gant-61 and Triple-Negative-Breast-Neoplasms

Triple negative breast cancer (TNBC), an aggressive and highly metastatic subtype of breast cancer. Glioma-associated oncogene 1 (GLI1) is a transcription factor and effector of the Hedgehog (Hh) signaling pathway, and is predictive of poor survival for TNBC patients. A nanostring DNA Damage Response (DDR) mRNA panel was used to identify GLI1-induced regulation of DDR genes. Western blots, immunohistochemistry and immunofluorescence were used to evaluate protein expression. Colony assays and mammosphere formation assays were utilized to assess survival of cancer cells. Flow cytometry analyses were employed to evaluate changes in the cell cycle profile, and DNA fiber assays were used to analyze alterations in replication dynamics in TNBC cells. The UALCAN portal and Ensemble programs were used for computational analysis of TCGA data. CompuSyn software was used to calculate combination index (CI) values to assess synergism in drug combination experiments. Inhibition of GLI1 in TNBC cells transcriptionally downregulate expression of FANCD2 and its foci formation, and causes a homologous recombination repair (HR) deficiency. As HR-deficient cancer cells are sensitive to PARP-targeted therapies, we evaluated a combination of the GLI1 inhibitor, GANT61, and a PARP inhibitor (olaparib) in TNBC cells. Combination of GANT61 and olaparib elevated DNA damage levels and these drug combinations caused synergistic lethality to TNBC cells. Aberrantly activated GLI1 regulates HR-mediated DNA repair by transcriptionally regulating FANCD2 to overcome chemotherapy-induced replication stress and DNA damage, and it contributes to resistance of TNBC cells to therapeutics.

Topics: Apoptosis; Cell Cycle; Cell Movement; Cell Proliferation; DNA Replication; Drug Synergism; Drug Therapy, Combination; Fanconi Anemia Complementation Group D2 Protein; Homologous Recombination; Humans; Oxidative Stress; Poly(ADP-ribose) Polymerase Inhibitors; Prognosis; Pyridines; Pyrimidines; Survival Rate; Triple Negative Breast Neoplasms; Tumor Cells, Cultured; Zinc Finger Protein GLI1

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Cell Line, Tumor; Cell Movement; Cell Proliferation; Drug Carriers; Drug Combinations; Drug Liberation; Female; Humans; Lipoproteins, HDL; Mice; Nanoparticles; Paclitaxel; Pyridines; Pyrimidines; Signal Transduction; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays

Triple-negative breast cancer (TNBC) exhibits biologically aggressive behavior and has a poor prognosis. Novel molecular targeting agents are needed to control TNBC. Recent studies revealed that the non-canonical hedgehog (Hh) signaling pathway plays important roles in the regulation of cancer stem cells (CSCs) in breast cancer. Therefore, the anti-cell growth and anti-CSC effects of the non-canonical Hh inhibitor GANT61 were investigated in TNBC cells.. The effects of GANT61 on cell growth, cell cycle progression, apoptosis, and the proportion of CSCs were investigated in three TNBC cell lines. Four ER-positive breast cancer cell lines were also used for comparisons. The expression levels of effector molecules in the Hh pathway: glioma-associated oncogene (GLI) 1 and GLI2, were measured. The combined effects of GANT61 and paclitaxel on anti-cell growth and anti-CSC activities were also investigated.. Basal expression levels of GLI1 and GLI2 were significantly higher in TNBC cells than in ER-positive breast cancer cells. GANT61 dose-dependently decreased cell growth in association with G1-S cell cycle retardation and increased apoptosis. GANT61 significantly decreased the CSC proportion in all TNBC cell lines. Paclitaxel decreased cell growth, but not the CSC proportion. Combined treatments of GANT61 and paclitaxel more than additively enhanced anti-cell growth and/or anti-CSC activities.. The non-canonical Hh inhibitor GANT61 decreased not only cell growth, but also the CSC population in TNBC cells. GANT61 enhanced the anti-cell growth activity of paclitaxel in these cells. These results suggest for the first time that GANT61 has potential as a therapeutic agent in the treatment of patients with TNBC.

Topics: Antineoplastic Agents, Phytogenic; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Drug Synergism; Female; Fluorescent Antibody Technique; Hedgehog Proteins; Humans; Molecular Targeted Therapy; Neoplastic Stem Cells; Nuclear Proteins; Paclitaxel; Pyridines; Pyrimidines; Signal Transduction; Spheroids, Cellular; Triple Negative Breast Neoplasms; Zinc Finger Protein GLI1; Zinc Finger Protein Gli2