Selective Targeting of Protein Kinase C (PKC)-θ Nuclear Translocation Reduces Mesenchymal Gene Signatures and Reinvigorates Dysfunctional CD8+ T Cells in Immunotherapy-Resistant and Metastatic Cancers

Jenny Dunn; Robert D McCuaig; Abel H Y Tan; Wen Juan Tu; Fan Wu; Kylie M Wagstaff; Anjum Zafar; Sayed Ali; Himanshu Diwakar; Jane E Dahlstrom; Elaine G Bean; Jade K Forwood; Sofiya Tsimbalyuk; Emily M Cross; Kristine Hardy; Amanda L Bain; Elizabeth Ahern; Riccardo Dolcetti; Roberta Mazzieri; Desmond Yip; Melissa Eastgate; Laeeq Malik; Peter Milburn; David A Jans; Sudha Rao

doi:10.3390/cancers14061596

Selective Targeting of Protein Kinase C (PKC)-θ Nuclear Translocation Reduces Mesenchymal Gene Signatures and Reinvigorates Dysfunctional CD8⁺ T Cells in Immunotherapy-Resistant and Metastatic Cancers

Cancers (Basel). 2022 Mar 21;14(6):1596. doi: 10.3390/cancers14061596.

Authors

Jenny Dunn^{1

2}, Robert D McCuaig^{1

2}, Abel H Y Tan², Wen Juan Tu^{1

2}, Fan Wu², Kylie M Wagstaff³, Anjum Zafar², Sayed Ali⁴, Himanshu Diwakar⁵, Jane E Dahlstrom^{6

7

8}, Elaine G Bean⁶, Jade K Forwood⁹, Sofiya Tsimbalyuk⁹, Emily M Cross⁹, Kristine Hardy², Amanda L Bain¹, Elizabeth Ahern^{10

11}, Riccardo Dolcetti^{12

13

14

15}, Roberta Mazzieri^{12

15}, Desmond Yip^{7

16}, Melissa Eastgate^{17

18}, Laeeq Malik^{7

16}, Peter Milburn⁸, David A Jans¹⁹, Sudha Rao^{1

2}

Affiliations

¹ Gene Regulation and Translational Medicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, QLD 4006, Australia.
² Melanie Swan Memorial Translational Centre, Faculty of Science and Technology, University of Canberra, Canberra, ACT 2617, Australia.
³ Cancer Targeting and Nuclear Therapeutics Lab, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC 3800, Australia.
⁴ Medical Oncology, St John of God Midland Public and Private Hospitals, Perth, WA 6056, Australia.
⁵ Woden Specialist Medical Centre, I-MED Radiology Network, Canberra, ACT 2606, Australia.
⁶ Anatomical Pathology, ACT Pathology, The Canberra Hospital, Canberra Health Services, Canberra, ACT 2605, Australia.
⁷ ANU Medical School, College of Health and Medicine, The Australian National University, Canberra, ACT 0200, Australia.
⁸ The John Curtin School of Medical Research, The Australian National University, Canberra, ACT 0200, Australia.
⁹ School of Dentistry and Medical Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
¹⁰ Department of Medical Oncology, Monash Health and Monash University, Melbourne, VIC 3168, Australia.
¹¹ Cancer Immunoregulation and Immunotherapy Laboratory, QIMR Berghofer Medical Research Institute, Herston, QLD 4006, Australia.
¹² Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia.
¹³ Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia.
¹⁴ Department of Microbiology and Immunology, The University of Melbourne, Melbourne, VIC 3010, Australia.
¹⁵ The University of Queensland Diamantina Institute, Translational Research Institute, The University of Queensland, Brisbane, QLD 4102, Australia.
¹⁶ Department of Medical Oncology, Canberra Health Services, The Canberra Hospital, Canberra, ACT 2605, Australia.
¹⁷ Department of Medical Oncology, Royal Brisbane and Women's Hospital, Brisbane, QLD 4029, Australia.
¹⁸ Faculty of Medicine, University of Queensland, Herston, QLD 4006, Australia.
¹⁹ Nuclear Signaling Lab, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC 3800, Australia.

Abstract

Protein kinase C (PKC)-θ is a serine/threonine kinase with both cytoplasmic and nuclear functions. Nuclear chromatin-associated PKC-θ (nPKC-θ) is increasingly recognized to be pathogenic in cancer, whereas its cytoplasmic signaling is restricted to normal T-cell function. Here we show that nPKC-θ is enriched in circulating tumor cells (CTCs) in patients with triple-negative breast cancer (TNBC) brain metastases and immunotherapy-resistant metastatic melanoma and is associated with poor survival in immunotherapy-resistant disease. To target nPKC-θ, we designed a novel PKC-θ peptide inhibitor (nPKC-θi2) that selectively inhibits nPKC-θ nuclear translocation but not PKC-θ signaling in healthy T cells. Targeting nPKC-θ reduced mesenchymal cancer stem cell signatures in immunotherapy-resistant CTCs and TNBC xenografts. PKC-θ was also enriched in the nuclei of CD8⁺ T cells isolated from stage IV immunotherapy-resistant metastatic cancer patients. We show for the first time that nPKC-θ complexes with ZEB1, a key repressive transcription factor in epithelial-to-mesenchymal transition (EMT), in immunotherapy-resistant dysfunctional PD1⁺/CD8⁺ T cells. nPKC-θi2 inhibited the ZEB1/PKC-θ repressive complex to induce cytokine production in CD8⁺ T cells isolated from patients with immunotherapy-resistant disease. These data establish for the first time that nPKC-θ mediates immunotherapy resistance via its activity in CTCs and dysfunctional CD8⁺ T cells. Disrupting nPKC-θ but retaining its cytoplasmic function may offer a means to target metastases in combination with chemotherapy or immunotherapy.

Keywords: T cell; breast cancer; cancer stem cell; epithelial-to-mesenchymal transition; immunotherapy; melanoma; metastasis; nuclear translocation; protein kinase C (PKC)-θ; resistance.

Grants and funding

GNT1105409/National Health and Medical Research Council