LXXLL Peptide Converts Transportan 10 to a Potent Inducer of Apoptosis in Breast Cancer Cells

Degenerate expression of transcription coregulator proteins is observed in most human cancers. Therefore, in targeted anti-cancer therapy development, intervention at the level of cancer-specific transcription is of high interest. The steroid receptor coactivator-1 (SRC-1) is highly expressed in breast, endometrial, and prostate cancer. It is present in various transcription complexes, including those containing nuclear hormone receptors. We examined the effects of a peptide that contains the LXXLL-motif of the human SRC-1 nuclear receptor box 1 linked to the cell-penetrating transportan 10 (TP10), hereafter referred to as TP10-SRC1LXXLL, on proliferation and estrogen-mediated transcription of breast cancer cells in vitro. Our data show that TP10-SRC1LXXLL induced dose-dependent cell death of breast cancer cells, and that this effect was not affected by estrogen receptor (ER) status. Surprisingly TP10-SRC1LXXLL severely reduced the viability and proliferation of hormone-unresponsive breast cancer MDA-MB-231 cells. In addition, the regulation of the endogenous ERα direct target gene pS2 was not affected by TP10-SRC1LXXLL in estrogen-stimulated MCF-7 cells. Dermal fibroblasts were similarly affected by treatment with higher concentrations of TP10-SRC1LXXLL and this effect was significantly delayed. These results suggest that the TP10-SRC1LXXLL peptide may be an effective drug candidate in the treatment of cancers with minimal therapeutic options, for example ER-negative tumors

Risk factor control in treated hypertensives from Estonia and Sweden. Why the difference?

Background. It is of importance to study the risk factor control in treated hypertensives (tHT), both longitudinally within one country and between neighbouring countries, as hypertensive patients still run an increased cardiovascular risk in spite of treatment. Methods. In sample of 1135 tHT from Estonia and a similar number of age- and sex- matched Swedish tHT, the control of blood pressure and other cardiovascular risk factors were assessed as part of national surveys in primary health care. Data were retrieved form consecutive patients visiting primary health care centres all over each country. Results. The mean age of male patients (n=421) was 50 years and for female patients (n=714) it was 52 years. tHT from Sweden were more likely to be in better control of blood pressure and risk factor levels than corresponding Estonian patients, matched for age and gender. However, there was a significantly (p=0.0003) higher rate of smoking in Swedish female patients (22.4%) than in corresponding Estonian patients (16.0%). More Swedish women than men were prescribed thiazide diuretics, but fewer were prescribed angiotensin- converting enzyme (ACE) inhibitors. No similar Estonian data were available. Conclusion. Most cardiovascular risk factors were better controlled in the Swedish hypertensives, except for a higher smoking prevalence in Swedish female patients. This could be related not only to differences in clinical practice, but also influenced by social and lifestyle factors

Alternative Splicing Targeting the hTAF4-TAFH Domain of TAF4 Represses Proliferation and Accelerates Chondrogenic Differentiation of Human Mesenchymal Stem Cells

<div><p>Transcription factor IID (TFIID) activity can be regulated by cellular signals to specifically alter transcription of particular subsets of genes. Alternative splicing of TFIID subunits is often the result of external stimulation of upstream signaling pathways. We studied tissue distribution and cellular expression of different splice variants of TFIID subunit <i>TAF4</i> mRNA and biochemical properties of its isoforms in human mesenchymal stem cells (hMSCs) to reveal the role of different isoforms of TAF4 in the regulation of proliferation and differentiation. Expression of <i>TAF4</i> transcripts with exons VI or VII deleted, which results in a structurally modified hTAF4-TAFH domain, increases during early differentiation of hMSCs into osteoblasts, adipocytes and chondrocytes. Functional analysis data reveals that TAF4 isoforms with the deleted hTAF4-TAFH domain repress proliferation of hMSCs and preferentially promote chondrogenic differentiation at the expense of other developmental pathways. This study also provides initial data showing possible cross-talks between TAF4 and TP53 activity and switching between canonical and non-canonical WNT signaling in the processes of proliferation and differentiation of hMSCs. We propose that TAF4 isoforms generated by the alternative splicing participate in the conversion of the cellular transcriptional programs from the maintenance of stem cell state to differentiation, particularly differentiation along the chondrogenic pathway.</p></div

Expression of TAF4 splice variants and isoforms in human MSCs differentiated into adipocytes, osteoblasts or chondrocytes and treated with <i>TAF4</i> RNAi.

<p>(<b>A</b>) RT-PCR analysis of different individual hMSCs clones (hMSCs 1–5) using <i>TAF4_v1a</i> (full length) specific primers (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074799#pone.0074799.s002" target="_blank">Table S2</a>). Expression of <i>GAPDH</i> mRNA is shown at the bottom. (<b>B</b>) Expression of <i>TAF4</i> ASVs encoding proteins with compromised hTAF4-TAFH domain is dominant in differentiated hMSCs. RT-PCR analysis using <i>TAF4</i> ASV-specific primers was performed 7 days after induction of differentiation of hMSCs towards adipo-, osteo- and chondrogenic lineages. <i>GAPDH</i> mRNA expression was used for the normalization. (<b>C</b>) Expression of <i>TAF4</i> ASVs following treatment of human MSCs with control and hTAF4-TAFH-domain targeting <i>TAF4</i> siRNAs. Cells were treated with <i>TAF4</i> or control siRNAs at the indicated time points and RT-PCR analysis performed using <i>TAF4</i> ASV-specific primers. Analysis of <i>GAPDH</i> mRNA expression was used for normalization. (<b>D</b>) siRNA-mediated silencing targeting <i>TAF4</i> exons V or VI induces changes in the expression of TAF4 protein isoforms as detected at 48 h post-treatment using Western blot analysis. The asterisk indicates the canonical form of TAF4 protein with the molecular weight of 135 kDa, two asterisks indicate TAF4_v2 isoform with a calculated molecular weight of about 73 kDa.</p