ABSTRACT
BACKGROUND: Tumor metastasis is a terrifying characteristic of cancer. Numerous studies have been conducted to overcome metastasis by targeting tumor microenvironment (TME). However, due to complexity of tumor microenvironment, it remained difficult for accurate targeting. Dwarf-lillytruf tuber monomer-13 (DT-13) possess good potential against TME. OBJECTIVE: As TME is supportive for tumor metastasis, alternatively it is a challenging for therapeutic intervention. In our present study, we explored molecular mechanism through which TME induced cell migration and how DT-13 interferes in this mechanism. METHODS: We used a novel model of co-culture system which is eventually developed in our lab. Tumor cells were co-cultured with hypoxia induced cancer-associated fibroblasts (CAF) or with chemically induced cancer-associated adipocytes (CAA). The effect of hypoxia in conditioned medium for CAF was assessed through expression of α-SMA and HIF by western blotting while oil red staining was done to assess the successful chemical induction for adipocytes (CAA), the effect of TME through conditioned medium on cell migration was analyzed by trans-well cell migration, and cell motility (wound healing) analyses. The expression changes in cellular proteins were assessed through western blotting and immunofluorescent studies. RESULTS AND CONCLUSION: Our results showed that tumor microenvironment has a direct role in promoting breast cancer cell migration by stromal cells; moreover, we found that DT-13 restricts this TME regulated cell migration via targeting stromal cells in vitro. Additionally we also found that DT-13 targets NMII-A for its effect on breast cancer cell migration for the regulation of stromal cells in TME.
Subject(s)
Breast Neoplasms/drug therapy , Myosin Heavy Chains/metabolism , Saponins/pharmacology , Animals , Breast Neoplasms/immunology , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cancer-Associated Fibroblasts/drug effects , Cancer-Associated Fibroblasts/metabolism , Cancer-Associated Fibroblasts/pathology , Cell Line, Tumor , Cell Movement/immunology , Female , Humans , Liriope Plant/chemistry , Mice , Myosin Heavy Chains/genetics , Signal Transduction , Tumor Microenvironment/drug effects , Tumor Microenvironment/immunologyABSTRACT
The binding of red pigment concentrating hormone (RPCH) to membrane receptors in crustacean chromatophores triggers Ca²âº/cGMP signaling cascades that activate cytoskeletal motors, driving pigment granule translocation. We investigate the distributions of microfilaments and microtubules and their associated molecular motors, myosin and dynein, by confocal and transmission electron microscopy, evaluating a functional role for the cytoskeleton in pigment translocation using inhibitors of polymer turnover and motor activity in vitro. Microtubules occupy the chromatophore cell extensions whether the pigment granules are aggregated or dispersed. The inhibition of microtubule turnover by taxol induces pigment aggregation and inhibits re-dispersion. Phalloidin-FITC actin labeling, together with tannic acid fixation and ultrastructural analysis, reveals that microfilaments form networks associated with the pigment granules. Actin polymerization induced by jasplaquinolide strongly inhibits RPCH-induced aggregation, causes spontaneous pigment dispersion, and inhibits pigment re-dispersion. Inhibition of actin polymerization by latrunculin-A completely impedes pigment aggregation and re-dispersion. Confocal immunocytochemistry shows that non-muscle myosin II (NMMII) co-localizes mainly with pigment granules while blebbistatin inhibition of NMMII strongly reduces the RPCH response, also inducing spontaneous pigment dispersion. Myosin II and dynein also co-localize with the pigment granules. Inhibition of dynein ATPase by erythro-9-(2-hydroxy-3-nonyl) adenine induces aggregation, inhibits RPCH-triggered aggregation, and inhibits re-dispersion. Granule aggregation and dispersion depend mainly on microfilament integrity although microtubules may be involved. Both cytoskeletal polymers are functional only when subunit turnover is active. Myosin and dynein may be the molecular motors that drive pigment aggregation. These mechanisms of granule translocation in crustacean chromatophores share various features with those of vertebrate pigment cells.