Comparison of Tumor Penetration of Podophyllotoxin–Carboxymethylcellulose Conjugates with Various Chemical Compositions in Tumor Spheroid Culture and In Vivo Solid Tumor

Polymer conjugation is an attractive approach for delivering insoluble and highly toxic drugs to tumors. However, most reports in the literature only disclose the optimal composition without emphasizing rational design or composition optimization to achieve maximized biological effects. In this study, we aimed to demonstrate that composition of a polymer conjugate would determine its physiochemical characteristics, tumor penetration, and, ultimately, the in vivo efficacy. We also aimed to examine whether the tumor spheroid model could generate comparable results with the in vivo tumor model in terms of tumor penetration and efficacy of the various polymer conjugates. We have designed a polymer conjugate delivery system for a chemotherapeutic drug podophyllotoxin (PPT) by covalently conjugating PPT and polyethylene glycol (PEG) with acetylated carboxymethyl cellulose to yield conjugates containing various amounts of PPT and PEG. Depending on the composition, these conjugates self-assembled into nanoparticles (NPs) with different physicochemical properties. Conjugates with an increased PPT content formed particles with an increased diameter. In the present study, we selected three conjugates representing compositions containing high, medium, and low drug content, and compared their particle formation, drug release kinetics, their ability to penetrate tumor spheroid and in vivo s.c. tumor, and finally their antitumor efficacy in spheroid culture and an in vivo s.c. tumor model. We found that the low drug content conjugate formed smaller NPs (20 nm) compared to the high drug content conjugates (30–120 nm), and displayed faster drug release kinetics (5%/day vs 1–3%/day), improved tumor penetration, and enhanced antitumor efficacy in both the spheroid model and s.c. tumor model. In particular, the low drug content conjugate preferentially accumulated in the hypovascular region within the tumor, inducing complete regression of s.c. tumors and the metastasis to the lungs. Our data indicate composition optimization is needed to select the optimal conjugate, and tumor spheroid culture is a robust screening tool to help select the optimal formulation

Organocatalyzed Photoredox Polymerization from Aromatic Sulfonyl Halides: Facilitating Graft from Aromatic C–H Bonds

Aromatic sulfonyl halides are readily accessible from many sources. With newly synthesized <i>N</i>-aryl­phenothiazine catalysts, organocatalyzed photoredox polymerization has been developed with arylsulfonyl halides initiators using white or purple LEDs light sources. This method allows the preparation of poly­(meth)­acrylates and poly­(meth)­acrylamides possessing a broad scope of (hetero)­aryl chain ends without metal-contamination concern. Investigations such as MALDI-TOF analysis, chain extension, and “ON/OFF” control experiments confirmed the fidelity of the polymer structure and reliability of this method. Moreover, this method facilitates the two-step preparation of brush polymers from polystyrene through an electrophilic aromatic substitution/organocatalyzed photopolymerization sequence

The comparison of transcript abundances of the twelve candidate reference genes.

<p>Boxes indicate the 25th/75th percentiles, the lines represent the median, squares represent the means and whiskers represent the maximum and minimum values.</p

Determination of the optimal numbers of reference genes for normalization by pairwise variation using geNorm.

<p>Pairwise variation (Vn/n+1) analysis between the normalization factors (NFn and NFn+1) was performed in all treated samples. Different treatments are included and markerd as square frame with different colors. The total group refers to all samples. The V (variation) value with which below 0.15 was labeled with asterisk, representing that addition of a further reference gene does not result in any improvement of normalization.</p

Expression stability of twelve candidate genes in <i>P</i>. <i>praeruptorum</i> as predicted by geNorm analysis.

<p>Average expression stability (M) in each treatment is calculated. The least stable gene which has a high M value is on the left, and the most stable gene on the right. The methods of treatment or group classification are listed in the picture correspondingly.</p

Information of candidate reference genes selected for evaluation of expression stability in <i>P</i>. <i>praeruptorum</i>.

<p>Information of candidate reference genes selected for evaluation of expression stability in <i>P</i>. <i>praeruptorum</i>.</p

Selection of Reference Genes for Gene Expression Normalization in <i>Peucedanum praeruptorum</i> Dunn under Abiotic Stresses, Hormone Treatments and Different Tissues

<div><p><i>Peucedanum praeruptorum</i> Dunn is one of the main traditional Chinese medicines producing coumarins and plenty of literatures are focused on the biosynthesis of coumarins. Quantitative real-time reverse transcription PCR (qRT-PCR) is a widely used method in studying the biosynthesis pathway and the selection of reference genes plays a crucial role in accurate normalization. To facilitate biosynthesis study of coumarins, twelve candidate reference genes were selected from the transcriptome database of <i>P</i>. <i>praeruptorum</i> according to previous studies. Then, BestKeeper, geNoFrm and NormFinder were used for selecting stably expressed reference genes in different tissues and under various stress treatments. The results indicated that, among the twelve candidate reference genes, the <i>SAND</i> family protein (<i>SAND</i>), actin 2 (<i>ACT2</i>), ubiquitin-conjugating enzyme 9 (<i>UBC9</i>), protein phosphatase 2A gene (<i>PP2A</i>) and polypyrimidine tract-binding protein (PTBP1) were the most stable reference genes under different experimental treatments, while glyceraldehyde 3-phosphate dehydrogenase (<i>GAPDH</i>) and tubulin beta-6 (<i>TUB6</i>) were the least stable genes. In addition, the suitability of <i>SAND</i>, <i>TIP41</i>-like protein (<i>TIP41</i>), <i>UBC9</i>, <i>ACT2</i>, <i>TUB6</i> and their combination as reference genes were confirmed by normalizing the expression of 1-aminocyclopropane-1-carboxylate oxidase (<i>ACO</i>) in different treatments. This work is the first survey of the stability of reference genes in <i>P</i>. <i>praeruptorum</i> and provides guidelines to obtain more accurate qRT-PCR results in <i>P</i>. <i>praeruptorum</i> and other plant species.</p></div

Validation of the reference genes. Relative expression level of <i>ACO</i> was normalized using candidate reference genes under different treatments.

<p>(A) Expression level was normalized using most and least stable reference genes under cold treatment. (B) Expression level was normalized using different reference genes under NaCl treatment. <i>TIP41</i>, <i>SAND</i> and <i>ACT2</i> represent the three most stable reference genes and <i>UBC9</i> is a least stable gene. (C) Expression level was normalized using different combination. Data are displayed as means ± SEM, and the statistical analyses were performed using the Student’s t-test to compare those between two reference genes or combination for normalization. <i>*P</i>< 0.05; <i>***P</i>< 0.001; N.S.: No significant difference.</p

Expression stability values of twelve reference genes as calculated by the NormFinder in <i>P</i>. <i>praeruptorum</i>.

<p>Expression stability values of twelve reference genes as calculated by the NormFinder in <i>P</i>. <i>praeruptorum</i>.</p