Breast Cancer Cells Research Articles

Ten-Step Total Synthesis of (±)-Phaeocaulisin A Enabled by Cyclopropanol Ring-Opening Carbonylation.

We report an efficient total synthesis of (±)-phaeocaulisin A, a guaianolide sesquiterpene natural product possessing a complex tetracyclic skeleton embedded with an oxaspirolactone and a fused bicyclic lactone, four oxygen-containing stereocenters, and an 8-oxabicyclo[3.2.1]octane core. Our synthesis features a novel palladium-catalyzed cyclopropanol ring-opening carbonylation to access a key γ-ketoester, a chemo- and stereoselective aldol cyclization to form the seven-membered carbocycle, and a cascade ketalization-lactonization to construct the desired tetracyclic skeleton. With these strategically important C-C and C-O bond formation transformations, a 10-step total synthesis of (±)-phaeocaulisin A was achieved. We further developed the cyclopropanol ring-opening carbonylation chemistry to provide an alternative approach to prepare γ-ketoesters. Biologically, the penultimate intermediate with an α-methylene γ-butyrolactone moiety was identified as a promising lead compound with anticancer proliferation activity against a panel of triple-negative or HER2+ breast cancer cell lines.

Phase Ib clinical and pharmacodynamic study of the TIE2 kinase inhibitor rebastinib with paclitaxel or eribulin in HER2-negative metastatic breast cancer.

Breast cancer cells disseminate to distant sites via Tumor Microenvironment of Metastasis (TMEM) doorways. The TIE2 inhibitor rebastinib blocks TMEM doorway function in the PyMT mouse model of breast cancer. We aimed to assess the safety and pharmacodynamics of rebastinib plus paclitaxel or eribulin in patients with HER2-negative metastatic breast cancer (MBC). This phase Ib trial enrolled 27 patients with MBC who received 50 mg or 100 mg of rebastinib PO BID in combination with weekly paclitaxel 80 mg/m2 (if ≤ 2 prior non-taxane regimens) or eribulin 1.4 mg/m2 on days 1 & 8 (if ≥ 1 prior regimen). Safety, tolerability and pharmacodynamic parameters indicating TIE2 kinase inhibition and TMEM doorway function were evaluated. No dose-limiting toxicities in cycle 1 or 2 were observed among the first 12 patients at either rebastinib dose level. The most common treatment-emergent adverse events (AEs) were anemia (85%), fatigue (78%), anorexia (67%), leukopenia (67%), increased alanine aminotransferase (59%), hyperglycemia (56%), nausea (52%), and neutropenia (52%). AEs attributed to rebastinib include muscular weakness and myalgias. Intraocular pressure increased at the 100 mg rebastinib dose level, whereas angiopoietin-2 levels increased at both dose levels, providing pharmacodynamic evidence for TIE2 blockade. Circulating tumor cells decreased significantly with the combined treatment. Objective response occurred in 5/23 (22%) evaluable patients. In patients with MBC, the recommended phase 2 dose of rebastinib associated with pharmacodynamic evidence of TIE2 inhibition is either 50 or 100 mg PO BID in combination with paclitaxel or eribulin.

EHD1 promotes breast cancer metastasis through upregulating HIF2a expression via activating mTOR pathway.

The multistep dynamic process of metastasis is the primary cause of breast cancer deaths. C-terminal Eps15-homology domain-containing protein 1 (EHD1), a translocator associated with endocytic recycling, has been implicated in various oncogenic processes. However, the precise molecular mechanisms of EHD1-induced breast cancer metastases remain largely unexplored. Here we found that the upregulation of EHD1 in breast cancer was positively associated with distant lymph node metastasis in patients. Meanwhile, EHD1 promoted epithelial-mesenchymal transition (EMT), invasion, and metastasis of breast cancer cells in both two-dimensional (2D) and three-dimensional (3D) culture models invitro, as well as invivo. Remarkably, EHD1 can activate the AKT-mTOR pathway to upregulate the protein expression of hypoxia-inducible factor 2α (HIF2α) under normoxic conditions and subsequently enhance the invasive and metastatic breast cancer. Our findings indicated EHD1 as a new regulator of HIF2α and a potential therapeutic target for inhibiting breast cancer metastasis.

UPLC-QToF-MS/MS screening and characterization of Symphorema polyandrum Wight and in vitro assessment of its antioxidant, anticancer, and anti-inflammatory potential.

Symphorema polyandrum belongs to the Lamiaceae family and is locally known as Badichang or mahasindhu. In this study, we performed Soxhlet extraction to prepare methanolic and hydromethanolic extracts, followed by quantification of their total phenolic content and total flavonoid content. Qualitative analysis of both the extracts was conducted to determine the presence of different phytochemicals. In addition, we aimed to identify the important phytochemical constituents in the methanolic extracts of S. polyandrum (SPM) using ultra-performance liquid chromatography hyphenated with high-resolution mass spectrometry (UPLC-ESI-QTOF-MSE). Furthermore, this study investigated the antioxidant, anticancer and anti-inflammatory properties of SPM and its safety profile in the normal fibroblastcell line L929. A colony proliferation assay and a Griess assay were performed to evaluate the effects of SPM on colony formation and nitric oxide (NO) production. A total of 13 important phytochemicals were identified and reported. The methanolic extract of SPM demonstrated significant antioxidant activity. SPM also showed substantial antiproliferative activity on MDA-MB-231 triple-negative breast cancer cells, with an IC50 value of 45.53± 1.63µg/ml, and also reduced the survival of these cancer cells by promoting nuclear fragmentation and condensation without causing harm to normal cells. SPM inhibits the colony formation and reduces the nitric oxide (NO) production. The anti-inflammatory potential of SPM was assessed utilizing the murine alveolar macrophages (J774.A.1) as an in vitro model, and SPM effectively lowered the levels of proinflammatory cytokines such as TNF-α and IL-6. These findings emphasized the antiproliferative potential of SPM to cancer cells, along with its anti-inflammatory, and antioxidant capabilities, indicating the therapeutic efficacy of this medicinal plant.

Combinatorial effects of cannabinoid receptor 1 and 2 agonists on characteristics and proteomic alteration in MDA-MB-231 breast cancer cells.

Breast cancer is the most common cancer diagnosed in women worldwide. However, the effective treatment for breast cancer progression is still being sought. The activation of cannabinoid receptor (CB) has been shown to negatively affect breast cancer cell survival. Our previous study also reported that breast cancer cells responded to various combinations of CB1 and CB2 agonists differently. Nonetheless, the mechanism underlying this effect and whether this phenomenon can be seen in other cancer characteristics remain unknown. Therefore, this study aims to further elucidate the effects of highly selective CB agonists and their combination on triple-negative breast cancer proliferation, cell cycle progression, invasion, lamellipodia formation as well as proteomic profile of MDA-MB-231 breast cancer cells. The presence of CB agonists, specifically a 2:1 (ACEA: GW405833) combination, prominently inhibited colony formation and induced the S-phase cell cycle arrest in MDA-MB-231 cells. Furthermore, cell invasion ability and lamellipodia formation of MDA-MB-231 were also attenuated by the exposure of CB agonists and their 2:1 combination ratio. Our proteomic analysis revealed proteomic profile alteration in MDA-MB-231 upon CB exposure that potentially led to breast cancer suppression, such as ZPR1/SHC1/MAPK-mediated cell proliferation and AXL/VAV2/RAC1-mediated cell motility pathways. Our findings showed that selective CB agonists and their combination suppressed breast cancer characteristics in MDA-MB-231 cells. The exposure of CB agonists also altered the proteomic profile of MDA-MB-231, which could lead to cell proliferation and motility suppression.

Biochanin A Induces Apoptosis in MCF-7 Breast Cancer Cells through Mitochondrial Pathway and Pi3K/AKT Inhibition.

The study aimed to investigate the molecular mechanisms by which Biochanin A inhibits proliferation and induces apoptosis in breast cancer cells. Cultured MCF-7 cells were divided into four groups: Group 1-control, while Groups 2, 3, and 4 were treated with Biochanin A at different concentrations. After treatment, the cells were monitored, and morphological changes were examined after 24 h of incubation. The results showed that Biochanin A inhibited cell proliferation, increased reactive oxygen species formation, and induced apoptosis. Furthermore, western blot analysis revealed that Biochanin A-treated cells exhibited lower expression of the Bcl-2, p-PI3K and p-AKT and higher expression of proapoptotic genes, including Bax, Caspase-3, Caspase-9, and cytochrome c. Additionally, PCR array analysis indicated that the gene expression levels of cyclin D3, cyclin B1, CDK1, CDK2, and CDK4 were downregulated, while the expression levels of p21, p27, and p53 were significantly upregulated. These results suggest that Biochanin A can suppress the viability of breast cancer cells and induce apoptosis via the mitochondrial pathway, along with inhibition of the Pi3K/Akt signaling pathway and modulation of cell cycle markers.

TMIC-01. TARGETABLE GENE EXPRESSION CHANGES MEDIATE EXTRAVASATION OF BREAST CANCER CELLS FROM THE CIRCULATION AND LOCAL PROLIFERATION IN THE BRAIN

Abstract As breast cancer migrates into the brain, it acquires distinct genomic, immunologic and phenotypic changes through interactions with the local microenvironment. We sought to determine how targetable gene expression changes mediate breast cancer extravasation into and proliferation within the brain. We created a brain metastatic cell line (“brain-seeking”) via serial intracardiac injection of mCherry+ 4T1 breast cancer cells in Balb/c mice and flow cytometry isolation of micrometastases. We conducted in vitro and in-vivo studies to uncover immunological and genetic differences between primary breast cancer and brain metastases. In culture, we observed significant upregulation in adhesion (p=0.01) and invasion (p=0.0004) along with upregulation of adhesion-promoting genes such as Sdc3, Serpine2 or ECM1 in brain-seeking cells. We observed significant differences in survival of Balb/c mice injected intracranially with brain-seeking cells vs. breast cancer cells (p=0.04). In the mammary fat pad (MFP), parental 4T1 cells caused increased mortality vs. brain-seeking cells (p=0.003). This rejection of brain-seeking 4T1 cells in the MFP could be due to prior adaptation to the brain microenvironment, while rejection of parental 4T1 cells in the brain could be due to lacking said adaptations. Consistent with this finding, of 20,382 analyzed genes in both cell lines, 108 related to immune regulation were significantly upregulated in brain-seeking cells including Cxcl1, Dusp1, C3. Flow cytometry showed increased cytotoxic and helper T cells in intracranially injected parental vs. brain-seeking cells (p <0.001). In the MFP, however, 4T1 parental cells displayed CD3+ T cell depletion and an increased number of neutrophils (p <0.05) while the “brain-seeking cells” showed increased numbers of CD3+ and CD4+ cells (p <0.01) and macrophages (p<0.05). This suggests that brain metastases evolve from their primary tumor through adhesive and invasive adaptations promoting extravasation, along with unique immunological adaptations that allow their proliferation free of immune surveillance in the brain microenvironment.

DDDR-29. MATRIX STIFFNESS INDUCED PHENOTYPE IN BRAIN METASTATIC BREAST CANCER CELLS DETERMINES RESPONSE TO THERAPY

Abstract Breast cancer is the most prevalent form of cancer, representing 12.5% of all cancer cases diagnosed worldwide. Breast cancer cells can metastasize to distant organs (i.e., brain) and remain dormant for extended periods of time. This aspect makes it very difficult to treat these cells as they exhibit reduced growth as well as resistance to therapy. Despite advances in our understanding of breast cancer metastasis, the specific mechanisms that enable dormant cancer cells to resist therapeutics, particularly in brain metastatic breast cancer (BMBC), remain unclear. Herein, we employed brain tissue mimetic hyaluronic acid (HA) hydrogels of varying stiffness (i.e., ~0.4 kPa vs. ~4.5 kPa) to investigate the response to chemo or targeted therapy in dormant versus proliferative BMBC cells. It was revealed that BMBC cells grown on soft HA hydrogels (~0.4 kPa) displayed a non-proliferative (i.e., dormant) phenotype and exhibited resistance to Paclitaxel (PTX) or Lapatinib (LAP). However, BMBC cells grown on stiff HA hydrogels (~4.5 kPa) displayed a proliferative phenotype and sensitivity to PTX or LAP. Furthermore, we found that resistance to therapy was due to the enhanced expression of the serum/glucocorticoid regulated kinase 1 (SGK1) gene, mediated, in part, via the p38 mitogen-activated protein kinase (MAPK) pathway. Consequently, SGK1 inhibition using a SGK inhibitor in BMBC cells cultured on soft HA hydrogels resulted in a dormant-to-proliferative switch as well as response to PTX or LAP. In sum, our study demonstrated that matrix stiffness plays a major role in the dormancy-associated therapy response, mediated, in part, via the p38/SGK1 pathway.

DDEL-14. NOVEL BLOOD BRAIN BARRIER PENETRATING BI-SPECIFIC ANTIBODY THERAPY FOR BREAST CANCER BRAIN METASTASIS

Abstract Breast cancer is the second leading cause for brain metastasis after lung cancer. While Her2 +ve tumors respond to her2 targeted antibody therapy, these antibodies are unable to cross the blood brain tumor barrier to effectively target metastases hidden in the ‘CNS sanctuary’. To overcome this hurdle, we have modified Her2 targeting Herceptin to create a CNS penetrating antibody that is transported in a unidirectional fashion into brain tumors. The modified BBB penetrating Herceptin is processed by the tumor specific microenvironment after crossing the BBB, such that the modified antibody is then trapped in the tumor ECM. This has the potential to increase tumor retention and reduce systemic toxicity. The BBB penetrant anti Her2 antibody (Herceptin) binds to Her2 on breast cancer cells and suppresses activation of Her2 signaling in vitro. Western blot analysis shows reduction of Her2 phosphorylation and down stream signaling with both unmodified and BBB modified Herceptin. This permits recruitment and retention of the antibody into the CNS tumors. Using fluorescence imaging and IHC of intracranial tumors we have validated that the BBB modified Herceptin is localized into intracranial tumors. We are currently evaluating the safety and therapeutic benefit of this approach in mice bearing intracranial tumors.

TMIC-58. LEVERAGING VIRO-IMMUNOTHERAPY BY TARGETING IGF2-IGF1R SIGNALING

Abstract While an FDA-approved oncolytic herpes simplex-1 virus (oHSV) has shown therapeutic promise with superior safety, accumulating clinical data revealed that its therapeutic efficacy is observed in a small subset of patients. Here, we show that NFκB-mediated Insulin-like Growth Factor 2 (IGF2)/Insulin-like Growth Factor-1 Receptor (IGF1R) signaling pathway as a key modulator for oHSV therapy-mediated tumor resistance. RNA sequencing on the oHSV-infected primary glioblastoma (GBM) and breast cancer (BC) cells identified IGF2 as one of the top 10 upregulated secretomes. Transcriptomic analysis also revealed significant upregulation/enrichment of genes related to IGF2-IGF1R-MAPK pathway in oHSV-treated tumor cells. Infection with oHSV in GBM and BC cells up-regulated IGF2 transcription via direct binding of NFκB in the IGF2 promoter 3. Compromising the IGF2-IGF1R signaling pathway using IGF2 neutralizing antibody significantly increased oHSV-mediated tumor cell killing in vitro and mice survival in vivo. To circumvent this and promptly translate our findings in clinical settings, we have developed a novel oHSV, oHSV-D11mt, by incorporating modified IGF2R domain 11 into the parental oHSV genome to function as IGF2 decoy receptor as a single-agent modality. oHSV-D11mt specifically bind to IGF2 not IGF1, blocks oHSV-induced IGF2-IGF1R signaling, increases tumor cell killing, decreases oHSV-induced neutrophils/PMN-MDSCs infiltration, immune suppressive/proangiogenic cytokine secretion, and increases CD8+ cytotoxic T lymphocytes (CTLs) activation, resulting in increased virus propagation and mice survival. These findings suggest that IGF2-IGF1R signaling is a novel target to overcome oHSV therapy resistance and oHSV-D11mt could be used for improved viro-immunotherapy.

TMIC-48. THREE DIMENSIONAL CANCER CELL-MONOCYTE CO-CULTURE SPHEROIDS RECAPITULATE IMMUNOSUPPRESSIVE AND PRO-TUMORIGENIC MICROENVIRONMENTS IN BRAIN METASTATIC BREAST CANCER

Abstract Brain metastasis occurs in 15 % of breast cancer patients and is one of the major causes of breast cancer related morbidity. Brain metastatic breast cancer (BMBC) microenvironment is a heterogeneous niche of cellular and acellular components of which the innate immune cells, microglia, and macrophages, comprise the major fraction. However, the role of these innate immune cells in the tumor microenvironment (TME) in mediating cancer progression and response to therapy is not well understood. To address this need, herein, we developed three dimensional (3D) co-culture spheroids using brain metastatic triple negative breast cancer (TNBC) cell line MDA-MB-231Br or patient derived brain metastatic TNBC cell line F2-7 with THP1 monocytes. Under co-culture conditions MDA-MB-231Br co-culture spheroids assumed highly protrusive morphology with enhanced mesenchymal and proliferative characteristics. Additionally, phenotypic determination of cocultured macrophages revealed elevated levels of markers associated with alternatively activated macrophages i.e. CD163, CD206, and c-Myc. Furthermore, we found that under coculture conditions immunosuppressive and evasive markers PD1, PDL1, CD47 and CD24 were significantly upregulated. Similarly, F2-7 and monocyte cocultures also led to an immunosuppressive environment with elevated levels of M2 type markers and associated anti-inflammatory cytokines. We further found that the presence of M2 type macrophages in the microenvironment of BMBC spheroids led to acquired resistance against Paclitaxel, a clinically relevant chemotherapeutic drug against BMBC. In sum, in our coculture conditions, brain metastatic TNBC cells polarized monocytes into immunosuppressive and pro-tumorigenic tumor associated macrophages leading to a pro-tumoral microenvironment. Thus, 3D co-culture spheroids of BMBC cells and monocytes can serve as robust platform for studying cancer cell and innate immune cell interactions occurring in the BMBC environment.

EXTH-05. STEM CELL-BASED THERAPEUTIC STRATEGY FOR LEPTOMENINGEAL METASTASIS OF SOLID CANCERS

Abstract Leptomeningeal dissemination (LMD), known as carcinomatous meningitis, presents an extremely poor prognosis with an average life expectancy of 4-6 weeks. Although whole brain/spinal cord irradiation and intrathecal injection of anticancer drugs are sometimes performed, their effects are limited, so new therapeutic strategies for LMD are urgently needed. Based on the following greatest advantage of stem cell (SC) based therapeutic strategy for LMD, we tested its efficacy in LMD of various solid cancers; LMD is a condition in which cancer cells spread within a huge single space without separation, and the SCs with the characteristic of cancer tropism and chemotaxis can reach cancer cells easily; Repetitive intrathecal injection of therapeutic agents for patients is an invasive and risky procedure, but SCs can continuously secrete/release therapeutic agents into the cerebrospinal fluid after a few injections and increase local concentration of therapeutic substances. We have shown that treatment using engineered SCs may be effective treatment option against LMD from breast cancer, lung cancer, and malignant melanoma. Specifically, we reported that engineered allogeneic SCs which simultaneously targeting epidermal growth factor receptor (EGFR) and death receptor (DR) has efficacy for LMD of triple negative breast cancer and non-small cell lung cancer. Also, we reported that SCs releasing oncolytic herpes virus, granulocyte-macrophage colony-stimulating factor (GM-CSF), and single-chain variable region fragments (scFv) against programmed death receptor-1 (PD-1) has efficacy in LMD of malignant melanoma. Overall, we believe that SC therapy has the potential to become a new therapeutic option for LMD in the future.

M5C related-regulator-mediated methylation modification patterns and prognostic significance in breast cancer

5-Methylcytosine (m5C) is closely associated with cancer. However, the role of m5C in breast cancer(BC)remains unclear. This study combined single-cell RNA sequencing (scRNA-Seq) and transcriptomics datasets to screen m5C regulators associated with BC progression and analyze their clinical values. Firstly, This study elucidates the mechanisms of the m5C landscape and the specific roles of m5C regulators in BC patients. we found that the dysregulation of m5C regulators with m5Cscore play the essential role of the carcinogenesis and progression in epithelial cells and myeloid cells of BC at single cell level. External validation was conducted using an independent scRNA-Seq datasets. Then, three distinct m5C modification patterns were identified by transcriptomics datasets. Based on the m5C differentially expressed regulators, the m5Cscore was constructed, and used to divide patients with BC into high and low m5Cscore groups. Patients with a high m5Cscore had more abundant immune cell infiltration, stronger antitumor immunity, and better prognoses. Finally, Quantitative real-time (PCR) and immunohistochemistry were used for the in vitro experimental validation, which had extensive prognostic value. In this study, we aimed to assess the expression of m5C regulators involved in BC and investigate their correlation with the tumor microenvironment, clinicopathological characteristics, and prognosis of BC. The m5C regulators could be used to effectively assess the cell specific regulation prognosis of patients with BC and develop more effective immunotherapy strategies.

Retraction: miR-219-5p targets TBXT and inhibits breast cancer cell EMT and cell migration and invasion.

Retraction: miR-219-5p targets TBXT and inhibits breast cancer cell EMT and cell migration and invasion.

Insight on novel sulfamoylphenyl pyrazole derivatives as anticancer carbonic anhydrase inhibitors.

As another part continue for our previous study, variable substituted pyrazoles bearing sulfamoylphenyl moiety were synthesized and screened against two cancer related human carbonic anhydrase (hCA) isoforms and acetazolamide (AAZ) used as a reference standard. Some compounds as 4e and 6c manifested a promising inhibitory activity against both isoforms (KI = 0.072, 0.081 and 0.073, 0.095 µM), respectively. While others as 4a and 5e showed inhibitory activity against hCA IX only (KI = 0.062, 0.04 µM) or against hCA XII only as compound 5b (KI = 0.106 µM) compared to AAZ (KI = 0.065, 0.046 µM), respectively. Also, the anticancer efficacy against 60 cancer cell lines for the target compounds was assessed, and the most promising ones were 4d and 5a-d. Further investigation of the anticancer activity of 5b on MCF-7 cell line explored (IC50 = 5.21 µM) compared to doxorubicin (IC50 = 11.58 µM). Moreover, compound 5b was exposed to cell cycle analysis and apoptotic assay on MCF-7 breast cancer cell line under both normal and hypoxic conditions at its IC50 concentration with elevation of total apoptotic cells % in MCF-7 relative to the control cells; respectively. Finally, molecular modelling simulations rationalized the in vitro testing results.

Enhancing antitumor activity of herceptin in HER2-positive breast cancer cells: a novel DNMT-1 inhibitor approach.

HER2 antagonists remain the cornerstone of therapy for patients with HER2-positive breast cancer. This study introduces a novel small-molecule inhibitor of DNA methyltransferase 1 (DNMT-1), referred to as DI-1, designed to synergize with HER2 antagonists in treating HER2-positive breast cancer cells. Clinical data reveal a negative correlation between DNMT-1 expression and PTEN levels, and a positive correlation with the methylation rates of PTEN's promoter. In experiments with SKBR3 and BT474 cells, DI-1 effectively reduced the methylation of PTEN's promoter region, thereby upregulating PTEN expression. This upregulation, in turn, enhanced the cells' sensitivity to HER2 antagonists, indicating that DI-1's mechanism involves inhibiting DNMT-1's recruitment to PTEN's promoter region. Consequently, by increasing PTEN expression, DI-1 amplifies the sensitivity of HER2-positive breast cancer cells to treatment, suggesting its potential as a promising therapeutic strategy in this context.

Hedgehog Pathway Is a Regulator of Stemness in HER2-Positive Trastuzumab-Resistant Breast Cancer

HER2 overexpression occurs in 20–30% of breast cancers and is associated with poor prognosis. Trastuzumab is a standard treatment for HER2-positive breast cancer; however, resistance develops in approximately 50% of patients within a year. The Hedgehog (Hh) signalling pathway, known for its role in maintaining stemness in various cancers, may contribute to trastuzumab resistance in HER2-positive breast cancer. This study aimed to investigate the role of Hedgehog signalling in maintaining stemness and contributing to trastuzumab resistance in HER2-positive breast cancer cell lines. Trastuzumab-resistant HER2-positive breast cancer cell lines, SKBR3 and HCC1954, were developed through continuous trastuzumab exposure. Cells were treated with GANT61 (Hh inhibitor, IC50:10 µM) or SAG21K (Hh activator, IC50:100 nM) for 24 h to evaluate the Hedgehog signalling response. Stemness marker expression (Nanog, Sox2, Bmi1, Oct4) was measured using qRT-PCR. The combination index (CI) of GANT61 with trastuzumab was calculated using CompuSyn software(version 1.0) to identify synergistic doses (CI < 1). The synergistic concentrations’ impact on stemness markers was assessed. Data were analysed using two-way ANOVA and Tukey’s post hoc test (p < 0.05). Trastuzumab-resistant cells exhibited increased Hedgehog signalling activity. Treatment with GANT61 significantly downregulated stemness marker expression, while SAG21K treatment led to their upregulation in both SKBR3-R and HCC1954-R cells. The combination of GANT61 and trastuzumab demonstrated a synergistic effect, markedly reducing the expression of stemness markers. These findings indicate that Hedgehog signalling plays a pivotal role in maintaining stemness in trastuzumab-resistant cells, and that the inhibition of this pathway may prevent tumour progression. Hedgehog signalling is crucial in regulating stemness in trastuzumab-resistant HER2-positive breast cancer. Targeting this pathway could overcome resistance and enhance trastuzumab efficacy. Further studies should explore the clinical potential of Hedgehog inhibitors in combination therapies.

Harnessing curcumin and nanotechnology for enhanced treatment of breast cancer bone metastasis.

Breast cancer (BC) bone metastasis poses a significant clinical challenge due to its impact on patient prognosis and quality of life. Curcumin (CUR), a natural polyphenol compound found in turmeric, has shown potential in cancer therapy due to its anti-inflammatory, antioxidant, and anticancer properties. However, its metabolic instability and hydrophobicity have hindered its clinical applications, leading to a short plasma half-life, poor absorption, and low bioavailability. To enhance the drug-like properties of CUR, nanotechnology-based delivery strategies have been employed, utilizing polymeric, lipidic, and inorganic nanoparticles (NPs). These approaches have effectively overcome CUR's inherent limitations by enhancing its stability and cellular bioavailability both in vitro and in vivo. Moreover, targeting molecules with high selectivity towards bone metastasized breast cancer cells can be used for site specific delivery of curcumin. Alendronate (ALN), a bone-seeking bisphosphonate, is one such moiety with high selectivity towards bone and thus can be effectively used for targeted delivery of curcumin loaded nanocarriers. This review will detail the process of bone metastasis in BC, elucidate the mechanism of action of CUR, and assess the efficacy of nanotechnology-based strategies for CUR delivery. Specifically, it will focus on how these strategies enhance CUR's stability and improve targeted delivery approaches in the treatment of BC bone metastasis.

Discovery of the First-in-Class Dual-Target ROCK/HDAC Inhibitor with Potent Antitumor Efficacy in Vivo That Trigger Antitumor Immunity.

Triple-negative breast cancer (TNBC) represents a highly aggressive and heterogeneous malignancy. Currently, multitarget drug approaches present a promising therapeutic approach for TNBC. Utilizing a combinatorial chemistry strategy to construct a virtual screening database, dual ROCK/HDAC-targeting benzothiophene compounds were identified. Notably, compound 10h effectively inhibits ROCK1/2 and HDAC1/2/3/6/8 while demonstrating potent antiproliferative activity against breast cancer cells. In an orthotopic mouse model of breast cancer, 10h significantly suppressed tumor growth without apparent toxicity. Importantly, 10h induced immunogenic cell death (ICD), promoted dendritic cells (DCs) maturation, and activated T cells, thereby initiating antitumor immunity. In conclusion, compound 10h is a novel dual-target ROCK/HDAC inhibitor that represents a promising treatment strategy for TNBC.

P21Waf1/Cip1 Is a Novel Downstream Target of 40S Ribosomal S6 Kinase 2

Background/Objectives: The ribosomal S6 kinase 2 (S6K2) acts downstream of the mechanistic target of rapamycin complex 1 and is a homolog of S6K1 but little is known about its downstream effectors. The objective of this study was to use an unbiased transcriptome profiling to uncover how S6K2 promotes breast cancer cell survival. Methods: RNA-Seq analysis was performed to identify novel S6K2 targets. Cells were transfected with siRNAs or plasmids containing genes of interest. Western blot analyses were performed to quantify total and phosphorylated proteins. Apoptosis was monitored by treating cells with different concentrations of doxorubicin. Results: Silencing of S6K2, but not S6K1, decreased p21 in MCF-7 and T47D breast cancer cells. Knockdown of Akt1 but not Akt2 decreased p21 in MCF-7 cells whereas both Akt1 and Akt2 knockdown attenuated p21 in T47D cells. While Akt1 overexpression enhanced p21 and partially reversed the effect of S6K2 deficiency on p21 downregulation in MCF-7 cells, it had little effect in T47D cells. S6K2 knockdown increased JUN mRNA and knockdown of cJun enhanced p21. Low concentrations of doxorubicin increased, and high concentrations decreased p21 levels in T47D cells. Silencing of S6K2 or p21 sensitized T47D cells to doxorubicin via c-Jun N-terminal kinase (JNK)-mediated downregulation of Mcl-1. Conclusions: S6K2 knockdown enhanced doxorubicin-induced apoptosis by downregulating the cell cycle inhibitor p21 and the anti-apoptotic protein Mcl-1 via Akt and/or JNK.