GDF15 predict platinum response during first-line chemotherapy and can act as a complementary diagnostic serum biomarker with CA125 in epithelial ovarian cancer

Potential tools for predicting response to chemotherapy in OC: Assessment of immune dysbiosis, participant's self-rated health and microbial dynamics

Epithelial ovarian cancer (OC) is the deadliest female reproductive cancer; an estimated 13,270 women will die from OC in 2023. Platinum-based chemotherapy resistance mechanisms contribute to poor OC 5-year survival rates. Peripheral inflammation is linked to various disease states and we previously identified unique peritoneal microbial features predictive of OC. We hypothesized that unique peripheral immune profiles and peritoneal microbial features may be predictive of disease-free interval (time to recurrence) and response to chemotherapy in participants with OC. We also investigated self-rated health (SRH) scores in the context of peripheral inflammation as a potential screening tool for OC. Blood and peritoneal fluid were collected from participants with OC or a benign adnexal mass (BPM). Lymphocyte populations were analyzed using Fluorescence Activated Cell Sorting, serum cytokine levels were analyzed using the Human Th17 Magnetic Bead Panel assay and peritoneal fluid microbial features were analyzed using Next Generation Sequencing (NGS). Participants completed a standardized questionnaire on self-rated physical and emotional health. Participants were classified into three chemotherapy response categories: platinum-refractory, platinum-resistant or platinum-sensitive. A significant positive correlation was found between elevated inflammatory status on the day of surgery and longer disease-free interval. SRH measures did not correlate with immune status in participants with OC or a BPM. We identified a correlation between peritoneal microbial features and chemotherapy response. We conclude that immune dysbiosis may be useful in predicting OC recurrence. The immune findings reported here set the framework for additional studies utilizing immune profiles to predict platinum-based chemotherapy responsiveness in OC.

GPX3 supports ovarian cancer tumor progression in vivo and promotes expression of GDF15

OBJECTIVE

We previously reported that high expression of the extracellular glutathione peroxidase GPX3 is associated with poor patient outcome in ovarian serous adenocarcinomas, and that GPX3 protects ovarian cancer cells from oxidative stress in culture. Here we tested if GPX3 is necessary for tumor establishment in vivo and to identify novel downstream mediators of GPX3's pro-tumorigenic function.

METHODS

GPX3 was knocked-down in ID8 ovarian cancer cells by shRNA to test the role of GPX3 in tumor establishment using a syngeneic IP xenograft model. RNA sequencing analysis was carried out in OVCAR3 cells following shRNA-mediated GPX3 knock-down to identify GPX3-dependent gene expression signatures.

RESULTS

GPX3 knock-down abrogated clonogenicity and intraperitoneal tumor development in vivo, and the effects were dependent on the level of GPX3 knock-down. RNA sequencing showed that loss of GPX3 leads to decreased gene expression patterns related to pro-tumorigenic signaling pathways. Validation studies identified GDF15 as strongly dependent on GPX3. GDF15, a member of the TGF-β growth factor family, has known oncogenic and immune modulatory activities. Similarly, GPX3 expression positively correlated with pro-tumor immune cell signatures, including regulatory T-cell and macrophage infiltration, and displayed significant correlation with PD-L1 expression.

CONCLUSIONS

We show for the first time that tumor produced GPX3 is necessary for ovarian cancer growth in vivo and that it regulates expression of GDF15. The immune profile associated with GPX3 expression in serous ovarian tumors suggests that GPX3 may be an alternate marker of ovarian tumors susceptible to immune check-point inhibitors.

GDF15 induces chemoresistance to oxaliplatin by forming a reciprocal feedback loop with Nrf2 to maintain redox homeostasis in colorectal cancer

PURPOSE

Growth differentiating Factor 15 (GDF15) is linked to several cancers, but its effect on chemoresistance in colorectal cancer (CRC) remains unclear. Here, we investigated the role of GDF15 in the chemotherapeutic response of CRC patients to oxaliplatin (L-OHP).

METHODS

GDF15 levels in serum and tumour tissues were detected in CRC patients have received L-OHP-based neoadjuvant chemotherapy. The effects of GDF15 neutralization or GDF15 knockdown on cell proliferation, apoptosis and intracellular reactive oxygen species (ROS) levels were analysed in vitro and in vivo. Co-immunoprecipitation (Co-IP), Chromatin Immunoprecipitation (ChIP) and luciferase reporter assays were used to explore the interaction between GDF15 and Nrf2.

RESULTS

In this study, we found that GDF15 alleviates oxidative stress to induce chemoresistance of L-OHP in CRC. Mechanically, GDF15 posttranscriptionally regulates protein stability of Nrf2 through the canonical PI3K/AKT/GSK3β signaling pathway, and in turn, Nrf2 acts as a transcription factor to regulate GDF15 expression to form a positive feedback loop, resulting in the maintenance of redox homeostasis balance in CRC. Furthermore, a positive correlation between GDF15 and Nrf2 was observed in clinical CRC samples, and simultaneous overexpression of both GDF15 and Nrf2 was associated with poor prognosis in CRC patients treated with L-OHP. Simultaneous inhibition of both GDF15 and Nrf2 significantly increases the response to L-OHP in an L-OHP-resistant colorectal cancer cells-derived mouse xenograft model.

CONCLUSION

This study identified a novel GDF15-Nrf2 positive feedback loop that drives L-OHP resistance and suggested that the GDF15-Nrf2 axis is a potential therapeutic target for the treatment of L-OHP-resistant CRC.

GPX3 supports ovarian cancer tumor progression in vivo and promotes expression of GDF15

Objective

We previously reported that high expression of the extracellular glutathione peroxidase GPX3 is associated with poor patient outcome in ovarian serous adenocarcinomas, and that GPX3 protects ovarian cancer cells from oxidative stress in culture. Here we tested if GPX3 is necessary for tumor establishment in vivo and to identify novel downstream mediators of GPX3's pro-tumorigenic function.

Methods

GPX3 was knocked-down in ID8 ovarian cancer cells by shRNA to test the role of GPX3 in tumor establishment using a syngeneic IP xenograft model. RNA sequencing analysis was carried out in OVCAR3 cells following shRNA-mediated GPX3 knock-down to identify GPX3-dependent gene expression signatures.

Results

GPX3 knock-down abrogated clonogenicity and intraperitoneal tumor development in vivo, and the effects were dependent on the level of GPX3 knock-down. RNA sequencing showed that loss of GPX3 leads to decreased gene expression patterns related to pro-tumorigenic signaling pathways. Validation studies identified GDF15 as strongly dependent on GPX3. GDF15, a member of the TGF-β growth factor family, has known oncogenic and immune modulatory activities. Similarly, GPX3 expression positively correlated with pro-tumor immune cell signatures, including regulatory T-cell and macrophage infiltration, and displayed significant correlation with PD-L1 expression.

Conclusions

We show for the first time that tumor produced GPX3 is necessary for ovarian cancer growth in vivo and that it regulates expression of GDF15. The immune profile associated with GPX3 expression in serous ovarian tumors suggests that GPX3 may be an alternate marker of ovarian tumors susceptible to immune check-point inhibitors.

VCAM-1 complements CA-125 in detecting recurrent ovarian cancer

BACKGROUND

Close to three-quarters of ovarian cancer cases are frequently diagnosed at an advanced stage, with more than 70% of them failing to respond to primary therapy and relapsing within 5 years. There is an urgent need to identify strategies for early detection of ovarian cancer recurrence, which may lead to earlier intervention and better outcomes.

METHODS

A customized magnetic bead-based 8-plex immunoassay was evaluated using a Bio-Plex 200 Suspension Array System. Target protein levels were analyzed in sera from 58 patients diagnosed with advanced ovarian cancer (including 34 primary and 24 recurrent tumors) and 46 healthy controls. The clinical performance of these biomarkers was evaluated individually and in combination for their ability to detect recurrent ovarian cancer.

RESULTS

An 8-plex immunoassay was evaluated with high analytical performance suitable for biomarker validation studies. Logistic regression modeling selected a two-marker panel of CA-125 and VCAM-1 that improved the performance of CA-125 alone in detecting recurrent ovarian cancer (AUC: 0.813 versus 0.700). At a fixed specificity of 83%, the two-marker panel significantly improved sensitivity in separating primary from recurrent tumors (70.8% versus 37.5%, P = 0.004), demonstrating that VCAM-1 was significantly complementary to CA-125 in detecting recurrent ovarian cancer.

CONCLUSIONS

A two-marker panel of CA-125 and VCAM-1 showed strong diagnostic performance and improvement over the use of CA-125 alone in detecting recurrent ovarian cancer. The experimental results warrant further clinical validation to determine their role in the early detection of recurrent ovarian cancer.

Growth differentiation factor 15 is required for triple-negative breast cancer cell growth and chemoresistance

Growth differentiation factor 15 (GDF15) is a pleiotropic cytokine, which is involved in the cellular stress response following acute damage. However, the functional role of GDF15 in triple-negative breast cancer (TNBC) has not been fully elucidated. ELISA, Western blot, and PCR assays as well as bioinformatics analyses were conducted to observe the expression of GDF15. Cell Counting Kit-8, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet staining assays were conducted to evaluate paclitaxel resistance and cell viability. Cell apoptosis was analyzed by Western blotting. Murine xenograft model assay was employed to evaluate tumor growth in vivo . Our data indicate that GDF15 is markedly elevated in paclitaxel-resistant TNBC cells, which is significantly associated with unfavorable prognosis. Silencing of GDF15 robustly inhibits the proliferation of tumor cells and increases their sensitivity to paclitaxel in vitro and in vivo , whereas the treatment of purified GDF15 protein confers breast cancer cells with chemoresistance ability. Moreover, GDF15 activates protein kinase B (AKT) /mammalian target of rapamycin (mTOR) signaling, inhibition of AKT or mTOR reverses the prosurvival effect of GDF15 and enhances the antitumor efficacy of paclitaxel in TNBC cells. Altogether, our study uncovers the role of GDF15 in tumor growth and paclitaxel resistance, implicating a potential therapeutic target for TNBC.

Plasma GDF15 levels associated with circulating immune cells predict the efficacy of PD-1/PD-L1 inhibitor treatment and prognosis in patients with advanced non-small cell lung cancer

PURPOSE

Although increased plasma growth differentiation factor-15 (GDF15) levels have been reported in patients with various cancers, the predictive role of PD-1/PD-L1 inhibitors in advanced cancers remains unknown. This study aimed to investigate GDF15 levels as a predictive marker in advanced non-small cell lung cancer (NSCLC) treated with PD-1/PD-L1 inhibitors and analyze their association with immune cell populations.

METHODS

This study included 87 patients with advanced NSCLC receiving anti-PD-1/PD-L1 inhibitors between March 2018 and May 2020. Blood samples were obtained immediately before and months after PD-1/PD-L1 inhibitor administration.

RESULTS

The objective response rate (ORR) was significantly higher in the low GDF15 than in the high GDF15 group (39.2% vs. 15.3%, P = 0.013). The median progression-free survival (PFS) was significantly longer in the low GDF15 than in the high GDF15 group (13.2 [95% CI 7.6-18.9] vs. 7.2 [95% CI 4.8-9.6] months, P = 0.048). Moreover, plasma GDF15 levels negatively correlated with PD-1⁺/CD8⁺ T cells (r = - 0.399, P = 0.003) and positively with PD-1⁺/Treg cells (r = 0.507, P < 0.001) and PD-1⁺Treg/CD4⁺ T cells (r = 0.439, P < 0.001). The ORR was significantly higher in the group with decreased GDF15 from baseline than in the increased GDF15 group (37.2% vs. 10.0%, P = 0.026). The median PFS was significantly longer in the decreased GDF15 group (14.8 [95% CI 10.4-19.2] vs. 5.9 [95% CI 2.8-9.0] months, P = 0.002). Plasma GDF15 levels were associated with PD-1⁺CD8⁺ T cells and PD-1⁺ Treg cells.

CONCLUSION

Plasma GDF15 could be a potential biomarker for predicting the efficacy and survival benefit of immunotherapy in advanced NSCLC.

GDF15 negatively regulates chemosensitivity via TGFBR2-AKT pathway-dependent metabolism in esophageal squamous cell carcinoma

Treating patients with esophageal squamous cell carcinoma (ESCC) is challenging due to the high chemoresistance. Growth differentiation factor 15 (GDF15) is crucial in the development of various types of tumors and negatively related to the prognosis of ESCC patients according to our previous research. In this study, the link between GDF15 and chemotherapy resistance in ESCC was further explored. The relationship between GDF15 and the chemotherapy response was investigated through in vitro and in vivo studies. ESCC patients with high levels of GDF15 expression showed an inferior chemotherapeutic response. GDF15 improved the tolerance of ESCC cell lines to low-dose cisplatin by regulating AKT phosphorylation via TGFBR2. Through an in vivo study, we further validated that the anti-GDF15 antibody improved the tumor inhibition effect of cisplatin. Metabolomics showed that GDF15 could alter cellular metabolism and enhance the expression of UGT1A. AKT and TGFBR2 inhibition resulted in the reversal of the GDF15-induced expression of UGT1A, indicating that TGFBR2-AKT pathway-dependent metabolic pathways were involved in the resistance of ESCC cells to cisplatin. The present investigation suggests that a high level of GDF15 expression leads to ESCC chemoresistance and that GDF15 can be targeted during chemotherapy, resulting in beneficial therapeutic outcomes.

Growth Differentiation Factor-15 as a candidate biomarker in gynecologic malignancies: A meta-analysis

Growth Differentiation Factor-15 (GDF-15), though emerged as a novel marker in gynecological cancers, is yet to be recognized in clinical diagnostics. Eligible studies were sorted from multiple online databases, namely PubMed, Cochrane, ClinicalTrials.gov, Google Scholar, Web of Science, Embase, Scopus, LILACS, Opengrey. From six studies, histopathologically diagnosed cases without prior treatment, and with diagnostic accuracy data for GDF-15 in gynecological cancers, were included. Our meta-analysis shows that GDF-15 has pooled diagnostic odds ratio of 12.74 at 80.5% sensitivity and 74.1% specificity, and an AUC of 0.84. Hence, GDF-15 is a potential marker to differentiate gynecological malignancy from non-malignant tumors.

Macrophage inhibitory cytokine-1 in cancer: Beyond the cellular phenotype

Despite technological advances in diagnostic abilities and improved treatment methods, the burden of cancers remains high, leading to significant morbidity and mortality. One primary reason is that cancer cell secretory factors modulate the tumor microenvironment, supporting tumor growth and circumvents anticancer activities of conventional therapies. Macrophage inhibitory cytokine-1 (MIC-1) is a pleiotropic cytokine elevated in various cancers. MIC-1 regulates various cancer hallmarks, including sustained proliferation, tumor-promoting inflammation, avoiding immune destruction, inducing invasion, metastasis, angiogenesis, and resisting cell death. Despite these facts, the molecular regulation and downstream signaling of MIC-1 in cancer remain elusive, partly because its receptor (GFRAL) was unknown until recently. Binding of MIC-1 to GFRAL recruits the coreceptor tyrosine kinase RET to execute its downstream signaling. So far, studies have shown that GFRAL expression is restricted to the brain stem and is responsible for MIC-1/GFRAL/RET-mediated metabolic disorders. Nevertheless, abundant levels of MIC-1 expression have been reported in all cancer types and have been proposed as a surrogate biomarker. Given the ubiquitous expression of MIC-1 in cancers, it is crucial to understand both upstream regulation and downstream MIC-1/GFRAL/RET signaling in cancer hallmark traits.

GDF15 Is an Eribulin Response Biomarker also Required for Survival of DTP Breast Cancer Cells

Simple Summary

Drug tolerant persister (DTP) cells are a unique, small sub-population of cancer cells that maintain viability under anti-cancer cytotoxic treatments. These cells enter into a reversible drug-tolerant state, which is believed to be the root of tumor recurrence. Therefore, there is a great need to find novel ways to monitor and eliminate DTP cells. We have identified the secretion of GDF15 as a response biomarker of eribulin treatment, as well as a specific biomarker of DTP cells in breast cancer. GDF15 expression is low or absent in cells sensitive to eribulin, strongly upregulated during response to the drug, and then downregulated when stable resistance is ultimately established. We have also shown that GDF15 plays a direct role in the survival of DTP cells. Thus, targeting GDF15 could help eradicate DTP cells and block the onset of stable acquired resistance. Most importantly, our data suggest that the combination of eribulin plus a GDF15 neutralizing antibody might be beneficial in the treatment of breast cancer.

Abstract

Drug tolerant persister (DTP) cells enter into a reversible slow-cycling state after drug treatment. We performed proteomic characterization of the breast cancer (BC) DTP cell secretome after eribulin treatment. We showed that the growth differentiation factor 15 (GDF15) is a protein significantly over-secreted upon eribulin treatment. The biomarker potential of GDF15 was confirmed in 3D-cell culture models using BC cells lines and PDXs, as well as in a TNBC in vivo model. We also found that GDF15 is required for survival of DTP cells. Direct participation of GDF15 and its receptor GFRAL in eribulin-induction of DTPs was established by the enhanced cell killing of DTPs by eribulin seen under GDF15 and GFRAL loss of function assays. Finally, we showed that combination therapy of eribulin plus an anti-GDF15 antibody kills BC-DTP cells. Our results suggest that targeting GDF15 may help eradicate DTP cells and block the onset of acquired resistance.

Growth differentiation factor-15 for prediction of bleeding in cancer patients

BACKGROUND

Growth differentiation factor-15 (GDF-15) is a strong predictor for bleeding in patients with atrial fibrillation, but there are no data on cardiovascular outcomes for this biomarker in cancer patients. Bleeding risk assessment is important in cancer patients when considering primary thromboprophylaxis because it is associated with an increased bleeding risk.

OBJECTIVES

To evaluate GDF-15 as predictor for bleeding events in cancer patients previously enrolled in the AVERT trial.

PATIENTS/METHODS

In this trial, 574 participants were randomized to prophylactic apixaban or placebo and followed for 180 days for venous thromboembolism, major bleeding, clinically relevant nonmajor bleeding, and any bleeding. Plasma concentrations of GDF-15 were measured centrally with the Elecsys GDF-15 commercial assay kit (Roche Diagnostics GmbH).

RESULTS

In apixaban recipients, the area under the receiver operator characteristic curve of GDF-15 for major bleeding was 0.73 (95% confidence interval [CI], 0.44-1.00). Compared with the lowest GDF-15 tertile (<1470 ng/L), major bleeding risk was significantly higher in the highest tertile (≥2607 ng/L; hazard ratio [HR] 3.19; 95% CI, 2.41-4.22), also when adjusting for sex, age, antiplatelet use, and gastrointestinal cancer (adjusted HR 2.80; 95% CI, 1.91-4.11). GDF-15 was also significantly associated with clinically relevant nonmajor bleeding (adjusted HR 1.67; 95% CI, 1.08-2.58) and any bleeding (adjusted HR 2.12; 95% CI, 1.38-3.25).

CONCLUSIONS

Although hypothesis generating, this is the first study to show that GDF-15 predicts bleeding in cancer patients receiving thromboprophylaxis.

A Combined Analysis of Serum Growth Differentiation Factor-15 and Cancer Antigen 15-3 Enhances the Diagnostic Efficiency in Breast Cancer

INTRODUCTION

Existing diagnostic biomarkers of breast cancer (BC) are limited by poor sensitivity. In this study, we evaluated the role of serum GDF-15 in early BC diagnosis, independently and in combination with CA15-3, a known blood biomarker of BC.

MATERIAL AND METHODS

A total of 113 diagnosed, pre-therapy BC patients and 54 healthy controls were recruited. Clinical characteristics, TNM staging, and hormone receptor status of the patients were recorded. Serum GDF-15 and serum CA15-3 were measured by sandwich ELISA and chemiluminescence assay, respectively.

RESULTS

The serum GDF-15 levels were significantly (p<0.001) elevated in BC patients compared to healthy controls and in patients with larger tumor size, advanced disease stage, and distant metastasis. ROC analysis revealed that at the cut-off of 525.77 pg/mL, GDF-15 had greater sensitivity than CA15-3. GDF-15 and CA15-3 performed better in combination than individually, with the combined test having an AUC of 0.85 and sensitivity and specificity of 0.63 and 0.98, respectively.Further, serum GDF-15 had a better predictive ability for early-stage BC compared to CA15-3. GDF-15 could independently diagnose BC patients after adjusting for age.

CONCLUSION

We conclude that serum GDF-15 is a promising, robust marker for detecting early-stage BC. However, larger prospective studies are necessary to validate this claim.

Predictive and prognostic impact of ferroptosis-related genes ACSL4 and GPX4 on breast cancer treated with neoadjuvant chemotherapy

BACKGROUND

Recent evidence shows that inducing ferroptosis may improve efficacy of tumor therapy. However, ferroptosis-related genes have been little studied in patients with breast cancer especially in the neoadjuvant setting. ACSL4 and GPX4 have been well established as the positive and negative regulator of ferroptosis, respectively. This study aimed to explore the predictive value of ACSL4 and GPX4 for patients with breast cancer administered neoadjuvant chemotherapy.

METHODS

This study included patients treated with paclitaxel-cisplatin-based neoadjuvant chemotherapy. Immunohistochemistry staining of ACSL4 and GPX4 was carried out on the core needle biopsy specimens. Logistic regression was performed to explore the predictive biomarkers of pathological complete response (pCR). Survival analyses were examined by log-rank test and Cox proportional hazard regression.

FINDINGS

A total of 199 patients were included for the analyses. Both ACSL4 expression and ACSL4/GPX4 combination status could serve as independent predictive factors for pCR. The interaction for pCR was observed between ACSL4 and clinical tumor stage. Besides, ACSL4 expression, GPX4 expression, and their combination status were independent prognostic factors for disease-free survival. Analyses of the Kaplan-Meier Plotter database suggested that higher ACSL4 expression is related to better overall survival, and higher GPX4 expression is related to better distant metastasis-free survival. Pathway analyses revealed that ACSL4 and GPX4 might function in crucial pathways including apoptosis, autophagy, cell adhesion, lipid metabolism, etc. INTERPRETATION: This study revealed the critical value of ACSL4 and GPX4 serving as novel predictive and prognostic biomarkers for patients with breast cancer receiving neoadjuvant chemotherapy. It might be a novel strategy to induce ferroptosis to promote chemosensitivity. Future studies are required to elucidate the potential mechanisms.

FUNDING

This work was supported by Shanghai Natural Science Foundation [grant number 19ZR1431100], Clinical Research Plan of Shanghai Hospital Development Center [grant numbers SHDC2020CR3003A, 16CR3065B, and 12016231], Shanghai "Rising Stars of Medical Talent" Youth Development Program for Youth Medical Talents - Specialist Program [grant number 2018-15], Shanghai "Rising Stars of Medical Talent" Youth Development Program for Outstanding Youth Medical Talents [grant number 2018-16], Shanghai Collaborative Innovation Center for Translational Medicine [grant number TM201908], Multidisciplinary Cross Research Foundation of Shanghai Jiao Tong University [grant numbers YG2017QN49, ZH2018QNA42, and YG2019QNA28], Nurturing Fund of Renji Hospital [grant numbers PYMDT-002, PY2018-IIC-01, PY2018-III-15, and PYIII20-09], Science and Technology Commission of Shanghai Municipality [grant numbers 20DZ2201600 and 15JC1402700], and Shanghai Municipal Key Clinical Specialty.

Value of Growth/Differentiation Factor 15 in Diagnosis and the Evaluation of Chemotherapeutic Response in Lung Cancer

PURPOSE

There is a need for efficient, convenient, and inexpensive methods to accurately diagnose the clinical stage of lung cancer and evaluate the efficacy of chemotherapy in patients with lung cancer. Although growth/differentiation factor 15 (GDF)-15 has great potential as a tumor marker, supporting clinical evidence is still lacking. In this study, we aimed to analyze the relationship between serum GDF15 concentration and the clinical characteristics of patients with lung cancer, and to assess the value of GDF15 in the diagnosis and curative effect of chemotherapy.

METHODS

The study comprised 160 participants in total, of whom 88 had lung cancer, 31 had pneumonia, and 41 were control subjects. Among the 88 patients with lung cancer, 64 were willing to participate in follow-up chemotherapy-related studies and meet the inclusion criteria. The serum GDF15 concentration in 288 samples (31 cases, pneumonia group samples; 41 cases, control samples; 88 cases, lung cancer group samples; 64 cases, after 1 chemotherapy cycle; and 64 cases, after 2 chemotherapy cycles) with advanced lung cancer were detected by ELISA. The possible correlations between serum GDF15 level and sex, age, height, weight, body mass index, smoking history, diabetes status, and laboratory findings (hemoglobin, prealbumin, and lactate dehydrogenase) were analyzed using parametric and nonparametric tests. Thereafter, the sensitivity of GDF15 in diagnosing lung cancer was calculated. The serum levels of GDF15, carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), and cytokeratin 19 fragment (CYFRA) 21-1 were determined in 64 patients with lung cancer, before and after chemotherapy reception. For the evaluation of the efficacy of chemotherapy, receiver operating characteristic curves were plotted.

FINDINGS

Serum GDF15 concentration at baseline was significantly higher in the lung cancer group than were those in the pneumonia and control groups (both, P < 0.001). An increased expression of serum GDF15 was significantly correlated with diabetes, anemia, and clinical stage (tumor size, nodal involvement, and presence/absence of metastasis). After 2 cycles of chemotherapy among the 64 patients who received it, serum GDF15 concentrations were significantly different from baseline in those who had progressive disease (P = 0.003), stable disease (P < 0.001), or partial response (P = 0.039). The AUC of GDF15 was greater than those of CEA, NSE, and CYFRA 21-1 (0.851 vs 0.630, 0.720, and 0.654, respectively).

IMPLICATIONS

GDF15 is complementary to CEA, NSE, and CYFRA 21-1 in diagnosing lung cancer and, when used in combination, it could be of great diagnostic value and may facilitate correct predictions of the efficacy of chemotherapy. Therefore, serum GDF15 concentration is valuable in lung cancer diagnosis and in the evaluation of the efficacy of chemotherapy.

Exosomes derived from 5-fluorouracil-resistant colon cancer cells are enriched in GDF15 and can promote angiogenesis

Background: Angiogenesis is important for tumor proliferation and distant metastasis. However, the role of drug-resistant tumor cells in angiogenesis remains largely unknown. Current anti-angiogenic strategies also have limitations and it would be useful to develop novel targets and treatment strategies.

Methods: Differential ultracentrifugation was used to isolate conditioned medium-derived exosomes from 5-flurouracil (5-FU)-sensitive or -resistant colon cancer cells. Exosome endocytosis into human umbilical vein endothelial cells was observed via immunofluorescence. Differentially expressed proteins in the exosomes were confirmed via qRT-PCR and Western blotting. The angiogenic capacity of endothelial cells was evaluated using cell function assays and a rat model of abdominal aortic neovascularization. The underlying mechanisms were verified using qRT-PCR and Western blotting assays. Immunohistochemistry was used to evaluate in vivo angiogenesis.

Results: We observed that the conditioned medium and exosomes from 5-FU-resistant colon cancer cells could promote angiogenesis. Exosomal growth/differentiation factor 15 (GDF15) was a potent inducer of this angiogenesis in vitro by inhibiting the Smad signaling pathway, thus increasing periostin (POSTN) levels. Moreover, 5-FU-resistant colon cancer cells showed high microvascular density in vivo. TGF-β1, an activator of the Smad signaling pathway, could partly eliminate those effects.

Conclusions: Our study reveals the molecular regulation of angiogenesis in 5-FU-resistant colon cancer and suggests that the GDF15-POSTN axis may be a novel target for anti-angiogenic therapies in colon cancer.

Growth/Differentiation Factor-15 (GDF-15): From Biomarker to Novel Targetable Immune Checkpoint

Growth/differentiation factor-15 (GDF-15), also named macrophage inhibitory cytokine-1, is a divergent member of the transforming growth factor β superfamily. While physiological expression is barely detectable in most somatic tissues in humans, GDF-15 is abundant in placenta. Elsewhere, GDF-15 is often induced under stress conditions, seemingly to maintain cell and tissue homeostasis; however, a moderate increase in GDF-15 blood levels is observed with age. Highly elevated GDF-15 levels are mostly linked to pathological conditions including inflammation, myocardial ischemia, and notably cancer. GDF-15 has thus been widely explored as a biomarker for disease prognosis. Mechanistically, induction of anorexia via the brainstem-restricted GDF-15 receptor GFRAL (glial cell-derived neurotrophic factor [GDNF] family receptor α-like) is well-documented. GDF-15 and GFRAL have thus become attractive targets for metabolic intervention. Still, several GDF-15 mediated effects (including its physiological role in pregnancy) are difficult to explain via the described pathway. Hence, there is a clear need to better understand non-metabolic effects of GDF-15. With particular emphasis on its immunomodulatory potential this review discusses the roles of GDF-15 in pregnancy and in pathological conditions including myocardial infarction, autoimmune disease, and specifically cancer. Importantly, the strong predictive value of GDF-15 as biomarker may plausibly be linked to its immune-regulatory function. The described associations and mechanistic data support the hypothesis that GDF-15 acts as immune checkpoint and is thus an emerging target for cancer immunotherapy.

Multi-platform Affinity Proteomics Identify Proteins Linked to Metastasis and Immune Suppression in Ovarian Cancer Plasma

A central reason behind the poor clinical outcome of patients with high-grade serous carcinoma (HGSC) of the ovary is the difficulty in reliably detecting early occurrence or recurrence of this malignancy. Biomarkers that provide reliable diagnosis of this disease are therefore urgently needed. Systematic proteomic methods that identify HGSC-associated molecules may provide such biomarkers. We applied the antibody-based proximity extension assay (PEA) platform (Olink) for the identification of proteins that are upregulated in the plasma of OC patients. Using binders targeting 368 different plasma proteins, we compared 20 plasma samples from HGSC patients (OC-plasma) with 20 plasma samples from individuals with non-malignant gynecologic disorders (N-plasma). We identified 176 proteins with significantly higher levels in OC-plasma compared to N-plasma by PEA (p < 0.05 by U-test; Benjamini-Hochberg corrected), which are mainly implicated in immune regulation and metastasis-associated processes, such as matrix remodeling, adhesion, migration and proliferation. A number of these proteins have not been reported in previous studies, such as BCAM, CDH6, DDR1, N2DL-2 (ULBP2), SPINT2, and WISP-1 (CCN4). Of these SPINT2, a protease inhibitor mainly derived from tumor cells within the HGSC microenvironment, showed the highest significance (p < 2 × 10⁻⁷) similar to the previously described IL-6 and PVRL4 (NECTIN4) proteins. Results were validated by means of the aptamer-based 1.3 k SOMAscan proteomic platform, which revealed a high inter-platform correlation with a median Spearman ρ of 0.62. Likewise, ELISA confirmed the PEA data for 10 out of 12 proteins analyzed, including SPINT2. These findings suggest that in contrast to other entities SPINT2 does not act as a tumor suppressor in HGSC. This is supported by data from the PRECOG and KM-Plotter meta-analysis databases, which point to a tumor-type-specific inverse association of SPINT2 gene expression with survival. Our data also demonstrate that both the PEA and SOMAscan affinity proteomics platforms bear considerable potential for the unbiased discovery of novel disease-associated biomarkers.

Growth differentiation factor 15 and its role in carcinogenesis: an update

Growth differentiation factor-15 (GDF-15) is a novel cytokine secreted by a variety of cells like macrophages, adipocytes, normally expressed in high amounts by placenta. It is also highly expressed in multiple carcinomas like Colon, Breast, Pancreas, Liver, and Ovarian. Several reports on serum GDF-15 as a potential biomarker for diagnosis and prognosis of cancer are hampered by the lack of robust data, with large sample size and critical patient recruitment. However, experimental accounts on cancer tumors, cell lines, and animal models suggest GDF-15's role in cancer progression via endothelial mesenchymal transition, angiogenesis, metastasis, drug resistance and even stemness of various cancers. GDF-15 could be the point of amalgamation for the various hallmarks of cancer and can prove a useful therapeutic target in cancer. The current review was conceptualized with a thought of critically appraising the existing information of GDF-15 in carcinogenesis.

Downregulated Long Noncoding RNA GAS5 Fails to Function as Decoy of CEBPB, Resulting in Increased GDF15 Expression and Rapid Ovarian Cancer Cell Proliferation

Introduction: Growth differentiation factor 15 (GDF15), a newly identified member of transforming growth factor (GDF) superfamily, is upregulated in ovarian (OV) cancer. Upregulated GDF15 positively correlates with poor prognosis of OV cancer. Thus, elucidation of the mechanism underlying GDF15 overexpression is important. Method and Results: PROMO and JASPAR prediction software were used to find transcription factors for GDF15 expression. Data from TCGA database were analyzed to find long noncoding RNAs (lncRNAs) that were also abnormally expressed in OV cancer and had associations with GDF15 expression. Transcription factor CEBPB was predicted as an important regulator of GDF15, confirmed by luciferase reporter assay. However, CEBPB expression was not significantly changed in OV cancer. Data from TCGA database showed that lncRNA GAS5 is downregulated in OV cancer and its expression is negatively correlated with GDF15 expression. RPISeq showed high affinity of GAS5 to CEBPB and this was confirmed by RNA-binding protein immunoprecipitation assay. GAS5 overexpression increased its binding to CEBPB and consequently downregulated GDF15. GAS5 overexpression and GDF15 knockdown decreased viability and increased apoptosis of OV cancer cells, but CEBPB overexpression had opposite effects. However, simultaneous GAS5 and CEBPB overexpression or CEBPB overexpression together with GDF15 knockdown had no effect on cell viability and apoptosis. Conclusion: GAS5 functions as decoy of CEBPB, blocking transcription-promoting effect of CEBPB on GDF15.

Downregulation of TGF-β1 suppressed proliferation and increased chemosensitivity of ovarian cancer cells by promoting BRCA1/Smad3 signaling

BACKGROUND

Studies have demonstrated that transforming growth factor beta-1 (TGF-β1) exhibits oncogenic activity in different types of cancer, including ovarian cancer (OC). However, its regulatory mechanism in OC and whether TGF-β1 is involved in chemosensitivity regulation remains unclear. Thus, the aim of this study was to investigate the role of TGF-β1 in OC.

METHODS

The OC cell line SKOV3 was employed, and TGF-β1 overexpression or knockdown vectors were constructed. The cell proliferation of SKOV3 was evaluated with the cell counting kit (CCK8) kit after treatment with different concentrations of cis-platinum. Western blot and protein immunoprecipitation were employed to detect changes in BRCA1 and Smad3 expression and their interactions. Tumor growth in nude mice was evaluated.

RESULTS

The results showed that TGF-β1 knockdown increased chemosensitivity by promoting BRCA1 expression and Smad3 phosphorylation. In vivo studies showed that TGF-β1 knockdown significantly inhibited the growth of tumors, also by upregulating BRCA1 expression and Smad3 phosphorylation.

CONCLUSION

Taken together, our results suggest that TGF-β1 knockdown inhibits tumor growth and increases chemosensitivity by promotion of BRCA1/Smad3 signaling.