Influence of Antiestrogens on the Invasiveness and Laminin Attachment of Breast Cancer Cells

Induction of 1C aldoketoreductases and other drug dose-dependent genes upon acquisition of anthracycline resistance

OBJECTIVES

Recent studies suggest that tumor cells overexpressing aldoketoreductases (AKRs) exhibit increased resistance to DNA damaging agents such as anthracyclines. AKRs may induce resistance to the anthracycline doxorubicin by catalyzing its conversion to the less toxic 13-hydroxy metabolite doxorubicinol. However, it has not been established whether during selection for anthracycline resistance, AKR overexpression in tumor cells can be correlated with the onset or magnitude of drug resistance and with appreciable conversion of anthracyclines to 13-hydroxy metabolites.

METHODS AND FINDINGS

Through microarray and quantitative polymerase chain reaction studies involving rigid selection criteria and both correlative discriminate statistics and time-course models, we have identified several genes whose expression can be correlated with the onset and/or magnitude of anthracycline resistance, including AKR1C2 and AKR1C3. Also associated with the onset or magnitude of anthracycline resistance were genes involved in drug transport (ABCB1, ABCC1), cell signaling and transcription (RDC1, CXCR4), cell proliferation or apoptosis (BMP7, CAV1), protection from reactive oxygen species (AKR1C2, AKR1C3, FTL, FTH, TXNRD1, MT2A), and structural or immune system proteins (IFI30, STMN1). As expected, doxorubicin-resistant and epirubicin-resistant cells exhibited higher levels of doxorubicinol than wild-type cells, although at insufficient levels to account for significant drug resistance. Nevertheless, an inhibitor of Akr1c2 (5beta-cholanic acid) almost completely restored sensitivity to doxorubicin in ABCB1-deficient doxorubicin-resistant cells, while having no effect on ABCB1-expressing epirubicin-resistant cells.

CONCLUSION

Taken together, we show for the first time that a variety of genes (particularly redox genes such as AKR1C2 and AKR1C3) can be temporally and causally correlated with the acquisition of anthracycline resistance in breast tumor cells.

Raloxifene in breast cancer prevention

BACKGROUND

Raloxifene is a benzothiophene, selective estrogen receptor modulator with estrogen-agonist effects in the skeleton and the cardiovascular system but estrogen-antagonist effects in the uterus and the mammary gland. This compound was first approved in different countries for the prevention and treatment of osteoporosis.

OBJECTIVE/METHODS

We performed a literature search to review available preclinical and clinical data that has led to the recent FDA approval of raloxifene as a chemopreventive agent for breast cancer in postmenopausal women.

RESULTS/CONCLUSIONS

Different placebo-controlled trials indicated that raloxifene is effective in reducing invasive breast cancer risk in postmenopausal women. In a recent comparative study, a similar efficacy between raloxifene and tamoxifen for breast cancer prevention was demonstrated, but raloxifene showed a more favorable safety profile.

Fulvestrant (‘Faslodex’) in heavily pretreated postmenopausal patients with advanced breast cancer: single centre clinical experience from the compassionate use programme

BACKGROUND

Fulvestrant (Faslodex) is an oestrogen receptor (ER) antagonist with demonstrated efficacy in patients with advanced and pretreated breast cancer.

PATIENTS AND METHODS

We present a single-centre experience with fulvestrant administered under the compassionate use programme (CUP) to a total of 54 postmenopausal women with metastatic breast cancer progressing on multiple endocrine and cytotoxic therapies. Patients received 250 mg fulvestrant i.m. once monthly as second- (n = 8), third- (n = 30), fourth- (n = 14) and fifth-line (n = 2) hormonal treatment. The median number of previous endocrine therapies was 2 (range 1-4). Most of the patients also had multiple palliative chemotherapies with a median of 1.7 (range 0-6) prior therapies. The median duration of fulvestrant treatment was 6.3 months (range 1-39 months) and the median duration of follow-up was 19.4 months (range 1-63 months).

RESULTS

Objective response was achieved by five patients (9.3%): one complete remission (CR) (1.9%) and four partial remissions (PR) (7.4%). Stable disease (SD) lasting > or =6 months was achieved by 16 patients (29.6%). Thus in all, fulvestrant conferred clinical benefit (CB) on 21 women (38.9%). The median time to progression (TTP) was 6.4 months. In all patients with CR and PR, tumour cells were positive for both ER and progesterone receptor (PgR), but lacked HER2/neu overexpression; one patient with PR had an unknown HER2/neu status. Overall, the drug was well tolerated. No grade 3/4 toxicities were reported.

CONCLUSIONS

Fulvestrant appears to be an efficient and well-tolerated drug even in women with advanced breast cancer progressing after multiple endocrine and/or cytotoxic treatments.