Progastrin a new pro-angiogenic factor in colorectal cancer

Relationship between Helicobacter pylori infection and colorectal polyp/colorectal cancer

Helicobacter pylori (H. pylori) plays an important role in the development of gastric cancer, although its association to colorectal polyp (CP) or colorectal cancer (CRC) is unknown. In this issue of World Journal of Gastrointestinal Surgery, Zhang et al investigated the risk factors for H. pylori infection after colon polyp resection. Importantly, the researchers used R software to create a prediction model for H. pylori infection based on their findings. This editorial gives an overview of the association between H. pylori and CP/CRC, including the clinical significance of H. pylori as an independent risk factor for CP/CRC, the underlying processes of H. pylori-associated carcinogenesis, and the possible risk factors and identification of H. pylori.

Progastrin: An Overview of Its Crucial Role in the Tumorigenesis of Gastrointestinal Cancers

Defining predictive biomarkers for targeted therapies and optimizing anti-tumor immune response is a main challenge in ongoing investigations. Progastrin has been studied as a potential biomarker for detecting and diagnosing various malignancies, and its secretion has been associated with cell proliferation in the gastrointestinal tract that may promote tumorigenesis. Progastrin is a precursor molecule of gastrin, synthesized as pre-progastrin, converted to progastrin after cleavage, and transformed into amidated gastrin via biosynthetic intermediates. In cancer, progastrin does not maturate in gastrin and becomes a circulating and detectable protein (hPG80). The development of cancer is thought to be dependent on the progressive dysregulation of normal signaling pathways involved in cell proliferation, thus conferring a growth advantage to the cells. Understanding the interaction between progastrin and the immune system is essential for developing future cancer strategies. To that end, the present review will approach the interlink between gastrointestinal cancers and progastrin by exploring the underlying molecular steps involved in the initiation, evolution, and progression of gastrointestinal cancers. Finally, this review will focus on the clinical applications of progastrin and investigate its possible use as a diagnostic and prognostic tumor circulating biomarker for disease progression and treatment effectiveness, as well as its potential role as an innovative cancer target.

Elevated Serum Gastrin Is Associated with Melanoma Progression: Putative Role in Increased Migration and Invasion of Melanoma Cells

Micro-environmental factors, including stromal and immune cells, cytokines, and circulating hormones are well recognized to determine cancer progression. Melanoma cell growth was recently shown to be suppressed by cholecystokinin/gastrin (CCK) receptor antagonists, and our preliminary data suggested that melanoma patients with Helicobacter gastritis (which is associated with elevated serum gastrin) might have an increased risk of cancer progression. Therefore, in the present study, we examined how gastrin may act on melanoma cells. In 89 melanoma patients, we found a statistically significant association between circulating gastrin concentrations and melanoma thickness and metastasis, which are known risk factors of melanoma progression and prognosis. Immunocytochemistry using a validated antibody confirmed weak to moderate CCK2R expression in both primary malignant melanoma cells and the melanoma cell lines SK-MEL-2 and G361. Furthermore, among the 219 tumors in the Skin Cutaneous Melanoma TCGA Pan-Cancer dataset showing gastrin receptor (CCKBR) expression, significantly higher CCKBR mRNA levels were linked to stage III-IV than stage I-II melanomas. In both cell lines, gastrin increased intracellular calcium levels and stimulated cell migration and invasion through mechanisms inhibited by a CCK2 receptor antagonist. Proteomic studies identified increased MMP-2 and reduced TIMP-3 levels in response to gastrin that were likely to contribute to the increased migration of both cell lines. However, the effects of gastrin on tumor cell invasion were relatively weak in the presence of the extracellular matrix. Nevertheless, dermal fibroblasts/myofibroblasts, known also to express CCK2R, increased gastrin-induced cancer cell invasion. Our data suggest that in a subset of melanoma patients, an elevated serum gastrin concentration is a risk factor for melanoma tumor progression, and that gastrin may act on both melanoma and adjacent stromal cells through CCK2 receptors to promote mechanisms of tumor migration and invasion.

Association between post-operative hPG80 (circulating progastrin) detectable level and worse prognosis in glioblastoma

BACKGROUND

Patients with glioblastomas have a dismal prognosis, and there is no circulating predictive or prognostic biomarker. Circulating progastrin, hPG80, is a tumor-promoting peptide present in the blood of patients with various cancers that has been shown to have prognostic value. We evaluated the prognostic value of plasma hPG80 in patients with isocitrate dehydrogenase-wild type glioblastoma after surgery.

PATIENTS AND METHODS

A multicentric retrospective study in glioblastoma patients treated with standard radio-chemotherapy was conducted. The hPG80 levels were measured in plasma EDTA samples collected after surgery with an ELISA DxPG80.lab kit (Biodena Care, Montpellier, France), which has a detection threshold of 1.2 pM. The relationship between post-operative hPG80 plasma levels, in combination with other known prognostic factors, and patients' progression-free survival (PFS) and overall survival (OS) was evaluated.

RESULTS

Sixty-nine patients were assessable. Plasma samples were collected after tumor biopsy (B), partial resection (PR), and complete resection (CR) for 22, 25, and 22 patients, respectively. At a median concentration of 5.37 pM (interquartile range 0.00-13.90 pM), hPG80 was detected in 48 (70%) patients (hPG80+). CR was associated with significant lower values of hPG80 levels: the median value was 0.7 versus 9.1 pM for PR (P = 0.02) and 8.3 pM for B (P = 0.004). The hPG80 detection rate was also significantly lower: 50% (CR) versus 72% (PR) versus 86% (B) (P = 0.005). The median follow-up was 39 months [22.4 months-not reached]. hPG80 post-operative detection was associated with numerically shorter PFS (6.4 versus 9.4 months, P = 0.13) and OS (14.5 versus 20.9 months, P = 0.11). In multivariate analysis, hPG80 was a prognostic factor for OS (P = 0.034).

CONCLUSIONS

Circulating hPG80 could serve as a new prognostic biomarker after surgery in patients with glioblastoma treated with radio-chemotherapy.

hPG80 (circulating progastrin) as a blood biomarker for high-grade glial tumors: A pilot study

Background

Currently, the long-term prognosis and survival rate of patients with high-grade glial tumors remains poor and there are no biomarkers. hPG₈₀ (circulating progastrin) secreted into the blood by tumor cells has been widely studied in colorectal cancer. Its involvement in tumorigenesis has been demonstrated in the literature. Moreover, according to a recent study, hPG₈₀ is expressed in the blood of cancer patients at a significantly higher concentration than in the control group composed of healthy blood donors.

Methods

The PROGLIO study is a pilot, single-center, longitudinal study that primarily seeks to evaluate circulating plasma hPG₈₀ concentrations over time in patients with high-grade glial tumors. A fasting blood sample will be taken on the start and end day of radiotherapy and during the adjuvant chemotherapy (every 3 cycles). Follow-up monitoring will be performed for 9 months, with a blood sample taken every 3 months on the day of the follow-up MRI. The study plans to recruit 30 patients and recruitment started in February 2022.

Trial registration

ClinicalTrials.gov, ID NCT05157594; registered on October 27, 2021.

[hPG80 and cancer: A new blood biomarker in development for patient monitoring]

Recent technological advances coupled with our improved understanding of the molecular and cellular mechanisms associated with cancer development have enabled better overall patient care. Among the newly identified biomarkers such as circulating tumor DNA or circulating tumor cells, hPG₈₀ (circulating progastrin) that is easy to detect and quantify by a simple ELISA assay has the potential to become a new routine clinical tool in oncology if on-going studies validated its utility. Indeed, on the one hand, hPG₈₀ was found in the blood of patients with different tumors (colorectal, pancreatic, liver, lung, stomach, kidney cancers) at a significantly higher concentration than in healthy donors. Moreover, some studies suggested a potential association between hPG₈₀ concentration changes and anti-cancer treatment efficacy in patients with gastro-intestinal and hepatocellular carcinomas. Finally, hPG₈₀ might be a prognostic factor for overall survival in metastatic renal cell carcinoma cancer (mRCC) and in hepatocellular carcinoma (HCC). If these hypotheses were validated, hPG₈₀ might help better stratify patients according to their prognosis, and also become a tool to monitor relapse and predict treatment response. Prospective validation studies are on-going.

Plasma hPG80 (Circulating Progastrin) as a Novel Prognostic Biomarker for Hepatocellular Carcinoma

Simple Summary

Liver cancer is the sixth most common cancer world-wide and hepatocellular carcinoma (HCC), the most common form of primary liver cancer, accounts for 90% of the cases. The diagnosis of HCC is usually based on non-invasive criteria using detection of a liver nodule in abdominal ultrasonography or high serum alpha-fetoprotein (AFP) levels. However, as it is only elevated in 60% of patients with HCC, AFP has limited accuracy, especially in early stages, as both a diagnostic and prognostic test. We investigated hPG80 (circulating progastrin), which is associated with liver cancer biology, and found that hPG80 levels is both an independent prognostic marker in HCC and used in combination with AFP, it improves the stratification of the patients in good and poor prognosis, especially for those patients at early-stage. This will help stratify HCC patients more accurately in the future and improve the management of these patients.

Abstract

Alpha-fetoprotein (AFP) is the most widely used biomarker for hepatocellular carcinoma (HCC) prognosis. However, AFP is not useful in establishing a prognosis for patients with a tumor in the early stages. hPG₈₀ (circulating progastrin) is a tumor promoting peptide present in the blood of patients with various cancers, including HCC. In this study, we evaluated the prognostic value of plasma hPG₈₀ in patients with HCC, alone or in combination with AFP. A total of 168 HCC patients were tested prospectively for hPG₈₀ and analyzed retrospectively. The prognostic impact of hPG₈₀ and AFP levels on patient survival was assessed using Kaplan-Meier curves and log-rank tests. hPG₈₀ was detected in 84% of HCC patients. There was no correlation between hPG₈₀ and AFP levels in the training and validation cohorts. Both cohorts showed higher sensitivity of hPG₈₀ compared to AFP, especially at early stages. Patients with high hPG₈₀ (hPG₈₀+) levels (optimal cutoff value 4.5 pM) had significantly lower median overall survival (OS) compared to patients with low hPG₈₀ (hPG₈₀−) levels (12.4 months versus not reached respectively, p < 0.0001). Further stratification by combining hPG₈₀ and AFP levels (cutoff 100 ng/mL) improved prognosis in particular for those patients with low AFP level (hPG₈₀−/AFP+ and hPG₈₀−/AFP−, 13.4 months versus not reached respectively, p < 0.0001 and hPG₈₀+/AFP+ and hPG₈₀+/AFP−, 5.7 versus 26 months respectively, p < 0.0001). This was corroborated when analyses were performed using the BCLC staging especially at early stages. Our findings show that hPG₈₀ could serve as a new prognostic biomarker in HCC. Used in combination with AFP, it improves the stratification of the patients in good and poor prognosis, especially for those patients with negative AFP and early-stage HCC.

A novel method to detect hPG80 (human circulating progastrin) in the blood

hPG₈₀ (human circulating progastrin) is produced and released by cancer cells. We recently reported that hPG₈₀ is detected in the blood of patients with cancers from different origins, suggesting its potential utility for cancer detection. To accurately measure hPG₈₀ in the blood of patients, we developed the DxPG₈₀ test, a sandwich Enzyme-Linked Immunosorbent Assay (ELISA). This test quantifies hPG₈₀ in EDTA plasma samples. The analytical performances of the DxPG₈₀ test were evaluated using standard procedures and guidelines specific to ELISA technology. We showed high specificity for hPG₈₀ with no cross-reactivity with human glycine-extended gastrin (hG17-Gly), human carboxy-amidated gastrin (hG17-NH₂) or the CTFP (C-Terminus Flanking Peptide) and no interference with various endogenous or exogenous compounds. The test is linear between 0 and 50 pM hPG₈₀ (native or recombinant). We demonstrated a trueness of measurement, an accuracy and a variability of hPG₈₀ quantification with the DxPG₈₀ test below the 20% relative errors as recommended in the guidelines. The limit of detection of hPG₈₀ and the limit of quantification were calculated as 1 pM and 3.3 pM respectively. In conclusion, these results show the strong analytical performance of the DxPG₈₀ test to measure hPG₈₀ in blood samples.

Prognostic Value of Plasma hPG80 (Circulating Progastrin) in Metastatic Renal Cell Carcinoma

Simple Summary

Metastatic renal cell carcinoma (mRCC) accounts for one-third of all newly diagnosed renal cell cancers. A better understanding of the biology and molecular basis of disease progression has resulted in several drug targets being identified and led to approval of several new drugs for treating mRCC in the past decade. A growing need has emerged for identifying novel molecular tumor biology based and stage-specific prognostic and predictive biomarkers in mRCC reflective of biology beyond the currently available prognostic models which are solely based on clinical characteristics. We investigated hPG80 (circulating progastrin), which is associated with kidney cancer biology and found that hPG80 levels is both an independent prognostic marker in mRCC and also improves current clinical prognostic models. This will help stratify mRCC patients more accurately in future and improve the management of mRCC patients.

Abstract

Precise management of kidney cancer requires the identification of prognostic factors. hPG₈₀ (circulating progastrin) is a tumor promoting peptide present in the blood of patients with various cancers, including renal cell carcinoma (RCC). In this study, we evaluated the prognostic value of plasma hPG₈₀ in 143 prospectively collected patients with metastatic RCC (mRCC). The prognostic impact of hPG₈₀ levels on overall survival (OS) in mRCC patients after controlling for hPG₈₀ levels in non-cancer age matched controls was determined and compared to the International Metastatic Database Consortium (IMDC) risk model (good, intermediate, poor). ROC curves were used to evaluate the diagnostic accuracy of hPG₈₀ using the area under the curve (AUC). Our results showed that plasma hPG₈₀ was detected in 94% of mRCC patients. hPG₈₀ levels displayed high predictive accuracy with an AUC of 0.93 and 0.84 when compared to 18–25 year old controls and 50–80 year old controls, respectively. mRCC patients with high hPG₈₀ levels (>4.5 pM) had significantly lower OS compared to patients with low hPG₈₀ levels (<4.5 pM) (12 versus 31.2 months, respectively; p = 0.0031). Adding hPG₈₀ levels (score of 1 for patients having hPG₈₀ levels > 4.5 pM) to the six variables of the IMDC risk model showed a greater and significant difference in OS between the newly defined good-, intermediate- and poor-risk groups (p = 0.0003 compared to p = 0.0076). Finally, when patients with IMDC intermediate-risk group were further divided into two groups based on hPG₈₀ levels within these subgroups, increased OS were observed in patients with low hPG₈₀ levels (<4.5 pM). In conclusion, our data suggest that hPG₈₀ could be used for prognosticating survival in mRCC alone or integrated to the IMDC score (by adding a variable to the IMDC score or by substratifying the IMDC risk groups), be a prognostic biomarker in mRCC patients.

The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management

Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.

The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management

Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.

The oncogenic and druggable hPG80 (Progastrin) is overexpressed in multiple cancers and detected in the blood of patients

BACKGROUND

In colorectal cancer, hPG80 (progastrin) is released from tumor cells, promotes cancer stem cells (CSC) self-renewal and is detected in the blood of patients. Because the gene GAST that encodes hPG80 is a target gene of oncogenic pathways that are activated in many tumor types, we hypothesized that hPG80 could be expressed by tumors from various origins other than colorectal cancers, be a drug target and be detectable in the blood of these patients.

METHODS

hPG80 expression was monitored by fluorescent immunohistochemistry and mRNA expression in tumors from various origins. Cancer cell lines were used in sphere forming assay to analyze CSC self-renewal. Blood samples were obtained from 1546 patients with 11 different cancer origins and from two retrospective kinetic studies in patients with peritoneal carcinomatosis or hepatocellular carcinomas. These patients were regularly sampled during treatments and assayed for hPG80.

FINDINGS

We showed that hPG80 was present in the 11 tumor types tested. In cell lines originating from these tumor types, hPG80 neutralization decreased significantly CSC self-renewal by 28 to 54%. hPG80 was detected in the blood of patients at significantly higher concentration than in healthy blood donors (median hPG80: 4.88 pM versus 1.05 pM; p < 0.0001) and shown to be correlated to GAST mRNA levels in the matched tumor (i.e., lung cancers, Spearman r = 0.8; p = 0.0023). Furthermore, we showed a strong association between longitudinal hPG80 concentration changes and anti-cancer treatment efficacy in two independent retrospective studies. In the peritoneal carcinomatosis cohort, median hPG80 from inclusion to the post-operative period decreased from 5.36 to 3.00 pM (p < 0.0001, n = 62) and in the hepatocellular carcinoma cohort, median hPG80 from inclusion to remission decreased from 11.54 pM to 1.99 pM (p < 0.0001, n = 63).

INTERPRETATION

Because oncogenic hPG80 is expressed in tumor cells from different origins and because circulating hPG80 in the blood is related to the burden/activity of the tumor, it is a promising cancer target for therapy and for disease monitoring.

FUNDINGS

ECS-Progastrin.

The prognostic and therapeutic role of hormones in colorectal cancer: a review

Colorectal cancer (CRC) is one of the commonest cancers in Western society with a poor prognosis in patients with advanced disease. Targeted therapy is of increasing interest and already, targeted hormone treatment for breast and prostate cancer has improved survival. The aim of this literature review is to summarise the role of hormones in CRC prognosis and treatment. A literature review of all human and animal in vivo and in vitro studies in the last 20 years, which assessed the role of hormones in CRC treatment or prognosis, was carried out. The hormones described in this review have been subdivided according to their secretion origin. Most of the studies are based on in vitro or animal models. The main findings point to adipokines, insulin and the insulin growth factor axis as key players in the link between obesity, type 2 diabetes mellitus and a subset of CRC. Gut-derived hormones, especially uroguanylin and guanylin are being increasingly investigated as therapeutic targets, with promising results. Using hormones as prognostic and therapeutic markers in CRC is still in the preliminary stages for only a fraction of the hormones affecting the GIT. In light of the increasing interest in tailoring treatment strategies, hormones are an important area of focus in the future of CRC management.

Progastrin: a potential predictive marker of liver metastasis in colorectal cancer

BACKGROUND AND AIMS

Staging of colorectal cancer often fails to discriminate outcomes of patients with morphologically similar tumours that exhibit different clinical behaviours. Data from several studies suggest that the gastrin family of growth factors potentiates colorectal cancer tumourigenesis. The aim of this study was to investigate whether progastrin expression may predict clinical outcome in colorectal cancer.

METHODS

Patients with colorectal adenocarcinoma of identical depth of invasion who had not received neoadjuvant therapy were included. The patients either had stage IIa disease with greater than 3-year disease-free survival without adjuvant therapy or stage IV disease with liver metastases on staging CT. Progastrin expression in tumour sections was scored with reference to the intensity and area of immunohistochemical staining.

RESULTS

Progastrin expression by stage IV tumours was significantly greater than stage IIa tumours with mean progastrin immunopositivity scores of 2.1 ± 0.2 versus 0.5 ± 0.2, respectively (P < 0.001).

CONCLUSIONS

This is the first study to show that progastrin expression may be predictive of aggressive tumour behaviour in patients with colorectal cancer and supports its clinical relevance and potential use as a biomarker.

Targeting the Wnt Pathway and Cancer Stem Cells with Anti-progastrin Humanized Antibodies as a Potential Treatment for K-RAS-Mutated Colorectal Cancer

Purpose: Patients with metastatic colorectal cancer suffer from disease relapse mainly due to cancer stem cells (CSC). Interestingly, they have an increased level of blood progastrin, a tumor-promoting peptide essential for the self-renewal of colon CSCs, which is also a direct β-catenin/TCF4 target gene. In this study, we aimed to develop a novel targeted therapy to neutralize secreted progastrin to inhibit Wnt signaling, CSCs, and reduce relapses.Experimental Design: Antibodies (monoclonal and humanized) directed against progastrin were produced and selected for target specificity and affinity. After validation of their effectiveness on survival of colorectal cancer cell lines harboring B-RAF or K-RAS mutations, their efficacy was assessed in vitro and in vivo, alone or concomitantly with chemotherapy, on CSC self-renewal capacity, tumor recurrence, and Wnt signaling.Results: We show that anti-progastrin antibodies decrease self-renewal of CSCs both in vitro and in vivo, either alone or in combination with chemotherapy. Furthermore, migration and invasion of colorectal cancer cells are diminished; chemosensitivity is prolonged in SW620 and HT29 cells and posttreatment relapse is significantly delayed in T84 cells, xenografted nude mice. Finally, we show that the Wnt signaling activity in vitro is decreased, and, in transgenic mice developing Wnt-driven intestinal neoplasia, the tumor burden is alleviated, with an amplification of cell differentiation in the remaining tumors.Conclusions: Altogether, these data show that humanized anti-progastrin antibodies might represent a potential new treatment for K-RAS-mutated colorectal patients, for which there is a crucial unmet medical need. Clin Cancer Res; 23(17); 5267-80. ©2017 AACR.

Targeting progastrin enhances radiosensitization of colorectal cancer cells

A high percentage of advanced rectal cancers are resistant to radiation. Therefore, increasing the efficacy of radiotherapy by targeting factors involved in radioresistance seems to be an attractive strategy. Here we demonstrated that the pro-hormone progastrin (PG), known to be over-expressed in CRC, and recognized as a pro-oncogenic factor, is a radioresistance factor that can be targeted to sensitize resistant rectal cancers to radiations. First, we observed an increase in PG mRNA expression under irradiation. Our results also demonstrated that down-regulating PG mRNA expression using a shRNA strategy, significantly increases the sensitivity to irradiation (IR) in a clonogenic assay of different colorectal cancer cell lines. We also showed that the combination of PG gene down-regulation and IR strongly inhibits tumours progression in vivo. Then, we demonstrated that targeting PG gene radiosensitizes cancer cells by increasing radio-induced apoptosis shown by an increase in annexin V positive cells, caspases activation and PARP cleavage. We also observed the up-regulation of the pro-apoptotic pathway, JNK and the induction of the expression of pro-apoptotic factors such as BIM. In addition, we demonstrated in this study that inhibition of PG gene expression enhances radiation-induced DNA damage. Our data also suggest that, in addition to increase radio-induced apoptosis, targeting PG gene also leads to the inhibition of the survival pathways, AKT and ERK induced by IR. Taken together, our results highlight the role of PG in radioresistance and provide a preclinical proof of concept that PG represents an attractive target for sensitizing resistant rectal tumours to irradiation. .

SARI inhibits angiogenesis and tumour growth of human colon cancer through directly targeting ceruloplasmin

SARI, also called as BATF2, belongs to the BATF family and has been implicated in cancer cell growth inhibition. However, the role and mechanism of SARI in tumour angiogenesis are elusive. Here we demonstrate that SARI deficiency facilitates AOM/DSS-induced colonic tumorigenesis in mice. We show that SARI is a novel inhibitor of colon tumour growth and angiogenesis in mice. Antibody array and HUVEC-related assays indicate that VEGF has an essential role in SARI-controlled inhibition of angiogenesis. Furthermore, Co-IP/PAGE/mass spectrometry indicates that SARI directly targets ceruloplasmin (Cp), and induces protease degradation of Cp, thereby inhibiting the activity of the HIF-1α/VEGF axis. Tissue microarray results indicate that SARI expression inversely correlates with poor clinical outcomes in colon cancer patients. Collectively, our results indicate that SARI is a potential target for therapy by inhibiting angiogenesis through the reduction of VEGF expression and is a prognostic indicator for patients with colon cancer.

The great escape; the hallmarks of resistance to antiangiogenic therapy

The concept of antiangiogenic therapy in cancer treatment has led to the approval of different agents, most of them targeting the well known vascular endothelial growth factor pathway. Despite promising results in preclinical studies, the efficacy of antiangiogenic therapy in the clinical setting remains limited. Recently, awareness has emerged on resistance to antiangiogenic therapies. It has become apparent that the intricate complex interplay between tumors and stromal cells, including endothelial cells and associated mural cells, allows for escape mechanisms to arise that counteract the effects of these targeted therapeutics. Here, we review and discuss known and novel mechanisms that contribute to resistance against antiangiogenic therapy and provide an outlook to possible improvements in therapeutic approaches.