synergistic anti-cancer effect in TNBC cell lines and patient-derived organoids in vitro and leads to a significant increase in survival to tumor endpoint in xenograft models in vivo, compared to control or single-agent treatment. Further preclinical and proof-of-concept clinical studies are warranted to characterize molecular mechanisms of action of this combination and its potential applications in clinical practice.

Current Issues in Conduct and Reporting of Noninferiority Randomized Controlled Trials in Surgical Management of Cancer Patients.

BACKGROUND: Serious concerns regarding quality of conduct and reporting of noninferiority trials (NITs) have been raised. Systematic analysis of the quality of the surgical NITs is lacking. Assessing the quality of conduct, reporting, and interpretation of surgical NITs in cancer patients is critical given their potential clinical impact. We aim to assess the quality of conduct, reporting, and interpretation of NITs that investigate the effects of surgical management in cancer patients. METHODS: A cross-sectional analysis of papers identified through a comprehensive literature database search was performed. Forty papers employing a phase III noninferiority (NI) randomized trial design to study effects of surgical methodology or sequencing of surgery in patients with solid cancers were included. Papers were assessed for type of analysis, justification of the noninferiority margin (NIM), consistency of type I error with confidence intervals (CIs), ability to achieve the predefined sample size, and interpretations regarding NI. RESULTS: Only half of the papers used both intention-to-treat and per protocol analyses; 62.5% provided no or poor justification for the NIM; 42.5% showed inconsistency of the type I error rate with CIs; 52.5% were deemed poor or fair quality, and 60.0% did not achieve the predefined sample size. One-fifth of the papers provided interpretation of the NI hypothesis that was not in concordance with the CONSORT guidelines. CONCLUSIONS: The quality of conduct, reporting, and interpretation of surgical NITs is suboptimal, requiring further improvements through adherence to guidelines and rigorous assessment at the stages of the study approval, funding, and the peer-review process.

The effect of a simultaneous versus a staged resection of metastatic colorectal cancer on time to adjuvant chemotherapy.

BACKGROUND AND OBJECTIVES: Patients with colorectal cancer with synchronous liver metastases may undergo a staged or a simultaneous resection. This study aimed to determine whether the time to adjuvant chemotherapy was delayed in patients undergoing a simultaneous resection. METHODS: A retrospective cohort study was conducted between 2005 and 2016. The primary outcome was time to adjuvant chemotherapy. A multivariate linear regression was conducted to ascertain the adjusted effect of a simultaneous versus a staged approach on time to adjuvant chemotherapy. RESULTS: A total of 155 patients were included. A total of 127 patients underwent a staged resection, whereas 28 patients underwent a simultaneous resection. Age, sex, and American Society of Anesthesiologists class as well tumor, node, metastasis stage, tumor location, and number and size of metastases were not significantly different between the groups. The median time to adjuvant chemotherapy was 70 and 63 days for the staged and simultaneous groups, respectively (P = .27). Multivariate analysis did not demonstrate an increased propensity for prolonged time to chemotherapy after simultaneous resection (rate ratio: 0.97, 95% CI: 0.71-1.32, P = .84). There were no significant differences in the length of stay, complications, overall survival, and disease-free survival between the groups (P > .05). CONCLUSIONS: This study demonstrated that simultaneous resection does not result in significant delay of adjuvant chemotherapy compared with a staged approach.

Evaluating the Impact of Breast Density on Preoperative MRI in Invasive Lobular Carcinoma.

BACKGROUND: The focus of this study was to assess the accuracy of breast MRI in predicting pathologic tumor size in invasive lobular carcinoma (ILC) and to evaluate the incidence and factors associated with the detection of additional MRI lesions in ILC patients. STUDY DESIGN: We retrospectively reviewed data from patients with stage I to III ILC diagnosed between 2010 and 2016 at our institution. Univariable and multivariable logistic regression were used to determine factors associated with detection of additional suspicious lesions on MRI. RESULTS: The cohort included 99 women with ILC who underwent preoperative MRI, with a median age of 61 years (range 35 to 80 years). The sensitivity of MRI for detecting invasive lobular carcinoma was 99%, higher than that of mammography (68%) and ultrasound (92%). Mammography and ultrasound had a tendency to underestimate ILC, and MRI estimates of final tumor size were concordant in the majority (58.6%) of cases, with a median discordance of -2 mm. Magnetic resonance imaging detected additional ipsilateral malignancy in 23.2%, occult contralateral disease in 3.0%, and altered surgical management in 29.3% of ILC cases. In multivariable analyses, factors significantly associated with additional suspicious findings on MRI included higher breast density (odds ratio 3.19; 95% CI 1.01 to 10.0) and lymph node-positive disease (odds ratio 4.02; 95% CI 0.96 to 16.9). CONCLUSIONS: Preoperative MRI is a useful adjunct to conventional breast imaging in ILC, particularly in women with dense breast tissue.

Fibroepithelial breast lesions diagnosed by core needle biopsy demonstrate a moderate rate of upstaging to phyllodes tumors.

BACKGROUND: Fibroepithelial lesions of the breast (FEL) are atypical lesions diagnosed on core-needle biopsy. The purpose of this study was to determine the rate at which FELs are upstaged to phyllodes tumor on excision, and to examine the clinical and radiological factors that may be predictive of upstaging. METHODS: A retrospective review from the medical records of patients diagnosed with FEL on CNB at a single institution between 2010 and 2015 was performed. Patients diagnosed with benign or borderline phyllodes tumors were compared to those diagnosed with fibroadenoma. RESULTS: Of 74 patients diagnosed with FEL, 48 underwent excision (64.9%). Of the 48 lesions excised, pathology revealed 30 fibroadenomas (62.5%), 14 benign phyllodes tumors (29.2%), and 4 borderline phyllodes tumor (8.3%). No malignant phyllodes tumors were identified. On preoperative ultrasound, heterogeneous echotexture (p = 0.03) and lack of internal vascularity (p = 0.03) were significantly associated with upstaging to phyllodes tumor. CONCLUSIONS: Surgical excision of FELs yield a pathological diagnosis of benign and borderline phyllodes tumor in 37.5% of cases. A high BIRADs score (≥4b), heterogeneous echotexture and lack of internal vascularity on ultrasound may help predict upstaging to phyllodes tumor.

Influence of preoperative magnetic resonance imaging on the surgical management of breast cancer patients.

BACKGROUND: Magnetic resonance imaging (MRI) is gaining popularity in the preoperative management of breast cancer patients. However, the role of this modality remains controversial. We aimed to study the impact of preoperative MRI (pMRI) on the surgical management of breast cancer patients. METHODS: This retrospective study included 766 subjects with breast cancer treated operatively at the specialized academic center. RESULTS: Between those who underwent pMRI (MRI group, n = 307) and those who did not (no-MRI group, n = 458), there were no significant differences (P = .254) in the proportions of either total mastectomies (20.5% vs 17.2%, respectively) or segmental mastectomies (79.5% vs 82.8%). Patients in the MRI group were significantly more likely (P = .002) to undergo contralateral surgery (11.7% vs 5.5%). Similar results were obtained in multivariate analysis adjusting for age, with the proportions of contralateral breast operations significantly higher in the MRI group (Odds Ratio = 2.25, P = .007). pMRI had no significant effect (P = .54) on the proportion of total re-excisions (7.5% vs 8.7%) or the type of re-excision (total vs segmental mastectomy) between the groups. CONCLUSIONS: pMRI does not have a significant impact on the type of operative intervention on the ipsilateral breast but is associated with an increase in contralateral operations. Similarly, pMRI does not change the proportion of re-excisions or the type of the re-excision performed. This study demonstrates that pMRI has little impact on the surgical management of breast cancer, and its value as a routine adjunct in the preoperative work-up of recently diagnosed breast cancer patients needs to be re-examined.

Parathyroid hormone levels 1 hour after thyroidectomy: an early predictor of postoperative hypocalcemia.

BACKGROUND: Parathyroid dysfunction leading to symptomatic hypocalcemia is not uncommon following a total or completion thyroidectomy and is often associated with significant patient morbidity and a prolonged hospital stay. A simple, reliable indicator to identify patients at risk would permit earlier pharmacologic prophylaxis to avoid these adverse outcomes. We examined the role of intact parathormone (PTH) levels 1 hour after surgery as a predictor of post-thyroidectomy hypocalcemia. METHODS: We prospectively reviewed the cases of consecutive patients undergoing total or completion thyroidectomy. Ionized calcium (Ca(2+)) and intact PTH levels were measured preoperatively and at 1-, 6- and 24-hour intervals postoperatively. The specificity, sensitivity, negative and positive predictive values of the 1-hour PTH serum levels (PTH-1) in predicting 24-hour post-thyroidectomy hypocalcemia and eucalcemia were determined. RESULTS: We reviewed the cases of 149 patients. Biochemical hypocalcaemia (Ca(2+) < 1.1 mmol/L) developed in 38 of 149 (25.7%) patients 24 hours after thyroidectomy. The sensitivity, specificity, positive and negative predictive values of a low PTH-1 were 89%, 100%, 97% and 100%, respectively. CONCLUSION: We found that PTH-1 levels were predictive of symptomatic hypocalcemia 24 hours after thyroidectomy. Routine use of this assay should be considered, as it could prompt the early administration of calcitriol in patients at risk of hypocalcemia and allow for the safe and timely discharge of patients expected to remain eucalcemic.

CONTEXTE: Il n'est pas rare qu'un dysfonctionnement des glandes parathyroïdes entraînant une hypocalcémie symptomatique s'observe après une thyroïdectomie totale ou de complétion et il est souvent associé à une importante morbidité chez les patients et à un séjour hospitalier prolongé. Un indicateur simple et fiable permettant de reconnaître les patients à risque pourrait favoriser une prophylaxie pharmacologique précoce afin d'éviter ces complications. Nous avons examiné le rôle des taux de parathormone (PTH) intacte une heure après la chirurgie comme prédicteurs de l'hypocalcémie post-thyroïdectomie. MÉTHODES: Nous avons passé en revue de manière prospective des cas consécutifs de patients soumis à une thyroïdectomie totale ou de complétion. Les taux de calcium ionisé (Ca2+) et de PTH intacte ont été mesurés avant l'intervention, puis 1 heure, 6 heures et 24 heures après. Il a ainsi été possible de déterminer la spécificité, la sensibilité, la valeur prédictive négative et positive des taux sériques de PTH 1 heure après l'intervention (PTH-1) pour ce qui est de prédire l'hypocalcémie et l'eucalcémie 24 heures après la thyroïdectomie. RÉSULTATS: Nous avons analysé 149 cas. L'hypocalcémie biochimique (Ca2+ < 1,1 mmol/L) a été observée chez 38 patients sur 149 (25,7 %) 24 heures après la thyroïdectomie. La sensibilité, la spécificité, la valeur prédictive positive et négative d'un taux de PTH-1 faible ont été respectivement de 89 %, 100 %, 97 % et 100 %. CONCLUSION: Nous avons noté que les taux de PTH-1 étaient prédictifs d'une hypocalcémie symptomatique 24 heures après la thyroïdectomie. L'utilisation d'emblée de ce test est à envisager puisqu'elle permettrait l'administration précoce de calcitriol chez les patients exposés à un risque d'hypocalcémie et un congé sécuritaire et rapide chez les patients dont on s'attend à ce qu'ils demeurent eucalcémiques.

Impact of preoperative breast MRI on surgical decision making and clinical outcomes: a systematic review.

BACKGROUND: Preoperative magnetic resonance imaging (MRI) is increasingly used in the workup of breast cancer patients and could lead to changes in surgical management. It is unclear how the information gained from MRI studies affects surgical decision making and influences clinical outcomes. These issues are addressed in this review. METHODS: PubMed database searches were performed to retrieve and analyze respective original research and review articles on preoperative MRI in the evaluation of breast cancer patients. RESULTS: Preoperative MRI is a highly sensitive but nonspecific method that leads to changes in surgical management with increased numbers of more extended surgical interventions. It appears that a relatively large proportion of MRI-driven changes in surgical management result in overtreatment without conclusively proven beneficial effects on such clinical outcomes as decrease in reoperation rates or improved patient survival. CONCLUSIONS: Thus, routine use of supplementary preoperative breast MRI should be discouraged until compelling evidence of its effectiveness is available.

Control of synaptic plasticity and memory via suppression of poly(A)-binding protein.

Control of protein synthesis is critical for synaptic plasticity and memory formation. However, the molecular mechanisms linking neuronal activity to activation of mRNA translation are not fully understood. Here, we report that the translational repressor poly(A)-binding protein (PABP)-interacting protein 2A (PAIP2A), an inhibitor of PABP, is rapidly proteolyzed by calpains in stimulated neurons and following training for contextual memory. Paip2a knockout mice exhibit a lowered threshold for the induction of sustained long-term potentiation and an enhancement of long-term memory after weak training. Translation of CaMKIIα mRNA is enhanced in Paip2a⁻/⁻ slices upon tetanic stimulation and in the hippocampus of Paip2a⁻/⁻ mice following contextual fear learning. We demonstrate that activity-dependent degradation of PAIP2A relieves translational inhibition of memory-related genes through PABP reactivation and conclude that PAIP2A is a pivotal translational regulator of synaptic plasticity and memory.

Selective regulation of GluA subunit synthesis and AMPA receptor-mediated synaptic function and plasticity by the translation repressor 4E-BP2 in hippocampal pyramidal cells.

The eukaryotic initiation factor 4E-binding protein-2 (4E-BP2) is a repressor of cap-dependent mRNA translation and a major downstream effector of the mammalian target of rapamycin (mTOR) implicated in hippocampal long-term synaptic plasticity and memory. Yet, synaptic mechanisms regulated by 4E-BP2 translational repression remain unknown. Combining knock-out mice, whole-cell recordings, spine analysis, and translation profiling, we found that 4E-BP2 deletion selectively upregulated synthesis of glutamate receptor subunits GluA1 and GluA2, facilitating AMPA receptor (AMPAR)-mediated synaptic transmission and affecting translation-dependent chemically induced late long-term potentiation (cL-LTP). In 4E-BP2 knock-out (4E-BP2(-/-)) mice, evoked and miniature EPSCs were increased, an effect mimicked by short-hairpin RNA knockdown of 4E-BP2 in wild-type mice, indicating that 4E-BP2 level regulates basal transmission at mature hippocampal AMPAR-containing synapses. Remarkably, in 4E-BP2(-/-) mice, the AMPA to NMDA receptor (NMDAR) EPSC ratio was increased, without affecting NMDAR-mediated EPSCs. The enhanced AMPAR function concurred with increased spine density and decreased length resulting from greater proportion of regular spines and less filopodia in 4E-BP2(-/-) mice. Polysome profiling revealed that translation of GluA1 and GluA2 subunits, but not GluN1 or GluN2A/B, was selectively increased in 4E-BP2(-/-) hippocampi, consistent with unaltered I-V relation of EPSCs mediated by GluA1/GluA2 heteromers. Finally, translation-dependent cL-LTP of unitary EPSCs was also affected in 4E-BP2(-/-) mice, lowering induction threshold and removing mTOR signaling requirement while impairing induction by normal stimulation. Thus, translational control through 4E-BP2 represents a unique mechanism for selective regulation of AMPAR synthesis, synaptic function, and long-term plasticity, important for hippocampal-dependent memory processes.

On the Diversification of the Translation Apparatus across Eukaryotes.

Diversity is one of the most remarkable features of living organisms. Current assessments of eukaryote biodiversity reaches 1.5 million species, but the true figure could be several times that number. Diversity is ingrained in all stages and echelons of life, namely, the occupancy of ecological niches, behavioral patterns, body plans and organismal complexity, as well as metabolic needs and genetics. In this review, we will discuss that diversity also exists in a key biochemical process, translation, across eukaryotes. Translation is a fundamental process for all forms of life, and the basic components and mechanisms of translation in eukaryotes have been largely established upon the study of traditional, so-called model organisms. By using modern genome-wide, high-throughput technologies, recent studies of many nonmodel eukaryotes have unveiled a surprising diversity in the configuration of the translation apparatus across eukaryotes, showing that this apparatus is far from being evolutionarily static. For some of the components of this machinery, functional differences between different species have also been found. The recent research reviewed in this article highlights the molecular and functional diversification the translational machinery has undergone during eukaryotic evolution. A better understanding of all aspects of organismal diversity is key to a more profound knowledge of life.

Translation initiation in colorectal cancer.

Colorectal cancers (CRC) are one of the most common causes of morbidity and mortality in high-income countries. Targeted screening programs have resulted in early treatment and a substantial decrease in mortality. However, treatment strategies for CRC still require improvement. Understanding the etiology and pathogenesis of CRC would provide tools for improving treatment of patients with this disease. It is only recently that deregulation of the protein synthesis apparatus has begun to gain attention as a major player in cancer development and progression. Among the numerous steps of protein synthesis, deregulation of the process of translation initiation appears to play a key role in cancer growth and proliferation. This manuscript discusses a fascinating and rapidly growing field exploring translation initiation as a fundamental component in CRC development and progression and summarizing CRC treatment perspectives based on agents targeting translation initiation.

mRNA helicases: the tacticians of translational control.

The translation initiation step in eukaryotes is highly regulated and rate-limiting. During this process, the 40S ribosomal subunit is usually recruited to the 5' terminus of the mRNA. It then migrates towards the initiation codon, where it is joined by the 60S ribosomal subunit to form the 80S initiation complex. Secondary structures in the 5' untranslated region (UTR) can impede binding and movement of the 40S ribosome. The canonical eukaryotic translation initiation factor eIF4A (also known as DDX2), together with its accessory proteins eIF4B and eIF4H, is thought to act as a helicase that unwinds secondary structures in the mRNA 5' UTR. Growing evidence suggests that other helicases are also important for translation initiation and may promote the scanning processivity of the 40S subunit, synergize with eIF4A to 'melt' secondary structures or facilitate translation of a subset of mRNAs.