PELP1 inhibition by SMIP34 reduces endometrial cancer progression via attenuation of ribosomal biogenesis.
作者: Xue Yang ; Zexuan Liu ; Weiwei Tang ; Uday P Pratap ; Alexia B Collier ; Kristin A Altwegg ; Rahul Gopalam ; Xiaonan Li ; Yaxia Yuan ; Daohong Zhou ; Zhao Lai ; Yidong Chen ; Gangadhara R Sareddy ; Philip T Valente ; Edward R Kost ; Suryavathi Viswanadhapalli ; Ratna K Vadlamudi
Endometrial carcinoma (ECa) is the fourth most common cancer among women. The oncogene PELP1 is frequently overexpressed in a variety of cancers, including ECa. We recently generated SMIP34, a small-molecule inhibitor of PELP1 that suppresses PELP1 oncogenic signaling. In this study, we assessed the effectiveness of SMIP34 in treating ECa. Treatment of established and primary patient-derived ECa cells with SMIP34 resulted in a significant reduction of cell viability, colony formation ability and induction of apoptosis. SMIP34 enhanced the efficacy of mTOR inhibitors in reducing viability of ECa cells. RNA-seq analyses showed that SMIP34 regulated genes that are negatively correlated with ribosome biogenesis and eukaryotic translation pathways. Mechanistic studies showed that the Rix complex, which is essential for ribosomal biogenesis, is disrupted upon SMIP34 binding to PELP1. Biochemical assays confirmed that SMIP34 reduced ribosomal biogenesis and new protein synthesis. SMIP34 is also effective in reducing cell viability in ECa organoids in vitro and explants ex vivo. Importantly, SMIP34 treatment resulted in a significant reduction of the growth of ECa xenografts. Collectively, these findings underscore the potential of SMIP34 in treating ECa.
2023-05-18·Breast cancer research and treatment
Targeting PELP1 oncogenic signaling in TNBC with the small molecule inhibitor SMIP34.
作者: Kristin A Altwegg ; Uday P Pratap ; Zexuan Liu ; Junhao Liu ; John R Sanchez ; Xue Yang ; Behnam Ebrahimi ; Durga Meenakshi Panneerdoss ; Xiaonan Li ; Gangadhara R Sareddy ; Suryavathi Viswanadhapalli ; Manjeet K Rao ; Ratna K Vadlamudi
Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Oncogenic PELP1 is frequently overexpressed in TNBC, and it has been demonstrated that PELP1 signaling is essential for TNBC progression. The therapeutic utility of targeting PELP1 in TNBC, however, remains unknown. In this study, we investigated the effectiveness of SMIP34, a recently developed PELP1 inhibitor for the treatment of TNBC.
To ascertain the impact of SMIP34 treatment, we used seven different TNBC models for testing cell viability, colony formation, invasion, apoptosis, and cell cycle analysis. Western blotting and RT-qPCR were used to determine the mechanistic insights of SMIP34 action. Using xenograft and PDX tumors, the ability of SMIP34 in suppressing proliferation was examined both ex vivo and in vivo.
TNBC cells' viability, colony formation, and invasiveness were all decreased by SMIP34 in in vitro cell-based assays, while apoptosis was increased. SMIP34 treatment promoted the degradation of PELP1 through the proteasome pathway. RT-qPCR analyses confirmed that SMIP34 treatment downregulated PELP1 target genes. Further, SMIP34 treatment substantially downregulated PELP1 mediated extranuclear signaling including ERK, mTOR, S6 and 4EBP1. Mechanistic studies confirmed downregulation of PELP1 mediated ribosomal biogenesis functions including downregulation of cMyc and Rix complex proteins LAS1L, TEX-10, and SENP3. The proliferation of TNBC tumor tissues was decreased in explant experiments by SMIP34. Additionally, SMIP34 treatment markedly decreased tumor progression in both TNBC xenograft and PDX models.
Together, these findings from in vitro, ex vivo, and in vivo models show that SMIP34 may be a useful therapeutic agent for inhibiting PELP1 signaling in TNBC.
A first-in-class inhibitor of ER coregulator PELP1 targets ER+ breast cancer.
作者: Kristin A Altwegg ; Suryavathi Viswanadhapalli ; Monica Mann ; Dimple Chakravarty ; Samaya Rajeshwari Krishnan ; Zexuan Liu ; Junhao Liu ; Uday P Pratap ; Behnam Ebrahimi ; John R Sanchez ; Xiaonan Li ; Shihong Ma ; Ben H Park ; Bindu Santhamma ; Yidong Chen ; Zhao Lai ; Ganesh V Raj ; Yaxia Yuan ; Daohong Zhou ; Gangadhara R Sareddy ; Rajeshwar R Tekmal ; Stanton F McHardy ; Tim Hui-Ming Huang ; Manjeet K Rao ; Hariprasad Vankayalapati ; Ratna K Vadlamudi
Most patients with estrogen receptor alpha-positive breast cancers (ER+ BC) initially respond to treatment but eventually develop therapy resistance with disease progression. Overexpression of oncogenic ER coregulators, including proline, glutamic acid, and leucine-rich protein 1 (PELP1), are implicated in BC progression. The lack of small molecules that inhibits PELP1 represents a major knowledge gap. Here, using a yeast-two-hybrid screen, we identified novel peptide inhibitors of PELP1 (PIPs). Biochemical assays demonstrated that one of these peptides, PIP1, directly interacted with PELP1 to block PELP1 oncogenic functions. Computational modeling of PIP1 revealed key residues contributing to its activity and facilitated the development of a small molecule inhibitor of PELP1, SMIP34, and further analyses confirmed that SMIP34 directly bound to PELP1. In BC cells, SMIP34 reduced cell growth in a PELP1-dependent manner. SMIP34 inhibited proliferation of not only wild-type (WT) but also mutant (MT) ER+ and therapy-resistant (TR) BC cells, in part by inducing PELP1 degradation via the proteasome pathway. RNA-seq analyses showed that SMIP34 treatment altered the expression of genes associated with estrogen response, cell cycle, and apoptosis pathways. In cell line-derived and patient-derived xenografts of both WT- and MT- ER+ BC models, SMIP34 reduced proliferation and significantly suppressed tumor progression. Collectively, these results demonstrate SMIP34 as a first-in-class inhibitor of oncogenic PELP1 signaling in advanced BC.