Combination treatment of tamoxifen with risperidone in breast cancer

Decoding cell death signalling: Impact on the response of breast cancer cells to approved therapies

Breast cancer is a principal cause of cancer-related mortality in female worldwide. While many approved therapies have shown promising outcomes in treating breast cancer, understanding the intricate signalling pathways controlling cell death is crucial for optimizing the treatment outcome. A growing body of evidence has unveiled the aberrations in multiple cell death pathways across diverse cancer types, highlighting these pathways as appealing targets for therapeutic interventions. In this review, we provide a comprehensive overview of the current state of knowledge on the cell death signalling mechanisms with a particular focus on their impact on the response of breast cancer cells to approved therapies. Additionally, we discuss the potentials of combination therapies that exploit the synergy between approved drugs and therapeutic agents targeting modulators of cell death pathways.

Epidermal growth factor receptor inhibition potentiates chemotherapeutics-mediated sensitization of metastatic breast cancer stem cells

BACKGROUND

Metastasis has been a cause of the poor prognosis and cancer relapse of triple-negative breast cancer (TNBC) patients. The metastatic nature of TNBC is contributed by the breast cancer stem cells (CSCs) which have been implicated in tumorigenesis. Higher expression of epidermal growth factor receptor (EGFR) in breast CSCs has been used as a molecular target for breast cancer therapeutics. Thus, it necessitates the design and generation of efficacious EGFR inhibitors to target the downstream signaling associated with the cellular proliferation and tumorigenesis of breast cancer.

AIM

To generate efficacious EGFR inhibitors that can potentiate the chemotherapeutic-mediated mitigation of breast cancer tumorigenesis.

METHODS AND RESULTS

We identified small molecule EGFR inhibitors using molecular docking studies. In-vitro screening of the compounds was undertaken to identify the cytotoxicity profile of the small-molecule EGFR inhibitors followed by evaluation of the non-cytotoxic compounds in modulating the doxorubicin-induced migration, in-vitro tumorigenesis potential, and their effect on the pro-apoptotic genes' and protein markers' expression in TNBC cells. Compound 1e potentiated the doxorubicin-mediated inhibitory effect on proliferation, migration, in-vitro tumorigenesis capacity, and induction of apoptosis in MDA-MB-231 cells, and in the sorted CD24+-breast cancer cells and CD24-/CD44+-breast CSC populations. Orthotopic xenotransplantation of the breast CSCs-induced tumors in C57BL/6J mice was significantly inhibited by the low dose of Doxorubicin in the presence of compound 1e as depicted by molecular and immunohistochemical analysis.

CONCLUSION

Thus, the study suggests that EGFR inhibition-mediated sensitization of the aggressive and metastatic breast CSCs in TNBCs toward chemotherapeutics may reduce the relapse of the disease.

Combination of tamoxifen and D-limonene enhances therapeutic efficacy in breast cancer cells

Breast cancer one of the most common diseases in women, has a high death and morbidity rate. Tamoxifen being very much effective in the chemoprevention of breast cancer has been shown to develop resistance during the course of treatment making it difficult for patient's survival. By combining tamoxifen with naturally occurring substances having similar activities, might control the toxicity and increase the susceptibility towards the treatment. As a natural compound, D-limonene has been reported to inhibit the growth of certain malignancies significantly. The main goal of our work is to investigate the combinatorial antitumor effects of D-limonene and tamoxifen in MCF-7 cells, as well as understand the potential underlying anticancer mechanism. MTT assays, colony formation assays, DAPI and Annexin V-FITC labeling, flow cytometer analysis, and western blot analysis were used to explore the details of anticancer mechanism. The combined effects of tamoxifen with D-limonene have shown significant decrease in the cell viability of MCF 7 cells. According to flow cytometer analyses and Annexin V/PI staining, D-limonene has been found to increase tamoxifen-mediated apoptosis as compared to the treatment alone in these cells. Additionally, cell growth has been found to be arrested at G1 phase by regulating cyclin D1 and cyclin B1. Our research consequently provided the first evidence that combining D-limonene and tamoxifen might increase the anticancer efficacy by inducing apoptosis in MCF 7 breast cancer cells. This combinatorial treatment strategy demands more research which might fulfill the need for improved treatment efficacy in controlling breast cancer.

Combinatorial treatments of tamoxifen and SM6Met, an extract from Cyclopia subternata Vogel, are superior to either treatment alone in MCF-7 cells

Synergistic drug combinations are not only popular in antibiotic, anti-microbial, immune disease (i.e., AIDS) and viral infection studies, but has also gained traction in the field of cancer research as a multi-targeted approach. It has the potential to lower the doses needed of standard of care (SOC) therapeutic agents, whilst maintaining an effective therapeutic level. Lower dosages could ameliorate the fundamental problems such as drug resistance and metastasis associated with current SOC therapies. In the current study, we show that the combination of SM6Met with (2)-4-hydroxytamoxifen (4-OH-Tam, the active metabolite of tamoxifen) produces a strong synergistic effect in terms of inhibiting MCF7 ER-positive (ER⁺) breast cancer cell proliferation and that a 20 times lower dose of 4-OH-Tam in combination with SM6Met is required to produce the same inhibitory effect on cell proliferation as 4-OH-Tam on its own. Cell cycle analyses of the best combination ratios of SM6Met and 4-OH-Tam also suggests that the combination results in increased accumulation of cells in the S-phase and in the apoptotic phase. Moreover, the best combination ratio (20:1) of SM6Met with 4-OH-Tam displayed greater anti-metastatic potential in terms of inhibiting ER⁺ breast cancer cell migration, invasion, and colony formation than the SOC therapy alone, suggesting that SM6Met together with 4-OH-Tam could be a viable drug combination for not only delaying resistance and ameliorating the negative side-effects associated with current SOC therapies, like tamoxifen, but could also provide a novel, more affordable therapeutic alternative for treating or preventing ER⁺ breast cancer metastasis.

Association of Risperidone With Gastric Cancer: Triangulation Method From Cell Study, Animal Study, and Cohort Study

Purpose: To examine the effects of risperidone, an atypical antipsychotic agent, on gastric cancer. Methods: A triangulation method comprising bench studies, including cell and animal experiments, and a retrospective cohort study, was subsequently performed. Results: The bench study indicated that risperidone exerted more prominent tumor inhibition effects than other atypical antipsychotics on the proliferation of KATO-III cells, a human gastric cancer cell line. Significant and dose-dependent cell viability was observed in Hs27 cells (control cells) in the presence of risperidone compared with in KATO-III cells. Both in vivo and in vitro results indicated that risperidone significantly inhibited the proliferation of KATO-III cells by inducing ROS and apoptosis, and that it suppressed the growth of xenografted KATO-III tumors in nude mice. In addition, the population-based cohort study found that risperidone users had reduced risks of gastric cancer compared with non-users, with lowered adjusted hazard ratios (HRs) for two induction periods (HR = 0.75; 95% confidence interval [CI] 0.68-0.83 for the one-year induction period, and HR = 0.68; 95% CI 0.61-0.75 for the two-year induction period). Conclusion: The findings are consistent with anticancer effects associated with risperidone, but further research and evaluations are warranted.

JNK and Autophagy Independently Contributed to Cytotoxicity of Arsenite combined With Tetrandrine via Modulating Cell Cycle Progression in Human Breast Cancer Cells

Novel therapeutic strategies for breast cancer are urgently needed due to the sustained development of drug resistance and tumor recurrence. Trivalent arsenic derivative (arsenite, As^III) has been reported to induce cytotoxicity in breast cancer cells. We recently demonstrated that As^III plus tetrandrine (Tetra), a Chinese plant-derived alkaloid, exerted potent antitumor activity against human breast cancer cells, however, the underlying mechanisms for their action have not been well defined. In order to provide fundamental insights for understanding the action of As^III plus Tetra, the effects of the combined regimen on two breast cancer cell lines T47D and MDA-MB-231 were evaluated. Compared to T47D cells, MDA-MB-231 cells were much more susceptible to the synergistic cytotoxic effects of As^III and Tetra. Besides the induction of apoptotic/necrotic cell death, S-phase arrest and autophagic cell death were also observed in MDA-MB-231 cells. Exposure of MDA-MB-231 cells to As^III and Tetra caused the activation of MAPKs. Cytotoxicity of the combined regimen in MDA-MB-231 cell was significantly abrogated by SP600125, a potent c-Jun N-terminal kinase (JNK) inhibitor. However, similar abrogation was not caused by p38 and ERK inhibitors. The addition of either autophagy inhibitors (3-methyladenine or wortmannin) or SP600125 corrected the combined regimen-triggered S-phase arrest, whereas had little effect on the apoptosis/necrosis induction in the cells. Surprisingly, SP600125NC, a negative control for SP600125, significantly strengthened S-phase arrest and the cytotoxicity induced by the combined regimen. The addition of SP600125 did not alter autophagy induction. In conclusion, the cytotoxicity of As^III combined with Tetra was attributed to the induction of S-phase arrest, apoptotic/necrotic and autophagic cell death. The enhanced cytotoxicity of the two drugs by SP600125NC might be explained by its capability to strengthen S-phase arrest. Our results suggested that JNK and autophagy independently contributed to the cytotoxicity via modulating cell cycle progression. The study further provides fundamental insights for the development of As^III in combination with Tetra for patients with different types of breast cancer.

Long-Term Use of Tamoxifen Is Associated With a Decreased Subsequent Meningioma Risk in Patients With Breast Cancer: A Nationwide Population-Based Cohort Study

Background: Earlier studies have indicated a relatively higher risk of occurring meningioma among female breast cancer survivors and have suggested that tamoxifen might decrease this risk. The present study evaluated whether tamoxifen use in breast cancer patients can reduce the risk of meningioma.

Methods: We designed a population-based cohort study by using data from the National Health Insurance system of Taiwan to assess this issue. Between January 1, 2000, and December 31, 2008, women with breast cancer and of age ≥20 years were included. They were divided into two groups: those who had not received tamoxifen therapy and those who had. The Cox’s proportion hazard regression analysis was conducted to estimate the effects of tamoxifen treatment and the subsequent meningioma risk.

Results: We identified a total of 50,442 tamoxifen users and 30,929 non-tamoxifen users. Tamoxifen users had a borderline significantly lower overall risk of meningioma than non-tamoxifen users [adjusted hazard ratio (aHR) = 0.64, 95% confidence interval (95% CI) = 0.40–1.02]. A statistically significant difference was found in those patients with tamoxifen treatment duration longer than 1,500 days (aHR = 0.42, 95% CI = 0.19–0.91) or with cumulative dosage exceeding 26,320 mg (aHR = 0.44, 95% CI = 0.22–0.88). Furthermore, no statistically significant joint effect of aromatase inhibitors and tamoxifen on the occurrence of meningioma among breast cancer patients was seen.

Conclusion: Tamoxifen users had a non-significantly (36%) lower risk of developing meningioma than did tamoxifen non-users; however, our data indicated that tamoxifen therapy is associated with a reduced meningioma risk for Taiwanese breast cancer patients receiving long duration or high cumulative dosage treatment with tamoxifen.

Molecular mechanisms of anti-psychotic drugs for improvement of cancer treatment

Anti-psychotic medications are widely used to treat schizophrenia and bipolar disorder. Besides their medical applications, anti-psychotic drugs have other pharmacological properties which are involved in multiple intracellular functions including metabolism, cell stress, cell-cycle regulation, survival and apoptosis through modulation of cellular signaling pathways such as PI3K/Akt/GSK-3β, STAT3 and wingless (Wnt)-related intracellular signaling. Also, anti-psychotics counteract the growth of tumor cells by stimulating the cellular immune system and natural killer cells. On the other hand, the positive charge and the lipophilicity of anti-psychotics have significant roles in the inhibition of P-gp pumps resulting in accumulation of chemotherapy drugs as well as increasing the cellular susceptibility to chemotherapy, autophagy, angiogenesis inhibition, stem cells differentiation induction and changing the expression of tumor suppressor genes and oncogenes. Overall, anti-psychotics are able to inhibit the proliferation of cancer cells through modulation of different cellular pathways. Anti-psychotics act as anti-cancer drugs and besides can increase the efficacy of anti-cancer agents in cancer cells. In this study, the anti-cancer effects of different anti-psychotic medicines on various malignant tumor cells and their molecular mechanisms have been discussed.

The modulatory role of low concentrations of bisphenol A on tamoxifen-induced proliferation and apoptosis in breast cancer cells

Selective estrogen receptor modulators such as tamoxifen (TAM) significantly reduce the risks of developing estrogen receptor-positive (ER+) breast cancer. Low concentrations (nanomolar range) of bisphenol A (BPA) shows estrogenic effects and further promotes the proliferation of hormone-dependent breast cancer cells. However, whether or not BPA can influence TAM-treatment resistance in breast cancer has not drawn much attention. In the current study, low concentrations of BPA reduced TAM-induced cytotoxicity of MCF-7 cells, which was proved by the suppression of cell apoptosis, transition of cell cycle from G1 to S phase, and upregulation of cyclin D1 and ERα. Simultaneously, the mRNA levels of estrogen-related receptor γ (ERRγ) and its coactivators, peroxisome proliferation-activated receptor γ coactivator-1α (PGC-1α), and PGC-1β, were increased. However, the similar effects were not observed in MDA-MB-231 cells. Our results indicated that low concentrations of BPA decreased the sensitivity of TAM in MCF-7 cells rather than in MDA-MB-231 cells. These different actions likely involved the interaction of relative receptors and coactivators. This study provided a possible support that the exposure of BPA in environmental media may potentially induce TAM resistance to breast cancer treatment.

Development of Hot Melt Extruded Solid Dispersion of Tamoxifen Citrate and Resveratrol for Synergistic Effects on Breast Cancer Cells

Primary standard therapy for ER-positive breast cancer being tamoxifen, newer delivery approach for enhancement of dissolution and therapeutic efficiency of tamoxifen through oral route could be a possible solution. In the present study, we investigated combination of tamoxifen (TAM) with resveratrol (RES) and observed that the combination is effective on MCF-7 breast cancer cells. To ensure co-delivery of the drugs, we explored the hot melt extrusion technique for simultaneously extruding two drugs together in order to enhance their bioavailability. As both are class II drugs with dissolution limited bioavailability, detailed formulation and process parameter analyses were carried out. Detailed characterization using microscopy, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray powder diffraction (XRD) confirmed that both the drugs were molecularly dispersed in the matrix of Soluplus, CremophorRH40, and Poloxamer188, and no interactions between the ingredients were there during hot melt extrusion (HME) process. Dissolution studies confirmed that HME extrudates were able to release drug more rapidly than simple suspension formulation. Further, pharmacokinetic studies in rats were carried out for tamoxifen. Results demonstrated that extrusion significantly increased the tamoxifen oral bioavailability (p < 0.05) (Tmax = 2.00 ± 0.56 h, Cmax = 3.66 ± 1.49 μg/mL, AUC = 39.80 ± 16.24 μg h/mL, MRT = 20.49 ± 5.71) compared to the conventional suspension of tamoxifen (Tmax = 2.00 ± 0.71 h, Cmax = 2.41 ± 0.84 μg/mL, AUC = 12.82 ± 3.99 μg h/mL, MRT = 18.24 ± 5.95 h). In vitro cytotoxicity studies of TAM, RES, and their combination (TAM-RES) were evaluated with MCF7 cells. The combination showed significantly lower IC50 compared to TAM with increasing ratio of RES which is a result of apoptosis. HME-based simultaneous extrusion of TAM and RES formulation provides a suitable formulation strategy for breast cancer treatment and establishes proof of concept for extruding multiple drugs simultaneously for other applications in future.

Estrogen receptor-1 is a key regulator of HIV-1 latency that imparts gender-specific restrictions on the latent reservoir

The molecular mechanisms leading to the creation and maintenance of the latent HIV reservoir remain incompletely understood. Unbiased shRNA screens showed that the estrogen receptor acts as a potent repressor of proviral reactivation in T cells. Antagonists of ESR-1 activate latent HIV-1 proviruses while agonists, including β-estradiol, potently block HIV reactivation. Using a well-matched set of male and female donors, we found that ESR-1 plays an important role in regulating HIV transcription in both sexes. However, women are much more responsive to estrogen and appear to harbor smaller inducible RNA reservoirs. Accounting for the impact of estrogen on HIV viral reservoirs will therefore be critical for devising curative therapies for women, a group representing 51% of global HIV infections.

Unbiased shRNA library screens revealed that the estrogen receptor-1 (ESR-1) is a key factor regulating HIV-1 latency. In both Jurkat T cells and a Th17 primary cell model for HIV-1 latency, selective estrogen receptor modulators (SERMs, i.e., fulvestrant, raloxifene, and tamoxifen) are weak proviral activators and sensitize cells to latency-reversing agents (LRAs) including low doses of TNF-α (an NF-κB inducer), the histone deacetylase inhibitor vorinostat (soruberoylanilide hydroxamic acid, SAHA), and IL-15. To probe the physiologic relevance of these observations, leukapheresis samples from a cohort of 12 well-matched reproductive-age women and men on fully suppressive antiretroviral therapy were evaluated by an assay measuring the production of spliced envelope (env) mRNA (the EDITS assay) by next-generation sequencing. The cells were activated by T cell receptor (TCR) stimulation, IL-15, or SAHA in the presence of either β-estradiol or an SERM. β-Estradiol potently inhibited TCR activation of HIV-1 transcription, while SERMs enhanced the activity of most LRAs. Although both sexes responded to SERMs and β-estradiol, females showed much higher levels of inhibition in response to the hormone and higher reactivity in response to ESR-1 modulators than males. Importantly, the total inducible RNA reservoir, as measured by the EDITS assay, was significantly smaller in the women than in the men. We conclude that concurrent exposure to estrogen is likely to limit the efficacy of viral emergence from latency and that ESR-1 is a pharmacologically attractive target that can be exploited in the design of therapeutic strategies for latency reversal.

STAT3 is required for MiR-17-5p-mediated sensitization to chemotherapy-induced apoptosis in breast cancer cells

Signal transducer and activator of transcription 3 (STAT3) controls cell survival, growth, migration, and invasion. Here, we observed that STAT3 exerted anti-apoptotic effects in breast cancer cells. On the other hand, miR-17-5p induced apoptosis in breast cancer cells, and overexpression of miR-17-5p sensitized MCF-7 cells to paclitaxel-induced apoptosis via STAT3. Overexpression of STAT3 in MCF-7 cells decreased paclitaxel-induced apoptosis, but STAT3 knockout abolished the miR-17-5p-induced increases in apoptosis. Finally, miR-17-5p promoted apoptosis by increasing p53 expression, which was inhibited by STAT3. These results demonstrate a novel pathway via which miR-17-5p inhibits STAT3 and increases p53 expression to promote apoptosis in breast cancer cells.

Advances in combination therapy of lung cancer: Rationales, delivery technologies and dosage regimens

Lung cancer is a complex disease caused by a multitude of genetic and environmental factors. The progression of lung cancer involves dynamic changes in the genome and a complex network of interactions between cancer cells with multiple, distinct cell types that form tumors. Combination therapy using different pharmaceuticals has been proven highly effective due to the ability to affect multiple cellular pathways involved in the disease progression. However, the currently used drug combination designs are primarily based on empirical clinical studies, and little attention has been given to dosage regimens, i.e. how administration routes, onsets, and durations of the combinations influence the therapeutic outcome. This is partly because combination therapy is challenged by distinct physicochemical properties and in vivo pharmacokinetics/pharmacodynamics of the individual pharmaceuticals, including small molecule drugs and biopharmaceuticals, which make the optimization of dosing and administration schedule challenging. This article reviews the recent advances in the design and development of combinations of pharmaceuticals for the treatment of lung cancer. Focus is primarily on rationales for the selection of specific combination therapies for lung cancer treatment, and state of the art of delivery technologies and dosage regimens for the combinations, tested in preclinical and clinical trials.

BreastDefend enhances effect of tamoxifen in estrogen receptor-positive human breast cancer in vitro and in vivo

BACKGROUND

Tamoxifen (TAM) has been widely used for the treatment of estrogen receptor (ER)-positive breast cancer and its combination with other therapies is being actively investigated as a way to increase efficacy and decrease side effects. Here, we evaluate the therapeutic potential of co-treatment with TAM and BreastDefend (BD), a dietary supplement formula, in ER-positive human breast cancer.

METHODS

Cell proliferation and apoptosis were determined in ER-positive human breast cancer cells MCF-7 by MTT assay, quantitation of cytoplasmic histone-associated DNA fragments and expression of cleaved PARP, respectively. The molecular mechanism was identified using RNA microarray analysis and western blotting. Tumor tissues from xenograft mouse model were analyzed by immunohistochemistry.

RESULTS

Our data clearly demonstrate that a combination of 4-hydroxytamoxifen (4-OHT) with BD lead to profound inhibition of cell proliferation and induction of apoptosis in MCF-7 cells. This effect is consistent with the regulation of apoptotic and TAM resistant genes at the transcription and translation levels. Importantly, TAM and BD co-treatment significantly enhanced apoptosis, suppressed tumor growth and reduced tumor weight in a xenograft model of human ER-positive breast cancer.

CONCLUSION

BD sensitized ER-positive human breast cancer cells to 4-OHT/TAM treatment in vitro and in vivo. BreastDefend can be used in an adjuvant therapy to increase the therapeutic effect of tamoxifen in patients with ER-positive breast cancer.

Tamoxifen-induced cytotoxicity in breast cancer cells is mediated by glucose-regulated protein 78 (GRP78) via AKT (Thr308) regulation

Glucose regulated protein 78 (GRP78) has recently been suggested to be associated with drug resistance in breast cancer patients. However, the precise role of GRP78 in drug resistance and the involved signaling pathways are not clearly understood. In the present study, we show that among a panel of drugs, namely Paclitaxel (TAX), Doxorubicin (DOX), 5-fluorouracil (5-FU), UCN-01 and Tamoxifen (TAM) used, TAM alone up-regulated the expression of GRP78 significantly and induced apoptosis in MCF-7 and MDA-MB-231 cells. Interestingly, inhibition of GRP78 by a specific pharmacological inhibitor, VER-155008 augmented TAM-induced apoptosis, and overexpression of GRP78 rendered the cells resistant to TAM-induced cell death suggesting a role for GRP78 in TAM-induced cytotoxicity. Mechanistically, the expression of phosphorylated AKT as determined by Western blot analyses revealed that TAM selectively upregulated phosphorylation of AKT at Thr308 but not at Ser473, and siRNA silencing of GRP78 resulted in inhibition of AKT phosphorylation at Thr308 but not at Ser473. Further, a GRP78 inhibitor, VER155008 inhibited TAM-induced phosphorylation of GSK3β, a downstream substrate of AKT. These results, thus suggests a role for GRP78 in TAM-induced AKT activation. Additionally, co-localization studies by immunofluorescence, and immunoprecipitation experiments demonstrated a complex formation of AKT and GRP78. Furthermore, in glucose-free medium, the cells were sensitized to TAM-induced cell death that was associated with reduced AKT phosphorylation at Thr308, thus strengthening the association of AKT regulation with drug response. Collectively, our findings identify a role of GRP78 in AKT regulation in response to TAM in breast cancer cells.

Long-term use of tamoxifen reduces the risk of dementia: a nationwide population-based cohort study

BACKGROUND

To assess the possible association between tamoxifen treatment and the subsequent risk of dementia in patients with breast cancer, a population-based cohort study was conducted using the Taiwanese National Health Insurance Research Database.

METHODS

The study cohort contained 24 197 patients diagnosed with breast cancer between 1 January 2000 and 31 December 2004. Among them, 16 556 cases received tamoxifen treatment and 7641 did not. Four women without breast cancer were frequency matched to each case by age and index-year as the cancer-free group. The outcome of the analysis of is dementia. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariate Cox proportional hazards regression models.

RESULTS

Patients with breast cancer exhibited a similar risk of developing dementia (adjusted HR = 0.95, 95% CI = 0.86-1.04) compared with the cancer-free group. In addition, among women diagnosed with breast cancer, tamoxifen users exhibited a significant 17% lower risk of dementia compared with those not using tamoxifen (adjusted HR = 0.83, 95% CI = 0.69-0.98), but the significant difference was limited to 5 years or more use (adjusted HR = 0.47, 95% CI = 0.32-0.69). Both tamoxifen and aromatase inhibitor use had a joint effect, with a significantly lower risk of dementia among patients.

CONCLUSION

The results of this population-based cohort study suggest that long-term use of tamoxifen in patients with breast cancer is associated with a lower risk of dementia.

Relationship between prolactin, breast cancer risk, and antipsychotics in patients with schizophrenia: a critical review

OBJECTIVE

A recent meta-analysis showed that breast cancer probably is more common in female patients with schizophrenia than in the general population (effect size = 1.25, P < 0.05). Increasing experimental and epidemiological data have alerted researchers to the influence of prolactin (PRL) in mammary carcinogenesis. We therefore investigated the possible relationship between antipsychotic-induced hyperprolactinemia (HPRL) and breast cancer risk in female patients with schizophrenia.

METHOD

A literature search (1950 until January 2015), using the MEDLINE database, was conducted for English-language published clinical trials to identify and synthesize data of the current state of knowledge concerning breast cancer risk (factors) in women with schizophrenia and its (their) relationship between HPRL and antipsychotic medication.

RESULTS

Although an increasing body of evidence supports the involvement of PRL in breast carcinogenesis, results of human prospective studies are limited, equivocal, and correlative (with risk ratios ranging from 0.70 to 1.9 for premenopausal women and from 0.76 to 2.03 for postmenopausal women). Moreover, these studies equally do not take into account the local production of PRL in breast epithelium, although amplification or overexpression of the local autocrine/paracrine PRL loop may be a more important mechanism in tumorigenesis. Until now, there is also no conclusive evidence that antipsychotic medication can increase the risk of breast malignancy and mortality.

CONCLUSION

Other breast risk factors than PRL, such as nulliparity, obesity, diabetes mellitus, and unhealthy lifestyle behaviours (alcohol dependence, smoking, low physical activity), probably are of greater relevance in individual breast cancer cases within the population of female patients with schizophrenia.

Tamoxifen induces hepatotoxicity and changes to hepatocyte morphology at the early stage of endocrinotherapy in mice

Clinically, hepatotoxicity is an inevitable side effect during long-term endocrinotherapy in breast cancer patients. Various studies have reported the specific mechanism and protective methods for this long-term hepatotoxicity, however, the short-term influences of tamoxifen (TAM) on hepatocytes remain to be elucidated. The previous study investigated TAM-induced liver injury at the early stage of endocrine treatment. Mice were assigned into 2 groups: The experiment group was administrated with intraperitoneal (i.p.) injection of 6 mg/kg/day TAM for 2 weeks, and the control group was administrated with i.p. injection of physiological saline of the same dose. Body weights in each group were detected every day, and alanine aminotransferase and aspartate aminotransferase levels were measured every 3 days. Small pieces of the liver tissues were obtained and processed for protein extraction, biochemical detection and histopathological analysis 2 weeks later. The results indicated that TAM decreased the mice body weights. Morphologically, with the treatment of TAM for only 2 weeks, at the microscopic and ultrastructural levels the structure of hepatic cords became blurred in sections of the regions, although the lobules of the liver remained visible. Partially, hepatic cells were swelled in spherical shapes. Nuclei appeared to be pyknotic and exhibited uneven chromatin distribution. In addition, it was observed in the transmission electron microscopy analysis that nuclei became pyknotic and unevenly distributed. The majority of the nuclei were endowed with distinct heterochromatin and thick nucleoli. The mitochondrial cristae became vague and disorganized. Finally, western blotting was used and detected a significant increase of the caspase-3 level in the liver tissues. In conclusion, the experiments elucidated that TAM (6 mg/kg/day) would cause hepatotoxicity at the early stage of endocrine treatment in mice, and the underlying mechanism was involved with hepatocyte apoptosis.

The combination of methylsulfonylmethane and tamoxifen inhibits the Jak2/STAT5b pathway and synergistically inhibits tumor growth and metastasis in ER-positive breast cancer xenografts

BACKGROUND

Combination therapy, which reduces the dosage intensity of the individual drugs while increasing their efficacy, is not a novel approach for the treatment of cancer. Methylsulfonylmethane (MSM) is an organic sulfur compound shown to act against tumor cells. Tamoxifen is a commercially available therapeutic agent for breast malignancies.

METHODS

In the current study, we analyzed the combinatorial effect of MSM and tamoxifen on the suppression of ER-positive breast cancer xenograft growth and metastasis. Additionally, we also validated the molecular targets by which the drug combination regulated tumor growth and metastasis.

RESULTS

We observed that the combination of MSM and tamoxifen regulated cell viability and migration in vitro. The intragastric administration of MSM and subcutaneous implantation of tamoxifen tablets led to tumor growth suppression and inhibition of the Janus kinase 2 (Jak2)/signal transducer and activator of transcription 5b (STAT5b) pathway. Our study also assessed the regulation of signaling molecules implicated in the growth, progression, differentiation, and migration of cancer cells, such as Jak2, STAT5b, insulin-like growth factor-1Rβ, and their phosphorylation status.

CONCLUSIONS

Study results indicated that this combination therapy inhibited tumor growth and metastasis. Therefore, this drug combination may have a synergistic and powerful anticancer effect against breast cancer.

Regulatory effects of caffeic acid phenethyl ester on neuroinflammation in microglial cells

Microglial activation has been widely demonstrated to mediate inflammatory processes that are crucial in several neurodegenerative disorders. Pharmaceuticals that can deliver direct inhibitory effects on microglia are therefore considered as a potential strategy to counter balance neurodegenerative progression. Caffeic acid phenethyl ester (CAPE), a natural phenol in honeybee propolis, is known to possess antioxidant, anti-inflammatory and anti-microbial properties. Accordingly, the current study intended to probe the effects of CAPE on microglia activation by using in vitro and in vivo models. Western blot and Griess reaction assay revealed CAPE significantly inhibited the expressions of inducible nitric oxide synthase (NOS), cyclooxygenase (COX)-2 and the production of nitric oxide (NO). Administration of CAPE resulted in increased expressions of hemeoxygenase (HO)-1and erythropoietin (EPO) in microglia. The phosphorylated adenosine monophosphate-activated protein kinase (AMPK)-α was further found to regulate the anti-inflammatory effects of caffeic acid. In vivo results from immunohistochemistry along with rotarod test also revealed the anti-neuroinflammatory effects of CAPE in microglia activation. The current study has evidenced several possible molecular determinants, AMPKα, EPO, and HO-1, in mediating anti-neuroinflammatory responses in microglial cells.

Association of tamoxifen use and increased diabetes among Asian women diagnosed with breast cancer

Background:

We conducted a population-based cohort study to assess whether tamoxifen treatment is associated with an increased incidence of diabetes.

Methods:

Data obtained from the Taiwanese National Health Insurance Research Database were used for a population-based cohort study. The study cohort included 22 257 breast cancer patients diagnosed between 1 January 2000 and 31 December 2004. Among them, 15 210 cases received tamoxifen treatment and 7047 did not. Four subjects without breast cancer were frequency-matched by age and index year as the control group. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariate Cox proportional hazards regression analysis.

Results:

Breast cancer patients exhibited a 14% higher rate of developing diabetes (adjusted HR=1.14, 95% CI=1.08–1.20) compared with non-breast cancer controls, but the significant difference was limited to tamoxifen users. In addition, tamoxifen users exhibited a significantly increased risk of diabetes compared with non-tamoxifen users among women diagnosed with breast cancer (adjusted HR=1.31, 95% CI=1.19–1.45). Stratification by age groups indicated that both younger and older women diagnosed with breast cancer exhibited a significantly higher risk of diabetes than the normal control subjects did, and tamoxifen users consistently exhibited a significantly higher diabetes risk than non-tamoxifen users or normal control subjects did, regardless of age. Both recent and remote uses of tamoxifen were associated with an increased likelihood of diabetes.

Conclusions:

The results of this population-based cohort study suggested that tamoxifen use in breast cancer patients might increase subsequent diabetes risk. The underlying mechanism remains unclear and further larger studies are mandatory to validate our findings.