Novel Anti-CRR9/CLPTM1L Antibodies with Antitumorigenic Activity Inhibit Cell Surface Accumulation, PI3K Interaction, and Survival Signaling

Abstract

We and others have recently shown Cisplatin Resistance-Related Protein 9 (CRR9)/Cleft Lip and Palate Transmembrane 1-Like (CLPTM1L) to affect survival and proliferation in lung and pancreatic tumor cells. Our research has indicated that CLPTM1L affects multiple survival signaling pathways in tumor cells under oncogenic, genotoxic, and microenvironmental stress. We have confirmed the association of CLPTM1L with pancreatic cancer by demonstrating overexpression of CLPTM1L in pancreatic tumors and poor survival in patients with high tumor expression of CLPTM1L. Predicting a transmembrane structure, we determined that CLPTM1L could be targeted at the plasma membrane. Herein, we describe the development of monoclonal antibodies targeting CLPTM1L. Lead antibodies inhibited surface accumulation of CLPTM1L, Akt phosphorylation, anchorage-independent growth, and chemotherapeutic resistance in lung and pancreatic tumor cells. Gemcitabine promoted a physical interaction between CLPTM1L and p110α in pancreatic tumor cells, which was inhibited by anti-CLPTM1L. In-vivo treatment with anti-CLPTM1L robustly inhibited the growth of both lung and pancreatic adenocarcinoma xenografts. The efficacy of anti-CLPTM1L correlated with specific epitopes representing important targets in human cancers, particularly those driven by KRas, for which effective targeted therapies have been elusive. This study is the first to report cell-surface exposure of the tumor survival protein CLPTM1L and inhibition of the function of surface CLPTM1L with novel, systematically developed inhibitory monoclonal antibodies establishing proof of concept of clinically practical agents inhibiting this compelling new tumor survival target in cancer.

CLPTM1L/CRR9 ectodomain interaction with GRP78 at the cell surface signals for survival and chemoresistance upon ER stress in pancreatic adenocarcinoma cells

“…We have investigated CLPTM1L as a potential therapeutic target in pancreatic tumors and its association with mediators of the UPR. Our published data confirms that CLPTM1L is overexpressed in over 90% of pancreatic cancers and that high expression is associated with poor survival . We have demonstrated for the first time that CLPTM1L is expressed on the surface of pancreatic, lung and ovarian tumor cells and its function can be inhibited with antibodies .…”

“…We have demonstrated for the first time that CLPTM1L is expressed on the surface of pancreatic, lung and ovarian tumor cells and its function can be inhibited with antibodies . We have shown that CLPTM1L inhibition with both shRNA and our antibodies robustly inhibited tumorigenesis, anchorage independent growth, Akt phosphorylation, and Bcl‐xL accumulation . Plasma membrane accumulation of CLPTM1L and the interaction of CLPTM1L with PI3K‐alpha in pancreatic tumor cells was enhanced by gemcitabine treatment and ER‐stress induction, but inhibited by anti‐CLPTM1L antibody treatment.…”

“…Our published data confirms that CLPTM1L is overexpressed in over 90% of pancreatic cancers and that high expression is associated with poor survival . We have demonstrated for the first time that CLPTM1L is expressed on the surface of pancreatic, lung and ovarian tumor cells and its function can be inhibited with antibodies . We have shown that CLPTM1L inhibition with both shRNA and our antibodies robustly inhibited tumorigenesis, anchorage independent growth, Akt phosphorylation, and Bcl‐xL accumulation .…”

Fine mapping in TERT‐CLPTM1L region identified three independent lung cancer susceptibility signals: A large‐scale multi‐ethnic population study

“…This signal was located in the promoter of CLPTM1L . Increased expression of CLPTM1L was observed associated with cell migration and invasion in lung cancer cells . James MA and colleagues found that rs31489 could regulate the expression of CLPTM1L by detecting the CLPTM1L expression in 32 tumor adjacent normal lung tissues .…”

MiR-182 regulates cell proliferation and apoptosis in laryngeal squamous cell carcinoma by targeting the CRR9

“…The current research on CRR9 has made some breakthroughs. It has shown that CRR9 is abnormally highly expressed in various human malignant tumor tissues and corresponding cell lines, especially in some malignant tumors with high invasiveness and metastasis [17]. CRR9 was first isolated by screening of the cisplatin (CDDP) resistance-related gene.…”