Preclinical efficacy studies of a novel nanoparticle-based formulation of paclitaxel that out-performs Abraxane

Poly-(γ-l-glutamylglutamine)–paclitaxel (PGG–PTX) is a novel polymer-based formulation of paclitaxel (PTX) in which the PTX is linked to the polymer via ester bonds. PGG–PTX is of interest because it spontaneously forms very small nanoparticles in plasma. In mouse models, PGG–PTX increased tumor exposure to PTX by 7.7-fold relative to that produced by PTX formulated in Cremophor. In this study, the efficacy of PGG–PTX was compared to that of Abraxane, an established nanoparticular formulation of PTX, in three different tumor models. Efficacy was quantified by delay in tumor growth of NCI H460 human lung cancer, 2008 human ovarian cancer and B16 melanoma xenografts growing in athymic mice following administration of equitoxic doses of PGG–PTX and Abraxane administered on either a single dose or every 7 day schedule. Toxicity was assessed by change in total body weight. The efficacy and toxicity of PGG–PTX was shown to increase with dose in the H460 model. PGG–PTX was ~1.5-fold less potent than Abraxane. PGG–PTX produced statistically significantly greater inhibition of tumor growth than Abraxane in all three tumor models when mice were given single equitoxic doses of drug. When given every 7 days for 3 doses, PGG–PTX produced greater inhibition of tumor growth while generating much less weight loss in mice bearing H460 tumors. PGG–PTX has activity that is superior to that of Abraxane in multiple tumor models. PGG–PTX has the potential to out-perform Abraxane in enhancing the delivery of PTX tumors while at the same time further reducing the toxicity of both single dose and weekly treatment regimens

Co-expression of CD147 (EMMPRIN), CD44v3-10, MDR1 and monocarboxylate transporters is associated with prostate cancer drug resistance and progression

Background: The aim of this study is to seek an association between markers of metastatic potential, drug resistance-related protein and monocarboxylate transporters in prostate cancer (CaP). Methods: We evaluated the expression of invasive markers (CD147, CD44v3-10), drug-resistance protein (MDR1) and monocarboxylate transporters (MCT1 and MCT4) in CaP metastatic cell lines and CaP tissue microarrays (n=140) by immunostaining. The co-expression of CD147 and CD44v3-10 with that of MDR1, MCT1 and MCT4 in CaP cell lines was evaluated using confocal microscopy. The relationship between the expression of CD147 and CD44v3-10 and the sensitivity (IC50) to docetaxel in CaP cell lines was assessed using MTT assay. The relationship between expression of CD44v3-10, MDR1 and MCT4 and various clinicopathological CaP progression parameters was examined. Results: CD147 and CD44v3-10 were co-expressed with MDR1, MCT1 and MCT4 in primary and metastatic CaP cells. Both CD147 and CD44v3-10 expression levels were inversely related to docetaxel sensitivity (IC50) in metastatic CaP cell lines. Overexpression of CD44v3-10, MDR1 and MCT4 was found in most primary CaP tissues, and was significantly associated with CaP progression. Conclusions: Our results suggest that the overexpression of CD147, CD44v3-10, MDR1 and MCT4 is associated with CaP progression. Expression of both CD147 and CD44v3-10 is correlated with drug resistance during CaP metastasis and could be a useful potential therapeutic target in advanced disease

Drug-Tolerant Cancer Cells Show Reduced Tumor-Initiating Capacity: Depletion of CD44+ Cells and Evidence for Epigenetic Mechanisms

Cancer stem cells (CSCs) possess high tumor-initiating capacity and have been reported to be resistant to therapeutics. Vice versa, therapy-resistant cancer cells seem to manifest CSC phenotypes and properties. It has been generally assumed that drug-resistant cancer cells may all be CSCs although the generality of this assumption is unknown. Here, we chronically treated Du145 prostate cancer cells with etoposide, paclitaxel and some experimental drugs (i.e., staurosporine and 2 paclitaxel analogs), which led to populations of drug-tolerant cells (DTCs). Surprisingly, these DTCs, when implanted either subcutaneously or orthotopically into NOD/SCID mice, exhibited much reduced tumorigenicity or were even non-tumorigenic. Drug-tolerant DLD1 colon cancer cells selected by a similar chronic selection protocol also displayed reduced tumorigenicity whereas drug-tolerant UC14 bladder cancer cells demonstrated either increased or decreased tumor-regenerating capacity. Drug-tolerant Du145 cells demonstrated low proliferative and clonogenic potential and were virtually devoid of CD44+ cells. Prospective knockdown of CD44 in Du145 cells inhibited cell proliferation and tumor regeneration, whereas restoration of CD44 expression in drug-tolerant Du145 cells increased cell proliferation and partially increased tumorigenicity. Interestingly, drug-tolerant Du145 cells showed both increases and decreases in many “stemness” genes. Finally, evidence was provided that chronic drug exposure generated DTCs via epigenetic mechanisms involving molecules such as CD44 and KDM5A. Our results thus reveal that 1) not all DTCs are necessarily CSCs; 2) conventional chemotherapeutic drugs such as taxol and etoposide may directly target CD44+ tumor-initiating cells; and 3) DTCs generated via chronic drug selection involve epigenetic mechanisms

Chemotherapy-induced hyaluronan production: a novel chemoresistance mechanism in ovarian cancer

Background: Hyaluronan (HA) an important component of the extracellular matrix, has been linked to tumor progression and drug resistance in several malignancies. However, limited data is available for ovarian cancer. This study investigated the role of hyaluronan (HA) and a potential link between the HA-CD44 pathway and membrane ATP binding cassette (ABC) transporter proteins in ovarian cancer chemoresistance. Methods: We investigated the ability of HA to block the cytotoxic effects of the chemotherapy drug carboplatin, and to regulate the expression of ABC transporters in ovarian cancer cells. We also examined HA serum levels in ovarian cancer patients prior to and following chemotherapy and assessed its prognostic relevance. Results: HA increased the survival of carboplatin treated ovarian cancer cells expressing the HA receptor, CD44 (OVCAR-5 and OV-90). Carboplatin significantly increased expression of HAS2, HAS3 and ABCC2 and HA secretion in ovarian cancer cell conditioned media. Serum HA levels were significantly increased in patients following platinum based chemotherapy and at both 1st and 2nd recurrence when compared with HA levels prior to treatment. High serum HA levels (>50 μg/ml) prior to chemotherapy treatment were associated with significantly reduced progression-free (P = 0.014) and overall survival (P = 0.036). HA production in ovarian cancer cells was increased in cancer tissues collected following chemotherapy treatment and at recurrence. Furthermore HA treatment significantly increased the expression of ABC drug transporters (ABCB3, ABCC1, ABCC2, and ABCC3), but only in ovarian cancer cells expressing CD44. The effects of HA and carboplatin on ABC transporter expression in ovarian cancer cells could be abrogated by HA oligomer treatment. Importantly, HA oligomers increased the sensitivity of chemoresistant SKOV3 cells to carboplatin. Conclusions: Our findings indicate that carboplatin chemotherapy induces HA production which can contribute to chemoresistance by regulating ABC transporter expression. The HA-CD44 signaling pathway is therefore a promising target in platinum resistant ovarian cancer.Carmela Ricciardelli, Miranda P Ween, Noor A Lokman, Izza A Tan, Carmen E Pyragius, and Martin K Oehle

Hyaluronic Acid-Paclitaxel: Antitumor Efficacy against CD44(+) Human Ovarian Carcinoma Xenografts1

Numerous human tumor types, including ovarian cancer, display a significant expression of the CD44 family of cell surface proteoglycans. To develop tumor-targeted drugs, we have initially evaluated whether the CD44 ligand hyaluronic acid (HA) could serve as a backbone for paclitaxel (TXL) prodrugs. HA-TXL was prepared by modification of previous techniques. The in vitro cytotoxicity of HA-TXL against the CD44(+) human ovarian carcinoma cell lines SKOV-3ip and NMP-1 could be significantly blocked by preincubation with a molar excess of free HA. Female nude mice bearing intraperitoneal implants of NMP-1 cells were treated intraperitoneally with a single sub-maximum tolerated dose dose of HA-TXL or with multiple-dose regimens of paclitaxel (Taxol; Mead Johnson, Princeton, NJ) to determine the effects of these regimens on host survival and intraperitoneal tumor burden, with the latter being assessed by magnetic resonance imaging. NMP-1 xenografts were highly resistant to Taxol regimens, as host survival was only nominally improved compared to controls (T//C ∼ 120), whereas single-dose HA-TXL treatment significantly improved survival in this model (T//C ∼ 140; P = .004). In both NMP-1 and SKOV-3ip models, MR images of abdomens of HA-TXL-treated mice obtained shortly before controls required humane sacrifice revealed markedly reduced tumor burdens compared to control mice. This study is among the first to demonstrate that HA-based prodrugs administered locoregionally have antitumor activity in vivo