ABSTRACT
p21-activated kinases (Paks) are Cdc42/Rac-activated serine-threonine protein kinases that regulate several key cancer-relevant signaling pathways, such as the Mek/Erk, PI3K/Akt and Wnt/b-catenin signaling pathways. Pak1 is frequently overexpressed and/or hyperactivated in different human cancers, including human breast, ovary, prostate and brain cancer, due to amplification of the PAK1 gene in an 11q13 amplicon. Genetic or pharmacological inactivation of Pak1 has been shown to reduce proliferation of different cancer cells in vitro and reduce tumor progression in vivo. In this work, we examined the roles of Pak1 in cellular and animal models of PAK1-amplified ovarian cancer. We found that inhibition of Pak1 leads to decreased proliferation and migration in PAK1-amplified/overexpressed ovarian cancer cells, and has no effect in cell that lack such amplification/overexpression. Further, we observed that loss of Pak1 function causes 11q13-amplified ovarian cancer cells to arrest in the G2/M phase of the cell cycle. This arrest correlates with activation of p53 and p21(Cip) and decreased expression of cyclin B1. These findings suggest that small-molecule inhibitors of Pak1 may have a therapeutic role in the ~25% of ovarian cancers characterized by PAK1 gene amplification.
Subject(s)
Cell Proliferation/genetics , Ovarian Neoplasms/genetics , p21-Activated Kinases/biosynthesis , Animals , Cell Cycle/genetics , Cell Cycle Checkpoints/genetics , Cyclin B1/biosynthesis , Female , Gene Expression Regulation, Neoplastic , Humans , Mice , Ovarian Neoplasms/pathology , Signal Transduction , Tumor Suppressor Protein p53/biosynthesis , Xenograft Model Antitumor Assays , p21-Activated Kinases/antagonists & inhibitors , p21-Activated Kinases/geneticsABSTRACT
BACKGROUND: Resistance to chemotherapeutic agents is a major obstacle to cancer treatment. A group of ABC efflux pumps, the Multidrug Resistance Proteins, is a source of resistance. Herein, we investigated the role of ABCC10 in mammary tumours, given the important role we have defined for ABCC10 in transporting taxanes, and the recognition that some ABCC proteins have roles in tumour growth. METHODS: ABCC10 expression was correlated to human breast cancer subtype using breast tissue microarrays. Real-time quantitative PCR and western blot analysis were used to examine ABCC10 expression in human breast cancer lines. Abcc10(-/-) mice were crossed to MMTV-PyVmT mice to produce Abcc10(-/-) vs Abcc10(+/+) mammary tumours and derivative cell lines. We used allograft and cellular assays to perform baseline and drug sensitization analysis of tumours and cell lines. RESULTS: Clinical sample analyses indicated that ABCC10 was more highly expressed in Her2+ and ER+ than in Her2-, ER-, and triple-negative breast cancer. Unexpectedly, PyVmT; Abcc10(-/-) tumours grew more rapidly than PyVmT; Abcc10(+/+) tumours and were associated with significantly reduced apoptosis and metastasis. PyVmT; Abcc10(-/-) lines were less migratory than PyVmT; Abcc10(+/+) lines. Finally, we showed increased survival of docetaxel-treated MMTV-PyVmT; Abcc10(-/-) mice compared with wild-type mice. CONCLUSIONS: These data identify roles for Abcc10 in breast cancer pathogenesis and in vivo docetaxel resistance.
Subject(s)
Antineoplastic Agents/pharmacology , Breast Neoplasms/metabolism , Lung Neoplasms/metabolism , Mammary Neoplasms, Experimental/metabolism , Multidrug Resistance-Associated Proteins/genetics , Taxoids/pharmacology , Animals , Antineoplastic Agents/therapeutic use , Breast Neoplasms/drug therapy , Breast Neoplasms/pathology , Cell Cycle/drug effects , Cell Line, Tumor , Docetaxel , Drug Resistance, Neoplasm , Female , Gene Expression , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/secondary , Mammary Neoplasms, Experimental/drug therapy , Mammary Neoplasms, Experimental/pathology , Mice , Mice, Knockout , Mice, SCID , Multidrug Resistance-Associated Proteins/metabolism , Neoplasm Transplantation , Paclitaxel/pharmacology , Receptor, ErbB-2/metabolism , Receptors, Estrogen/metabolism , Taxoids/therapeutic use , Tissue Array Analysis , Tumor BurdenABSTRACT
BACKGROUND: Increased Aurora kinase A gene copy number (AURKA-CN) has been reported in metastatic colorectal cancer (mCRC), with unknown relationship to clinical outcome. We correlated increased AURKA-CN in mCRC tumours with KRAS mutation status, overall and progression-free survival (OS, PFS). METHODS: Sixty-one mCRC tumours were analysed for AURKA-CN using q-PCR, and KRAS mutation status by direct sequencing. Expression of AURKA protein was analysed by immunohistochemistry. Cox-proportional hazard method, Kaplan-Meier curves and log-rank statistics were used to estimate and compare the hazard ratios and median survival between the groups. RESULTS: In all, 68% of tumour exhibited high AURKA-CN, and 29% had a KRAS mutation, without correlation between the two. Patients with high AURKA-CN tumours had longer median OS (48.6 vs 18.8 months, P=0.01), with stronger trend among KRAS wild-type tumours (median OS not reached vs 18.8 months, P=0.003). Progression-free survival was longer on first-line or second-line chemotherapy among patients with KRAS wild-type and high vs low AURKA-CN (first: 17.6 vs 5.13 months, P=0.04; second: 10.4 vs 5.1 months, P=0.01). AURKA-CN level did not affect outcomes among patients with KRAS mutant tumours. CONCLUSION: Increased AURKA-CN is common in mCRC tumours and is associated with longer OS and longer PFS during chemotherapy, particularly in KRAS wild-type tumours.
