Targeted Approaches to Triple-Negative Breast Cancer: Current Practice and Future Directions

Synthesis and Biological Evaluation of (S)-2-(Substituted arylmethyl)-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide Analogs and Their Synergistic Effect against PTEN-Deficient MDA-MB-468 Cells

A series of twenty-six compounds of furfuryl or benzyl tetrahydropyrazino[1,2-a]indole analogs were synthesized and evaluated for cytotoxic activity against the estrogen receptor (ER)-positive breast cancer cell line (MCF-7) and the epidermal growth factor receptor (EGFR) over-expressed triple-negative breast cancer cell line (MDA-MB-468). Among them, compounds 2b, 2f and 2i showed more potent activity and selectivity against MDA-MB-468 cells than gefitinib, as an EGFR- tyrosine kinase inhibitor. In addition, it was confirmed by means of isobologram analysis of combinational treatment with gefitinib that they have a synergistic effect, especially compounds 2b and 2f, which inhibit Akt T308 phosphorylation. Moreover, it was confirmed that 2-benzyl-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide analogs (2b, 2f, and Ref 2) tend to selectively inhibit PI3Kβ, which is involved in the phosphorylation of Akt.

Phosphorylation of the histone demethylase KDM5B and regulation of the phenotype of triple negative breast cancer

Epigenetic modifications are known to play critical roles in the expression of genes related to differentiation and dedifferentiation. Histone lysine demethylase KDM5B (PLU-1) catalyzes the demethylation of histone H3 on Lys 4 (H3K4), which results in the repression of gene expression. KDM5B is involved in regulation of luminal and basal cell specific gene expression in breast cancers. However, the mechanisms by which KDM5B is regulated in breast cancer, in particular in response to post-translational signals is not well-defined. Here, we demonstrate that KDM5B is phosphorylated at Ser1456 by the cyclin-dependent kinase 1 (CDK1). Phosphorylation of KDM5B at Ser1456 attenuated the occupancy of KDM5B on the promoters of pluripotency genes. Moreover, KDM5B inhibited the expression of pluripotency genes, SOX2 and NANOG, and decreased the stem cell population in triple-negative breast cancer cell lines (TNBC). We previously reported that the tumor suppressor HEXIM1 is a mediator of KDM5B recruitment to its target genes, and HEXIM1 is required for the inhibition of nuclear hormone receptor activity by KDM5B. Similarly, HEXIM1 is required for regulation of pluripotency genes by KDM5B.

Osteonecrosis of the Jaws in Patients Receiving Anti-Angiogenic Drugs and Chemotherapeutics: Literature Review and Case Reports

Medication-related osteonecrosis of the jaw (MRONJ) is a relatively rare but serious pathology associated with the use of bisphosphonates (BPs) and antiresorptive drugs in patients with bone metastases, multiple myeloma and osteoporosis. Various cases of patients with jaw bone necrosis due to BPs have recently been reported in the literature. Anti-angiogenic drugs are novel anticancer agents prescribed to patients with renal carcinoma, lung carcinoma, soft tissue metastases, etc. Anti-angiogenic drugs target the vascular endothelial growth factor’s (VEGF) signaling pathways via different mechanisms and thus inhibit tumor cell proliferation, neoangiogenesis and tumor growth. Several reports have suggested a higher incidence of MRONJ in patients treated with BPs in combination with anti-angiogenic drugs. However, there is currently no sufficient data in the literature about the risk of ONJ in patients taking anti-angiogenic drugs or cancer chemotherapy alone. We present two clinical cases of osteonecrosis of the jaw in patients treated with chemotherapy, but no history of BPs. In the first case the necrosis is related to the anti-angiogenic agent sunitinib in a patient with lung metastases and in the second case- to complex chemotherapy in a patient with acute myeloid leukemia. We recommend conservative treatment with antibiotics in both cases, together with antiseptics and surgical removal of the necrotic bone following total demarcation of the sequesters.

Antineoplastic effects of selective CDK9 inhibition with atuveciclib on cancer stem-like cells in triple-negative breast cancer

Treatment options for triple-negative breast cancer (TNBC) are limited due to the lack of efficient targeted therapies, frequently resulting in recurrence and metastatic disease. Accumulating evidence suggests that a small population of cancer stem-like cells (CSLCs) is responsible for tumor recurrence and therapy resistance. Here we investigated the role of cyclin-dependent kinase 9 (CDK9) in TNBC. Using The Cancer Genome Atlas (TCGA) data we found high-CDK9 expression correlates with worse overall survival in TNBC patients. Pharmacologic inhibition of CDK9 with atuveciclib in high-CDK9 expressing TNBC cell lines reduced expression of CDK9 targets MYC and MCL1 and decreased cell proliferation and survival. Importantly, atuveciclib inhibited the growth of mammospheres and reduced the percentage of CD24^low/CD44^high cells, indicating disruption of breast CSLCs (BCSLCs). Furthermore, atuveciclib impaired 3D invasion of tumorspheres suggesting inhibition of both invasion and metastatic potential. Finally, atuveciclib enhanced the antineoplastic effects of Cisplatin and promoted inhibitory effects on BCSLCs grown as mammospheres. Together, these findings suggest CDK9 as a potential therapeutic target in aggressive forms of CDK9-high TNBC.

Alarming Burden of Triple-Negative Breast Cancer in India

Breast cancer is the most prevalent cancer among women worldwide. Among the different breast cancer subtypes, triple-negative breast cancer (TNBC), which is more prevalent among younger age women, is the most aggressive form. Numerous clinicopathologic studies performed throughout the world strongly support the utterly poor prognoses and high recurrence rate of TNBC. The present report details a thorough data survey from Google and PubMed on the burden of TNBC worldwide and other associated factors, with special emphasis on its ever increasing incidence among Indian women. Our analysis revealed that the proportion of TNBC ranges from 6.7% to 27.9% in different countries, with the highest reported percentage in India among all, followed by Indonesia, Algeria, and Pakistan. Most of the other countries (Netherlands, Italy, London, Germany) had a TNBC incidence less than the mean level (ie, 15%). The high incidence of TNBC in the Indian population is associated with vivid risk factors, which primarily include lifestyle, deprivation status, obesity, family history, high mitotic indexes, and BRCA1 mutations. The treatment of TNBC is greatly hampered due to the lack of targeted therapies. Hence, it requires earnest attention towards extensive research for the prevention and development of treatment modalities with high efficacy.

Breast Cancer Stem Cell Therapeutics, Multiple Strategies Versus Using Engineered Mesenchymal Stem Cells With Notch Inhibitory Properties: Possibilities and Perspectives

Relapse cases of cancers are more vigorous and difficult to control due to the preponderance of cancer stem cells (CSCs). Such CSCs that had been otherwise dormant during the first incidence of cancer gradually appear as radiochemoresistant cancer cells. Hence, cancer therapeutics aimed at CSCs would be an effective strategy for mitigating the cancers during relapse. Alternatively, CSC therapy can also be proposed as an adjuvant therapy, along-with the conventional therapies. As regenerative stem cells (RSCs) are known for their trophic effects, anti-tumorogenicity, and better migration toward an injury site, this review aims to address the use of adult stem cells such as dental pulp derived; cord blood derived pure populations of regenerative stem cells for targeting CSCs. Indeed, pro-tumorogenicity of RSCs is of concern and hence has also been dealt with in relation to breast CSC therapeutics. Furthermore, as notch signaling pathways are upregulated in breast cancers, and anti-notch antibody based and sh-RNA based therapies are already in the market, this review focuses the possibilities of engineering RSCs to express notch inhibitory proteins for breast CSC therapeutics. Also, we have drawn a comparison among various possibilities of breast CSC therapeutics, about, notch1 inhibition. J. Cell. Biochem. 119: 141-149, 2018. © 2017 Wiley Periodicals, Inc.

miR-424(322)/503 is a breast cancer tumor suppressor whose loss promotes resistance to chemotherapy

In this study, Rodriguez-Barrueco et al. analyzed ∼3000 primary tumors and show that miR-424(322)/503 is commonly lost in a subset of aggressive breast cancers; they then describe the genetic aberrations that inactivate its expression. Their data show that miR-424(322)/503 is a tumor suppressor in breast cancer and provide a link between mammary epithelial involution, tumorigenesis, and the phenomenon of chemoresistance.

The female mammary gland is a very dynamic organ that undergoes continuous tissue remodeling during adulthood. Although it is well established that the number of menstrual cycles and pregnancy (in this case transiently) increase the risk of breast cancer, the reasons are unclear. Growing clinical and experimental evidence indicates that improper involution plays a role in the development of this malignancy. Recently, we described the miR-424(322)/503 cluster as an important regulator of mammary epithelial involution after pregnancy. Here, through the analysis of ∼3000 primary tumors, we show that miR-424(322)/503 is commonly lost in a subset of aggressive breast cancers and describe the genetic aberrations that inactivate its expression. Furthermore, through the use of a knockout mouse model, we demonstrate for the first time that loss of miR-424(322)/503 promotes breast tumorigenesis in vivo. Remarkably, we found that loss of miR-424(322)/503 promotes chemoresistance due to the up-regulation of two of its targets: BCL-2 and insulin-like growth factor-1 receptor (IGF1R). Importantly, targeted therapies blocking the aberrant activity of these targets restore sensitivity to chemotherapy. Overall, our studies reveal miR-424(322)/503 as a tumor suppressor in breast cancer and provide a link between mammary epithelial involution, tumorigenesis, and the phenomenon of chemoresistance.

Inhibition of GPR30 by estriol prevents growth stimulation of triple-negative breast cancer cells by 17β-estradiol

Background

Due to the lack of ERα, triple negative breast cancers (TNBCs) are not susceptible to endocrine therapy using antiestrogens. However, the majority of TNBCs express the membrane bound estrogen receptor GPR30. We have recently shown that knock-down of GPR30 expression prevented growth stimulation of TNBC cell lines by 17β-estradiol. Now we analyzed whether specific inhibition of GPR30 represents a new option for therapy of TNBC.

Methods

Growth of TNBC cells was assessed using Alamar-blue colorimetric assay. Activation of c-Src and EGF-receptor was assessed using Western blots. Expression of c-fos, cyclin D1 and aromatase was quantified by RT-PCR. Gα-specific signaling of GPR30 was analyzed by electrophoretic mobility shift assay.

Results

HCC1806 cells showed the highest GPR30 expression, in HCC70 cells it was clearly lower, in MDA-MB-231 cells it was lowest. 10^-8 M 17β-estradiol significantly increased proliferation of HCC1806 cells to 134 ± 12% of control (p < 0.01). Proliferation of HCC70 cells was slightly increased to 116 ± 8% of control. Estriol significantly reduced cell number of HCC1806 cells to 16 ± 12% (p < 0.01). Cell number of HCC70 cells and of MDA-MB-231 cells was reduced to 68 ± 25% and to 61 ± 10%, respectively.

Activity of Src kinase increased to 150 ± 10% (p < 0.05) by 10^-8 M 17β-estradiol treatment in HCC1806 and to 220 ± 20% in HCC70 cells (p < 0.01). Estriol treatment completely inhibited 17β-estradiol-induced p-src activation. Transactivation of EGF-receptor increased by estradiol treatment to 350% in HCC1806 and to 280% in HCC70 cells. Estriol completely suppressed EGF-receptor transactivation. c-fos expression increased to 260% and to 190%, respectively. Estriol reduced this induction to 160% (HCC1806) and below control in HCC70 cells. Cyclin D1 was induced to 290% (HCC1806) and 170% (HCC70) and completely inhibited by estriol. 17β-estradiol increased CREB-phosphorylation to 400%. Binding of phospho-CREB to a CRE of cyclin D1 was enhanced to 320%.

Conclusion

Specific pharmacological inhibition of GPR30 might become a promising targeted therapy for TNBC in future.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-935) contains supplementary material, which is available to authorized users.

Photochemical activation of the recombinant HER2-targeted fusion toxin MH3-B1/rGel; Impact of HER2 expression on treatment outcome

HER2 is overexpressed in 20-30% of breast tumors and is associated with aggressiveness and increased risk of recurrence and death. The HER2 protein is internalized as a part of its activity, and may therefore be utilized as a target for the specific intracellular delivery of drugs. Photochemical internalization (PCI) is a novel technology now undergoing clinical evaluation for its ability to improve the release into the cytosol of drugs entrapped in the endo/lysosomal compartment. PCI employs an amphiphilic photosensitizer which localizes in the membranes of endo/lysosomes. Subsequent light exposure (visible light) causes destabilization of the endo/lysosomal membranes. PCI has been proven highly effective for improving the cytosolic delivery of targeted toxins based on type I ribosome inactivating protein toxins such as gelonin. We examined the impact of the level of target antigen expression on PCI efficacy. Four human breast cancer cell lines (MDA-MB-231, BT-20, Zr-75-1 and SK-BR-3) covering a wide range of HER2 expression were included in the present study. PCI of the HER2-targeted fusion toxin MH3-B1/rGel was found to be highly effective in all four cell lines. The increase in PCI-mediated efficacy was not directly correlated with the cellular levels of HER2 as assessed by western blots, the overall uptake of MH3-B1/rGel as measured by flow cytometry, the amount of MH3-B1/rGel localized to endo/lysosomes assessed by confocal microscopy or the cell sensitivity to the photochemical treatment itself (photosensitizer and light without MH3-B1/rGel). However, correcting the PCI efficacy for the baseline cellular sensitivity to rGel revealed a linear correlation (R(2)=0.80) with HER2 expression. The present report therefore concludes the cellular sensitivity to the toxin as an important parameter for PCI efficacy and also indicates PCI of a HER2-targeted fusion toxin as an attractive treatment alternative for breast cancer patients with both HER2-low and -high expression.

Loss of androgen receptor expression predicts early recurrence in triple-negative and basal-like breast cancer

Treatment of triple-negative invasive breast cancers, defined by the absence of estrogen and progesterone receptors and c-erbB2 expression, remains challenging. Androgen receptor, a member of the nuclear receptor superfamily that is involved in signaling pathways regulating cell proliferation, has been implicated in breast tumorigenesis. We immunohistochemically examined the expression of androgen receptor, basal markers (CK14, 34βE12) and EGFR in 699 triple-negative invasive breast cancers in tissue microarrays using the streptavidin-biotin method, and correlated the findings with clinical outcome. Positive androgen receptor expression was defined as staining of 1% or more of tumor cell nuclei. Survival outcomes were estimated with the Kaplan-Meier method and compared between groups with log-rank statistics. Cox proportional hazards models were used to determine the effect of androgen receptor on survival outcomes. Immunohistochemical positivity was observed in 38% of tumors, with the proportion of stained tumor cells ranging from 1 to 95% (mean 29%, median 10%). Androgen receptor expression was inversely associated with histologic grade and mitotic score. CK14, 34βE12 and EGFR confirmed 85% of cases to be basal-like, without significant association of basal-like phenotype with androgen receptor expression. Disease-free survival was significantly better in androgen receptor-positive triple-negative breast cancer, with a trend for improved overall survival. Decreased recurrence likelihood in both triple-negative and basal-like tumors (hazard ratio, 0.704; 95% confidence intervals, 0.498-0.994; P=0.0464; and hazard ratio, 0.675; 95% confidence intervals, 0.468-0.974; P=0.0355, respectively) was noted within 5 years of diagnosis but not thereafter. Our study suggests that loss of androgen receptor in triple-negative breast cancers augurs a worse prognosis, including those with basal-like features. More work in elucidating its relationship with mechanisms of progression, as well as trials of targeted treatment for androgen receptor-expressing triple-negative tumors, needs to be performed.

Clinicopathologic implications of EpCAM and Sox2 expression in breast cancer

BACKGROUND

The purpose of this study was to investigate the clinicopathologic significance of EpCAM and Sox2 expression in breast cancer and to study their correlation during breast cancer progression.

PATIENTS AND METHODS

EpCAm and Sox2 expression were assessed using immunohistochemistry in ductal carcinoma insitu (DCIS), invasive breast cancer (IBC) and matched lymph node metastasis (LNM), if present.

RESULTS

EpCAM overexpression was found in 63.2% of DCIS, 72.2% of IBC and 74.4% of LNM. In IBC cases, EpCAM overexpression was associated with high grade (P < .001), large tumor size (P = .051), poor Nottingham Prognostic Index (NPI) (P = .006), histological tumor types (P = .044) and the triple negative phenotype (P = .008). LNM frequently reflected the expression phenotype of the matched primary tumors with no significant differences between LNM and their primary tumors (P = .564). Sox2 expression was detected in 47.4%, 33.3% and 54.7% of DCIS, IBC and LNM respectively. In DCIS group, Sox2 expression was significantly associated with comedo type (P = .037), negative ER (P = .012) and PR (P = .037) and the triple negative phenotype (P = .006). In IBC cases, Sox2 expression showed significant associations with high grade (P = .045), nodal spread (P = .037), poor NPI (P = .018) and the triple negative phenotype (P < .001). LNM showed significantly higher Sox2 expression rates than primary tumors (P < .001). Significant positive associations between EpCAM overexpression and Sox2 positivity in DCIS (P = .027), IBC (P = .001) and LNM (P < .001) were found.

CONCLUSION

This study emphasized the potential role of EpCAM and Sox2 in breast carcinogenesis and revealed their involvement during breast cancer progression and LN metastases.

1-Phenyl-4-benzoyl-1H-1,2,3-triazoles as orally bioavailable transcriptional function suppressors of estrogen-related receptor α

Estrogen-related receptor α is a potential candidate target for therapeutic treatment of breast cancer. We describe the discovery and structure-activity relationship study of a series of 1-phenyl-4-benzoyl-1H-1,2,3-triazoles as novel suppressors of ERRα transcriptional functions. The most promising compound, 2-aminophenyl-(1-(3-isopropylphenyl)-1H-1,2,3-triazol-4-yl)methanone (14n), potently suppressed the transcriptional functions of ERRα with IC50 = 0.021 μM in a cell-based reporter gene assay and also decreased both the mRNA levels and the protein levels of ERRα and the downstream targets. This compound inhibited the proliferation and migration of breast cancer cells with high level of ERRα. Preliminary pharmacokinetic studies suggested that it possessed a good pharmacokinetic profile with an oral bioavailability of 71.8%. The compounds may serve as novel small molecule probes for further validation of ERRα as a molecular target for anticancer drug development.