Dataset Information

MTI-101 (cyclized HYD1) binds a CD44 containing complex and induces necrotic cell death in multiple myeloma.

ABSTRACT: Our laboratory recently reported that treatment with the d-amino acid containing peptide HYD1 induces necrotic cell death in multiple myeloma cell lines. Because of the intriguing biological activity and promising in vivo activity of HYD1, we pursued strategies for increasing the therapeutic efficacy of the linear peptide. These efforts led to a cyclized peptidomimetic, MTI-101, with increased in vitro activity and robust in vivo activity as a single agent using two myeloma models that consider the bone marrow microenvironment. MTI-101 treatment similar to HYD1 induced reactive oxygen species, depleted ATP levels, and failed to activate caspase-3. Moreover, MTI-101 is cross-resistant in H929 cells selected for acquired resistance to HYD1. Here, we pursued an unbiased chemical biology approach using biotinylated peptide affinity purification and liquid chromatography/tandem mass spectrometry analysis to identify binding partners of MTI-101. Using this approach, CD44 was identified as a predominant binding partner. Reducing the expression of CD44 was sufficient to induce cell death in multiple myeloma cell lines, indicating that multiple myeloma cells require CD44 expression for survival. Ectopic expression of CD44s correlated with increased binding of the FAM-conjugated peptide. However, ectopic expression of CD44s was not sufficient to increase the sensitivity to MTI-101-induced cell death. Mechanistically, we show that MTI-101-induced cell death occurs via a Rip1-, Rip3-, or Drp1-dependent and -independent pathway. Finally, we show that MTI-101 has robust activity as a single agent in the SCID-Hu bone implant and 5TGM1 in vivo model of multiple myeloma.

SUBMITTER: Gebhard AW

PROVIDER: S-EPMC3859963 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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MTI-101 (cyclized HYD1) binds a CD44 containing complex and induces necrotic cell death in multiple myeloma.

Gebhard Anthony W AW Jain Priyesh P Nair Rajesh R RR Emmons Michael F MF Argilagos Raul F RF Koomen John M JM McLaughlin Mark L ML Hazlehurst Lori A LA

Molecular cancer therapeutics 20130918 11

Our laboratory recently reported that treatment with the d-amino acid containing peptide HYD1 induces necrotic cell death in multiple myeloma cell lines. Because of the intriguing biological activity and promising in vivo activity of HYD1, we pursued strategies for increasing the therapeutic efficacy of the linear peptide. These efforts led to a cyclized peptidomimetic, MTI-101, with increased in vitro activity and robust in vivo activity as a single agent using two myeloma models that consider ...[more]

PMID: 24048737

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Project description:The endoplasmic reticulum stress sensor, the unfolded protein response (UPR), regulates intracellular protein homeostasis. While transient activation of the reactive UPR by unfolded protein is protective, prolonged and sustained activation of the reactive UPR triggers CHOP-mediated apoptosis. In the recently characterized, evolutionarily conserved anticipatory UPR, mitogenic hormones and other effectors pre-activate the UPR; how strong and sustained activation of the anticipatory UPR induces cell death was unknown. To characterize this cell death pathway, we used BHPI, a small molecule that activates the anticipatory UPR through estrogen receptor ? (ER?) and induces death of ER?+ cancer cells. We show that sustained activation of the anticipatory UPR by BHPI kills cells by inducing depletion of intracellular ATP, resulting in classical necrosis phenotypes, including plasma membrane disruption and leakage of intracellular contents. Unlike reactive UPR activation, BHPI-induced hyperactivation of the anticipatory UPR does not induce apoptosis or sustained autophagy. BHPI does not induce CHOP protein or PARP cleavage, and two pan-caspase inhibitors, or Bcl2 overexpression, have no effect on BHPI-induced cell death. Moreover, BHPI does not increase expression of autophagy markers, or work through recently identified programmed-necrosis pathways, such as necroptosis. Opening of endoplasmic reticulum IP3R calcium channels stimulates cell swelling, cPLA2 activation, and arachidonic acid release. Notably, cPLA2 activation requires ATP depletion. Importantly, blocking rapid cell swelling or production of arachidonic acid does not prevent necrotic cell death. Rapid cell death is upstream of PERK activation and protein synthesis inhibition, and results from strong and sustained activation of early steps in the anticipatory UPR. Supporting a central role for ATP depletion, reversing ATP depletion blocks rapid cell death, and the onset of necrotic cell death is correlated with ATP depletion. Necrotic cell death initiated by strong and sustained activation of the anticipatory UPR is a newly discovered role of the UPR.

Project description:MTI-101 is a first-in-class novel cyclic peptide shown to have anti-tumor activity in both multiple myeloma and castrate-resistant prostate in vivo cancer models. These data suggest the potential for a broad spectrum of anti-cancer activity for this class of compounds. To further delineate determinants of sensitivity and resistance that were not dependent on oncogenic drivers, two isogenic drug resistant cell lines were generated with chronic exposure to MTI-101 in a non-small cell lung cancer (NSCLC) PC-9 (EGFR driven) and a small cell lung cancer (SCLC) H446 (PTEN deleted and c-MYC amplified). Using the isogenic cell line systems coupled with RNA-SEQ, the top enriched GSEA hallmark was downregulation of genes that contribute to epithelial to mesenchymal transition (EMT), a finding that was consistent in both acquired MTI-101 selected resistant cell lines. The RNA-SEQ data correlated with predicted changes in the phenotype, including significant decreased invasion in Matrigel and changes of EMT markers (E-Cadherin, Vimentin and Twist) at the protein level. Furthermore, in the EGFR driven PC-9 cell line, selection for resistance towards MTI-101 resulted in collateral sensitivity toward EGFR inhibitors. To determine the stability of the MET phenotype, cells were removed from drug and tested for invasion and drug resistance every month. These data indicated that the mesenchymal to epithelial transition (MET) phenotype and genotype was stable for a minimum of six months. MTI-101 treatment in PC-9 and H446 cells showed synergistic activity with the standard of care agents Erlotinib, Osimertinib, and Cisplatin when used in combination in PC-9 and H446 cells, respectively. Finally, in vivo data indicates that MTI-101 treatment selects for increased E-Cadherin and decreased Vimentin in H446. In addition, treatment with MTI-101 decreased incidence of bone metastasis in the PC-9 in vivo model. Together, these data indicate that MTI-101 treatment could be used as a tool to delay the emergence of metastatic disease for the treatment of lung cancer.

Dataset Information

MTI-101 (cyclized HYD1) binds a CD44 containing complex and induces necrotic cell death in multiple myeloma.

Publications

MTI-101 (cyclized HYD1) binds a CD44 containing complex and induces necrotic cell death in multiple myeloma.

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