Pharmacotherapy of triple-negative breast cancer

Effect of Diallyl Trisulfide on TNF-α-induced CCL2/MCP-1 Release in Genetically Different Triple-negative Breast Cancer Cells

BACKGROUND/AIM

Diallyl trisulfide (DATS) has been shown to prevent and inhibit breast carcinogenesis. CCL2/MCP-1 has been shown to play a significant role in breast cancer. This study explored DATS efficacy on triple-negative breast cancer (TNBC) cells.

MATERIALS AND METHODS

DATS efficacy on TNF-α induced TNBC cells were examined via trypan blue exclusion test, wound-healing assay, human cytokine arrays, ELISA, and RT-PCR.

RESULTS

DATS significantly induced cell death and inhibited cell migration. Expression of CCL2/MCP-1, IL-6, PDGF-BB, NT-3, and GM-CSF in TNF-α-treated cells increased. However, DATS significantly decreased the expression of CCL2/MCP-1 in TNF-α-treated MDA-MB-231 but not in MDA-MB-468 cells. DATS significantly down-regulated mRNA expression of IKBKE and MAPK8 in both cell lines, indicating a possible effect in genes involved in the NF-κB and MAPK signaling.

CONCLUSION

DATS may have a role in TNBC therapy and prevention by targeting CCL2.

The putative endogenous AHR ligand ITE reduces JAG1 and associated NOTCH1 signaling in triple negative breast cancer cells

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor. Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype. TNBC expresses AHR and AHR ligands have anti-cancer activity in TNBC. The aggressiveness of TNBC is due in part to JAG1-NOTCH1 signaling. ITE is a putative endogenous AHR ligand. We show that ITE reduces the expression of JAG1 the amount of Notch 1 intracellular domain (NICD1) and the phosphorylation of STAT3 (at tyrosine 705) in TNBC MDA-MB-231 cells. The STAT3 inhibitor STATTIC also reduced JAG1. STAT3, thus, mediates regulation of JAG1 in MDA-MB-231 cells. Reducing the expression of JAG1 with short interfering RNA decreases the growth, migration and invasiveness of MDA-MB-231 cells. JAG1, therefore, has cellular effects in MDA-MB-231 cells under basal conditions. We consequently evaluated if exposing cells to greater amounts of JAG1 would counteract ITE cellular effects in MDA-MB-231 cells. The results show that JAG1 does not counteract the cellular effects of ITE. JAG1, thus, has no effect on growth or invasiveness in MDA-MB-231 cells treated with ITE. JAG1, therefore, has context dependent roles in MDA-MB-231 cells (basal versus ITE treatment). The results also show that other pathways, not inhibition of the JAG1-NOTCH1 pathway, are important for mediating the growth and invasive inhibitory effect of ITE on MDA-MB-231 cells.

Berberine attenuates XRCC1-mediated base excision repair and sensitizes breast cancer cells to the chemotherapeutic drugs

Berberine (BBR) is a natural isoquinoline alkaloid, which is used in traditional medicine for its anti‐microbial, anti‐protozoal, anti‐diarrhoeal activities. Berberine interacts with DNA and displays anti‐cancer activities, yet its effects on cellular DNA repair and on synthetic treatments with chemotherapeutic drugs remain unclear. In this study, we investigated the effects of BBR on DNA repair and on sensitization of breast cancer cells to different types of DNA damage anti‐tumoural drugs. We found BBR arrested cells in the cell cycle S phase and induced DNA breaks. Cell growth analysis showed BBR sensitized MDA‐MB‐231 cells to cisplatin, camptothecin and methyl methanesulfonate; however, BBR had no synergistic effects with hydroxurea and olaparib. These results suggest BBR only affects specific DNA repair pathways. Western blot showed BBR down‐regulated XRCC1 expressions, and the rescued XRCC1 recovered the resistance of cancer cells to BBR. Therefore, we conclude that BBR interferes with XRCC1‐mediated base excision repair to sensitize cancer cells to chemotherapeutic drugs. These finding can contribute to understanding the effects of BBR on cellular DNA repair and the clinical employment of BBR in treatment of breast cancer.

Cationic liposome codelivering PI3K pathway regulator improves the response of BRCA1-deficient breast cancer cells to PARP1 inhibition

Although some progresses have been made in breast cancer therapy, effective treatment for BRCA1-deficient breast cancer remains to be a great challenge. It has been demonstrated that the PI3K pathway is inappropriately activated in BRCA1-deficient breast cancers which can be downregulated by microRNA 451 (miR-451). In addition, although PARP1 inhibitors showed relatively positive results in both preclinical and clinical studies, additional efforts to decrease drug resistance as well as reduce systematic toxicity need to be addressed. To this end, by encapsulating the miR-451 mimic and PARP1 inhibitor in the same cationic liposome, we examined the potential of enhancing the response of PARP1 inhibition on BRCA1-deficient breast cancer by regulating the PI3K pathway. Our results revealed that in BRCA1-deficient human breast cancer cell line, PARP1 inhibition resulted in DNA damage with viability decrease, G2/M arrest as well as apoptosis. In contrast, single PI3K inhibition induced G1 arrest along with retarded cell proliferation. However, it was noted that combination of PARP inhibitor and PI3K regulator could exert synergetic function to evidently decrease cell proliferation compared with PARP inhibition alone, which was also confirmed by in vivo antitumor assay using xenograft tumor models. Collectively, our results offer an alternative but superior strategy for the therapy of BRCA1-deficient human breast cancers which may benefit the clinical applications.

Genetic polymorphisms and response to 5-fluorouracil, doxorubicin and cyclophosphamide chemotherapy in breast cancer patients

Clinical resistance to chemotherapy is one of the major problems in breast cancer treatment. In this study we analyzed possible impact of 22 polymorphic variants on the treatment response in 324 breast cancer patients. Selected genes were involved in FAC chemotherapy drugs transport (ABCB1, ABCC2, ABCG2, SLC22A16), metabolism (CYP1B1, CYP2C19, GSTT1, GSTM1, GSTP1, TYMS, MTHFR, DPYD), drug-induced damage repair (ERCC1, ERCC2, XRCC1) and involved in regulation of DNA damage response and cell cycle control (ATM, TP53).

Apart from preexisting metastases three polymorphic variants were independent prognostic high risk factors of lack of response to FAC chemotherapy. Our results showed that the response to treatment depended of the variability in genes engaged in drugs’ transport (ABCC2 c.-24C>T, ABCB1 p.Ser893Ala/Thr) and in DNA repair machinery (ERCC2 p.Lys751Gln). Furthermore, the growing number of high-risk genotypes was reflected in gradual increase in risk of the non-responsiveness to treatment- from OR 2.68 for presence of two genotypes to OR 9.93 for carriers of all three negative genotypes in the group of all patients. Similar gene-dosage effect was observed in the subgroup of TNBCs. Also, TFFS significantly shortened with the increasing number of high-risk genotypes, with median of 54.4 months for carriers of one variant, to 51.5 and 34.9 months for the carriers of two and three genotypes, respectively.

Our results demonstrate that results of cancer treatment are the effect of many clinical and genetic factors. It seems that multifactorial polymorphic models could be a potentially useful tool in personalization of cancer therapies. The novelty in our model is the over representation of triple negative breast cancer (TNBC) patients among the carriers of all unfavorable polymorphic variants. This finding contributes to the elucidation of the mechanisms of drug resistance in this subgroup of breast cancer patients.

Berberine activates caspase-9/cytochrome c-mediated apoptosis to suppress triple-negative breast cancer cells in vitro and in vivo

Berberine (BBR) is an isoquinoline alkaloid isolated from Cotridis rhizoma and exhibits multiple biological roles including anti-microbe, anti-inflammation and anti-tumor activities. In this study, two triple-negative breast cancer cell (TNBC) lines, MDA-MB-231 and BT549, were used to investigate the effect of BBR on growth of TNBC in vitro and in vivo. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate the viability of cells treated with BBR. After 48h treatments, a 50% inhibitory concentration (IC₅₀) of BBR to BT549 and MDA-MB-231 cells are at 16.575±1.219μg/ml and 18.525±6.139μg/ml respectively. BBR reduced colony formation of BT549 and MDA-MB-231 cells. The wound-healing assay showed BBR decreased breast cancer cell migrations (P<0.01). AnnexinV-PI staining assay confirmed BBR induced cellular apoptosis. The expressions of caspase-3, caspase-9, Bcl-2 and Bax were detected by western blot, which showed BBR activated caspase-3, 9 and Bax, but down-regulated Bcl-2 expression. BBR promoted the release of cytochrome c through the immunofluorescent analysis (P<0.01). We also found BBR increased the level of cellular γH2AX and increased the expression of Ligase4, which suggests BBR induces the double-strand breaks (DSB). These results thus demonstrated that BBR induced DSB, subsequently increased the release of cytochrome c and eventually triggered the caspase9-dependent apoptosis. In addition, we used a MDA-MB-231 mouse-xenograftmodel to evaluate the effect of BBR on tumor growth. BBR suppressed tumor growth and increased caspase-9 levels in xenograft tumors through immunohistochemistry analysis (P<0.01). Taken together, these results demonstrate that BBR activates caspase-9/cytochrome c-mediated apoptosis to inhibit the growth of TNBC breast cancer cells in vitro and in vivo.

Biologic, demographic, and social factors affecting triple negative breast cancer outcomes

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype that disproportionately affects women who are African American, younger, or carriers of the BRCA1 gene. No targeted treatments exist for the disease, which has distinct features and presents unique challenges to patients who have been diagnosed with it.

OBJECTIVES

TNBC is reviewed in this article according to incidence, tumor grade, stage of diagnosis, biologic and social risk factors, mortality, and treatment.

METHODS

Published articles pertaining to TNBC and located through online database searches were reviewed. Articles were selected either because they offered the most current information about TNBC or contributed to the understanding of TNBC.

FINDINGS

Biologic, demographic, and social factors present unique challenges in the treatment of women with TNBC. Knowing about the characteristics of TNBC and the populations who are most at risk for the disease might help healthcare providers better respond to their patients. It may also facilitate responsiveness to patients' needs and enhance their quality of life.

Contrasting breast cancer molecular subtypes across serial tumor progression stages: biological and prognostic implications

The relevance of the intrinsic subtypes for clinical management of metastatic breast cancer is not comprehensively established. We aimed to evaluate the prevalence and prognostic significance of drifts in tumor molecular subtypes during breast cancer progression. A well-annotated cohort of 304 women with advanced breast cancer was studied. Tissue microarrays of primary tumors and synchronous lymph node metastases were constructed. Conventional biomarkers were centrally assessed and molecular subtypes were assigned following the 2013 St Gallen guidelines. Fine-needle aspirates of asynchronous metastases were transcriptionally profiled and subtyped using PAM50. Discordant expression of individual biomarkers and molecular subtypes was observed during tumor progression. Primary luminal-like tumors were relatively unstable, frequently adopting a more aggressive subtype in the metastases. Notably, loss of ER expression and a luminal to non-luminal subtype conversion was associated with an inferior post-recurrence survival. In addition, ER and molecular subtype assessed at all tumor progression stages were independent prognostic factors for post-recurrence breast cancer mortality in multivariable analyses. Our results demonstrate that drifts in tumor molecular subtypes may occur during tumor progression, conferring adverse consequences on outcome following breast cancer relapse.

Breast cancer survival in African-American women by hormone receptor subtypes

Breast cancer accounts for over 200,000 annual cases among women in the United States, and is the second leading cause of cancer-related deaths. However, few studies have investigated the association between breast cancer subtype and survival among African-American women. We analyzed cancer-related deaths among African-American women using data obtained from the SEER database linked to the 2000 U.S. census data. We examined distribution of baseline socio-demographic and clinical characteristics by breast cancer subtypes and used Cox proportional hazard models to determine associations between breast cancer subtypes and cancer-related mortality, adjusting for age, socio-economic status, stage at diagnosis, and treatment. Among 19,836 female breast cancer cases, 54.4% were diagnosed with the HER2-/HR+ subtype, with the majority of those cases occurring among women ages 55 and older. However, after adjusting for age, stage, and treatment type (surgery, radiation, or no radiation and/or cancer-directed surgery), TNBC (HR 2.34; 95% CI 1.95-2.81) and HER2+/HR- (HR 1.39, 95% CI 1.08-1.79) cases had significantly higher hazards of cancer-related deaths compared with HER2+/HR+ cases. Adjusting for socio-economic status did not significantly alter these associations. African-American women with TNBC were more likely to have a cancer-related death than African-American women with other breast cancer subtypes. This association remained after adjustments for age, stage, treatment, and socio-economic status. Further studies are needed to identify subtype-specific risk and prognostic factors aimed at better informing prevention efforts for all women.

Antimetastatic Therapies of the Polysulfide Diallyl Trisulfide against Triple-Negative Breast Cancer (TNBC) via Suppressing MMP2/9 by Blocking NF-κB and ERK/MAPK Signaling Pathways

BACKGROUND

Migration and invasion are two crucial steps of tumor metastasis. Blockage of these steps may be an effective strategy to reduce the risk. The objective of the present study was to investigate the effects of diallyl trisulfide (DATS), a natural organosulfuric compound with most sulfur atoms found in garlic, on migration and invasion in triple negative breast cancer (TNBC) cells. Molecular mechanisms underlying the anticancer effects of DATS were further investigated.

METHODS AND RESULTS

MDA-MB-231 cells and HS 578t breast cancer cells were treated with different concentrations of DATS. DATS obviously suppressed the migration and invasion of two cell lines and changed the morphological. Moreover, DATS inhibited the mRNA/protein/ enzymes activities of MMP2/9 via attenuating the NF-κB pathway. DATS also inhibited ERK/MAPK rather than p38 and JNK.

CONCLUSION

DATS inhibits MMP2/9 activity and the metastasis of TNBC cells, and emerges as a potential anti-cancer agent. The inhibitory effects are associated with down-regulation of the transcriptional activities of NF-κB and ERK/MAPK signaling pathways.

Anti-tumor activity of novel biisoquinoline derivatives against breast cancers

Breast cancer is classified into three groups according to its expression of hormone/growth factor receptors: (i) estrogen receptor (ER) and progesterone receptor (PR)-positive; (ii) human epidermal growth factor receptor 2 (HER2)-positive; and (iii) ER, PR, and HER2-negative (triple-negative). A series of methoxy-substituted biisoquinoline compounds have been synthesized as a potential chemotherapeutic agent for the triple-negative breast cancers which are especially challenging to manage. Structure activity relationship study revealed that rigid 6,6'-dimethoxy biisoquinoline imidazolium compound (1c, DH20931) exhibited the significant growth inhibitory effects on both triple-positive and triple-negative human breast cancer cell lines with IC50 in the range of 0.3-3.9 μM. The 1c (DH20931) is more potent than structurally related noscapine for growth inhibition of MCF7 cell line (IC50=1.3 vs 57 μM) and MDA-MB231 cell line (IC50=3.9 vs 64 μM).

RB1 status in triple negative breast cancer cells dictates response to radiation treatment and selective therapeutic drugs

Triple negative breast cancer (TNBC) includes basal-like and claudin-low subtypes for which only chemotherapy and radiation therapy are currently available. The retinoblastoma (RB1) tumor suppressor is frequently lost in human TNBC. Knockdown of RB1 in luminal BC cells was shown to affect response to endocrine, radiation and several antineoplastic drugs. However, the effect of RB1 status on radiation and chemo-sensitivity in TNBC cells and whether RB1 status affects response to divergent or specific treatment are unknown. Using multiple basal-like and claudin-low cell lines, we hereby demonstrate that RB-negative TNBC cell lines are highly sensitive to gamma-irradiation, and moderately more sensitive to doxorubicin and methotrexate compared to RB-positive TNBC cell lines. In contrast, RB1 status did not affect sensitivity of TNBC cells to multiple other drugs including cisplatin (CDDP), 5-fluorouracil, idarubicin, epirubicin, PRIMA-1^met, fludarabine and PD-0332991, some of which are used to treat TNBC patients. Moreover, a non-biased screen of ∼3400 compounds, including FDA-approved drugs, revealed similar sensitivity of RB-proficient and -deficient TNBC cells. Finally, ESA⁺/CD24^−/low/CD44⁺ cancer stem cells from RB-negative TNBC lines were consistently more sensitive to gamma-irradiation than RB-positive lines, whereas the effect of chemotherapy on the cancer stem cell fraction varied irrespective of RB1 expression. Our results suggest that patients carrying RB-deficient TNBCs would benefit from gamma-irradiation as well as doxorubicin and methotrexate therapy, but not necessarily from many other anti-neoplastic drugs.

Another review on triple negative breast cancer. Are we on the right way towards the exit from the labyrinth?

Triple negative breast cancer is a heterogeneous group of tumors, lacking the expression of estrogen, progesterone and HER-2 receptors. As frequency, it accounts about 15-20% of all breast cancers. Although in the last years there was a "boom" in publishing over this issue, multiple molecular classifications being elaborated, "the triple negative breast cancer odyssey " is still far away from ending, as the complicated molecular pathways of pathogenesis and drug resistance mechanisms remain yet insufficiently explored. The aim of this review is presentation of molecular signatures that could predict outcome and drug resistance in triple negative breast cancer.

Antiproliferative effects of artemisinin on human breast cancer cells requires the downregulated expression of the E2F1 transcription factor and loss of E2F1-target cell cycle genes

Artemisinin, a sesquiterpene phytolactone derived from Artemisia annua, is a potent antimalarial compound with promising anticancer properties, although the mechanism of its anticancer signaling is not well understood. Artemisinin inhibited proliferation and induced a strong G1 cell cycle arrest of cultured MCF7 cells, an estrogen-responsive human breast cancer cell line that represents an early-stage cancer phenotype, and effectively inhibited the in-vivo growth of MCF7 cell-derived tumors from xenografts in athymic nude mice. Artemisinin also induced a growth arrest of tumorigenic human breast cancer cell lines with preneoplastic and late stage cancer phenotypes, but failed to arrest the growth of a nontumorigenic human mammary cell line. Concurrent with the cell cycle arrest of MCF7 cells, artemisinin selectively downregulated the transcript and protein levels of the CDK2 and CDK4 cyclin-dependent kinases, cyclin E, cyclin D1, and the E2F1 transcription factor. Analysis of CDK2 promoter-luciferase reporter constructs showed that the artemisinin ablation of CDK2 gene expression was accounted for by the loss of CDK2 promoter activity. Chromatin immunoprecipitation revealed that artemisinin inhibited E2F1 interactions with the endogenous MCF7 cell CDK2 and cyclin E promoters. Moreover, constitutive expression of exogenous E2F1 prevented the artemisinin-induced cell cycle arrest and downregulation of CDK2 and cyclin E gene expression. Taken together, our results demonstrate that the artemisinin disruption of E2F1 transcription factor expression mediates the cell cycle arrest of human breast cancer cells and represents a critical transcriptional pathway by which artemisinin controls human reproductive cancer cell growth.