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posted on 2023-03-31, 20:44 authored by Elaine Y. Chung, Yun Mai, Urvi A. Shah, Yongqiang Wei, Elise Ishida, Keisuke Kataoka, Xiaoxin Ren, Kith Pradhan, Boris Bartholdy, Xiaolei Wei, Yiyu Zou, Jinghang Zhang, Seishi Ogawa, Ulrich Steidl, Xingxing Zang, Amit Verma, Murali Janakiram, B. Hilda Ye Supplementary Figures Figure S1. Related to Materials and Methods Immunophenotype and viral gene expression status of the three NA-ATLL cell lines Figure S2. Related to Figure 1. PAK2 amplification pattern in ATLL and expression of PAK isoforms in published ATLL datasets Figure S3. Related to Figure 2. Survival curves for primary ATLL samples and ATLL cell lines treated with PF or IPA3 Figure S4. Related to Figure 3A. Apoptosis analysis of ATLL cell lines treated with PF for 24 and 48 hours Figure S5. Related to Figure 3B. Cell cycle analysis of Japanese ATLL cell lines treated with PF for 24 and 40 hours Figure S6. Related to Figure 3B. Cell cycle analysis of North American ATLL cell lines treated with PF for 24 and 40 hours Figure S7. Related to Figure 3C. Changes in the expression of apoptosis and cell survival regulators 48 hours post PF treatment Figure S8. Related to Figure 4. Roles of CADM1, PAK1, and PAK2 in cell adhesion to the HK feeder Figure S9. Related to Figure 5. Apoptosis and cell cycle analysis of ATL55T(+) and ATL43Tb(-) cells following siRNA-mediated PAK1 or PAK2 knock-down Figure S10. Related to Figure 5. Changes in proliferation and survival regulators in ATL43Tb(-) cells following siRNA-mediated PAK1 or PAK2 knock-down Figure S11. Related to Figure 6. PF response in CDX and PDX-derived xenograft models
Funding
NIH
NCI
NYSTEM
Leukaemia and Lymphoma Research
Louis Skarlow Memorial Trust
Aids Malignancy Consortium
Harry Eagle Scholarship from the Department of Cell Biology, Albert Einstein College of Medicine, and U.A.
History
ARTICLE ABSTRACT
To evaluate therapeutic activity of PAK inhibition in ATLL and to characterize the role of PAK isoforms in cell proliferation, survival, and adhesion of ATLL cells in preclinical models.
Frequency and prognostic impact of PAK2 amplification were evaluated in an ATLL cohort of 370 cases. Novel long-term cultures and in vivo xenograft models were developed using primary ATLL cells from North American patients. Two PAK inhibitors were used to block PAK kinase activity pharmacologically. siRNA-based gene silencing approach was used to genetically knockdown (KD) PAK1 and PAK2 in ATLL cell lines.
PAK1/2/4 are the three most abundantly expressed PAK family members in ATLL. PAK2 amplifications are seen in 24% of ATLLs and are associated with worse prognosis in a large patient cohort. The pan-PAK inhibitor PF-3758309 (PF) has strong in vitro and in vivo activity in a variety of ATLL preclinical models. These activities of PF are likely attributed to its ability to target several PAK isoforms simultaneously because genetic silencing of either PAK1 or PAK2 produced more modest effects. PAK2 plays a major role in CADM1-mediated stromal interaction, which is an important step in systemic dissemination of the disease. This finding is consistent with the observation that PAK2 amplification is more frequent in aggressive ATLLs and correlates with inferior outcome.
PAK2, a gene frequently amplified in ATLL, facilitates CADM1-mediated stromal interaction and promotes survival of ATLL cells. Taken together, PAK inhibition may hold significant promise as a targeted therapy for aggressive ATLLs.
