S-phase kinase-associated protein 2 expression interference inhibits breast cancer cell proliferation

Molecular targets and therapeutic strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is known for its heterogeneous complexity and is often difficult to treat. TNBC lacks the expression of major hormonal receptors like estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 and is further subdivided into androgen receptor (AR) positive and AR negative. In contrast, AR negative is also known as quadruple-negative breast cancer (QNBC). Compared to AR-positive TNBC, QNBC has a great scarcity of prognostic biomarkers and therapeutic targets. QNBC shows excessive cellular growth and proliferation of tumor cells due to increased expression of growth factors like EGF and various surface proteins. This study briefly reviews the limited data available as protein biomarkers that can be used as molecular targets in treating TNBC as well as QNBC. Targeted therapy and immune checkpoint inhibitors have recently changed cancer treatment. Many studies in medicinal chemistry continue to focus on the synthesis of novel compounds to discover new antiproliferative medicines capable of treating TNBC despite the abundance of treatments currently on the market. Drug repurposing is one of the therapeutic methods for TNBC that has been examined. Moreover, some additional micronutrients, nutraceuticals, and functional foods may be able to lower cancer risk or slow the spread of malignant diseases that have already been diagnosed with cancer. Finally, nanomedicines, or applications of nanotechnology in medicine, introduce nanoparticles with variable chemistry and architecture for the treatment of cancer. This review emphasizes the most recent research on nutraceuticals, medication repositioning, and novel therapeutic strategies for the treatment of TNBC.

Quadruple-negative breast cancer: novel implications for a new disease

Based on the androgen receptor (AR) expression, triple-negative breast cancer (TNBC) can be subdivided into AR-positive TNBC and AR-negative TNBC, also known as quadruple-negative breast cancer (QNBC). QNBC characterization and treatment is fraught with many challenges. In QNBC, there is a greater paucity of prognostic biomarkers and therapeutic targets than AR-positive TNBC. Although the prognostic role of AR in TNBC remains controversial, many studies revealed that a lack of AR expression confers a more aggressive disease course. Literature characterizing QNBC tumor biology and uncovering novel biomarkers for improved management of the disease remains scarce. In this comprehensive review, we summarize the current QNBC landscape and propose avenues for future research, suggesting potential biomarkers and therapeutic strategies that warrant investigation.

Rottlerin exerts its anti-tumor activity through inhibition of Skp2 in breast cancer cells

Studies have investigated the tumor suppressive role of rottlerin in carcinogenesis. However, the molecular mechanisms of rottlerin-induced anti-tumor activity are largely unclear. Skp2 (S-phase kinase associated protein 2) has been validated to play an oncogenic role in a variety of human malignancies. Therefore, inactivation of Skp2 could be helpful for the treatment of human cancers. In the current study, we explore whether rottlerin could inhibit Skp2 expression, leading to inhibition of cell growth, migration and invasion in breast cancer cells. We found that rottlerin treatment inhibited cell growth, induced apoptosis and cell cycle arrest. We also revealed that rottlerin suppressed cell migration and invasion in breast cancer cells. Mechanically, we observed that rottlerin significantly down-regulated the expression of Skp2 in breast cancer cells. Importantly, overexpression of Skp2 abrogated rottlerin-mediated tumor suppressive activity, whereas down-regulation of Skp2 enhanced rottlerin-triggered anti-tumor function. Strikingly, we identified that rottlerin exhibited its anti-tumor potential partly through inactivation of Skp2 in breast cancer. Our findings indicate that rottlerin could be a potential safe agent for the treatment of breast cancer.

Skp2 is over-expressed in breast cancer and promotes breast cancer cell proliferation

The F box protein Skp2 is oncogenic. Skp2 and Skp2B, an isoform of Skp2 are overexpressed in breast cancer. However, little is known regarding the mechanism by which Skp2B promotes the occurrence and development of breast cancer. Here, we determined the expression and clinical outcomes of Skp2 in breast cancer samples and cell lines using breast cancer database, and investigated the role of Skp2 and Skp2B in breast cancer cell growth, apoptosis and cell cycle arrest. We obtained Skp2 is significantly overexpressed in breast cancer samples and cell lines, and high Skp2 expression positively correlated with poor prognosis of breast cancer. Both Skp2 and Skp2B could promote breast cancer cell proliferation, inhibit cell apoptosis, change the cell cycle distribution and induce the increased S phase cells and therefore induce cell proliferation in breast cancer cells. Moreover, the 2 isoforms could both suppress PIG3 expression via independent pathways in the breast cancer cells. Skp2 suppressed p53 and inhibited PIG3-induced apoptosis, while Skp2B attenuated the function of PIG3 by inhibiting PHB. Our results indicate that Skp2 and Skp2B induce breast cancer cell development and progression, making Skp2 and Skp2B potential molecular targets for breast cancer therapy.