Effects of experimental chemoendocrine therapy with a combination of a pure antiestrogen and 5-fluorouracil on human breast cancer cells implanted in nude mice

Estrogenic actions of alkaloids: Structural characteristics and molecular mechanisms

This comprehensive review of estrogenic alkaloids reveals that although the number is small, they exhibit a wide range of structures, biosynthesis pathways, mechanisms of action, and applications. Estrogenic alkaloids belong to different classes, different biosynthetic pathways, different estrogenic actions (estrogenic/synergistic, anti-estrogenic/antagonistic, biphasic, and acting as a selective estrogen receptor modulator or SERM), different receptor-initiated signaling pathways, different ways of modulations of estrogen action, and different applications. The future applications of estrogenic alkaloids, such as those for diagnostics, drug development, and therapeutics, are considered with the help of new databases containing comprehensive descriptions of their relationships and more elaborate artificial intelligence-based prediction technologies. Structure-activity studies reveal the significance of the nitrogen atom for their structural and functional diversity, which may help support their broader applications. Based on the summary of previous reports, estrogenic alkaloids have significant potential for future applications.

Estrogen Down-regulator Fulvestrant Potentiates Antitumor Activity of Fluoropyrimidine in Estrogen-responsive MCF-7 Human Breast Cancer Cells

BACKGROUND

Endocrine therapy is clinically administered in hormone-responsive breast cancer. Combinations of fluoropyrimidine S-1 and an aromatase inhibitor or anti-estrogen are considered beneficial in Japan. Herein we assessed new combinations of S-1 and fulvestrant.

PATIENTS AND METHODS

Cytotoxicity of fulvestrant and 5-fluorouracil (5-FU) was assessed in hormone-responsive (MCF-7) and non-responsive (MDA-MB-231) breast cancer cell cultures. Fulvestrant and S-1 were evaluated for antitumor activity in mice and their effects on estrogen receptor (ER)-α and progesterone receptor (PgR) levels in MCF-7 xenografts using immunohistochemical methods.

RESULTS

Fulvestrant inhibited growth of MCF-7, but not of MDA-MB-231 xenografts. Combinations of 5-FU and fulvestrant were superior to monotherapy in vitro. In vivo antitumor activity of S-1/fulvestrant combination therapy was significantly (p<0.05) enhanced compared to that of both monotherapies. Fulvestrant partially down-regulated expression of ERα and PgR, but in combination with S-1, it almost completely blocked their expression.

CONCLUSION

Chemo-endocrine combination therapy using S-1 and fulvestrant is beneficial in estrogen-responsive breast cancer.

Oral fluoropyrimidine may augment the efficacy of aromatase inhibitor via the down-regulation of estrogen receptor in estrogen-responsive breast cancer xenografts

The present preclinical study was designed to evaluate a new combination therapy comprised of the aromatase inhibitor anastrozole (ANA) and the oral fluoropyrimidines, UFT and S-1 against the estrogen receptor (ER)-positive human breast cancer cell line MCF-7/Arom 14, which was stably transfected with the cDNA of human aromatase. MCF-7/Arom 14 cells showed a high aromatase activity and notably were able to grow in the presence of testosterone and estradiol (E(2)) in vitro. ANA and 5-fluorouracil (5-FU) inhibited cell growth at concentrations of 0.005-10 and 0.2-5 μM, respectively, and the combination of both drugs additively inhibited cell growth. The growth of MCF-7/Arom 14 tumors was significantly inhibited by ANA and S-1 or UFT in vivo. The combination of ANA with S-1 or UFT administered using a 21-day consecutive, metronomic-like regimen significantly enhanced the antitumor efficacy, suppressing tumor growth for 2-4 times longer than monotherapy. To investigate the mechanisms by which S-1 enhances the antitumor activity of ANA, the protein and mRNA expression levels of ER-α in tumor tissue after treatment with S-1, ANA, and the typical chemotherapeutic agents doxorubicin (ADM) or paclitaxel (TXL) were analyzed. The protein and mRNA expression levels of ER-α in the tumor tissue were markedly decreased after treatment with S-1 or S-1 + ANA, but not after treatment with either ADM or TXL. The reduced ER-α level after S-1 treatment might contribute to the increased antitumor activity of ANA by reducing ER-α-induced growth signaling in addition to the decrease in estrogen production induced by ANA. Based on these results, the combination of ANA and S-1 might yield a greater benefit than other chemotherapeutic agents in postmenopausal women with ER-positive breast cancer.

Effect of combined therapy with the antiestrogen agent toremifene and local hyperthermia on breast cancer cells implanted in nude mice

PURPOSE

We evaluated the effects of combined treatment with the antiestrogen agent toremifene (TOR) and local hyperthermia (LHT) on the MCF-7 breast cancer cell line.

METHODS

BALB/c mice implanted with MCF-7 cells were divided into six treatment groups: a control group, a TOR30 group (given 30 mg/kg/day), a TOR120 group (given 120 mg/kg/day), an LHT group (43.5 degrees C), a TOR30 + LHT group, and a TOR120 + LHT group. The effects of the treatments on tumor cells, estrogen receptor (ER) expression, and cell cycle kinetics were measured after 21 days. We calculated the apoptotic index and vascular density inside the tumors and evaluated the efficacy of the transmigration of TOR into the tumors.

RESULTS

The antitumor effects were significantly greater in both combined therapy groups than in any of the single therapy groups. Estrogen receptor expression was weaker in the combined therapy groups than in the single therapy groups, and there were more G0/G1-phase cells and fewer S-phase cells in both combined therapy groups than in the single therapy groups. The apoptotic index was increased and the tumor vascular density was decreased in the combined therapy groups.

CONCLUSIONS

We attributed the effects of this combined therapy to the induction of apoptosis, the decrease in vascular density, and the increase and decrease in G0/G1-phase and S-phase cells, respectively, in the tumors.

Prognostic significance of thymidylate synthase expression in patients with prostate cancer undergoing radical prostatectomy

OBJECTIVES

Thymidylate synthase (TS), a key enzyme in DNA synthesis, is overexpressed in a variety of cancer cells. 5-Fluorouracil (5-FU), an anticancer agent used clinically against various cancers, including prostate cancer, inhibits DNA synthesis by binding TS. In this study, we investigated the expression of TS in prostate cancer and its prognostic significance. Its association with the expression of dihydropyrimidine dehydrogenase (DPD), a principal enzyme in the degradation of 5-FU and pyrimidine nucleotides, was also examined.

METHODS

Fifty-two prostatic tissue specimens were obtained from patients who had undergone radical prostatectomy for prostate cancer without neoadjuvant hormonal therapy. We analyzed the cancerous tissue and normal prostatic tissue specimens for TS expression using immunohistochemistry.

RESULTS

TS was expressed at greater levels in the prostate cancer specimens than in the normal prostatic tissue specimens. The patients with prostate cancer with negative TS expression had a longer postoperative recurrence-free rate than did those with positive expression during the 5 years of follow-up. TS expression was significantly decreased in patients who received neoadjuvant hormonal therapy. No relationship was found between the expression of TS and DPD. Patients with prostate cancer with either negative TS or DPD expression had a significantly longer postoperative disease-free rate than those with positive expression of both during the 5 years of follow-up.

CONCLUSIONS

The results of the present study have shown for the first time that TS expression could be a prognostic marker for patients with prostate cancer undergoing radical prostatectomy. In addition, the combination of TS and DPD expression might also be helpful for the prediction of the prognosis of patients with prostate cancer.