Francine Durocher

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in xenobiotic metabolism, immune regulation, and cellular homeostasis. AhR-ligand interactions have traditionally been investigated using radioligand binding assays and, more recently, by microscale thermophoresis (MST) applied to purified recombinant AhR-aryl hydrocarbon receptor nuclear translocator (AhR-ARNT) complexes. Although these approaches enable characterization of ligand binding, they require either radiolabeled ligands or purified recombinant receptor systems and therefore do not fully reproduce the molecular complexity surrounding the receptor in cells. Here we develop a lysate-based MST assay to characterize ligand-dependent AhR responses within a cell-derived molecular environment without requiring receptor purification. An AhR-green fluorescent protein (AhR-GFP) rescue cell line was generated in an AHR knockout background, allowing the fluorescently tagged AhR to serve simultaneously as the target protein and intrinsic fluorescent tracer. Functional validation confirmed ligand-induced nuclear translocation of AhR-GFP and cytochrome P450 family 1 subfamily A member 1 (CYP1A1) induction with sensitivity comparable to that of wild-type cells. MST measurements performed directly in cellular lysates revealed concentration-dependent responses to the AhR agonists 6-formylindolo[3,2-b]carbazole (FICZ), 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), β-naphthoflavone, and 1-hydroxyphenazine, as well as the antagonists CH223191 and BAY 2416964, enabling determination of apparent half-maximal effective concentration (EC_50app). Collectively, these findings establish a purification-free MST assay for probing ligand-dependent AhR responses within a complex cell-derived molecular environment.

Background/Objectives: Mammary adipose tissue functions as an active endocrine organ, potentially influencing breast carcinogenesis through metabolic and inflammatory mechanisms. This systematic review synthesized evidence on associations between mammary adipocyte size, obesity-related adipose tissue dysfunction, and breast cancer. Methods: A comprehensive literature search was conducted across MEDLINE, EMBASE, CENTRAL, CINAHL and Web of Science (January 2010–September 2025) for observational studies measuring mammary adipocyte size in human breast tissue. Two reviewers independently conducted screening following the Cochrane Review’s rigorous methodology, and bias assessment using the ROBINS-E (Risk Of Bias In Non-randomized Studies of Exposure) tool. Random-effects meta-analyses were performed for quantifiable outcomes, with heterogeneity assessed using the I² statistic. Results: Twenty-one studies were included in the systematic review. Meta-analyses indicated that mammary adipocyte diameter was positively correlated with body mass index (8 studies; n = 720; correlation coefficient (r) = 0.44, 95% CI: 0.29–0.56), crown-like structure (CLS) density (5 studies; n = 383; r = 0.45, 95% confidence interval (CI): 0.36–0.54), aromatase expression (3 studies; n = 333; r = 0.36, 95% CI: 0.05–0.61), and three studies compared adipocyte diameter between CLS-positive and CLS-negative tissue (n = 297; mean difference = 9.69 μm, 95% CI: 4.94–14.44). Conclusions: This review summarizes moderate positive correlations of mammary adipocyte size with systemic adiposity, local breast inflammation, and aromatase expression, supporting a potential role for mammary adipose tissue in obesity-related metabolic dysfunction. Future prospective studies with standardized measurement protocols and improved control for confounding variables are needed to strengthen causal inference and clinical applications.

Background: The aminosteroid RM-581 exhibits strong antiproliferative activity against cell lines from more than 10 solid tumor cancers, including some with poor prognoses. However, RM-581’s impact has never been assessed on leukemia. Methods: Cellular responses to RM-581 were evaluated using complementary approaches. Cytotoxicity was quantified using MTS-based viability assays and drug interactions were analyzed according to the Chou-Talalay method. Flow cytometry was employed to assess apoptosis, cell cycle distribution and effects on lymphocytes subpopulations. The transcriptomic profile was investigated by mRNA sequencing to identify differentially expressed genes and associated pathways. Results: Its evaluation on six leukemia cell lines (HL-60, THP-1, JURKAT, K-562, HG-3 and JVM-2) showed that RM-581 efficiently blocked the proliferation of leukemia cells. In healthy peripheral blood lymphocytes, flow cytometry revealed a significant impact on T lymphocytes (CD3+), particularly cytotoxic T cells (CD8+), at 50 µM. In THP-1 cells, an acute monocytic leukemia cell line, RM-581 triggered apoptosis and induced G0/G1 cell cycle arrest, which was confirmed with a transcriptomic analysis of enriched pathways. The role of RM-581 as an endoplasmic reticulum (ER) stress aggravator was confirmed by observing an increase in ER stress markers, such as BIP (GRP-78), CHOP and HERP, and in unfolded protein response (UPR) effectors (PERK, IRE1α and ATF6). Conclusions: This study demonstrates that RM-581 could be a promising candidate to treat leukemia, notably through the induction of ER-stress mediated apoptosis.

Background/Objectives: CEU-938, an innovative antimicrotubule prodrug bioactivated by cytochrome P450 1A1 (CYP1A1), represents a promising targeted alternative for cancer cells overexpressing this enzyme. To optimize its clinical utility and minimize off-target effects in breast cancer (BC) patients, this study aims to identify predictive biomarkers of CEU-938 efficacy. Methods: The antiproliferative activity of CEU-938 was assessed across a panel of 39 human breast cancer and non-tumorigenic cell lines. Differential expression analyses were subsequently performed to distinguish CEU-938-responsive from non-responsive cell lines using a threshold of 1000 nM. Candidate biomarkers identified through this approach were then validated by RT-qPCR and Western blot analyses. Results: CEU-938 demonstrated marked and selective antiproliferative activity across molecular subtypes of human breast cancer, with efficacy observed in approximately 40% of triple-negative breast cancer (TNBC), 70% of estrogen receptor-positive (ER⁺), and 80% of human epidermal growth factor receptor 2-positive (HER2⁺) breast cancer cell lines, while sparing non-tumorigenic human breast cells (MCF 10A, MCF-12A, 184B5). Differential expression analysis identified five candidate biomarkers associated with CEU-938 responsiveness, namely, FOXA1 (log2-fold change (LFC) = 3.1), RAB25 (LFC = 3.8), RHOV (LFC = 2.9), PRKCH (LFC = 1.6), and HDAC9 (LFC = −1.7). Among these, FOXA1 and RAB25 robustly validated by RT-qPCR and Western blot analyses, showing strong inverse correlations with CEU-938 sensitivity (Spearman correlation coefficients of −0.82 and −0.61, respectively, at the protein level). The predictive value of FOXA1 and RAB25 was further confirmed by Western blot analyses in two independent breast cell line models, the non-responsive MCF-12A and the responsive MDA-kb2. Conclusions: Collectively, these findings identify FOXA1 and RAB25 as robust predictive biomarkers of response to CEU-938. Notably, FOXA1 and RAB25 are strongly implicated in breast cancer biology, and FOXA1 has been directly linked to the aryl hydrocarbon receptor (AHR), the main regulator of CYP1A1. These results position CEU-938 as a strong precision-therapy candidate that combines target selectivity, a favorable toxicity profile, and biomarker-enabled patient stratification, with potential clinical benefit in ER⁺ and HER2⁺ enriched tumors, as well as a subset of TNBC.

Bazedoxifene (BZA), a third‐generation selective estrogen receptor modulator (SERM) approved for osteoporosis treatment, is attracting attention for drug repurposing, especially in cancer research. While designed primarily for estrogen receptors, BZA exhibits in vitro off‐target interactions that may explain novel therapeutic benefits or account for potential side effects. This review comprehensively examines both established and newly identified targets of BZA beyond estrogen receptors. To gather relevant data, we reviewed over 1500 articles selecting key studies proposing insights into BZA targets and mechanisms. This review details BZA’s roles in estrogen receptor signaling and its interactions with glycoprotein 130, elaborating on vital components of each signaling pathway. It also compiles its potential interactions with cannabinoid receptors, as well as BZA targets related to biotransformation, absorption/transport, DNA cycle, Sars‐CoV‐2, ferroptosis, ROS production, and cholesterol biosynthesis. For each target, we discuss evidence from computational studies, direct interaction assay, and functional testing. This work provides the most complete overview of BZA’s molecular mechanisms to date and suggests new avenues for future research and potential applications beyond osteoporosis.

Errors in mitosis can contribute to aneuploidy and CIN and play a pivotal role in cancer. So the identification of altered mitotic regulators can contribute to the understanding of the development and progression of breast cancer. In the present study we used an in vitro model of disease progression (the MCF10A series of BC continuum) and analyzed the errors of chromosome segregation that occur during the progression of the disease. Our findings indicated that the MCF10A series exhibited several abnormalities in chromosome segregation and its frequency increased with the disease progression. These errors included anaphase lagging chromosomes, micronuclei, nuclear buds, nucleoplasmic bridges, errors of chromosome alignment, and centrosome loss/amplification. Moreover, the presence of centrosome amplification disrupted the proper orientation of the mitotic spindle, resulting in the generation asymmetrical cell lines and aneuploidy in the MCF10A series. Hyper stable kinetochore-microtubule (kt-MT) attachment was also found in premalignant, preinvasive, and invasive cell lines, which can also explain the presence of errors of chromosome alignment. The human transcriptome array also determined possible negative regulators of ciliogenesis that can explain the mechanism of chromosome missegregation that lead to CIN found in the MCF10A series. Collectively, these findings highlight the importance of mitotic defects in the progression of breast cancer.

Breast cancer (BC) is a heterogenous disease classified into four molecular subtypes (Luminal A, Luminal B, HER2 and triple-negative (TNBC)) depending on the expression of the estrogen receptor (ER), the progesterone receptor (PR) and the human epidermal receptor 2 (HER2). The development of effective treatments for BC, especially TNBC, remains a challenge. Aminosteroid derivative RM-581 has previously shown an antiproliferative effect in multiple cancers in vitro and in vivo. In this study, we evaluated its effect in BC cell lines representative of BC molecular subtypes, including metastatic TNBC. We found that RM-581 has an antiproliferative effect on all BC molecular subtypes, especially on Luminal A and TNBC, in 2D and 3D cultures. The combination of RM-581 and trastuzumab or trastuzumab-emtansine enhanced the anticancer effect of each drug for HER2-positive BC cell lines, and the combination of RM-581 and taxanes (docetaxel or paclitaxel) improved the antiproliferative effect of RM-581 in TNBC and metastatic TNBC cell lines. We also confirmed that RM-581 is an endoplasmic reticulum (EnR)-stress aggravator by inducing an increase in EnR-stress-induced apoptosis markers such as BIP/GRP78 and CHOP and disrupting lipid homeostasis. This study demonstrates that RM-581 could be effective for the treatment of BC, especially TNBC.

A human transcriptome array on ERα-positive breast cancer continuum of risk identified Secreted Frizzled-Related Protein 1 (SFRP1) as decreased during breast cancer progression. In addition, SFRP1 was inversely associated with breast tissue age-related lobular involution, and differentially regulated in women with regard to their parity status and the presence of microcalcifications. The causal role of SFRP1 in breast carcinogenesis remains, nevertheless, not well understood. In this study, we characterized mammary epithelial cells from both nulliparous and multiparous mice in organoid culture ex vivo, in the presence of estradiol (E2) and/or hydroxyapatite microcalcifications (HA). Furthermore, we have modulated SFRP1 expression in breast cancer cell lines, including the MCF10A series, and investigated their tumoral properties. We observed that organoids obtained from multiparous mice were resistant to E2 treatment, while organoids obtained from nulliparous mice developed the luminal phenotype associated with a lower ratio between Sfrp1 and Esr1 expression. The decrease in SFRP1 expression in MCF10A and MCF10AT1 cell lines increased their tumorigenic properties in vitro. On the other hand, the overexpression of SFRP1 in MCF10DCIS, MCF10CA1a, and MCF7 reduced their aggressiveness. Our results support the hypothesis that a lack of SFRP1 could have a causal role in early breast carcinogenesis.

Loss of mitotic regulation is commonly observed in cancer and is a major cause of whole-chromosome aneuploidy. The identification of genes that play a role in the proper progression of mitosis can help us to understand the development and evolution of this disease. Here, we generated a list of proteins implicated in mitosis that we used to probe a patient-derived breast cancer (BC) continuum gene-expression dataset generated by our group by human transcriptome analysis of breast lesions of varying aggressiveness (from normal to invasive). We identified cytoskeleton-associated protein 2 (CKAP2) as an important mitotic regulator in invasive BC. The results showed that CKAP2 is overexpressed in invasive BC tumors when compared with normal tissues, and highly expressed in all BC subtypes. Higher expression of CKAP2 is also related to a worse prognosis in overall survival and relapse-free survival in estrogen receptor (ER)-positive and human epidermal growth factor receptor type 2 (HER2)-negative BC patients. Knockdown of CKAP2 in SKBR3 cells impaired cell proliferation and cell migration and reduced aggregate formation in a 3D culture. Our results show the important role of CKAP2 in BC tumorigenesis, and its potential utility as a prognostic marker in BC.

Cannabinoid receptors (CBR) are potential therapeutic targets for breast cancer. However, the role of CBR in breast cancer survival remains poorly understood. Data from a prospective cohort of 522 women diagnosed with invasive breast cancer between 2010 and 2012 were analysed. Clinical and pathological features were retrieved from electronic medical records. CBR expression was measured by immunohistochemistry. Adjusted partial Spearman correlations and multivariate Cox models were used to estimate associations with breast cancer prognostic factors and survival, respectively. The median follow-up was 92.0 months (range 7.0–114.0). CBR expression was heterogenous in tumours. Cytoplasmic expression of CBR1 was positively correlated with lymph node invasion (r_s = 0.110; p = 0.0155) and positive status of the human epidermal growth factor receptor 2 (HER2) (r_s = 0.168; p = 0.0002), while nuclear CBR2 was negatively correlated with grade (r_s = −0.171; p = 0.0002) and positively correlated with oestrogen receptor and progesterone receptor-positive status (r_s = 0.173; p = 0.0002 and r_s = 0.121; p = 0.0084, respectively). High cytoplasmic expression of CBR2 was associated, with 13% higher locoregional and distant recurrences (HR = 1.13 [0.97–1.33]), though this association did not reach statistical significance. Although the few events occurring during follow-up may have limited the detection of significant associations, these results indicate that CBR expression in breast cancer deserves further investigation.