Raloxifene nano-micelles effect on triple-negative breast cancer is mediated through estrogen receptor-β and epidermal growth factor receptor

Raloxifene encapsulated spanlastic nanogel for the prevention of bone fracture risk via transdermal administration: Pharmacokinetic and efficacy study in animal model

This research work is to evaluate spanlastic-loaded raloxifene (RLX) nanogel administration via the transdermal route to avoid its hepatic metabolism and to enhance the bioavailability for better management of osteoporosis. RLX-loaded spanlastic nanogel was prepared and characterized for its viscosity, pH, spreadability, and texture profile. The formulation was applied on the skin surface of the animal for pharmacokinetic evaluation, and later, the efficacy of the formulation was assessed in ovariectomized female Wistar rats. The nanogel was obtained with a viscosity (2552.66 ± 30.61 cP), pH (7.1 ± 0.1), and spreadability (7.1 ± 0.2 cm). The texture properties, cohesiveness, and adhesiveness of the nanogel showed its suitability for transdermal application. Nanogel showed no sign of edema and erythema in the skin irritation test which revealed its safety for transdermal application. The t1/2 obtained for RLX-spanlastic nanogel (37.02 ± 0.59 h) was much higher than that obtained for RLX-oral suspension (14.43 h). The relative bioavailability was found to be 215.96% for RLX-spanlastic nanogel, and the drug and formulation did not show any toxicity in any of the vital organs, as well as no hematological changes occurring in blood samples. In microarchitectural measurement, RLX-spanlastic nanogel exhibited no unambiguous deviations along with improved bone mineral density compared to the RLX suspension treated group. Transdermal administration of RLX-spanlastic nanogel showed significant improvement of drug bioavailability (approx. twice to oral administration) without any toxic effect in the treated rats. Hence, spanlastic nanogel could be a better approach to deliver RLX via transdermal route for the management of osteoporosis.

Anticancer or carcinogenic? The role of estrogen receptor β in breast cancer progression

Estrogen receptor β (ERβ) is closely related to breast cancer (BC) progression. Traditional concepts regard ERβ as a tumor suppressor. As studies show the carcinogenic effect of ERβ, some people have come to a new conclusion that ERβ serves as a tumor suppressor in estrogen receptor α (ERα)-positive breast cancer, while it is a carcinogen in ERα-negative breast cancer. However, we re-examine the role of ERβ and find this conclusion to be misleading based on the last decade's research. A large number of studies have shown that ERβ plays an anticancer role in both ERα-positive and ERα-negative breast cancers, and its carcinogenicity does not depend solely on the presence of ERα. Herein, we review the anticancer and oncogenic effects of ERβ on breast cancer progression in the past ten years, discuss the mechanism respectively, analyze the main reasons for the inconsistency and update ERβ selective ligand library. We believe a detailed and continuously updated review will help correct the one-sided understanding of ERβ, promoting ERβ-targeted breast cancer therapy.

Folic acid anchored urchin-like raloxifene nanoparticles for receptor targeting in breast cancer: Synthesis, optimisation and in vitro biological evaluation

In this study, raloxifene hydrochloride (RLX) was loaded into bovine serum albumin nanoparticles (RLX-BSA-NPs) and further surface modified with folic acid (FA-RLX-BSA-NPs) for targeted breast cancer therapy. In statistical optimization of RLX-BSA-NPs, albumin and crosslinker concentration significantly affected particle size and entrapment efficiency of RLX-BSA-NPs. Structural characterizations confirmed that the formation of FA-RLX-BSA-NPs and SEM microphotographs resembled the urchin-like spiky feature. A sustained in vitro release pattern was observed till 120 h from FA-RLX-BSA-NPs in phosphate buffer. The MTT assay revealed maximum cell inhibition by FA-RLX-BSA-NPs against MCF-7 cells and MDA MB-231 cells at lower IC₅₀ values (0.5 µg/ml and 0.7 µg/ml) compared to RLX and RLX-BSA-NPs. The cell cycle analysis revealed that FA-RLX-BSA-NPs induced apoptosis of MCF-7 cells in the sub-G1 phase via folate receptor-α mediated endocytic uptake. Hence, the raloxifene nanoparticles stance as a potential nanocarrier for targeted therapy in breast cancer.

Clinical associations of ESR2 (estrogen receptor beta) expression across thousands of primary breast tumors

Estrogen receptor alpha (ERα, encoded by ESR1) is a well-characterized transcription factor expressed in more than 75% of breast tumors and is the key biomarker to direct endocrine therapies. On the other hand, much less is known about estrogen receptor beta (ERβ, encoded by ESR2) and its importance in cancer. Previous studies had some disagreement, however most reports suggested a more favorable prognosis for patients with high ESR2 expression. To add further clarity to ESR2 in breast cancer, we interrogated a large population-based cohort of primary breast tumors (n = 3207) from the SCAN-B study. RNA-seq shows ESR2 is expressed at low levels overall with a slight inverse correlation to ESR1 expression (Spearman R = −0.18, p = 2.2e−16), and highest ESR2 expression in the basal- and normal-like PAM50 subtypes. ESR2-high tumors had favorable overall survival (p = 0.006), particularly in subgroups receiving endocrine therapy (p = 0.03) and in triple-negative breast cancer (p = 0.01). These results were generally robust in multivariable analyses accounting for patient age, tumor size, node status, and grade. Gene modules consistent with immune response were associated to ESR2-high tumors. Taken together, our results indicate that ESR2 is generally expressed at low levels in breast cancer but associated with improved overall survival and may be related to immune response modulation.

ERβ in Triple-Negative Breast Cancer: Emerging Concepts and Therapeutic Possibilities

Despite the improvements in diagnostic and therapeutic approaches, breast cancer still remains one of the world’s leading causes of death among women. Particularly, triple negative breast cancer (TNBC) is characterized by aggressiveness, metastatic spreading, drug resistance and a very high percentage of death in patients. Nowadays, identification of new targets in TNBC appears very compelling. TNBC are considered negative for the estrogen receptor alpha (ERα) expression. Nevertheless, they often express ERβ and its variants. As such, this TNBC subtype still responds to estrogens. While the ERβ1 variant seems to act as a tumor-suppressor, the two variants ERβ2 and 5 exhibit pro-oncogenic activities in TNBC. Thus, ERβ1 activation might be used to limit the growth and spreading as well as to increase the drug sensitivity of TNBC. In contrast, the pro-oncogenic properties of ERβ2 and ERβ5 suggest the possible development and clinical use of specific antagonists in TNBC treatment. Furthermore, the role of ERβ might be regarded in the context of the androgen receptor (AR) expression, which represents another key marker in TNBC. The relationship between AR and ERβ as well as the ability to modulate the receptor-mediated effects through agonists/antagonists represent a challenge to develop more appropriate therapies in clinical management of TNBC patients. In this review, we will discuss the most recent data in the field. Therapeutic implications of these findings are also presented in the light of the discovery of specific ERβ modulators.

The role of estrogen receptor beta in breast cancer

Breast cancer, a malignant tumor originating from mammary epithelial tissue, is the most common cancer among women worldwide. Challenges facing the diagnosis and treatment of breast cancer necessitate the search for new mechanisms and drugs to improve outcomes. Estrogen receptor (ER) is considered to be important for determining the diagnosis and treatment strategy. The discovery of the second estrogen receptor, ERβ, provides an opportunity to understand estrogen action. The emergence of ERβ can be traced back to 1996. Over the past 20 years, an increasing body of evidence has implicated the vital effect of ERβ in breast cancer. Although there is controversy among scholars, ERβ is generally thought to have antiproliferative effects in disease progression. This review summarizes available evidence regarding the involvement of ERβ in the clinical treatment and prognosis of breast cancer and describes signaling pathways associated with ERβ. We hope to highlight the potential of ERβ as a therapeutic target.

Pluronic P123 modified nano micelles loaded with doxorubicin enhanced tumor-suppressing effect on drug-resistant breast cancer cells

OBJECTIVE

Nano micelles (NMs) have been widely used for various biomedical applications due to its unique physiochemical properties. This study aimed to investigated the anti-tumor effect of doxorubicin (Dox)-loaded Pluronic P123 (P123) and PEG2000-DSPE mixed NMs in drug-resistant breast cancer cells.

RESULTS

The expression of P-gp and MDR1 gene was highly expressed in MCF-7R but not MCF-7 cells. The cellular uptake of P123-PEG2000-DSPE (Dox) was higher than that of free Dox and PEG2000-DSPE (Dox) in MCF-7R cells. Furthermore, compared with free Dox, both PEG2000-DSPE (Dox) and P123-PEG2000-DSPE (Dox) significantly diminished cell viability, and promoted cell apoptosis in MCF-7R cells. In addition, the P123-modified NMs obviously inhibited the expression of P-gp and MDR1.

CONCLUSIONS

P123-PEG2000-DSPE (Dox) had a superior anti-tumor activity than PEG2000-DSPE (Dox) in MCF-7R cells through P-gp-mediated drug excretion and drug resistance mechanisms.

METHODS

The PEG2000-DSPE NMs (PEG2000-DSPE), P123 and PEG2000-DSPE mixed NMs (P123-PEG2000-DSPE), Dox-loaded PEG2000-DSPE NMs (PEG2000-DSPE (Dox)), and Dox-loaded Pluronic P123 and PEG2000-DSPE mixed NMs (P123-PEG2000-DSPE (Dox)) were prepared, and then the morphologies and the size distribution of PEG2000-DSPE (Dox) and P123-PEG2000-DSPE (Dox) were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively.