Liver cancer remains difficult to treat, owing to a paucity of drugs that target critical dependencies
; broad-spectrum kinase inhibitors such as sorafenib provide only a modest benefit to patients ...with hepatocellular carcinoma
. The induction of senescence may represent a strategy for the treatment of cancer, especially when combined with a second drug that selectively eliminates senescent cancer cells (senolysis)
. Here, using a kinome-focused genetic screen, we show that pharmacological inhibition of the DNA-replication kinase CDC7 induces senescence selectively in liver cancer cells with mutations in TP53. A follow-up chemical screen identified the antidepressant sertraline as an agent that kills hepatocellular carcinoma cells that have been rendered senescent by inhibition of CDC7. Sertraline suppressed mTOR signalling, and selective drugs that target this pathway were highly effective in causing the apoptotic cell death of hepatocellular carcinoma cells treated with a CDC7 inhibitor. The feedback reactivation of mTOR signalling after its inhibition
is blocked in cells that have been treated with a CDC7 inhibitor, which leads to the sustained inhibition of mTOR and cell death. Using multiple in vivo mouse models of liver cancer, we show that treatment with combined inhibition of of CDC7 and mTOR results in a marked reduction of tumour growth. Our data indicate that exploiting an induced vulnerability could be an effective treatment for liver cancer.
Cellular senescence is characterized as a stable proliferation arrest that can be triggered by multiple stresses. Most knowledge about senescent cells is obtained from studies in primary cells. ...However, senescence features may be different in cancer cells, since the pathways that are involved in senescence induction are often deregulated in cancer. We report here a comprehensive analysis of the transcriptome and senolytic responses in a panel of 13 cancer cell lines rendered senescent by two distinct compounds. We show that in cancer cells, the response to senolytic agents and the composition of the senescence-associated secretory phenotype are more influenced by the cell of origin than by the senescence trigger. Using machine learning, we establish the SENCAN gene expression classifier for the detection of senescence in cancer cell samples. The expression profiles and senescence classifier are available as an interactive online Cancer SENESCopedia.
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•Senescent cancer cells respond differently to senolytic ABT-263•SASP expression in cancer is heterogeneous and influenced by cell origin•The SENCAN classifier detects cancer cell senescence in vitro•The Cancer SENESCopedia contains transcriptome data from 37 senescence models
Jochems et al. define common vulnerabilities of senescent cancer cells and shared features for the unequivocal detection of cancer cell senescence. Comprehensive analysis in a cancer cell panel reveals the context dependency of cancer cell senescence and allows the establishment of a SENCAN classifier to detect cancer cell senescence.
Senescence is a proliferation arrest that can result from a variety of stresses. Cancer cells can also undergo senescence, but the stresses that provoke cancer cells to undergo senescence are ...unclear. Here, we use both functional genetic and compound screens in cancer cells harboring a reporter that is activated during senescence to find targets that induce senescence. We show that suppression of the SWI/SNF component SMARCB1 induces senescence in melanoma through strong activation of the MAP kinase pathway. From the compound screen, we identified multiple aurora kinase inhibitors as potent inducers of senescence in RAS mutant lung cancer. Senescent melanoma and lung cancer cells acquire sensitivity to the BCL2 family inhibitor ABT263. We propose a one-two punch approach for the treatment of cancer in which a drug is first used to induce senescence in cancer cells and a second drug is then used to kill senescent cancer cells.
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•CRISPR and chemical screens identify senescence inducers in cancer cells•SMARCB1 knockout induces senescence in melanoma•Aurora kinase inhibition induces senescence in multiple cancer types•Senescent cancer cells become vulnerable to killing by ABT263
Wang et al. find that CRISPR-mediated genetic screens and chemical screens serve as two types of high-throughput methods to identify senescence inducers in cancer cells. They also show that senescent cancer cells can be killed selectively by the BCL2-family inhibitor ABT263, providing a potential sequential drug treatment strategy for cancer.
The establishment of a functional, integrated vascular system is instrumental for tissue growth and homeostasis. Without blood vessels no adequate nutrition and oxygen would be provided to cells, nor ...could the undesired waste products be efficiently removed. Blood vessels constitute therefore one of the largest and most complex body network whose assembly depends on the precise balance of growth factors acting in a complementary and coordinated manner with cells of several identities. However, the vessels that are crucial for life can also foster death, given their involvement in cancer progression towards malignancy and metastasis. Targeting tumor vasculature has thus arisen as an appealing anti-cancer therapeutic approach. Since the milestone achievements that vascular endothelial growth factor (VEGF) blockade suppressed angiogenesis and tumor growth in mice and prolonged the survival of cancer patients when administered in combination with chemotherapy, the clinical development of anti-VEGF(R) drugs has accelerated remarkably. FDA has approved the use of bevacizumab – a humanized monoclonal antibody against VEGF – in colorectal, lung and metastatic breast cancers in combination with standard chemotherapy. Additional broad-spectrum VEGF receptor tyrosine kinase inhibitors, such as sunitinib and sorafenib, are used in monotherapy for metastatic renal carcinoma, while sunitinib is also approved for imatinib resistant gastrointestinal stromal tumors and sorafenib for advanced stage hepatocellular carcinoma. Nevertheless, the survival benefit offered by VEGF(R) blockers, either as single agents or in combination with chemotherapy, is calculated merely in the order of months. Posterior studies in preclinical models have reported that despite reducing primary tumor growth, the inhibition of VEGF increased tumor invasiveness and metastasis. The clinical implications of these findings urge the need to reconcile these conflicting results. Anti-angiogenic therapy represents a significant step forth in cancer therapy and in our understanding of cancer biology, but it is also clear that we need to learn how to use it. What is the biological consequence of VEGF-blockade? Does VEGF inhibition starve the tumor to death – as initially postulated – or does it rather foster malignancy? Can anti-VEGF(R) therapy favor tumor vessel formation by VEGF-independent means? Tumors are very diverse and plastic entities, able to adapt to the harshest conditions; this is also reflected by the tumor vasculature. Lessons from the bench to the bedside and vice versa have taught us that the diversity of signals underlying tumor vessel growth will likely be responsive (or resistant) to distinct therapeutic approaches. In this review, we propose a reflection of the different strategies tumors use to grow blood vessels and how these can have impact on the (un)success of current anti-angiogenic therapies.
PHD2 serves as an oxygen sensor that rescues blood supply by regulating vessel formation and shape in case of oxygen shortage. However, it is unknown whether PHD2 can influence arteriogenesis. Here ...we studied the role of PHD2 in collateral artery growth by using hindlimb ischaemia as a model, a process that compensates for the lack of blood flow in case of major arterial occlusion. We show that Phd2 (also known as Egln1) haplodeficient (Phd2(+/-)) mice displayed preformed collateral arteries that preserved limb perfusion and prevented tissue necrosis in ischaemia. Improved arteriogenesis in Phd2(+/-) mice was due to an expansion of tissue-resident, M2-like macrophages and their increased release of arteriogenic factors, leading to enhanced smooth muscle cell (SMC) recruitment and growth. Both chronic and acute deletion of one Phd2 allele in macrophages was sufficient to skew their polarization towards a pro-arteriogenic phenotype. Mechanistically, collateral vessel preconditioning relied on the activation of canonical NF-κB pathway in Phd2(+/-) macrophages. These results unravel how PHD2 regulates arteriogenesis and artery homeostasis by controlling a specific differentiation state in macrophages and suggest new treatment options for ischaemic disorders.
Abstract Activating mutations and translocations of the FGFR3 gene are commonly seen in urothelial cell carcinoma (UCC) of the bladder and urinary tract. Several fibroblast growth factor receptor ...(FGFR) inhibitors are currently in clinical development and response rates appear promising for advanced UCC. A common problem with targeted therapeutics is intrinsic or acquired resistance of the cancer cells. To find potential drug targets that can act synergistically with FGFR inhibition, we performed a synthetic lethality screen for the FGFR inhibitor AZD4547 using a short hairpin RNA library targeting the human kinome in the UCC cell line RT112 ( FGFR3 - TACC3 translocation). We identified multiple members of the phosphoinositide 3-kinase (PI3K) pathway and found that inhibition of PIK3CA acts synergistically with FGFR inhibitors. The PI3K inhibitor BKM120 acted synergistically with inhibition of FGFR in multiple UCC and lung cancer cell lines having FGFR mutations. Consistently, we observed an elevated PI3K-protein kinase B pathway activity resulting from epidermal growth factor receptor or Erb-B2 receptor tyrosine kinase 3 reactivation caused by FGFR inhibition as the underlying molecular mechanism of the synergy. Our data show that feedback pathways activated by FGFR inhibition converge on the PI3K pathway. These findings provide a strong rationale to test FGFR inhibitors in combination with PI3K inhibitors in cancers harboring genetic activation of FGFR genes.
Inducing senescence in cancer cells is emerging as a new therapeutic strategy. In order to find ways to enhance senescence induction by palbociclib, a CDK4/6 inhibitor approved for treatment of ...metastatic breast cancer, we performed functional genetic screens in palbociclib-resistant cells. Using this approach, we found that loss of CDK2 results in strong senescence induction in palbociclib-treated cells. Treatment with the CDK2 inhibitor indisulam, which phenocopies genetic CDK2 inactivation, led to sustained senescence induction when combined with palbociclib in various cell lines and lung cancer xenografts. Treating cells with indisulam led to downregulation of cyclin H, which prevented CDK2 activation. Combined treatment with palbociclib and indisulam induced a senescence program and sensitized cells to senolytic therapy. Our data indicate that inhibition of CDK2 through indisulam treatment can enhance senescence induction by CDK4/6 inhibition.
The success of chemotherapy in cancer treatment is limited by scarce drug delivery to the tumor and severe side-toxicity. Prolyl hydroxylase domain protein 2 (PHD2) is an oxygen/redox-sensitive ...enzyme that induces cellular adaptations to stress conditions. Reduced activity of PHD2 in endothelial cells normalizes tumor vessels and enhances perfusion. Here, we show that tumor vessel normalization by genetic inactivation of Phd2 increases the delivery of chemotherapeutics to the tumor and, hence, their antitumor and antimetastatic effect, regardless of combined inhibition of Phd2 in cancer cells. In response to chemotherapy-induced oxidative stress, pharmacological inhibition or genetic inactivation of Phd2 enhances a hypoxia-inducible transcription factor (HIF)-mediated detoxification program in healthy organs, which prevents oxidative damage, organ failure, and tissue demise. Altogether, our study discloses alternative strategies for chemotherapy optimization.
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► Combined loss of Phd2 in stromal and cancer cells sensitizes tumors to chemotherapy ► Loss of Phd2 protects healthy organs against chemotherapy-induced oxidative damage ► Loss of Phd2 in healthy organs unleashes a HIF-mediated anti-oxidative response
Pancreatic ductal adenocarcinoma (PDAC) is characterized by abundant stroma, the main cellular constituents of which are cancer‐associated fibroblasts (CAFs). Stroma‐targeting agents have been ...proposed to improve the poor outcome of current treatments. However, clinical trials using these agents showed disappointing results. Heterogeneity in the PDAC CAF population was recently delineated demonstrating that both tumor‐promoting and tumor‐suppressive activities co‐exist in the stroma. Here, we aimed to identify biomarkers for the CAF population that contribute to a favorable outcome. RNA‐sequencing reads from patient‐derived xenografts (PDXs) were mapped to the human and mouse genome to allocate the expression of genes to the tumor or stroma. Survival meta‐analysis for stromal genes was performed and applied to human protein atlas data to identify circulating biomarkers. The candidate protein was perturbed in co‐cultures and assessed in existing and novel single‐cell gene expression analysis from control, pancreatitis, pancreatitis‐recovered and PDAC mouse models. Serum levels of the candidate biomarker were measured in two independent cohorts totaling 148 PDAC patients and related them to overall survival. Osteoglycin (OGN) was identified as a candidate serum prognostic marker. Single‐cell analysis indicated that Ogn is derived from a subgroup of inflammatory CAFs. Ogn‐expressing fibroblasts are distinct from resident healthy pancreatic stellate cells and arise during pancreatitis. Serum OGN levels were prognostic for favorable overall survival in two independent PDAC cohorts (HR = 0.47, P = .042 and HR = 0.53, P = .006). Altogether, we conclude that high circulating OGN levels inform on a previously unrecognized subgroup of CAFs and predict favorable outcomes in resectable PDAC.
What's new?
The heterogeneity of cancer‐associated fibroblasts (CAFs) in pancreatic ductal adenocarcinoma (PDAC) with both tumor‐promoting and tumor‐suppressive properties has recently been recognized. Our study identifies osteoglycin as a distinct marker for an inflammatory and tumor‐suppressive CAF subpopulation. The favorable prognostic significance of high serum osteoglycin levels was observed in a cohort of 40 patients with resected PDAC and further validated in a nationwide multicenter cohort of 108 patients. The findings point to osteoglycin as a potential noninvasive biomarker that not only predicts favorable clinical outcomes but also distinguishes a novel CAFs subtype.
Cellular senescence is a natural safeguard against cancer. Pharmacologically, it can be induced by drugs that inhibit the CDK4/6 kinases such as palbociclib, but the exact mechanism has never been ...dissected. Recent research by Miettinen et al () reveals that senescence induced by this class of drugs is mediated by proteasome hyper‐activation.
New findings implicate ECM29‐dependent proteasome hyperactivation in senescence induced by the anti‐breast cancer drug palbociclib.
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