Targeting LINC00152 activates cAMP/Ca2+/ferroptosis axis and overcomes tamoxifen resistance in ER+ breast cancer.

Tamoxifen has been the mainstay therapy to treat early, locally advanced, and metastatic estrogen receptor-positive (ER + ) breast cancer, constituting around 75% of all cases. However, the emergence of resistance is common, necessitating the identification of novel therapeutic targets. Here, we demonstrated that long-noncoding RNA LINC00152 confers tamoxifen resistance by blocking tamoxifen-induced ferroptosis, an iron-mediated cell death. Mechanistically, inhibiting LINC00152 reduces the mRNA stability of phosphodiesterase 4D (PDE4D), leading to activation of the cAMP/PKA/CREB axis and increased expression of the TRPC1 Ca2+ channel. This causes cytosolic Ca2+ overload and generation of reactive oxygen species (ROS) that is, on the one hand, accompanied by downregulation of FTH1, a member of the iron sequestration unit, thus increasing intracellular Fe2+ levels; and on the other hand, inhibition of the peroxidase activity upon reduced GPX4 and xCT levels, in part by cAMP/CREB. These ultimately restore tamoxifen-dependent lipid peroxidation and ferroptotic cell death which are reversed upon chelating Ca2+ or overexpressing GPX4 or xCT. Overexpressing PDE4D reverses LINC00152 inhibition-mediated tamoxifen sensitization by de-activating the cAMP/Ca2+/ferroptosis axis. Importantly, high LINC00152 expression is significantly correlated with high PDE4D/low ferroptosis and worse survival in multiple cohorts of tamoxifen- or tamoxifen-containing endocrine therapy-treated ER+ breast cancer patients. Overall, we identified LINC00152 inhibition as a novel mechanism of tamoxifen sensitization via restoring tamoxifen-dependent ferroptosis upon destabilizing PDE4D, increasing cAMP and Ca2+ levels, thus leading to ROS generation and lipid peroxidation. Our findings reveal LINC00152 and its effectors as actionable therapeutic targets to improve clinical outcome in refractory ER+ breast cancer.

Durable radiologic and molecular complete response following nivolumab in an HNSCC patient with UV signature and HIV.

Cancer patients living with HIV (CPLWH) may experience increased mortality risk. Furthermore, they have been historically excluded from clinical trials due to safety concerns. Our patient with squamous cell carcinoma of the lower lip received radiotherapy and platinum-based chemotherapy but declined by multiple centers due to his accidental HIV status. Genomic profiling revealed CDKN2A/B, PBRM1, TP53, and TERT alterations corresponding to UV signature, and high tumor mutational burden with positive PD-L1 staining. Accordingly, we report a durable radiologic and molecular complete response upon nivolumab plus IVC and antiretroviral therapy (ART). We demonstrated the safety and efficacy of ICIs, and feasibility of managing adverse events caused by antitumor, antiviral, and integrative therapies.

Navigating uncharted territory: a case report and literature review on the remarkable response to personalized crizotinib containing combinational therapy in a pazopanib refractory patient with novel alterations.

This paper presents a patient with a novel Ig-like-III domain fibroblast growth factor receptor (FGFR2) alteration (W290_P307>C) along with CDKN2A/B alterations and a cadherin 1 (CDH1) alteration. Initial responsiveness to pazopanib monotherapy was encouraging, yet progression occurred after 7.5 months. Following progression, the molecular tumor board recommended a combination therapy approach comprising pazopanib, crizotinib, and palbociclib to target all of the changed pathways at the same time. Pazopanib was chosen to specifically target the FGFR2 alteration, while crizotinib was selected due to its potential synthetic lethality with the CDH1 alteration. In addition, the CDK4/6 inhibitor palbociclib was administered to address the CDKN2A/B alterations. The patient exhibited a remarkable and sustained response to this innovative combination. This case not only underscores the potential of tyrosine kinase inhibitors, exemplified by pazopanib, as a viable alternative for patients without access to pan-FGFR inhibitors, but it also emphasizes their efficacy beyond commonly detected point mutations and rearrangements. Notably, the outstanding response to combination therapy, including crizotinib, in a patient with a CDH1 alteration, further substantiates the preclinical evidence of synthetic lethality between crizotinib and CDH1 alterations. To our knowledge, this represents the first clinical evidence demonstrating the efficacy of crizotinib in a patient with a CDH1 alteration. Through careful dosage adjustments and consideration of individualized genomic information, this case exemplifies the power of personalized medicine in achieving favorable treatment outcomes.

PARP inhibitor combinations with high-dose vitamin C in the treatment of Ewing sarcoma: two case reports and mechanistic overview.

Ewing's sarcoma (ES) is a bone and soft tissue tumor that mainly occurs at a young age. The underlying cause of Ewing's sarcoma is the formation of fusion proteins between FET family genes and ETS family genes. Tumors with FET/ETS fusion genes can have defects in the DNA damage response and are sensitive to PARP inhibitors (PARPi). However, several studies have shown that PARPi alone is not sufficient to induce a meaningful antitumor response and that combinations of DNA-damaging agents with PARPi are required to achieve efficacy. Accordingly, preclinical studies have reported dramatic responses to PARPi treatment in combination with DNA-damaging agents such as temozolomide or irinotecan. Similarly, it has been previously reported that by generating reactive oxygen species, high-dose intravenous vitamin C (IVC) can induce DNA damage. This suggests that the combination of IVC with PARPi may increase genotoxic stress and enhance the antitumor response. In addition, unlike chemotherapeutic agents, IVC induces DNA damage selectively in cancer cells, and the side effects are significantly milder than those of chemotherapy. As ETS fusion-positive ES is deficient in faithful DNA repair, partly due to the interaction between ETS fusion products and PARP1, a PARPi plus IVC seems to be a logical and effective combination for the treatment of ETS fusion-positive ES. This paper reports significant responses to IVC (1-1.5 g/kg) in combination with PARPi (olaparib 300 mg BID or talazoparib 1 mg/day) in two patients with metastatic Ewing's sarcoma. The observations highlight an unmet therapeutic need for patients with advanced metastatic ES. The combination of PARPi with a selective DNA-damaging agent was effective in these cases. This case experience suggests that IVC may be incorporated into PARPi-based therapeutic strategies. Further studies are needed to confirm the efficacy of this combination in the treatment of Ewing sarcoma with ETS fusions.

Combining vitamin C with PARP inhibitors for Ewing sarcoma treatment: mechanistic insights and 2 case studies Ewing's sarcoma is a type of bone and soft tissue tumor that commonly affects young people and it is often resistant to conventional therapy. In this study, clinical cancer scientists and oncologists investigated a new approach to treating this cancer by combining high-dose vitamin C with PARP inhibitors. High-dose vitamin C can damage the DNA of cancer cells and PARP inhibitors block the damaged DNA sites so they can't be repaired and eventually this leads to cancer cells dying. The researchers found that when these two treatments were used together, there were significant improvements in two patients with advanced Ewing's sarcoma. Importantly, the combination led to fewer side effects compared to standard chemotherapy, suggesting it might be a more tolerable treatment option. These findings suggest that combining high-dose intravenous vitamin C with PARP inhibitors could be a promising treatment for Ewing's sarcoma. More research is needed to confirm these results, but this approach shows potential for helping patients with advanced forms of this type of cancer. This is the first clinical report demonstrating the benefits of using high-dose vitamin C with PARP inhibitors and the study emphasizes the importance of exploring more treatment options for this aggressive type of cancer and suggests that further investigations into this combined approach could lead to more effective and tolerable treatments for Ewing's sarcoma.

Toxic PARP trapping upon cAMP-induced DNA damage reinstates the efficacy of endocrine therapy and CDK4/6 inhibitors in treatment-refractory ER+ breast cancer.

Resistance to endocrine therapy and CDK4/6 inhibitors, the standard of care (SOC) in estrogen receptor-positive (ER+) breast cancer, greatly reduces patient survival. Therefore, elucidating the mechanisms of sensitivity and resistance to SOC therapy and identifying actionable targets are urgently needed. Here, we show that SOC therapy causes DNA damage and toxic PARP1 trapping upon generation of a functional BRCAness (i.e., BRCA1/2 deficiency) phenotype, leading to increased histone parylation and reduced H3K9 acetylation, resulting in transcriptional blockage and cell death. Mechanistically, SOC therapy downregulates phosphodiesterase 4D (PDE4D), a novel ER target gene in a feedforward loop with ER, resulting in increased cAMP, PKA-dependent phosphorylation of mitochondrial COXIV-I, ROS generation and DNA damage. However, during SOC resistance, an ER-to-EGFR switch induces PDE4D overexpression via c-Jun. Notably, combining SOC with inhibitors of PDE4D, EGFR or PARP1 overcomes SOC resistance irrespective of the BRCA1/2 status, providing actionable targets for restoring SOC efficacy.

Evaluation of the Relationship between Aromatase/Sirtuin1 Interaction and miRNA Expression in Human Neuroblastoma Cells.

BACKGROUND: Changes in activation/inhibition of Sirtuin-1 (SIRT1) and aromatase play an important role in a plethora of diseases. MicroRNAs (miRNAs) modulate multiple molecular pathways and affect a substantial number of physiological and pathological processes. OBJECTIVE: The aim of this study was to investigate any possible interaction between aromatase and SIRT1 in SH-SY5Y cells and to see how there is a connection between this interaction and miRNA expression, if there is an interaction. METHODS: In this study, cells were incubated in serum-deprived media for 6, 12, and 24 h. Aromatase and SIRT1 expressions were evaluated by Western blot. The IC50 concentration of SIRT1 activator (SRT1720), SIRT1 inhibitor (EX527), and aromatase inhibitors (letrozole and fadrozole) was determined by the XTT method. Then, CYP19A1 and SIRT1 levels were evaluated in the presence of SIRT1 siRNA or IC50 values for each activator/inhibitor. Finally, CYP19A1, SIRT1 expression and miRNA target gene were assessed with bioinformatic approaches. RESULTS: Aromatase and SIRT1 protein levels were significantly elevated in the cells incubated at 24 h in serum-deprived media (p ≤ 0.05). SIRT1 also positively regulated CYP19A1 in SH-SY5Y cells in media with/without FBS. Serum deprivation depending on time course caused changes in the oxidant/ antioxidant system. While oxidative stress index tended to decrease in the absence of FBS at 24 h compared to the control, it showed a significant decrease at 48 h in a serum-deprived manner (p ≤ 0.001). As a result of bioinformatics analysis, we determined 3 miRNAs that could potentially regulate SIRT1 and CYP19A1. hsa-miR-27a-3p and hsa-miR-181a-5p correlated in terms of their expressions at 24 h compared to 12 h, and there was a significant decrease in the expression of these miRNAs. On the contrary, the expression of hsa-miR-30c-5p significantly increased at 24 h compared to 12 h. CONCLUSION: Considering the results, a direct link between aromatase and SIRT1 was observed in human neuroblastoma cells. The identification of key miRNAs, hsa-miR-27a-3p, hsa-miR-30c-5p, and hsa-miR-181a-5p targeting both aromatase and SIRT1, provides an approach with novel insights on neurology-associated diseases.

Targeting LINC00152 activates cAMP/Ca2+/ferroptosis axis and overcomes tamoxifen resistance in ER+ breast cancer.

Tamoxifen has been the mainstay therapy to treat early, locally advanced, and metastatic estrogen receptor-positive (ER+) breast cancer, constituting around 75% of all cases. However, emergence of resistance is common, necessitating the identification of novel therapeutic targets. Here, we demonstrated that long-noncoding RNA LINC00152 confers tamoxifen resistance via blocking tamoxifen-induced ferroptosis, an iron-mediated cell death. Mechanistically, inhibiting LINC00152 reduces the mRNA stability of phosphodiesterase 4D (PDE4D), leading to activation of cAMP/PKA/CREB axis and increased expression of TRPC1 Ca2+ channel. This causes cytosolic Ca2+ overload and generation of reactive oxygen species (ROS) that is, on one hand, accompanied by downregulation of FTH1, a member of the iron sequestration unit, thus increasing intracellular Fe2+ levels; and on the other hand, inhibition of the peroxidase activity upon reduced GPX4 and xCT levels. These ultimately induce lipid peroxidation and ferroptotic cell death in combination with tamoxifen. Overexpressing PDE4D rescues LINC00152 inhibition-mediated tamoxifen sensitization by de-activating the cAMP/Ca2+/ferroptosis axis. Importantly, high LINC00152 expression is significantly correlated with high PDE4D/low ferroptosis and worse survival in multiple cohorts of tamoxifen- or tamoxifen-containing endocrine therapy-treated ER+ breast cancer patients. Overall, we identified LINC00152 inhibition as a novel mechanism of ferroptosis induction and tamoxifen sensitization, thereby revealing LINC00152 and its effectors as actionable therapeutic targets to improve clinical outcome in refractory ER+ breast cancer.

Targeting HIF1-alpha/miR-326/ITGA5 axis potentiates chemotherapy response in triple-negative breast cancer.

PURPOSE: Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer that is frequently treated with chemotherapy. However, many patients exhibit either de novo chemoresistance or ultimately develop resistance to chemotherapy, leading to significantly high mortality rates. Therefore, increasing the efficacy of chemotherapy has potential to improve patient outcomes. METHODS: Here, we performed whole transcriptome sequencing (both RNA and small RNA-sequencing), coupled with network simulations and patient survival data analyses to build a novel miRNA-mRNA interaction network governing chemoresistance in TNBC. We performed cell proliferation assay, Western blotting, RNAi/miRNA mimic experiments, FN coating, 3D cultures, and ChIP assays to validate the interactions in the network, and their functional roles in chemoresistance. We developed xenograft models to test the therapeutic potential of the identified key miRNA/proteins in potentiating chemoresponse in vivo. We also analyzed several patient datasets to evaluate the clinical relevance of our findings. RESULTS: We identified fibronectin (FN1) as a central chemoresistance driver gene. Overexpressing miR-326 reversed FN1-driven chemoresistance by targeting FN1 receptor, ITGA5. miR-326 was downregulated by increased hypoxia/HIF1A and ECM stiffness in chemoresistant tumors, leading to upregulation of ITGA5 and activation of the downstream FAK/Src signaling pathways. Overexpression of miR-326 or inhibition of ITGA5 overcame FN1-driven chemotherapy resistance in vitro by inhibiting FAK/Src pathway and potentiated the efficacy of chemotherapy in vivo. Importantly, lower expression of miR-326 or higher levels of predicted miR-326 target genes was significantly associated with worse overall survival in chemotherapy-treated TNBC patients. CONCLUSION: FN1 is central in chemoresistance. In chemoresistant tumors, hypoxia and resulting ECM stiffness repress the expression of the tumor suppressor miRNA, miR-326. Hence, re-expression of miR-326 or inhibition of its target ITGA5 reverses FN1-driven chemoresistance making them attractive therapeutic approaches to enhance chemotherapy response in TNBCs.

Targeting lysyl oxidase (LOX) overcomes chemotherapy resistance in triple negative breast cancer.

Chemoresistance is a major obstacle in triple negative breast cancer (TNBC), the most aggressive breast cancer subtype. Here we identify hypoxia-induced ECM re-modeler, lysyl oxidase (LOX) as a key inducer of chemoresistance by developing chemoresistant TNBC tumors in vivo and characterizing their transcriptomes by RNA-sequencing. Inhibiting LOX reduces collagen cross-linking and fibronectin assembly, increases drug penetration, and downregulates ITGA5/FN1 expression, resulting in inhibition of FAK/Src signaling, induction of apoptosis and re-sensitization to chemotherapy. Similarly, inhibiting FAK/Src results in chemosensitization. These effects are observed in 3D-cultured cell lines, tumor organoids, chemoresistant xenografts, syngeneic tumors and PDX models. Re-expressing the hypoxia-repressed miR-142-3p, which targets HIF1A, LOX and ITGA5, causes further suppression of the HIF-1α/LOX/ITGA5/FN1 axis. Notably, higher LOX, ITGA5, or FN1, or lower miR-142-3p levels are associated with shorter survival in chemotherapy-treated TNBC patients. These results provide strong pre-clinical rationale for developing and testing LOX inhibitors to overcome chemoresistance in TNBC patients.