Receptors for Insulin-Like Growth Factor-2 and Androgens as Therapeutic Targets in Triple-Negative Breast Cancer

Recent update on IGF-1/IGF-1R signaling axis as a promising therapeutic target for triple-negative breast cancer

Insulin-like growth factor 1/Insulin-like growth factor 1-receptor (IGF-1/IGF-1R) pathway is highly breast cancer subtype context-dependent. Triple-negative breast cancer (TNBC) is an aggressive, highly metastatic cancer showing early recurrence and poor prognosis. High expression of IGF-1 and its receptor IGF-1R, their interaction, autophosphorylation, and activation of intracellular signaling cascades have been significantly associated with TNBC pathophysiology. In the last five to seven years, marvelous work has been done to explore the role of IGF-1/IGF-1R axis in TNBC. In the present review, starting from the general introduction to IGF-1/IGF-1R pathway an up-to-date discussion was focused on its role in TNBC pathophysiology. Further we discussed the up/down stream molecular events of IGF-1/IGF-1R axis, clinical relevance of IGF-1 and IGF-1R levels in TNBC patients, anti-TNBC therapy and possible way-out for IGF-1/IGF-1R axis mediate therapy resistance in TNBC. Combination therapy strategy has been researched to overcome direct IGF-1/IGF-1R pathway inhibition mediated therapy resistance and produced promising results in the management of TNBC. The understanding of up/downstream of the IGF-1/IGF-1R axis provide immense focus on the pathway as a therapeutic target. It is expected within the next decade to determine its potentiality, or lack thereof, for TNBC treatment.

The role of pregnancy associated plasma protein-A in triple negative breast cancer: a promising target for achieving clinical benefits

Pregnancy associated plasma protein-A (PAPP-A) plays an integral role in breast cancer (BC), especially triple negative breast cancer (TNBC). This subtype accounts for the most aggressive BC, possesses high tumor heterogeneity, is least responsive to standard treatments and has the poorest clinical outcomes. There is a critical need to address the lack of effective targeted therapeutic options available. PAPP-A is a protein that is highly elevated during pregnancy. Frequently, higher PAPP-A expression is detected in tumors than in healthy tissues. The increase in expression coincides with increased rates of aggressive cancers. In BC, PAPP-A has been demonstrated to play a role in tumor initiation, progression, metastasis including epithelial-mesenchymal transition (EMT), as well as acting as a biomarker for predicting patient outcomes. In this review, we present the role of PAPP-A, with specific focus on TNBC. The structure and function of PAPP-A, belonging to the pappalysin subfamily, and its proteolytic activity are assessed. We highlight the link of BC and PAPP-A with respect to the IGFBP/IGF axis, EMT, the window of susceptibility and the impact of pregnancy. Importantly, the relevance of PAPP-A as a TNBC clinical marker is reviewed and its influence on immune-related pathways are explored. The relationship and mechanisms involving PAPP-A reveal the potential for more treatment options that can lead to successful immunotherapeutic targets and the ability to assist with better predicting clinical outcomes in TNBC.

Correction: Hamilton et al. Receptors for Insulin-Like Growth Factor-2 and Androgens as Therapeutic Targets in Triple-Negative Breast Cancer. Int. J. Mol. Sci. 2017, 18, 2305

In the original publication [...].

Targeting Receptor Tyrosine Kinases as a Novel Strategy for the Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) comprises a group of aggressive and heterogeneous breast carcinoma. Chemotherapy is the mainstay for the treatment of triple-negative tumors. Nevertheless, the success of chemotherapeutic treatments is limited by their toxicity and development of acquired resistance leading to therapeutic failure and tumor relapse. Hence, there is an urgent need to explore novel targeted therapies for TNBC. Receptor tyrosine kinases (RTKs) are a family of transmembrane receptors that are key regulators of intracellular signaling pathways controlling cell proliferation, differentiation, survival, and motility. Aberrant activity and/or expression of several types of RTKs have been strongly connected to tumorigenesis. RTKs are frequently overexpressed and/or deregulated in triple-negative breast tumors and are further associated with tumor progression and reduced survival in patients. Therefore, targeting RTKs could be an appealing therapeutic strategy for the treatment of TNBC. This review summarizes the current evidence regarding the antitumor activity of RTK inhibitors in preclinical models of TNBC. The review also provides insights into the clinical trials evaluating the use of RTK inhibitors for the treatment of patients with TNBC.

Updates on Triple-Negative Breast Cancer in Type 2 Diabetes Mellitus Patients: From Risk Factors to Diagnosis, Biomarkers and Therapy

Triple-negative breast cancer (TNBC) is usually the most malignant and aggressive mammary epithelial tumor characterized by the lack of expression for estrogen receptors and progesterone receptors, and the absence of epidermal growth factor receptor (HER)2 amplification. Corresponding to 15-20% of all breast cancers and well-known by its poor clinical outcome, this negative receptor expression deprives TNBC from targeted therapy and makes its management therapeutically challenging. Type 2 diabetes mellitus (T2DM) is the most common ageing metabolic disorder due to insulin deficiency or resistance resulting in hyperglycemia, hyperinsulinemia, and hyperlipidemia. Due to metabolic and hormonal imbalances, there are many interplays between both chronic disorders leading to increased risk of breast cancer, especially TNBC, diagnosed in T2DM patients. The purpose of this review is to provide up-to-date information related to epidemiology and clinicopathological features, risk factors, diagnosis, biomarkers, and current therapy/clinical trials for TNBC patients with T2DM compared to non-diabetic counterparts. Thus, in-depth investigation of the diabetic complications on TNBC onset, development, and progression and the discovery of biomarkers would improve TNBC management through early diagnosis, tailoring therapy for a better outcome of T2DM patients diagnosed with TNBC.

Novel Association of IGF2BP2 Gene Variants With Altered Risk of Breast Cancer and as Potential Molecular Biomarker of Triple Negative Breast Cancer

BACKGROUND

Several studies documented that insulin-like growth factor-2 mRNA-binding protein 2 (IGF2BP2) contributes to carcinogenesis, and 1 report documented the association of IGF2BP2 rs4402960 with increased risk of breast cancer (BC). This study investigated the association of rs4402960 and rs1470579 IGF2BP2 variants with BC and triple negative BC (TNBC).

MATERIALS AND METHODS

This case-control study included 488 BC patients comprising 130 TNBC and 358 non-TNBC patients, and 476 cancer-free controls. Genomic DNA was obtained from peripheral venous blood, and genotyping was done by allelic exclusion method on real-time PCR.

RESULTS

The rs440960, but not rs1470579, minor allele was significantly associated with BC, and significantly higher rs4402960 T/T genotype frequency was noted in BC patients than controls; the distribution of rs1470579 genotypes were comparable between BC patients and controls. In contrast, significantly lower rs1470579 minor allele frequency, and reduced rs1470579 A/C and C/C, and rs4402960 T/T genotype frequencies were seen in TNBC cases. Among TNBC cases, rs4402960 and rs1470579 correlated with menses pattern, histological type, breastfeeding, oral contraceptive use and hormonotherapy. Among non-TNBC patients, and rs1470579 correlated significantly with breast feeding, oral contraceptive use, hormonotherapy, and nodal status; rs4402960 also correlated with menses pattern. Two-locus (rs440960-rs1470579) haplotype analysis confirmed the positive association of TC, and negative association of GC and TA haplotypes with BC, while TC and GC haplotypes were negatively associated with TNBC.

CONCLUSION

Whereas rs440960 was positively associated with BC, both rs4402960 and rs1470579 were negatively associated with TNBC, suggesting potential diagnostic/prognostic role in BC and its complications.

Effects of methylation and imprinting expression of Insulin-like growth factor 2 gene in gastric cancer

BACKGROUND

Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) is a common malignant tumor associated with EBV infection. Insulin-like growth factor 2 (IGF2) is an imprinted gene and a key protein that regulates growth, especially during normal fetal development. Loss of imprinting (LOI), is a common epigenetic anomaly in a variety of human cancers. However, the promoter methylation, imprinting status and function of IGF2 gene in GC are unclear.

OBJECTIVE

To explore the role of IGF2 in the occurrence and development of gastric cancer.

METHODS

The biological function of IGF2 in gastric cancer was investigated by Transwell, wound healing, CCK-8 and flow cytometry assays. IGF2 imprinting status and gene promoter methylation in gastric cancer tissues were detected by PCR-RFLP and BGS.

RESULTS

The results showed that the expression of IGF2 was higher in GC tissues than adjacent tissues. IGF2 gene promoter methylation and LOI were significantly higher in EBVaGC tissues than in EBV-negative gastric cancer (EBVnGC) tissues. The high expression of IGF2 in gastric cancer can promote the migration and proliferation of gastric cancer cells.

CONCLUSION

Our data suggest that IGF2 is involved in the occurrence and development of gastric cancer. Targeting IGF2 may be a potential therapeutic target for gastric cancer.

Targeting Adipokines in Obesity-Related Tumors

Obesity, a global epidemic, is an independent risk factor for the occurrence and development of a variety of tumors, such as breast cancer, pancreatic cancer, ovarian cancer and colorectal cancer. Adipocytes are important endocrine cells in the tumor microenvironment of obesity-related tumors, which can secrete a variety of adipokines (such as leptin, adiponectin, estrogen, resistin, MIF and MCP-1, etc.), among which leptin, adiponectin and estrogen are the most in-depth and valuable ones. These adipokines are closely related to tumorigenesis and the progression of tumors. In recent years, more and more studies have shown that under chronic inflammatory conditions such as obesity, adipocytes secrete more adipokines to promote the tumorigenesis and development of tumors. However, it is worth noting that although adiponectin is also secreted by adipocytes, it has an anti-tumor effect, and can cross-talk with other adipokines (such as leptin and estrogen) and insulin to play an anti-tumor effect together. In addition, obesity is the main cause of insulin resistance, which can lead to the increase of the expression levels of insulin and insulin-like growth factor (IGF). As important regulators of blood glucose and lipid metabolism, insulin and IGF also play an important role in the progress of obesity related tumors. In view of the important role of adipokines secreted by adipocytes and insulin/IGF in tumors, this article not only elaborates leptin, adiponectin and estrogen secreted by adipocytes and their mechanism of action in the development of obesity- related tumors, but also introduces the relationship between insulin/IGF, a regulator of lipid metabolism, and obesity related tumors. At the same time, it briefly describes the cancer-promoting mechanism of resistin, MIF and MCP-1 in obesity-related tumors, and finally summarizes the specific treatment opinions and measures for various adipokines and insulin/insulin-like growth factors in recent years.

Mechanisms of tRNA-derived fragments and tRNA halves in cancer treatment resistance

The tRNA-derived fragments (tRFs) and tRNA halves (tiRNAs) are newly discovered noncoding RNAs in recent years. They are derived from specific cleavage of mature and pre-tRNAs and expressed in various cancers. They enhance cell proliferation and metastasis or inhibit cancer progression. Many studies have investigated their roles in the diagnosis, progression, metastasis, and prognosis of various cancers, but the mechanisms through which they are involved in resistance to cancer treatment are unclear. This review outlines the classification of tRFs and tiRNAs and their mechanisms in cancer drug resistance, thus providing new ideas for cancer treatment.

Transgenerational impairment of ovarian induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) associated with Igf2 and H19 in adult female rat

2,3,7,8-Tetrachlorobenze-p-dioxin (TCDD), one of representive Endocrine Disrupting Chemicals (EDCs), has potential adverse effects on human health. Direct exposure to TCDD has been implicated in ovarian follicles development and functions deficits in adulthood. However, it is rarely reported whether indirect exposure to TCDD can cause similar negative impact on F3. The aim of our study was to evaluate the effect of ancestral TCDD exposure on ovarian toxicity in offspring rats (F3), focusing on the Igf2/H19 pathway which was important for follicular development. Pregnant Sprague-Dawley female rats (F0) were given with either vehicle or TCDD (100 or 500 ng/kg BW/day) by gavages during days 8-14 of gestation. Ovarian development and functions of F3 generation was assessed using the ovary coefficient, the vaginal opening time, and regularity of estrous cycle, ovarian pathology, follicles counts and apoptosis of granular cells. The level of E2, FSH and LH in the serum was also detected. Results showed that in the F3 generation 500 ng/kg BW/day TCDD group, ovarian coefficient, LH concentration in serum and number of primary follicles were decreased, and the apoptosis of granular cells was significantly increased. The abnormal rate of estrous cycle and advance rate of vaginal opening time displayed a significantly increase in TCDD-treated groups. RT-PCR analysis showed that the expression level of H19 mRNA in ovary of TCDD treated F3 female rats was increased, compared to the control. Our data showed that ancestral TCDD exposure may impair transgenerational adult ovary development and functions, which may be related to an inhibition of the Igf2/H19 pathway in the ovarian.

The insulin-like growth factor family and breast cancer prognosis: A prospective cohort study among postmenopausal women in Denmark

OBJECTIVE

Circulating levels of insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) have been associated with breast cancer (BC) risk. The evidence in relation to BC prognosis is limited. We aimed to evaluate the association between pre-diagnostic serum levels of IGF-I, IGF-II, IGFBP-2, IGFBP-3 and BC prognosis (i.e. recurrence, BC specific mortality and all-cause mortality) among women diagnosed with BC. We hypothesized that higher serum levels of IGFs and IGFBPs were associated with poor BC prognosis and that the associations were modified by estrogen receptor (ER) status.

DESIGN

From the Danish Diet, Cancer and Health cohort, 412 postmenopausal women diagnosed with incident BC within 5 years of cohort baseline (1993-1997) were identified. Baseline serum samples were analyzed for IGF-I, IGF-II, IGFBP-2 and IGFBP-3. Follow-up was carried out through 2014 by linkage to national Danish registries. Exposures were related to BC prognosis by Cox Proportional Hazard models; effect modification by ER status was investigated and sensitivity analyses by follow-up time were made.

RESULTS

During a median of 15 years, 106 women experienced recurrence and 172 died (118 due to BC). Overall, no associations were observed between IGF-I, IGF-II, IGFBP-2, IGFBP-3 and BC prognosis and no effect modification by ER status was observed. However, higher levels of IGF-II were associated with higher BC specific mortality [Hazard Ratio (HR) (95% Confidence Intervals (CI)): 1.43 (1.01-2.04)] within 10 years of follow-up. Likewise, higher levels of IGFBP-2 were associated with higher BC specific mortality [HR (95% CI): 1.87 (1.19-2.94)] within 5 years of follow-up. In contrast, higher levels of IGFBP-3 were associated with lower risk of recurrence [HR (95% CI): 0.76 (0.60-0.97)] at 5 years of follow-up and BC specific mortality [HR (95% CI): 0.80 (0.65-0.98)] within 10 years of follow-up.

CONCLUSIONS

The present study did not support an association between higher serum levels of IGFs, IGFBPs and adverse BC prognosis. However, it is possible that the role of the IGF family in the etiology of the 5-10 year BC prognosis is different from that of longer-term BC prognosis.

Estrogen receptor-beta is a potential target for triple negative breast cancer treatment

Triple Negative breast cancer (TNBC) is a subtype of breast cancer that lacks the expression of estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2. TNBC accounts for 15-20% of all breast cancer cases but accounts for over 50% of mortality. We propose that Estrogen receptor-beta (ERβ) and IGF2 play a significant role in the pathogenesis of TNBCs, and could be important targets for future therapy.

Tissue microarrays (TMAs) from over 250 TNBC patients' were analyzed for ERβ and IGF2 expression by immunohistochemistry. Expression was correlated with clinical outcomes. In addition, TNBC cell lines Caucasians (CA): MB-231/BT549 and African Americans (AAs): MB-468/HCC70/HCC1806 were used to investigate the effect of hormonal and growth factor regulation on cell proliferation.

TMAs from AAs had higher expression of ERβ and IGF2 expression when compared to CA. ERβ and IGF2 were found to be upregulated in our TNBC cell lines when compared to other cell types. TNBC cells treated with ERβ agonist displayed significant increase in cell proliferation and migration when compared to controls. AA tissue samples from TNBC patients had higher expression of ERβ. African-American breast cancer TNBC tissue samples from TNBC patients have higher expression of ERβ. In addition, TNBC cell lines were also found to express high levels of ERβ. IGF2 increased transcription of ERβ in TNBC cells. Understanding the mechanisms of IGF2/ERβ axis in TNBC tumors could provide an opportunity to target this aggressive subtype of breast cancer.