Common Misconceptions about Diet and Breast Cancer: An Unclear Issue to Dispel.

Breast cancer (BC) constitutes a prevalent health condition among women. Recent years have witnessed the identification of dietary proto-oncogenic factors that deserve attention. Besides the well-known role of alcohol and red and processed meat in BC development, the impact of other dietary components remains unclear. Our narrative review aims to explore the diet-BC relationship, focusing on sugar, dairy, and soy consumption. We conducted a PubMed literature search covering the last decade (2013-2023) and included 35 papers. We found limited evidence on the association between high sugar intake and BC incidence. On the other hand, dairy and soy consumption displayed a protective effect in the majority of the analyzed papers. However, a significant degree of heterogeneity was reported among the results. Menopausal status and the specific BC molecular subtypes were the main factors influencing the interpretation of the results. Exploring dietary factors and BC revealed inconsistencies: high glycemic index post-menopause may be a risk factor, while sugar-sweetened drinks and artificial sweeteners yielded conflicting results; fermented dairy showed potential benefits, non-fermented dairy presented inconsistent findings; soy impact on BC varied according to molecular subtype, with some studies suggesting a positive association in luminal-like BC. Hence, further investigation is crucial to obtain a uniform consensus on the diet-BC relationship.

Ribociclib-Induced Cutaneous Adverse Events in Metastatic HR+/HER2- Breast Cancer: Incidence, Multidisciplinary Management, and Prognostic Implication.

BACKGROUND: Ribociclib is approved for hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer (ABC) treatment, in combination with endocrine therapy. Hematological, hepatic, and cardiac adverse events (AEs) emerged from pivotal trials, but little is known about cutaneous adverse events (CAEs). PATIENTS AND METHODS: We report data from a retrospective cohort study of all patients with HR+/HER2- ABC treated with ribociclib at Humanitas Cancer Center between June 2017 and December 2022. We recorded clinical-pathological data, the incidence, and treatment of ribociclib-related CAEs. These were evaluated according to the NCI-CTCAE v5.0 classification. Progression-free survival (PFS) was estimated by Kaplan-Meier method and the log-rank test was used to analyze differences between groups. RESULTS: Thirteen of 91 patients (14.3%) experienced treatment-related CAEs (mean time to the occurrence: 3.9 months). The most frequent CAEs were eczematous dermatitis (53.8%) and maculo-papular reaction (15.4%). Itch was reported by all 13 patients. The grade was G3 in 8 cases, G2 in 4, and G1 in 1. An integrated approach based on ribociclib dose modulation and dermatological interventions (oral antihistamine, moisturized cream, topical, and/or systemic steroids) could prevent ribociclib discontinuation in most patients. At a median follow-up of 20 months, the median PFS was 13 months (range, 1-66) with a better PFS curves for patients experiencing CAEs (P = .04). CONCLUSION: We mapped frequency and types of ribociclib-induced CAEs. An interdisciplinary management of CAEs incorporated into routine care may reduce the rate of drug discontinuation thus potentially contributing to better long-term outcomes.

Unlocking the Potential of Circulating miRNAs in the Breast Cancer Neoadjuvant Setting: A Systematic Review and Meta-Analysis.

The potential role of circulating microRNAs (miRNAs) as biomarkers in breast cancer (BC) management has been widely reported. However, the numerous discrepancies between studies in this regard hinders the implementation of circulating miRNAs in routine clinical practice. In the context of BC patients undergoing neoadjuvant chemotherapy (NAC), the possibility of predicting NAC response may lead to prognostic improvements by individualizing post-neoadjuvant therapy. In this context, the present meta-analysis aims to clarify circulating miRNAs' predictive role with respect to NAC response among BC patients. We conducted a comprehensive literature search on five medical databases until 16 February 2023. We pooled the effect sizes of each study by applying a random-effects model. Cochran's Q test (p-level of significance set at 0.05) scores and I2 values were assessed to determine between-study heterogeneity. The PROBAST (Prediction Model Risk of Bias Assessment Tool) tool was used to evaluate the selected studies' risk of bias. Overall, our findings support the hypothesis that circulating miRNAs, specifically miR-21-5p and miR-155-5p, may act as predictive biomarkers in the neoadjuvant setting among BC patients. However, due to the limited number of studies included in this meta-analysis and the high degrees of clinical and statistical heterogeneity, further research is required to confirm the predictive power of circulating miR-21-5p and miR-155-5p.

The Role of Female Reproductive Hormones in the Association between Migraine and Breast Cancer: An Unanswered Question.

Accumulating epidemiological studies have investigated a possible interconnection between migraine (Mi) and breast cancer (BC) because of the strong link between these diseases and female reproductive hormones. This review aims to consolidate findings from epidemiological studies and explore biologically plausible hypothetical mechanisms related to hormonal pathways. Current evidence suggests a protective role of Mi in BC development, particularly in case-control studies but not in cohort ones. The inconsistency among studies may be due to several reasons, including diagnostic criteria for Mi and the age gap between the development of these two diseases. Furthermore, recent research has challenged the concept of a net beneficial effect of Mi on BC, suggesting a more complex relationship between the two conditions. Many polymorphisms/mutations in hormone-related pathways are involved in at least one of the two conditions. The most promising evidence has emerged for a specific alteration in the estrogen receptor 1 gene (rs2228480). However, the possible specific mutation or polymorphism involved in this association has not yet been identified. Further studies with robust methodologies are needed to validate the protective role of Mi in BC and fully elucidate the precise nature of this causal relationship.

Profiling the Spectrum of Headache Disorders on 440 Breast Cancer Patients: Highlights on Clinical and Pathological Mechanisms.

Although widely studied, the association between migraines (M) and breast cancer (BC) risk remains evasive. In this prospective single-center study, 440 early or locally advanced BC patients were enrolled at IRCCS Humanitas Research Hospital. Clinical and demographical data were collected. Those who suffered from headaches were evaluated with the International Classification of Headache Disorders. M was found to be significantly more prevalent in BC patients: 56.1% versus an expected prevalence of 17% in the global population. M patients showed a higher risk of having stage II or III BC than stage I, which was more frequently found in the non-headache population. Interestingly, the frequency of headache attacks was positively correlated with estrogen (r = 0.11, p = 0.05) and progesterone (r = 0.15, p = 0.007) expression, especially in patients with migraine without aura. The higher the expression of hormone receptors in BC, the higher the headache frequency. Moreover, patients suffering from headaches showed an overall earlier onset of BC. Our findings challenge the idea of a net preventive role of M on BC, suggesting a rather complex interaction in which M mostly influences some BC subtypes and vice versa. Further multi-center studies with extended follow-up are needed.

Potential Role of Circulating miRNAs for Breast Cancer Management in the Neoadjuvant Setting: A Road to Pave.

Recently, circulating microRNAs (miRNAs) have emerged as potential non-invasive biomarkers for breast cancer (BC) management. In the context of BC patients undergoing neoadjuvant chemotherapy (NAC), the possibility of obtaining repeated, non-invasive biological samples from patients before, during, and after treatment is incredibly convenient and provides the opportunity to investigate circulating miRNAs as diagnostic, predictive, and prognostic tools. The present review aims to summarize major findings in this setting, thus highlighting their potential applicability in daily clinical practice and their possible limitations. In all the contexts (diagnostic, predictive, and prognostic), circulating miR-21-5p and miR-34a-5p have emerged as the most promising non-invasive biomarkers for BC patients undergoing NAC. Specifically, their high baseline level could discriminate between BC patients and healthy controls. On the other hand, in predictive and prognostic investigations, low circulating miR-21-5p and miR-34a-5p levels may identify patients with better outcomes, in terms of both treatment response and invasive disease-free survival. However, the findings in this field have been very heterogeneous. Indeed, pre-analytical and analytical variables, as well as factors related to patients, may explain the inconsistency among different study results. Thus, further clinical trials, with more precise patient inclusion criteria and more standardized methodological approaches, are definitely needed to better define the potential role of these promising non-invasive biomarkers.

The Relationship among Bowel [18]F-FDG PET Uptake, Pathological Complete Response, and Eating Habits in Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy.

Recently, the impact of patients' eating habits on both breast cancer (BC) management and inflammation have been proven. Here, we investigated whether inflammatory habits could correlate with baseline bowel [18]F-fluorodeoxyglucose (FDG) uptake and the latter, in turn, with pathological Complete Response (pCR) to neoadjuvant chemotherapy (NAC). We included stage I−III BC undergoing standard NAC at IRCCS Humanitas Research Hospital, Italy. Patients fulfilled a survey concerning eating/lifestyle behaviors and performed a staging [18]F-FDG positrone emission tomography/computed tomography (PET/CT). In the absence of data on the effects of individual foods, we aggregated drink and food intake for their known inflammatory properties. Data were recorded for 82 women (median age, 48). We found positive correlations between colon mean standardized uptake value (SUVmean) and pro-inflammatory drinks (alcohol and spirits; r = +0.33, p < 0.01) and foods (red and cured meats; r = +0.25, p = 0.04), and a significant negative correlation between rectum SUVmean and anti-inflammatory foods (fruits and vegetables; r = −0.23, p = 0.04). Furthermore, colon SUVmean was significantly lower in patients with pCR compared to non pCR (p = 0.02). Our study showed, for the first time, that patients' eating habits affected bowel [18]F-FDG uptake and that colon SUVmean correlated with pCR, suggesting that PET scan could be an instrument for identifying patients presenting unhealthy behaviors.

Plasma miRNA Levels for Predicting Therapeutic Response to Neoadjuvant Treatment in HER2-positive Breast Cancer: Results from the NeoALTTO Trial.

PURPOSE: To investigate the potential of circulating-miRNAs (ct-miRNA) as noninvasive biomarkers to predict the efficacy of single/dual HER2-targeted therapy in the NeoALTTO study. EXPERIMENTAL DESIGN: Patients with plasma samples at baseline (T0) and/or after 2 weeks (T1) of treatment were randomized into training (n = 183) and testing (n = 246) sets. RT-PCR-based high-throughput miRNA profiling was employed in the training set. After normalization, ct-miRNAs associated with pathologic complete response (pCR) were identified by univariate analysis. Multivariate logistic regression models were implemented to generate treatment-specific signatures at T0 and T1, which were evaluated by RT-PCR in the testing set. Event-free survival (EFS) according to ct-miRNA signatures was estimated by Kaplan-Meier method and Cox regression model. RESULTS: In the training set, starting from 51 ct-miRNAs associated with pCR, six signatures with statistically significant predictive capability in terms of area under the ROC curve (AUC) were identified. Four signatures were confirmed in the testing set: lapatinib at T0 and T1 [AUC 0.86; 95% confidence interval (CI), 0.73-0.98 and 0.71 (0.55-0.86)], respectively; trastuzumab at T1 (0.81; 0.70-0.92); lapatinib + trastuzumab at T1 (0.67; 0.51-0.83). These signatures were confirmed predictive after adjusting for known variables, including estrogen receptor status. ct-miRNA signatures failed to correlate with EFS. However, the levels of ct-miR-140-5p, included in the trastuzumab signature, were associated with EFS (HR 0.43; 95% CI, 0.22-0.84). CONCLUSIONS: ct-miRNAs discriminate patients with and without pCR after neoadjuvant lapatinib- and/or trastuzumab-based therapy. ct-miRNAs at week two could be valuable to identify patients responsive to trastuzumab, to avoid unnecessary combination with other anti-HER2 agents, and finally to assist deescalating treatment strategies.

Sodium 4-Carboxymethoxyimino-(4-HPR) a Novel Water-Soluble Derivative of 4-Oxo-4-HPR Endowed with In Vivo Anticancer Activity on Solid Tumors.

4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR), an active polar metabolite of the synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR), was shown to exert promising antitumor activity through at least two independent mechanisms of action. Specifically, differently from 4-HPR and other retinoids, 4-oxo-4-HPR targets microtubules and inhibits tubulin polymerization causing mitotic arrest and on the other hand, analogously to the parent drug, it induces apoptosis through the activation of a signaling cascade involving the generation of reactive oxygen species (ROS). However, the potential in vivo use of 4-oxo-4-HPR is impaired by its poor solubility. By chemical modification of 4-oxo-4-HPR, a new class of compounds with improved solubility and in vivo bioavailability was obtained. We demonstrated here that, among them, the most promising molecule, sodium 4-carboxymethoxyimino-(4-HPR), was endowed with in vitro antitumor efficacy and entirely preserved the double mechanism of action of the parent drug in cancer cells of different histotypes. In fact, the retinoid induced the activation of the apoptotic cascade related to the generation of ROS through endoplasmic reticulum stress response and upregulation of phospho c-Jun N-terminal kinases and PLAcental Bone morphogenetic protein, leading to cell death through caspase-3 cleavage. Otherwise, sodium 4-carboxymethoxyimino-(4-HPR) caused a marked mitotic arrest coupled with multipolar spindle formation and tubulin depolymerization. To assess the compound antitumor activity, in vivo experiments were performed in three mouse xenograft models (ovarian and breast cancers and mesothelioma). The in vivo results demonstrated that retinoid administration as single agent significantly increased the survival in ovarian cancer xenografts, induced a statistically significant decrease in tumor growth in breast cancer xenografts, and caused a 30% reduction in tumor growth in a mesothelioma mouse model. Even though further studies investigating sodium 4-carboxymethoxyimino-(4-HPR) toxicity and in vitro and in vivo activities in combination with other drugs are required, the double mechanism of action of the retinoid coupled with its in vivo antitumor efficacy and potential low toxicity suggest a promising therapeutic potential for the compound in different solid tumors.

Involvement of AF1q/MLLT11 in the progression of ovarian cancer.

The functional role of AF1q/MLLT11, an oncogenic factor involved in a translocation t(1;11)(q21;q23) responsible for acute myeloid leukaemia, has been investigated in hematological and solid malignancies and its expression was found to be linked to tumor progression and poor clinical outcome. In addition to its oncogenic function, AF1q has been shown to play a role in the onset of basal and drug-induced apoptosis in cancer cells of different histotypes, including ovarian cancer. Through in vitro, ex vivo, and in silico approaches, we demonstrated here that AF1q is also endowed with protumorigenic potential in ovarian cancer. In ovarian cancer cell lines, stable AF1q overexpression caused activation of epithelial-to-mesenchymal transition and increased motility/migratory/invasive abilities accompanied by gene expression changes mainly related to Wnt signaling and to signaling pathways involving in ERK/p38 activation. The potential role of AF1q in ovarian cancer progression was confirmed by immunohistochemical and in silico analyses performed in ovarian tumor specimens which revealed that the protein was absent in normal ovarian epithelium and became detectable when atypical proliferation was present. Moreover, AF1q was significantly lower in borderline ovarian tumors (i.e., tumors of low malignant potential without stromal invasion) than in invasive tumors, thus corroborating the association between high AF1q expression and increased migratory/invasive cell behavior and confirming its potential role in ovarian cancer progression. Our findings demonstrated, for the first time, that AF1q is endowed with protumorigenic activity in ovarian cancer, thus highlighting a dual behavior (i.e., protumorigenic and proapoptotic functions) of the protein in the malignancy.

Water-soluble derivatives of 4-oxo-N-(4-hydroxyphenyl) retinamide: synthesis and biological activity.

A novel series of 4-oxo-N-(4-hydroxyphenyl) retinamide (4-oxo-4-HPR) derivatives were synthesized with the aim of increasing the poor solubility of the parent compound in biological fluids, while maintaining the cytotoxic activity and the dual mechanism of action. The most promising compound 13a showed antiproliferative/apoptotic activity. The analysis of its mechanism of action revealed that it retained the particular characteristic of 4-oxo-4-HPR which is able to induce cell cycle arrest during the mitotic phase, coupled with the formation of aberrant mitotic spindles.

Proposal of supervised data analysis strategy of plasma miRNAs from hybridisation array data with an application to assess hemolysis-related deregulation.

BACKGROUND: Plasma miRNAs have the potential as cancer biomarkers but no consolidated guidelines for data mining in this field are available. The purpose of the study was to apply a supervised data analysis strategy in a context where prior knowledge is available, i.e., that of hemolysis-related miRNAs deregulation, so as to compare our results with existing evidence. RESULTS: We developed a structured strategy with innovative applications of existing bioinformatics methods for supervised analyses including: 1) the combination of two statistical (t- and Anderson-Darling) test results to detect miRNAs with significant fold change or general distributional differences in class comparison, which could reveal hidden differential biological processes worth to be considered for building predictive tools; 2) a bootstrap selection procedure together with machine learning techniques in class prediction to guarantee the transferability of results and explore the interconnections among the selected miRNAs, which is important for highlighting their inherent biological dependences. The strategy was applied to develop a classifier for discriminating between hemolyzed and not hemolyzed plasma samples, defined according to a recently published hemolysis score. We identified five miRNAs with increased expression in hemolyzed plasma samples (miR-486-5p, miR-92a, miR-451, miR-16, miR-22). CONCLUSIONS: We identified four miRNAs previously reported in the literature as hemolysis related together with a new one (miR-22).which needs further investigations. Our findings confirm the validity of the proposed strategy and, in parallel, the hemolysis score capability to be used as pre-analytic hemolysis detector. R codes for implementing the approaches are provided.

Circulating Biomarkers for Prediction of Treatment Response.

For cancer management, predicting and monitoring response to treatment and disease progression longitudinally is crucial due to changes in tumor biology and therapy responsiveness over time. However, solid tumors are usually sampled only at time of initial diagnosis, as obtaining tissue biopsies is an invasive procedures with associated risks. Thus, there is a pressing need for approaches able to serially detect function-related reliable biomarkers reflecting treatment response and/or disease progression through easy noninvasive procedures, amenable for longitudinal analysis of tumor molecular features. Recent evidences indicate that blood and other body fluids could replace invasive surgical biopsies and represent a "liquid biopsy" containing cells and nucleic acids released by primary and metastatic lesions, reflecting their biological features and allowing identification of clinically useful biomarkers and treatment-induced cancer adaption processes. The development of new and highly sensitive technologies that allow to detect and characterize circulating tumor cells, to identify cell-free nucleic acids (circulating tumor-associated microRNAs and cancer-specific mutations in circulating DNA) and to measure their eventual dynamic changes represents therefore a major achievement for disease monitoring. However, notwithstanding preliminary findings support the prognostic and/or predictive role of this new generation of biomarkers, there are a number of technical and biological caveats that still require additional studies to demonstrate and validate their clinical utility. A unique opportunity to rapidly assess the contribution of circulating tumor cells and cell-free nucleic acids to patient management and to personalized medicine could derive by their combined consideration in the neoadjuvant setting.

Challenges in using circulating miRNAs as cancer biomarkers.

In the last years, circulating miRNAs have emerged as a new class of promising cancer biomarkers. Independent studies have shown the feasibility of using these small RNAs as tools for the diagnosis and prognosis of different types of malignancies as well as for predicting and possibly monitoring treatment response. However, despite an initial enthusiasm for their possible clinical application, widespread inconsistencies have been observed among the studies, and miRNA-based tools still represent the object of research within clinical diagnostic or treatment protocols. The poor overlap of results could be explained, at least in part, by preanalytical and analytical variables and donor-related factors that could generate artefacts, impairing an accurate quantification of circulating miRNAs. In fact, critical issues are represented by nonuniform sample choice, handling, and processing, as well as by blood cell contamination in sample preparation and lack of consensus for data normalization. In this review, we address the potential technical biases and individual-related parameters that can influence circulating miRNA studies' outcome. The exciting potential of circulating miRNAs as cancer biomarkers could confer an important advance in the disease management, but their clinical significance might not be proven without a global consensus of procedures and standardized protocols for their accurate detection.

Implications of stemness-related signaling pathways in breast cancer response to therapy.

There is accumulating evidence that breast cancer may arise from a small subpopulation of transformed mammary stem/progenitor cells, termed breast cancer-initiating cells (BCICs), responsible for initiation and maintenance of cancer. BCICs have been identified in clinical specimens based on CD44(+)/CD24(-/low) membrane expression and/or enzymatic activity of aldehyde dehydrogenase 1 (ALDH1+), or isolated and in vitro propagated as non-adherent spheres. This cell population has been demonstrated to be able to recreate, when injected in mice even at very low concentrations, the same histopathological features of the tumor they were derived from and to escape from current therapeutic strategies. Alterations in genes involved in stemness-related pathways, such as Wnt, Notch, and Sonic Hedgehog, have been proven to play a role in breast cancer progression. Targeting these key elements represents an attractive option, with a solid rationale, although possible concerns may derive from the poor knowledge of tolerance and efficacy of inhibiting these mechanisms without inducing severe side effects. In addition, efforts to develop alternative BCIC-targeted therapies against stemness markers (CD44 and ALDH1) and molecules involved in regulating EMT- and HER2-related pathways, or able to reverse the multi-drug resistance phenotype, or to induce differentiation and to control cell survival pathways are currently ongoing and encouraging results from pre-clinical studies have already been obtained using in vitro and in vivo models.

OncomiR detection in circulating body fluids: a PDMS microdevice perspective.

There is an increasing interest in circulating microRNAs (miRNAs) as potential minimally invasive diagnostic biomarkers in oncology. Considerable efforts are being made in the development of lab-on-a-chip devices for biomedical applications to purify and detect miRNAs from biological fluids. Here, we report the development of an innovative polydimethylsiloxane (PDMS)-based parallel device whose internal surface can opportunely be functionalized with positively charged 3-aminopropyltriethoxysilane (APTES) alone or mixed with two different neutral poly(ethylene glycol) silanes (PEG-s). The differently functionalized internal surfaces of the PDMS chip were characterized with s-SDTB (sulfosuccinimidyl-4-o-(4,4-dimethoxytrityl) butyrate) and the portion of the surface able to adsorb a synthetic fluorescently labeled miRNA was determined. Interestingly, the adsorbed miRNA (both synthetic and cell supernatant-derived) was found mainly on the bottom surface of the chip and could be reverse transcribed into cDNA directly on the same PDMS chip used for its purification, saving hours with respect to the use of standard purification kits. We identified 0.1% APTES/0.9% PEG-silane as the most efficient PDMS functionalization to capture both synthetic and extracellular miRNA. Moreover, the amount of captured miRNA was increased by treating the cell supernatant with a commercially available lysis buffer for RNA extraction. We assessed that the available miRNA binding sites on the functionalized surface were efficiently saturated with only one incubation, shortening the time and greatly simplifying the protocol for miRNA purification from biological samples. Finally, the extracellular miRNA purification efficiency of the PDMS functionalized multichip determined via real-time quantitative polymerase chain reaction (RT-qPCR) was confirmed by droplet digital PCR (ddPCR) quantification. This work shows an innovative, rapid and easy to use microdevice for the purification and reverse transcription of circulating miRNAs, approaching the realization of diagnostic and prognostic oncomiR-based assays.

A lipemia-independent NanoDrop(®)-based score to identify hemolysis in plasma and serum samples.

BACKGROUND: The identification and management of hemolyzed samples are crucial issues in the development of new blood-based biomarkers. RESULTS: Using experiments of controlled hemolysis and lipemia and two plasma series from cancer patients, we developed and validated a lipemia-independent hemolysis score (HS). HS resulted strictly associated with the amount of lysed erythrocytes and with serum index measurement (reference method), highly reproducible, and able to identify as hemolyzed plasma/serum samples containing ≥6.1 mg/dl of free hemoglobin. CONCLUSION: We developed a simple, robust, sensitive, cost-effective, spectrophotometrically-based system to identify hemolyzed plasma/serum specimens. The procedure requires only 2 µl of sample, thus representing a useful tool for research studies and an essential pre-analytical quality control for an optimal biobanking of liquid biopsies.

Feasibility of circulating miRNA microarray analysis from archival plasma samples.

MicroRNAs have been found to be deregulated in several diseases and, due to their high stability in body fluids, represent promising noninvasively detectable biomarkers. However, numerous technical variables can affect accurate measurement of circulating miRNAs. Using a microarray-based method we assessed the: (i) adequate intra- and inter-array reproducibility of miRNA profiling; (ii) feasibility of using archival plasma samples stored for an extended period of time and available in limited amounts; (iii) good correlation between different batches; and (iv) time-dependent increase of background signals close to the chip expiration date.

AF1q: a novel mediator of basal and 4-HPR-induced apoptosis in ovarian cancer cells.

BACKGROUND: Fenretinide (4-HPR) is a synthetic retinoid that exhibits potent antitumor and chemopreventive activities against different malignancies, including ovarian tumors. We previously showed that in ovarian cancer cells, 4-HPR induces apoptosis through a signaling cascade starting from reactive oxygen species (ROS) generation and involving endoplasmic reticulum (ER) stress response, Jun N-terminal Kinase (JNK) activation, and induction of the proapoptotic PLAcental Bone morphogenetic protein (PLAB). Since recent studies have shown that the oncogene ALL1-fused from chromosome 1q (AF1q), a retinoic acid target gene, is implicated in apoptosis induction by several therapeutic agents, we investigated its possible involvement in the apoptosis induced by 4-HPR in ovarian cancer cells. METHODOLOGY/PRINCIPAL FINDINGS: Protein expression analysis, performed in ovarian cancer cells and extended to other histotypes (breast, neuroblastoma, and cervical), revealed that 4-HPR enhanced AF1q expression in cancer cells sensitive to the retinoid but not in resistant cells. Through gene silencing, AF1q was found functionally involved in 4-HPR-induced apoptosis in A2780, an ovarian cancer cell line highly sensitive to retinoid growth inhibitory and apoptotic effects. Inhibition of the signaling intermediates of the 4-HPR apoptotic cascade showed that AF1q upregulation was depended on prior generation of ROS, induction of ER stress response, JNK activation, and PLAB upmodulation. Finally, we found that direct overexpression of AF1q, in the absence of external stimuli, increased apoptosis in ovarian cancer cell lines. CONCLUSIONS/SIGNIFICANCE: The study expands the knowledge of the 4-HPR mechanism of action, which has not yet been completely elucidated, identifying AF1q as a novel mediator of retinoid anticancer activity. In addition, we demonstrate, for the first time, that AF1q plays a role in the onset of basal apoptosis in ovarian cancer cells, thus providing new information about the activity of this protein whose biologic functions are mostly unknown.