Aberrant nuclear factor-kappaB/Rel expression and the pathogenesis of breast cancer.

Expression of nuclear factor-kappaB (NF-kappaB)/Rel transcription factors has recently been found to promote cell survival, inhibiting the induction of apoptosis. In most cells other than B lymphocytes, NF-kappaB/Rel is inactive, sequestered in the cytoplasm. For example, nuclear extracts from two human untransformed breast epithelial cell lines expressed only very low levels of NF-kappaB. Unexpectedly, nuclear extracts from two human breast tumor cell lines displayed significant levels of NF-kappaB/Rel. Direct inhibition of this NF-kappaB/ Rel activity in breast cancer cells induced apoptosis. High levels of NF-kappaB/Rel binding were also observed in carcinogen-induced primary rat mammary tumors, whereas only expectedly low levels were seen in normal rat mammary glands. Furthermore, multiple human breast cancer specimens contained significant levels of nuclear NF-kappaB/Rel subunits. Thus, aberrant nuclear expression of NF-kappaB/Rel is associated with breast cancer. Given the role of NF-kappaB/Rel factors in cell survival, this aberrant activity may play a role in tumor progression, and represents a possible therapeutic target in the treatment of these tumors.

Paclitaxel and carboplatin in the treatment of advanced or recurrent endometrial cancer: a large retrospective study.

The aim of this study was to assess the efficacy and tolerability of paclitaxel and carboplatin (TC) in the treatment of patients with advanced or recurrent endometrial cancer. Patients eligible for this retrospective analysis had endometrial cancer with either advanced or recurrent measurable disease (untreated primary stage III/IV or stage III/IV patients with persistent, measurable disease [> or =2 cm] after surgery), Eastern Cooperative Oncology Group (ECOG) performance status > or =3, and received at least one cycle of TC. Response rates were determined using Response Evaluation Criteria in Solid Tumors criteria. Institutional Review Board approval was obtained prior to the initiation of this study. Eighty-five eligible patients, with a median age of 62 years (range 36-80) were identified. Fifty-seven (67%) of patients were treated at the time of recurrence. Prior radiation therapy had been used in the treatment of 36 (42%) patients, while 13 (15%) patients had received prior chemotherapy. Median follow-up time was 11.7 months (range 1.1-96.7 months), and the median number of cycles of therapy received was six (range 1-18). The overall response rate (ORR) was 43%, with a complete response rate of 5% and a partial response rate of 38%. Chemotherapy-naive patients had an ORR of 47%. Only seven (8%) patients had to discontinue therapy due to toxicity. Median progression-free survival was 5.3 months (95% CI, 4.6-7.4), with a median overall survival of 13.2 months (95% CI, 11.7-18.2). We conclude that TC is an active and tolerable regimen in the treatment of patients with advanced or recurrent endometrial cancer.

The inhibitory effects of transforming growth factor beta1 on breast cancer cell proliferation are mediated through regulation of aberrant nuclear factor-kappaB/Rel expression.

Nuclear factor (NF)-kappaB/Rel transcription factors normally exist in non-B cells, such as epithelial cells, in inactive forms sequestered in the cytoplasm with specific inhibitory proteins, termed IkappaBs. Recently, however, we discovered that breast cancer is typified by aberrant constitutive expression of NF-kappaB/Rel factors. Because these factors control genes that regulate cell proliferation, here we analyzed the potential role of NF-kappaB/Rel in the ability of transforming growth factor (TGF)-beta1 to inhibit the growth of breast cancer cells. The decreased growth of Hs578T and MCF7 breast cancer cell lines on TGF-beta1 treatment correlated with a drop in NF-kappaB/Rel binding. This decrease was due to the stabilization of the inhibitory protein IKB-alpha. Ectopic expression of c-Rel in Hs578T cells led to the maintenance of NF-kappaB/Rel binding and resistance to TGF-beta1-mediated inhibition of proliferation. Similarly, expression of the p65 subunit ablated the inhibition of Hs578T cell growth mediated by TGF-beta1. Thus, the inhibition of the aberrantly activated, constitutive NF-kappaB/Rel plays an important role in the arrest of the proliferation of breast cancer cells, which suggests that NF-kappaB/Rel may be a useful target in the treatment of breast cancer.

Activation of NF-kappaB/Rel occurs early during neoplastic transformation of mammary cells.

NF-kappaB/Rel is a family of transcription factors which are expressed in all cells; however, in most non-B cells, they are sequestered in the cytoplasm in inactive complexes with specific inhibitory proteins, termed IkappaBs. We have recently shown that NF-kappaB/Rel factors are aberrantly activated in human breast cancer and rodent mammary tumors, and function to promote tumor cell survival and proliferation. Here, we have examined the time-course of induction of NF-kappaB/Rel factors upon carcinogen treatment of female Sprague-Dawley (S-D) rats in vivo and in human mammary epithelial cells (HMECs) in culture. We observed that NF-kappaB/Rel activation is an early event, occurring prior to malignant transformation. In S-D rats, increased NF-kappaB/Rel binding was detected in nuclear extracts of mammary glands from 40% of animals 3 weeks post-treatment with 15 mg/kg 7,12-dimethylbenz[a]anthracene (DMBA); this is prior to formation of tumors which normally begin to be detected after 7-9 weeks. In non-tumorigenic MCF-10F cells, in vitro malignant transformation upon treatment with either DMBA or benzo[a]pyrene (B[a]P) resulted in a 4- to 12-fold increase in activity of classical NF-kappaB (p65/p50). NF-kappaB induction was corrrelated with a decrease in the stability of the NF-kappaB-specific inhibitory protein IkappaB-alpha. Ectopic expression of the transactivating p65 subunit of NF-kappaB in MCF-10F cells induced the c-myc oncogene promoter, which is driven by two NF-kappaB elements, and endogenous c-Myc levels. Furthermore, reduction mammoplasty-derived HMECs, immortalized following B[a]P exposure, showed dysregulated induction of classical NF-kappaB prior to malignant transformation. Together these findings suggest that activation of NF-kappaB plays an early, critical role in the carcinogen-driven transformation of mammary glands.