Lapatinib Resistance in HCT116 Cells Is Mediated by Elevated MCL-1 Expression and Decreased BAK Activation and Not by ERBB Receptor Kinase Mutation

Martin, Aditi Pandya; Miller, Anna V.; Emad, Luni; Rahmani, Mohamed; Walker, Teneille; Mitchell, Clint; Hagan, Michael P.; Park, Margaret A.; Yacoub, Adly; Fisher, Paul B.; Grant, Steven; Dent, Paul

doi:10.1124/mol.108.047365

Cited by 57 publications

(64 citation statements)

References 55 publications

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“…Products of many of the anti-apoptotic YB-1 target genes have previously been implicated in drug resistance. For example, inhibition of inhibitor of apoptosis-family members cIAP1 (BIRC2) and cIAP2 (BIRC3) increases apoptosis in response to trastuzumab, lapatinib or gefitinib in HER2-overexpressing cells (Foster et al, 2009), whereas inhibition of MCL-1 sensitizes cells to both lapatinib and trastuzumab (Henson et al, 2006;Martin et al, 2008). Moreover, TNFSF18 and TCF7L1 are associated with tamoxifen and erlotinib resistance, respectively (Treeck et al, 2004;Halatsch et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

MKNK1 is a YB-1 target gene responsible for imparting trastuzumab resistance and can be blocked by RSK inhibition

et al. 2012

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Trastuzumab (Herceptin) resistance is a major obstacle in the treatment of patients with HER2-positive breast cancers. We recently reported that the transcription factor Y-box binding protein-1 (YB-1) leads to acquisition of resistance to trastuzumab in a phosphorylationdependent manner that relies on p90 ribosomal S6 kinase (RSK). To explore how this may occur we compared YB-1 target genes between trastuzumab-sensitive cells (BT474) and those with acquired resistance (HR5 and HR6) using genome-wide chromatin immunoprecipitation sequencing (ChIP-sequencing), which identified 1391 genes uniquely bound by YB-1 in the resistant cell lines. We then examined differences in protein expression and phosphorylation between these cell lines using the Kinexus Kinex antibody microarrays. Cross-referencing these two data sets identified the mitogen-activated protein kinase-interacting kinase (MNK) family as potentially being involved in acquired resistance downstream from YB-1. MNK1 and MNK2 were subsequently shown to be overexpressed in the resistant cell lines; however, only the former was a YB-1 target based on ChIP-PCR and small interfering RNA (siRNA) studies. Importantly, loss of MNK1 expression using siRNA enhanced sensitivity to trastuzumab. Further, MNK1 overexpression was sufficient to confer resistance to trastuzumab in cells that were previously sensitive. We then developed a de novo model of acquired resistance by exposing BT474 cells to trastuzumab for 60 days (BT474LT). Similar to the HR5/HR6 cells, the BT474LT cells had elevated MNK1 levels and were dependent on it for survival. In addition, we demonstrated that RSK phosphorylated MNK1, and that this phosphorylation was required for ability of MNK1 to mediate resistance to trastuzumab. Furthermore, inhibition of RSK with the small molecule BI-D1870 repressed the MNK1-mediated trastuzumab resistance. In conclusion, this unbiased integrated approach identified MNK1 as a player in mediating trastuzumab resistance as a consequence of YB-1 activation, and demonstrated RSK inhibition as a means to overcome recalcitrance to trastuzumab.

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Section: Discussionmentioning

confidence: 99%

MKNK1 is a YB-1 target gene responsible for imparting trastuzumab resistance and can be blocked by RSK inhibition

et al. 2012

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“…Our prior studies demonstrated that obatoclax potentiated the cytotoxicity of lapatinib in human colon and breast cancer cells by inducing autophagic cell death (Martin et al, 2008. In the present article, we have endeavored to explore the mechanism by which obatoclax and lapatinib interacted to cause toxic autophagy.…”

Section: Discussionmentioning

confidence: 99%

“…As an alternative to lapatinib monotherapy, coadministration of lapatinib with the BCL-2/BCL-XL/MCL-1 antagonist obatoclax (GX-15-070) attenuated lapatinib resistance and produced synergistic cancer cell killing by eliciting autophagic cell death in a wide range of human breast and colon cancer cells (Martin et al, 2008Mitchell et al, 2010). However, molecular mechanisms by which obatoclax and lapatinib interact to cause toxic autophagy have not been fully described or understood.…”

Section: Introductionmentioning

confidence: 99%

“…Studies from our group showed that lapatinib-resistant cells increased expression of the prosurvival B cell CLL/ lymphoma-2 (BCL-2) family members MCL-1 and BCL-XL and decreased expression of proapoptosis BCL-2 family members BAX and BAK (Martin et al, 2008. As an alternative to lapatinib monotherapy, coadministration of lapatinib with the BCL-2/BCL-XL/MCL-1 antagonist obatoclax (GX-15-070) attenuated lapatinib resistance and produced synergistic cancer cell killing by eliciting autophagic cell death in a wide range of human breast and colon cancer cells (Martin et al, 2008Mitchell et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Obatoclax and Lapatinib Interact to Induce Toxic Autophagy through NOXA

Tang¹,

Hamed²,

Cruickshanks³

et al. 2012

Mol Pharmacol

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Prior studies demonstrated that resistance to the ERBB1/2 inhibitor lapatinib could be overcome by the B cell CLL/lymphoma-2 (BCL-2) family antagonist obatoclax (GX15-070). Coadministration of lapatinib with obatoclax caused synergistic cell killing by eliciting autophagic cell death that was dependent upstream on mitochondrial reactive oxygen species generation and increased p62 levels and downstream on activation of p38 mitogen-activated protein kinase and inactivation of mammalian target of rapamycin. By immunohistochemical analysis, in drug combination-treated cells, microtubule-associated protein light chain 3 (LC3) associated with mitochondrial (cytochrome c oxidase), autophagosome (p62), and autolysosome (lysosomal associated membrane protein 2) proteins. Treatment of cells with 3-methyladenine or knockdown of beclin 1 was protective, whereas chloroquine treatment had no protective effect. Expression of myeloid cell leukemia-1 (MCL-1), compared with that of BCL-2 or BCL-2-related gene long isoform, protected against drug combination lethality. Lapatinib and obatoclaxinitiated autophagy depended on NOXA-mediated displacement of the prosurvival BCL-2 family member, MCL-1, from beclin 1, which was essential for the initiation of autophagy. Taken together, our data argue that lapatinib and obatoclaxinduced toxic autophagy is due to impaired autophagic degradation, and this disturbance of autophagic flux leads to an accumulation of toxic proteins and loss of mitochondrial function.

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“…To achieve greater effects on survival, inhibition of multiple growth factor receptors and intracellular pathways has to be targeted. It has been noted that tumors presenting with alterations in ERBB receptors are often more aggressive and frequently convey poorer clinical outcome (Bigner and Vogelstein, 1990;Hynes and Lane, 2005;Martin et al, 2008). In addition, it is known that medulloblastoma and malignant glioma often exhibit expres-sion of constitutively activated or altered ERBB receptors; therefore, the use of small molecule kinase inhibitors, such as lapatinib and gefitinib, as anticancer therapeutics in CNS tumor types is logical (Miller, 2004;Hynes and Lane, 2005).…”

Section: Introductionmentioning

confidence: 99%

Lapatinib and Obatoclax Kill Tumor Cells through Blockade of ERBB1/3/4 and through Inhibition of BCL-xL and MCL-1

Cruickshanks

Hamed²,

Bareford³

et al. 2012

Mol Pharmacol

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Prior studies in breast cancer cells have shown that lapatinib and obatoclax interact in a greater than additive fashion to cause cell death and do so through a toxic form of autophagy. The present studies sought to extend our analyses to the central nervous system (CNS) tumor cells and to further define mechanisms of drug action. Lapatinib and obatoclax killed multiple CNS tumor isolates. Cells lacking PTEN (phosphatase and tensin homolog on chromosome 10) function were relatively resistant to drug combination lethality; expression of PTEN in PTEN-null cells restored drug sensitivity, and knockdown of PTEN promoted drug resistance. On the basis of knockdown of ERBB1-4 (erythroblastic leukemia viral oncogene homolog 1-4), we discovered that the inhibition of ERBB1/3/4 receptors were most important for enhancing obatoclax lethality rather than ERBB2. In parallel, we noted in CNS tumor cells that knockdown of BCL-XL (B-cell lymphomaextra large)and MCL-1 (myeloid cell leukemia-1) interacted in an additive fashion to facilitate lapatinib lethality. Pretreatment of tumor cells with obatoclax enhanced the lethality of lapatinib to a greater extent than concomitant treatment. Treatment of animals carrying orthotopic CNS tumor isolates with lapatiniband obatoclax-prolonged survival. Altogether, our data show that lapatinib and obatoclax therapy could be of use in the treatment of tumors located in the CNS.

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Lapatinib Resistance in HCT116 Cells Is Mediated by Elevated MCL-1 Expression and Decreased BAK Activation and Not by ERBB Receptor Kinase Mutation

Cited by 57 publications

References 55 publications

MKNK1 is a YB-1 target gene responsible for imparting trastuzumab resistance and can be blocked by RSK inhibition

MKNK1 is a YB-1 target gene responsible for imparting trastuzumab resistance and can be blocked by RSK inhibition

Obatoclax and Lapatinib Interact to Induce Toxic Autophagy through NOXA

Lapatinib and Obatoclax Kill Tumor Cells through Blockade of ERBB1/3/4 and through Inhibition of BCL-xL and MCL-1

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