Triple-negative breast cancers (TNBC) are notoriously difficult to treat because they lack hormone receptors and have limited targeted therapies. Recently, we demonstrated that p90 ribosomal S6 kinase (RSK) is essential for TNBC growth and survival indicating it as a target for therapeutic development. RSK phosphorylates Y-box binding protein-1 (YB-1), an oncogenic transcription/translation factor, highly expressed in TNBC (~70% of cases) and associated with poor prognosis, drug resistance and tumor initiation. YB-1 regulates the tumor-initiating cell markers, CD44 and CD49f however its role in Notch signaling has not been explored. We sought to identify novel chemical entities with RSK inhibitory activity. The Prestwick Chemical Library of 1120 off-patent drugs was screened for RSK inhibitors using both in vitro kinase assays and molecular docking. The lead candidate, luteolin, inhibited RSK1 and RSK2 kinase activity and suppressed growth in TNBC, including TIC-enriched populations. Combining luteolin with paclitaxel increased cell death and unlike chemotherapy alone, did not enrich for CD44+ cells. Luteolin’s efficacy against drug-resistant cells was further indicated in the primary x43 cell line, where it suppressed monolayer growth and mammosphere formation. We next endeavored to understand how the inhibition of RSK/YB-1 signaling by luteolin elicited an effect on TIC-enriched populations. ChIP-on-ChIP experiments in SUM149 cells revealed a 12-fold enrichment of YB-1 binding to the Notch4 promoter. We chose to pursue this because there are several reports indicating that Notch4 maintains cells in an undifferentiated, TIC state. Herein we report that silencing YB-1 with siRNA decreased Notch4 mRNA. Conversely, transient expression of Flag:YB-1WT or the constitutively active mutant Flag:YB-1D102 increased Notch4 mRNA. The levels of Notch4 transcript and the abundance of the Notch4 intracellular domain (N4ICD) correlated with activation of P-RSKS221/7 and P-YB-1S102 in a panel of TNBC cell lines. Silencing YB-1 or RSK reduced Notch4 mRNA and this corresponded with loss of N4ICD. Likewise, the RSK inhibitors, luteolin and BI-D1870, suppressed P-YB-1 S102 and thereby reduced Notch4. In conclusion, inhibiting the RSK/YB-1 pathway with luteolin is a novel approach to blocking Notch4 signaling and as such provides a means of inhibiting TICs.

Colorectal cancer (CRC) is the second most common cancer in the world and death from CRC accounts for 8% of all cancer deaths both in men and women in the United States. CRC is life-threatening disease due to therapy resistant cancerous cells. The exact mechanisms of cell growth, survival, metastasis and inter & intracellular signaling pathways involved in CRC is still a significant challenge. Hence, investigating the signaling pathways that lead to colon carcinogenesis may give insight into the therapeutic target. In this study, the role of atypical Protein Kinase C (aPKC) on CRC was investigated by using two inhibitors of that protein class: 1) ζ-Stat (8-hydroxynaphthalene-1,3,6-trisulfonic acid) is a specific inhibitor of PKC-ζ and 2) ICA-I 5-amino-1-(2,3-dihydroxy-4-hydroxymethyl)cyclopentyl)-1H-imidazole-4-carboxamide) is a specific inhibitor of PKC-ι. The cell lines tested were CCD18CO normal colon epithelial and LOVO metastatic CRC cells. The inhibition of aPKCs did not bring any significant toxicity on CCD18CO normal colon cell line. Although PKC-ι is an oncogene in many cancers, we found the overexpression of PKC-ζ and its direct association with Rac1. Our findings suggest that the PKC-ζ may be responsible for the abnormal growth, proliferation, and migration of metastatic LOVO colon cancer cells via PKC-ζ/Rac1/Pak1/β-Catenin pathway. These results suggest the possibility of utilizing PKC-ζ inhibitor to block CRC cells growth, proliferation, and metastasis.

Peri‐implant disease is an inflammatory condition affecting the soft and hard tissues surrounding a dental implant. However, current preventative methods are insufficient due to the limited bioactivity on the dental implant and poor patient compliance. Recently, photo‐biomodulation (PBM) therapy that can recover and regenerate peri‐implant soft tissue has attracted considerable attention in dentistry. In this paper, a seamless human oral motion‐powered dental implant system (called Smart Dental Implant or SDI) is presented as an ambulatory PBM therapy modality. SDI allows the in situ light delivery, which is enabled by the energy harvesting from dynamic human oral motions (chewing and brushing) via an engineered piezoelectric dental crown, an associated circuit, and micro light emitting diodes (LEDs). The SDI also offers adequate mechanical strength as the clinical standards. Using primary human gingival keratinocytes (HGKs) as a model host organism and Pseudomonas aeruginosa lipopolysaccharides (LPS) as a model inflammatory stimulus, effective SDI‐mediated PBM therapy is demonstrated. A new class of dental implants could be an ambulatory PBM therapy platform for the prevention of peri‐implant disease without patient dependency, warranting long‐lasting dental implants.

Advances in microelectronics and nanofabrication have led to the development of various implantable biomaterials. However, biofilm-associated infection on medical devices still remains a major hurdle that substantially undermines the clinical applicability and advancement of biomaterial systems. Given their attractive piezoelectric behavior, barium titanate (BTO)-based materials have also been used in biological applications. Despite its versatility, the feasibility of BTO-embedded biomaterials as anti-infectious implantable medical devices in the human body has not been explored yet.Here, the first demonstration of clinically viable BTO-nanocomposites is presented. It demonstrates potent antibiofilm properties against Streptococcus mutans without bactericidal effect while retaining their piezoelectric and mechanical behaviors. This antiadhesive effect led to ∼10-fold reduction in colony-forming units in vitro. To elucidate the underlying mechanism for this effect, data depicting unfavorable interaction energy profiles between BTO-nanocomposites and S. mutans using the classical and extended Derjaguin, Landau, Verwey, and Overbeek theories is presented. Direct cell-to-surface binding force data using atomic force microscopy also corroborate reduced adhesion between BTO-nanocomposites and S. mutans. Interestingly, the poling process on BTO-nanocomposites resulted in asymmetrical surface charge density on each side, which may help tackle two major issues in prostheticsbacterial contamination and tissue integration. Finally, BTO-nanocomposites exhibit superior biocompatibility toward human gingival fibroblasts and keratinocytes. Overall, BTO-embedded composites exhibit broad-scale potential to be used in biological settings as energy-harvestable antibiofilm surfaces.