Moonlighting with Melanoma and the Unfolded Protein Response — ASN Events
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  3. Moonlighting with Melanoma and the Unfolded Protein Response

Moonlighting with Melanoma and the Unfolded Protein Response (#229)

Erin K Sykes 1 , Swetlana Mactier 1 , Kimberley L Kaufman 2 , Duthika M Mallawaaratchy 1 , Munther Alomari 1 , Richard I Christopherson 1
  1. University of Sydney, Darlington, NSW, Australia
  2. Brain and Mind Research Institute, The University of Sydney, Darlington, NSW, Australia

Introduction and Objectives

Metastatic melanoma is a lethal neoplasm with rapid progression and systemic dissemination. The 5-year survival rate for patients with distant metastases is just 6%-18%. This is due not only to the aggressive nature of the disease but also a lack of effective therapies. Activation of the unfolded protein response (UPR), a stress response, in melanoma positively correlates with tumour progression, metastasis and poor outcome. The complete action of the UPR is yet to be determined, and its role in cancer progression is undefined.

Method

In the present study, proteomic analyses have been used to identify proteins involved in the UPR and to elucidate its role in melanoma. Subcellular proteomes of human melanoma cell lines (Mel-RM and WMM1175) treated with thapsigargin (TH), an inducer of ER stress, were labeled with iTRAQ and anaylsed using 2D LC-MS/MS. Differentially abundant proteins were validated using selected reaction monitoring (SRM) mass spectrometry and western blotting. Membrane-associated progesterone receptor component 1 (PGRMC1) and 4F2-cell surface antigen were labeled with Cy5-conjugated antibody and the sub-cellular trafficking with TH treatment monitored by fluorescence microscopy. Finally pull-downs of PGRMC1 and 4F2 were performed to elucidate their role in the UPR.

Results and Discussion

Following activation of the UPR, 80 differentially abundant proteins were identified by mass spectrometry. These proteins are involved in stress response, cell migration and adhesion, and apoptosis/survival. PGRMC1 and 4F2 are up-regulated and translocated as a result of UPR activation, both proteins have been linked with cancer progression and their association with the UPR novel.

Conclusions

The UPR affects several important oncogenic proteins and pathways, such as the Akt and MAPK pathways, showing the importance of the UPR in melanoma progression. The differentially abundant proteins identified here extend our understanding of how the UPR can modulate protein function and contribute to melanoma tumourigenesis.