Progranulin promotes melanoma progression by inhibiting natural killer cell recruitment to the tumor microenvironment Publication date: 28 November 2019 Source: Cancer Letters, Volume 465 Author(s): Ramouna Voshtani, Mei Song, Huan Wang, Xiaoqi Li, Wei Zhang, Mojdeh S. Tavallaie, Wenjun Yan, Joseph Sun, Fang Wei, Xiaojing Ma Abstract Progranulin (PGRN) is a growth factor with significant biological effects in different types of cancer. However, its role in melanoma progression has not been explored. In this study, we first analyze clinical datasets and show that high PGRN expression levels are correlated with poor prognosis of melanoma patients. Further, we demonstrate in a transplanted murine melanoma model in which the endogenous Grn gene encoding PGRN has been deleted that tumor-derived, not host-derived PGRN, promotes melanoma growth and metastasis. Immunological analyses reveal an enhanced infiltration of natural killer cells, but not T lymphocytes, into PGRN-deficient tumors compared to the wild type control. Antibody-mediated depletion confirms the critical role of NK cells in controlling B16 tumor growth. RNA-seq analysis reveals that several chemokines including CCL5 are strongly upregulated in PGRN-deficient tumor. Silencing CCL5 expression in PGRN-deficient tumor reduces NK cell recruitment and restores tumor growth to the control level. Lastly, we show that PGRN inhibits Ccl5 gene expression at the transcriptional level. This study highlights a novel and critical role of PGRN in melanoma growth and metastasis and suggests that it may represent a potential therapeutic target.

Concomitant targeting of Hedgehog signaling and MCL-1 synergistically induces cell death in Hedgehog-driven cancer cells Publication date: 28 November 2019 Source: Cancer Letters, Volume 465 Author(s): Michael Torsten Meister, Cathinka Boedicker, Benedikt Linder, Donat Kögel, Thomas Klingebiel, Simone Fulda Abstract In the present study, we show that concomitant inhibition of Hedgehog (HH) signaling by the Glioma-Associated Oncogene Homolog1 (GLI1)-targeting agent GANT61 and the antiapoptotic BCL-2 protein family member MCL-1 by A-1210477 synergistically induces cell death in HH-driven cancers, i.e. rhabdomyosarcoma (RMS) and medulloblastoma (MB) cells. Combined genetic and pharmacological inhibition emphasized that co-treatment of GANT61 and A-1210477 indeed relies on inhibition of GLI1 (by GANT61) and MCL-1 (by A-1210477). Mechanistic studies revealed that A-1210477 triggers the release of BIM from MCL-1 and its shuttling to BCL-xL and BCL-2. Indeed, BIM proved to be required for GANT61/A-1210477-induced cell death, as genetic silencing of BIM using siRNA significantly rescues cell death upon GANT61/A-1210477 co-treatment. Similarly, genetic silencing of NOXA results in a significant reduction of GANT61/A-1210477-mediated cell death. Also, overexpression of MCL-1 or BCL-2 significantly protects RMS cells from GANT61/A-1210477-triggered cell death. Addition of the pan-caspase inhibitor zVAD.fmk significantly decreases GANT61/A-1210477-stimulated cell demise, indicating apoptotic cell death. In conclusion, GANT61 and A-1210477 synergize to engage mitochondrial apoptosis. These findings provide the rationale for further evaluation of dual inhibition of HH signaling and MCL-1 in HH-driven cancer. Graphical abstract

MicroRNA-17 acts as a tumor chemosensitizer by targeting JAB1/CSN5 in triple-negative breast cancer Publication date: 28 November 2019 Source: Cancer Letters, Volume 465 Author(s): Sumei Wang, Do-Youn Oh, Vasiliki Leventaki, Elias Drakos, Ronghua Zhang, Aysegul A. Sahin, Erika Resetkova, Mary Elizabeth Edgerton, Wanyin Wu, Francois X. Claret Abstract Triple-negative breast cancer (TNBC) is the breast cancer subtype with the poorest prognosis. Evidence indicates that aberrant JAB1/CSN5 expression is associated with advanced tumor stage and poor prognosis in breast cancer. In this study, we evaluated expression of JAB1 in TNBC and potential mechanisms regulating this expression. We found that miR-17 expression was lower in TNBC than in normal breast tissue, and miR-17 expression in patients with TNBC was associated with a good prognosis. Furthermore, JAB1 expression was regulated by miR-17 in TNBC cells, and mice with miR-17-overexpressing tumors had less tumor growth and lower tumor JAB1 expression than control mice. We also demonstrated that miR-17 suppressed JAB1's oncogenic function, leading to tumor growth inhibition and sensitizing TNBC cells to chemotherapy treatment. JAB1 knockdown in TNBC cells mimicked the effect of miR-17 overexpression and led to significant decreases in cell proliferation, colony formation, and migration, increased p27 expression, and enhanced cisplatin sensitivity. Our findings suggest that miR-17 acts as a tumor suppressor by directly targeting JAB1 in TNBC; this may lead to novel therapeutic targets and strategies for treating TNBC patients.

Cullin7 enhances resistance to trastuzumab therapy in Her2 positive breast cancer via degrading IRS-1 and downregulating IGFBP-3 to activate the PI3K/AKT pathway Publication date: 1 November 2019 Source: Cancer Letters, Volume 464 Author(s): Ni Qiu, Yu-fang He, Si-ming Zhang, Yong-tao Zhan, Guo-dong Han, Ming Jiang, Wei-xing He, Jie Zhou, Hong-ling Liang, Xiang Ao, Hao-ming Xia, Jia Li, Yu-yang Yang, Zhi-min He, Zheng-zhi Zou, Hong-sheng Li Abstract Patients with Her2-positive breast cancer exhibit de novo resistance or develop acquired resistance in less than one year after Her2 targeting treatment, but the mechanism is not fully elucidated. Compensatory pathways such as the IGF-1R/IRS-1 pathway, are activated, leading to aberrant enhanced PI3K/Akt/mTOR pathway activity to attenuate the efficacy of trastuzumab. Cullin7 could participate in the degradation of IRS-1 in a mTOR/S6K dependent manner. Whether Cullin7 participates in trastuzumab resistance needs to be further investigated. Here, we reveals that Cullin7 is overexpressed in trastuzumab-resistant Her2 positive breast cancer cells. Knockdown of Cullin7 reduces degradation of Ser phosphorylation of IRS-1, attenuates activation of the PI3K/AKT pathway, and partly restores trastuzumab sensitivity in trastuzumab-resistant Her2 positive breast cancer cells. IGFBP-3 expression is decreased in trastuzumab-resistant Her2 positive breast cancer cells, which leads to release of the Wnt signaling pathway inhibition and an increase in Cullin7 expression, as mediated by TCF7L2. Overexpression of Cullin7 in Her2-amplified breast cancer tissues has clinical implications because it positively correlates with shorter disease-free survival (DFS) and inadequate response to trastuzumab. Thus, our results suggest a critical role for Cullin7 in response to trastuzumab, which has significant implications for selection of the optimal therapeutic strategy for Her2 positive breast cancers.

Downregulation of Epidermal Growth Factor Receptor in hepatocellular carcinoma facilitates Transforming Growth Factor-β-induced epithelial to amoeboid transition Publication date: 1 November 2019 Source: Cancer Letters, Volume 464 Author(s): Judit López-Luque, Esther Bertran, Eva Crosas-Molist, Oscar Maiques, Andrea Malfettone, Laia Caja, Teresa Serrano, Emilio Ramos, Victoria Sanz-Moreno, Isabel Fabregat Abstract The Epidermal Growth Factor Receptor (EGFR) and the Transforming Growth Factor-beta (TGF-β) are key regulators of hepatocarcinogenesis. Targeting EGFR was proposed as a promising therapy; however, poor success was obtained in human hepatocellular carcinoma (HCC) clinical trials. Here, we describe how EGFR is frequently downregulated in HCC patients while TGF-β is upregulated. Using 2D/3D cellular models, we show that after EGFR loss, TGF-β is more efficient in its pro-migratory and invasive effects, inducing epithelial to amoeboid transition. EGFR knock-down promotes loss of cell-cell and cell-to-matrix adhesion, favouring TGF-β-induced actomyosin contractility and acquisition of an amoeboid migratory phenotype. Moreover, TGF-β upregulates RHOC and CDC42 after EGFR silencing, promoting Myosin II in amoeboid cells. Importantly, low EGFR combined with high TGFB1 or RHOC/CDC42 levels confer poor patient prognosis. In conclusion, this work reveals a new tumour suppressor function for EGFR counteracting TGF-β-mediated epithelial to amoeboid transitions in HCC, supporting a rational for targeting the TGF-β pathway in patients with low EGFR expression. Our work also highlights the relevance of epithelial to amoeboid transition in human tumours and the need to better target this process in the clinic.

Cisplatin increases PD-L1 expression and optimizes immune check-point blockade in non-small cell lung cancer Publication date: 1 November 2019 Source: Cancer Letters, Volume 464 Author(s): Ludovic Fournel, Zherui Wu, Nicolas Stadler, Diane Damotte, Filippo Lococo, Geoffroy Boulle, Evelyne Ségal-Bendirdjian, Antonio Bobbio, Philippe Icard, Jean Trédaniel, Marco Alifano, Patricia Forgez Abstract The number of clinical protocols testing combined therapies including immune check-point inhibitors and platinum salts is currently increasing in lung cancer treatment, however preclinical studies and rationale are often lacking. Here, we evaluated the impact of cisplatin treatment on PD-L1 expression analyzing the clinicopathological characteristics of patients who received cisplatin-based neoadjuvant chemotherapy followed by surgery and showed that cisplatin-based induction treatment significantly increased PD-L1 staining in both tumor and immune cells from the microenvironment. Twenty-two patients exhibited positive PD-L1 staining variation after neoadjuvant chemotherapy; including 9 (23.1%) patients switching from <50% to ≥50% of stained tumor-cells. We also confirmed the up-regulation of PD-L1 by cisplatin, at both RNA and protein levels, in nude and immunocompetent mice bearing tumors grafted with A549, LNM-R, or LLC1 lung cancer cell lines. The combined administration of anti-PD-L1 antibodies (3 mg/kg) and cisplatin (1 mg/kg) to mice harboring lung carcinoma significantly reduced tumor growth compared to single agent treatments and controls. Overall, these results suggest that cisplatin treatment could synergize with PD-1/PD-L1 blockade to increase the clinical response, in particular through early and sustainable enhancement of PD-L1 expression.

Iron and lung cancer Publication date: 1 November 2019 Source: Cancer Letters, Volume 464 Author(s): Yanbin Kuang, Qi Wang Abstract Iron is an essential trace element in the human body, and its deficiency or excess induces diverse biological processes. Iron dysregulation is closely associated with the initiation and development of several malignant tumors, including lung cancer. Emerging evidence suggests a particularly important role for iron in lung cancer. Moreover, iron plays a prominent part in multiple forms of cell death, making it important for the development of potential strategies for lung cancer therapy. Here we review the function and characteristics of iron and new therapeutic opportunities in lung cancer.

Long non-coding RNAs in prostate cancer: Functional roles and clinical implications Publication date: 1 November 2019 Source: Cancer Letters, Volume 464 Author(s): Yun-Hua Xu, Jun-Li Deng, Guo Wang, Yuan-Shan Zhu Abstract Long noncoding RNAs (lncRNAs) are defined as RNA transcripts longer than 200 nucleotides that do not encode proteins. LncRNAs have been documented to exhibit aberrant expression in various types of cancer, including prostate cancer. Currently, screening for prostate cancer results in overdiagnosis. The consequent overtreatment of patients with indolent disease in the clinic is due to the lack of appropriately sensitive and specific biomarkers. Thus, the identification of lncRNAs as novel biomarkers and therapeutic targets for prostate cancer is promising. In the present review, we attempt to summarize the current knowledge of lncRNA expression patterns and mechanisms in prostate cancer. In particular, we focus on lncRNAs regulated by the androgen receptor and the specific molecular mechanism of lncRNAs in prostate cancer to provide a potential clinical therapeutic strategy for prostate cancer.

Keeping a clean research environment: Addressing research misconduct and improving scientific integrity in China Publication date: 1 November 2019 Source: Cancer Letters, Volume 464 Author(s): Lidong Wang, Zhihua Liu

Cancer stem cells in prostate cancer radioresistance Publication date: Available online 4 September 2019 Source: Cancer Letters Author(s): Tsao Tsing, Julia Beretov, Jie Ni, Xupeng Bai, Joseph Bucci, Peter Graham, Yong Li Abstract Cancer stem cells (CSCs) in prostate cancer (CaP) are regarded as major contributors to radioresistance due to complex mechanisms including enhanced DNA repair, increased intracellular reactive oxygen species scavenging, activation of anti-apoptotic pathways, microenvironment hypoxia, epithelial-to-mesenchymal transition (EMT) and autophagy. They are also believed to cause tumour recurrence and metastasis due to their unique capability to survive and replicate the heterogeneity of the original tumour. Finding markers of prostate CSCs (PCSC) for identification, prognostication and targeting is key in enhancing therapeutic and clinical outcomes. Markers such as aldehyde dehydrogenase, CD44, integrins and EMT markers been proved to show great potential in being sensitive and specific to the presence of PCSCs. Novel therapies such as Hedgehog and Wnt pathway inhibitors, angiogenesis inhibitors and metformin show potential in eliminating PCSCs to improve therapeutic outcomes. Here, we review the current state of the literature regarding mechanisms of PCSC radioresistance, promising PCSC markers and novel PCSC-specific therapeutic approaches and their implications in CaP treatment and prognosis.