Metastasis is the major cause of breast cancer mortality. Phosphoinositide 3-kinase (PI3K) generated PtdIns(3,4,5)P3 activates AKT, which promotes breast cancer cell proliferation and regulates ...migration. To date, none of the inositol polyphosphate 5-phosphatases that inhibit PI3K/AKT signaling have been reported as tumor suppressors in breast cancer. Here, we show depletion of the inositol polyphosphate 5-phosphatase PIPP (INPP5J) increases breast cancer cell transformation, but reduces cell migration and invasion. Pipp ablation accelerates oncogene-driven breast cancer tumor growth in vivo, but paradoxically reduces metastasis by regulating AKT1-dependent tumor cell migration. PIPP mRNA expression is reduced in human ER-negative breast cancers associated with reduced long-term outcome. Collectively, our findings identify PIPP as a suppressor of oncogenic PI3K/AKT signaling in breast cancer.
Display omitted
•Pipp knockout promotes oncogene-driven breast cancer initiation and growth•Ablation of Pipp impairs metastasis in a mouse model of breast cancer•PIPP regulates AKT1-dependent cell migration and invasion•Low PIPP expression is associated with ER-negative breast cancer and poor prognosis
Ooms et al. identify the inositol polyphosphate 5-phosphatase PIPP as a suppressor of oncogenic PI3K/AKT signaling in breast cancer. PIPP depletion increases transformation and accelerates oncogene-driven tumor growth in vivo, while paradoxically reducing cell migration, invasion, and metastasis.
The era of targeted therapies has seen significant improvements in depth of response, progression-free survival, and overall survival for patients with multiple myeloma. Despite these improvements in ...clinical outcome, patients inevitably relapse and require further treatment. Drug-resistant dormant myeloma cells that reside in specific niches within the skeleton are considered a basis of disease relapse but remain elusive and difficult to study. Here, we developed a method to sequence the transcriptome of individual dormant myeloma cells from the bones of tumor-bearing mice. Our analyses show that dormant myeloma cells express a distinct transcriptome signature enriched for immune genes and, unexpectedly, genes associated with myeloid cell differentiation. These genes were switched on by coculture with osteoblastic cells. Targeting AXL, a gene highly expressed by dormant cells, using small-molecule inhibitors released cells from dormancy and promoted their proliferation. Analysis of the expression of AXL and coregulated genes in human cohorts showed that healthy human controls and patients with monoclonal gammopathy of uncertain significance expressed higher levels of the dormancy signature genes than patients with multiple myeloma. Furthermore, in patients with multiple myeloma, the expression of this myeloid transcriptome signature translated into a twofold increase in overall survival, indicating that this dormancy signature may be a marker of disease progression. Thus, engagement of myeloma cells with the osteoblastic niche induces expression of a suite of myeloid genes that predicts disease progression and that comprises potential drug targets to eradicate dormant myeloma cells.
•Dormant multiple myeloma cells express a unique transcriptome signature.•This unique transcriptome signature controls dormancy, predicts survival, and identifies new treatment targets.
Display omitted
Human papilloma virus (HPV) infection is a major risk factor for a distinct subset of head and neck squamous cell carcinoma (HNSCC). The current review summarizes the epidemiology of HNSCC and the ...disease burden, the infectious cycle of HPV, the roles of viral oncoproteins, E6 and E7, and the downstream cellular events that lead to malignant transformation. Current techniques for the clinical diagnosis of HPV‐associated HNSCC will also be discussed, that is, the detection of HPV DNA, RNA, and the HPV surrogate marker, p16 in tumor tissues, as well as HPV‐specific antibodies in serum. Such methods do not allow for the early detection of HPV‐associated HNSCC and most cases are at an advanced stage upon diagnosis. Novel noninvasive approaches using oral fluid, a clinically relevant biological fluid, allow for the detection of HPV and cellular alterations in infected cells, which may aid in the early detection and HPV‐typing of HNSCC tumors. Noninvasive diagnostic methods will enable early detection and intervention, leading to a significant reduction in mortality and morbidity associated with HNSCC.
The current review summarizes the epidemiology of human papilloma virus (HPV)‐related head and neck squamous cell carcinoma (HNSCC) and the disease burden, the infectious cycle of HPV, the roles of viral oncoproteins, E6 and E7, and the downstream cellular events that lead to malignant transformation. We also reviewed the current regimes and novel noninvasive methods of HPV detection.
The HSP90 (heat-shock protein 90) inhibitor 17-AAG (17-allylamino-demethoxygeldanamycin) increases osteoclast formation both in vitro and in vivo, an action that can enhance cancer invasion and ...growth in the bone microenvironment. The cellular mechanisms through which 17-AAG exerts this action are not understood. Thus we sought to clarify the actions of 17-AAG on osteoclasts and determine whether other HSP90 inhibitors had similar properties. We determined that 17-AAG and the structurally unrelated HSP90 inhibitors CCT018159 and NVP-AUY922 dose-dependently increased RANKL receptor activator of NF-κB (nuclear factor κB) ligand-stimulated osteoclastogenesis in mouse bone marrow and pre-osteoclastic RAW264.7 cell cultures. Moreover, 17-AAG also enhanced RANKL- and TNF (tumour necrosis factor)-elicited osteoclastogenesis, but did not affect RANKL-induced osteoclast survival, suggesting that only differentiation mechanisms are targeted. 17-AAG affected the later stages of progenitor maturation (after 3 days of incubation), whereas the osteoclast formation enhancer TGFβ (transforming growth factor β) acted prior to this, suggesting different mechanisms of action. In studies of RANKL-elicited intracellular signalling, 17-AAG treatment did not increase c-Fos or NFAT (nuclear factor of activated T-cells) c1 protein levels nor did 17-AAG increase activity in luciferase-based NF-κB- and NFAT-response assays. In contrast, 17-AAG treatment (and RANKL treatment) increased both MITF (microphthalmia-associated transcription factor) protein levels and MITF-dependent vATPase-d2 (V-type proton ATPase subunit d2) gene promoter activity. These results indicate that HSP90 inhibitors enhance osteoclast differentiation in an NFATc1-independent manner that involves elevated MITF levels and activity.
Treatment with fatostatin, a small molecule inhibitor of sterol regulatory element-binding protein (SREBP) function that decreases the expression of MVK6 (see Fig E3, A, in this article's Online ...Repository at www.jacionline.org), enhanced the prenylation defect in MVA LCLs at 37°C and 40°C (Fig E3, B). Methods Cell isolation and culture Human PBMCs were isolated from buffy coat preparations of fresh blood samples, obtained with informed consent and with approval from the St Vincent's Hospital Human Research Ethics Committee. MVK mRNA expression was measured by quantitative PCR as previously described.E1 In vitro prenylation assay Cell lysates were prepared as previously describedE1 and 10 to 50 μg of protein were used for in vitro prenylation assays with recombinant GGTase I or with GGTase II and REP-1.E2In vitro prenylated (ie, biotinylated) proteins were detected on polyvinylidene difluoride blots using streptavidin-680RD (LiCOR).E2 Blots were also analyzed for unprenylated Rap1A using goat anti-Rap1A (Santa Cruz Biotechnology, Dallas, Tex; sc-1482).E2 Rab14 was detected in 2 μg of PBMC lysates using a 1/200 dilution of rabbit polyclonal anti-Rab14 (H-55, Santa Cruz Biotechnology), 1/5000 peroxidase-conjugated goat anti-rabbit (Pierce), and SuperSignal West Femto ECL reagent (ThermoFisher Scientific, Waltham, Mass). Patient Age (y) Sex Current statin use Approximate duration of statin treatment (y) 1 82 F Atorvastatin 10 2 78 F Rosuvastatin 20 3 71 M Rosuvastatin 0.25∗ 4 64 M Atorvastatin 5 5 74 M Rosuvastatin 10 6 58 M Atorvastatin 10 7 71 M Atorvastatin 14 8 88 F Atorvastatin 5 9 58 M Pravastatin 2 1 A. Simon, H.P. Kremer, R.A. Wevers, H. Scheffer, J.G. De Jong, J.W. Van Der Meer, Mevalonate kinase deficiency: evidence for a phenotypic continuum, Neurology, Vol. 62, 2004, 994-997 2 C.C. Palsuledesai, M.D. Distefano, Protein prenylation: enzymes, therapeutics, and biotechnology applications, ACS Chem Biol, Vol. 10, 2015, 51-62 3 Y.H. Park, G. Wood, D.L. Kastner, J.J. Chae, Pyrin inflammasome activation and RhoA signaling in the autoinflammatory diseases FMF and HIDS, Nat Immunol, Vol. 17, 2016, 914-921 4 M.K. Akula, M. Shi, Z. Jiang, C.E. Foster, D. Miao, A.S. Li, Control of the innate immune response by the mevalonate pathway, Nat Immunol, Vol. 17, 2016, 922-929 5 N. Ali, J. Jurczyluk, G. Shay, Z. Tnimov, K. Alexandrov, M.A. Munoz, A highly sensitive prenylation assay reveals in vivo effects of bisphosphonate drug on the Rab prenylome of macrophages outside the skeleton, Small GTPases, Vol. 6, 2015, 202-211 6 J. Jurczyluk, M.A. Munoz, O.P. Skinner, R. Chai, N. Ali, U. Palendira, Mevalonate kinase deficiency leads to decreased prenylation of Rab GTPases, Immunol Cell Biol, Vol. 94, 2016, 994-999 7 M.J. Rogers, J.C. Crockett, F.P. Coxon, J. Monkkonen, Biochemical and molecular mechanisms of action of bisphosphonates, Bone, Vol. 49, 2011, 34-41 8 L. Messer, G. Alsaleh, P. Georgel, R. Carapito, H.R. Waterham, N. Dali-Youcef, Homozygosity for the V377I mutation in mevalonate kinase causes distinct clinical phenotypes in two sibs with hyperimmunoglobulinaemia D and periodic fever syndrome (HIDS), RMD Open, Vol. 2, 2016, e000196 9 S.M. Houten, J. Frenkel, G.T. Rijkers, R.J. Wanders, W. Kuis, H.R. Waterham, Temperature dependence of mutant mevalonate kinase activity as a pathogenic factor in hyper-IgD and periodic fever syndrome, Hum Mol Genet, Vol. 11, 2002, 3115-3124
Purpose of Review
Bone is a complex tissue populated by a highly heterogeneous mix of cell types in different compartments. The endosteal compartment is a key site for bone remodelling and provides a ...supportive microenvironment to harbour haematopoietic and mesenchymal stem cells, as well as cancer cells that grow in bone. The purpose of this review is to summarize recent findings of studies in bone using single-cell RNA sequencing and emergent spatial RNA sequencing to describe different bone-resident cell types and their molecular programs.
Recent Findings
Single-cell RNA sequencing identified novel and transcriptionally distinct cell clusters within different bone cell lineages, including MSCs, osteoblasts, chondrocytes, fibroblasts, osteoclasts and cells of the vasculature. Spatial transcriptomics methods provide information on the localization of the different cell populations.
Summary
Single-cell transcriptomics provided valuable insights into long-standing knowledge gaps in the cellular heterogeneity of bone-resident cells in unprecedented detail, paving the way for studies to further investigate the different cell populations and to develop cell-based therapies for bone diseases.
HSF1 (heat-shock factor 1) is the master regulator of the heat-shock response; however, it is also activated by cancer-associated stresses and supports cellular transformation and cancer progression. ...We examined the role of HSF1 in relation to cancer cell clonogenicity, an important attribute of cancer cells. Ectopic expression or HSF1 knockdown demonstrated that HSF1 positively regulated cancer cell clonogenic growth. Furthermore, knockdown of mutant p53 indicated that HSF1 actions were mediated via a mutant p53-dependent mechanism. To examine this relationship more specifically, we ectopically co-expressed mutant p53(R273H) and HSF1 in the human mammary epithelial cell line MCF10A. Surprisingly, within this cellular context, HSF1 inhibited clonogenicity. However, upon specific knockdown of endogenous wild-type p53, leaving mutant p53(R273H) expression intact, HSF1 was observed to greatly enhance clonogenic growth of the cells, indicating that HSF1 suppressed clonogenicity via wild-type p53. To confirm this we ectopically expressed HSF1 in non-transformed and H-Ras(V12)-transformed MCF10A cells. As expected, HSF1 significantly reduced clonogenicity, altering wild-type p53 target gene expression levels consistent with a role of HSF1 increasing wild-type p53 activity. In support of this finding, knockdown of wild-type p53 negated the inhibitory effects of HSF1 expression. We thus show that HSF1 can affect clonogenic growth in a p53 context-dependent manner, and can act via both mutant and wild-type p53 to bring about divergent effects upon clonogenicity. These findings have important implications for our understanding of HSF1's divergent roles in cancer cell growth and survival as well as its disparate effect on mutant and wild-type p53.
The skeleton is a common site for the establishment of distant metastases. Once cancers occupy bone, the prognosis is poor as disease recurrence and visceral spread is imminent. Understanding the ...pathways and cellular interactions, which regulate tumour cell seeding, dormancy and growth in bone, is pertinent to improving outcomes for patients with advanced cancers. Advances in imaging techniques have facilitated the development of the concept that the behavior of bone marrow resident cells dictates the fate of tumour cells upon arrival in bone. This review summarises recent findings achieved through intravital imaging. It highlights the importance of developing both longitudinal static and acute dynamic data to develop our understanding of tumour cell engraftment, dormancy, activation and the subsequent establishment of metastases. We also describe how imaging techniques have developed our knowledge of the elements that make up the complex bone microenvironment which tumour cells interact with to survive and grow. We also discuss how through combining these imaging insights with single cell RNA sequencing data, we are entering a new era of research which has the power to define the cell-cell interactions which control tumour cell growth in bone.
•Intravital imaging in bone has revealed exciting new insights into bone cell biology.•Single cell imaging provides new insight into the initiation of bone tumours.•Single cell RNA sequencing unravels complexities of the tumour-bone niche.
Many anticancer therapeutic agents cause bone loss, which increases the risk of fractures that severely reduce quality of life. Thus, in drug development, it is critical to identify and understand ...such effects. Anticancer therapeutic and HSP90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) causes bone loss by increasing osteoclast formation, but the mechanism underlying this is not understood. 17-AAG activates heat shock factor 1 (Hsf1), the master transcriptional regulator of heat shock/cell stress responses, which may be involved in this negative action of 17-AAG upon bone. Using mouse bone marrow and RAW264.7 osteoclast differentiation models we found that HSP90 inhibitors that induced a heat shock response also enhanced osteoclast formation, whereas HSP90 inhibitors that did not (including coumermycin A1 and novobiocin) did not affect osteoclast formation. Pharmacological inhibition or shRNAmir knockdown of Hsf1 in RAW264.7 cells as well as the use of Hsf1 null mouse bone marrow cells demonstrated that 17-AAG-enhanced osteoclast formation was Hsf1-dependent. Moreover, ectopic overexpression of Hsf1 enhanced 17-AAG effects upon osteoclast formation. Consistent with these findings, protein levels of the essential osteoclast transcription factor microphthalmia-associated transcription factor were increased by 17-AAG in an Hsf1-dependent manner. In addition to HSP90 inhibitors, we also identified that other agents that induced cellular stress, such as ethanol, doxorubicin, and methotrexate, also directly increased osteoclast formation, potentially in an Hsf1-dependent manner. These results, therefore, indicate that cellular stress can enhance osteoclast differentiation via Hsf1-dependent mechanisms and may significantly contribute to pathological and therapeutic related bone loss.
HSP90 inhibitors increase osteoclast formation and bone loss.
Altered Hsf1 activity impacts the ability of stress-inducing compounds to modulate osteoclast formation.
Hsf1 plays an important role in stress-associated osteoclast formation, potentially via MITF.
We identified a novel pathway whereby agents inducing stress can enhance osteoclast formation.
PDF
