American Association for Cancer Research
00085472can151199-sup-149269_1_supp_3163626_nv3h3m.pdf (3.82 MB)

Supplemental Figures from Aberrant Activation of Notch Signaling Inhibits PROX1 Activity to Enhance the Malignant Behavior of Thyroid Cancer Cells

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journal contribution
posted on 2023-03-30, 23:53 authored by Dongwon Choi, Swapnika Ramu, Eunkyung Park, Eunson Jung, Sara Yang, Wonhyeuk Jung, Inho Choi, Sunju Lee, Kyu Eui Kim, Young Jin Seong, Mingu Hong, George Daghlian, Daniel Kim, Eugene Shin, Jung In Seo, Vicken Khatchadourian, Mengchen Zou, Wei Li, Roger De Filippo, Paul Kokorowski, Andy Chang, Steve Kim, Ana Bertoni, Tania Weber Furlanetto, Sung Shin, Meng Li, Yibu Chen, Alex Wong, Chester Koh, Jan Geliebter, Young-Kwon Hong

Supplemental Figures. Fig S1:Expression of HEY1 and HEY2 in thyroid cancers vs. normal thyroid tissues. Fig S2:PROX1 mislocalization in TPC-1 cells does not depend on CRM1, energy or temperature. Fig S3: T3 promotes PROX1 nuclear exclusion in a dose-dependent manner. Fig S4: Engineered BCPAP cells conditionally express FLAG-tagged PROX1 by doxycycline administration. Fig S5: Wnt/β-catenin signaling is suppressed in PTC cells. Fig S6: PROX1-mediated regulation of thyroid cancer-associated genes in TPC1 and 8505c cells. Fig S7: Single cell motility assay. Fig S8: Reinstatement of PROX1 expression in TPC1 and 8505c thyroid cancer cells. Fig S9: Dox-induced expression of PROX1 in BCPAP tumor cells in mouse. Fig S10: PROX1 re-expression inhibits tumor growth and aggressive tumor cell morphology of TPC1 thyroid carcinoma cells. Fig S11: PROX1 re-expression suppressed tumor growth and aggressive morphology of 8505c thyroid cancer cells. Fig S12: Cytoplasmic localization of PROX1 in other cancer cells.



Papillary thyroid cancer (PTC) is one of the most common endocrine malignancies associated with significant morbidity and mortality. Although multiple studies have contributed to a better understanding of the genetic alterations underlying this frequently arising disease, the downstream molecular effectors that impact PTC pathogenesis remain to be further defined. Here, we report that the regulator of cell fate specification, PROX1, becomes inactivated in PTC through mRNA downregulation and cytoplasmic mislocalization. Expression studies in clinical specimens revealed that aberrantly activated NOTCH signaling promoted PROX1 downregulation and that cytoplasmic mislocalization significantly altered PROX1 protein stability. Importantly, restoration of PROX1 activity in thyroid carcinoma cells revealed that PROX1 not only enhanced Wnt/β-catenin signaling but also regulated several genes known to be associated with PTC, including thyroid cancer protein (TC)-1, SERPINA1, and FABP4. Furthermore, PROX1 reexpression suppressed the malignant phenotypes of thyroid carcinoma cells, such as proliferation, motility, adhesion, invasion, anchorage-independent growth, and polyploidy. Moreover, animal xenograft studies demonstrated that restoration of PROX1 severely impeded tumor formation and suppressed the invasiveness and the nuclear/cytoplasmic ratio of PTC cells. Taken together, our findings demonstrate that NOTCH-induced PROX1 inactivation significantly promotes the malignant behavior of thyroid carcinoma and suggest that PROX1 reactivation may represent a potential therapeutic strategy to attenuate disease progression Cancer Res; 76(3); 582–93. ©2015 AACR.