Galectin-3C Inhibits Tumor Growth and Increases the Anticancer Activity of Bortezomib in a Murine Model of Human Multiple Myeloma

Galectin-3 is a human lectin involved in many cellular processes including differentiation, apoptosis, angiogenesis, neoplastic transformation, and metastasis. We evaluated galectin-3C, an N-terminally truncated form of galectin-3 that is thought to act as a dominant negative inhibitor, as a potential treatment for multiple myeloma (MM). Galectin-3 was expressed at varying levels by all 9 human MM cell lines tested. In vitro galectin-3C exhibited modest anti-proliferative effects on MM cells and inhibited chemotaxis and invasion of U266 MM cells induced by stromal cell-derived factor (SDF)-1α. Galectin-3C facilitated the anticancer activity of bortezomib, a proteasome inhibitor approved by the FDA for MM treatment. Galectin-3C and bortezomib also synergistically inhibited MM-induced angiogenesis activity in vitro. Delivery of galectin-3C intravenously via an osmotic pump in a subcutaneous U266 cell NOD/SCID mouse model of MM significantly inhibited tumor growth. The average tumor volume of bortezomib-treated animals was 19.6% and of galectin-3C treated animals was 13.5% of the average volume of the untreated controls at day 35. The maximal effect was obtained with the combination of galectin-3C with bortezomib that afforded a reduction of 94% in the mean tumor volume compared to the untreated controls at day 35. In conclusion, this is the first study to show that inhibition of galectin-3 is efficacious in a murine model of human MM. Our results demonstrated that galectin-3C alone was efficacious in a xenograft mouse model of human MM, and that it enhanced the anti-tumor activity of bortezomib in vitro and in vivo. These data provide the rationale for continued testing of galectin-3C towards initiation of clinical trials for treatment of MM.     

Effect of a fermented nutraceutical on thioredoxin level and TNF-alpha signalling in cirrhotic patients

The aim of this study is to gain further insights into the possible nutraceutical effect on redox balance via thioredoxin (Trx) modulation and on the intrinsic susceptibility of monocytes to generate an inflammatory response. The study group consisted of thirty-two patients with compensated Child A-C, HCV-related cirrhosis. The patients were supplemented for 6 months with 6g/day of a certified fermented papaya preparation (FPP). Fifteen unsupplemented, age/gender-matched healthy subjects served as controls. The patients filled in a detailed diet-life style questionnaire, and blood samples were collected to test routine biochemistry, Trx, redox status (GSH, GSSG, GSH/GSSG ratio, 4-HNE and alpha-tocopherol). Moreover, isolated monocytes were tested for ex-vivo LPS-stimulated TNF-alpha production and TNF-alpha mRNA. As compared to control, patients with liver cirrhosis showed a significantly higher serum level of Trx. A significant correlation occurred with GSH/GSSG ratio in Child B and C patients. FPP supplementation brought about a significant reduction of Trx with levels comparable to the ones of healthy controls. Ten patients Child C (31.2 percent) showed borderline low levels of alpha-tocopherol while all cirrhotic patients, as a whole, showed a significantly abnormal redox balance. Supplementation with FPP did not modify alpha-tocopherol depletion but significantly improved redox balance parameters. Patients with liver cirrhosis showed a significantly upregulated TNF-alpha production in a time-dependent manner and this effect was more pronounced in more advanced stages of the disease and showed a significant correlation with alpha-tocopherol level. Supplementation with FPP significantly, although partially, downregulated TNF-alpha production from monocytes. Taken altogether, it would appear that the typical oxidative-inflammatory biochemical milieu of these patients is mirrored by a significant TNF-alpha upregulation at a monocyte level while a targeted nutraceutical might be a potentially amenable intervention to be part of validated scheduled treatments.     

Antitumor activity of diethynylfluorene derivatives of gold(I)

A list of diethynylfluorenes and their gold(I) derivatives have been studied for their antitumor activity as a function of their structure–activity relationships. End-capping the fluoren-9-one unit with gold(I) moieties could significantly strengthen the cytotoxic activity in vitro on three human cancer cell lines with induction of reactive oxygen species generation on Hep3B hepatocellular carcinoma cells and exhibit attractive antitumor activity from in vivo nude mice Hep3B xenograft model with limited adverse effects on vital organs including liver and kidney.     

A study on the localization and distribution of GnRH and its receptor in rat submaxillary glands by immunohistochemical,in situ hybridization and RT-PCR

We investigated the rat submaxillary gland for the presence of GnRH and GnRH receptors, the localization and colocalization of GnRH, GnRH receptor and their mRNA, and studied the sequence of GnRH receptor complementary DNA (cDNA) by immunohistochemistry, in situ hybridization and RT-PCR. The results showed that GnRH and GnRH receptor immunoreactive materials were colocalized in the epithelial cells of the serous acinus and glandular duct. The GnRH and GnRH receptor mRNA hybridization signals were detected in the above cells. The sequence obtained from the RT-PCR product was identical to the published cDNA sequence of GnRH receptor in the rat pituitary. The results suggested that the rat submaxillary gland was capable of synthesizing GnRH and GnRH receptors. GnRH may be involved in the functional regulation of the submaxillary gland through autocrine or paracrine activity.     

Oral treatment with γ-aminobutyric acid improves glucose tolerance and insulin sensitivity by inhibiting inflammation in high fat diet-fed mice

Adipocyte and β-cell dysfunction and macrophage-related chronic inflammation are critical for the development of obesity-related insulin resistance and type 2 diabetes mellitus (T2DM), which can be negatively regulated by Tregs. Our previous studies and those of others have shown that activation of γ-aminobutyric acid (GABA) receptors inhibits inflammation in mice. However, whether GABA could modulate high fat diet (HFD)-induced obesity, glucose intolerance and insulin resistance has not been explored. Here, we show that although oral treatment with GABA does not affect water and food consumption it inhibits the HFD-induced gain in body weights in C57BL/6 mice. Furthermore, oral treatment with GABA significantly reduced the concentrations of fasting blood glucose, and improved glucose tolerance and insulin sensitivity in the HFD-fed mice. More importantly, after the onset of obesity and T2DM, oral treatment with GABA inhibited the continual HFD-induced gain in body weights, reduced the concentrations of fasting blood glucose and improved glucose tolerance and insulin sensitivity in mice. In addition, oral treatment with GABA reduced the epididymal fat mass, adipocyte size, and the frequency of macrophage infiltrates in the adipose tissues of HFD-fed mice. Notably, oral treatment with GABA significantly increased the frequency of CD4(+)Foxp3(+) Tregs in mice. Collectively, our data indicated that activation of peripheral GABA receptors inhibited the HFD-induced glucose intolerance, insulin resistance, and obesity by inhibiting obesity-related inflammation and up-regulating Treg responses in vivo. Given that GABA is safe for human consumption, activators of GABA receptors may be valuable for the prevention of obesity and intervention of T2DM in the clinic.     

Docosahexaenoic acid and eicosapentaenoic acid are converted by 3T3-L1 adipocytes to N-acyl ethanolamines with anti-inflammatory properties

n-3 PUFAs have beneficial health effects which are believed to be partly related to their anti-inflammatory properties, however the exact mechanisms behind this are unknown. One possible explanation could be via their conversion to N-acyl ethanolamines (NAEs), which are known to possess anti-inflammatory properties. Using fatty acid precursors we showed that 3T3-L1 adipocytes are indeed able to convert docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) to their NAE derivatives docosahexaenoyl ethanolamine (DHEA) and eicosapentaenoyl ethanolamine (EPEA), respectively. This synthesis took place on top of an apparent background formation of these NAEs in standard culture medium. In addition we were able to demonstrate the presence of DHEA, but not of EPEA, in human plasma. DHEA and EPEA were found to decrease LPS induced adipocyte IL-6 and MCP-1 levels. Results of combined incubations with PPAR-γ and CB2 antagonists suggest a role of these receptors in mediating the reduction of IL-6 by DHEA. Our results are in line with the hypothesis that in addition to other pathways, formation of N-acyl ethanolamines may contribute to the biological activity of n-3 PUFAs. Different targets, including the endocannabinoid system, may be involved in the immune-modulating activity of these “fish-oil-derived NAEs.”     

Genetic Diversity of Ostreopsis ovata (Dinophyceae) from Malaysia

The genus Ostreopsis is an important component of benthic and epiphytic dinoflagellate assemblages in coral reefs and seaweed beds of Malaysia. Members of the species may produce toxins that contribute to ciguatera fish poisoning. In this study, two species have been isolated and cultured, Ostreopsis ovata and Ostreopsis lenticularis. Analyses of the 5.8S subunit and internal transcribed spacer regions ITS1 and ITS2 of the ribosomal RNA gene sequences of these two species showed that they are separate species, consistent with morphological designations. The nucleotide sequences of the 5.8S subunit and ITS1 and ITS2 regions of the rRNA gene were also used to evaluate the interpopulation and intrapopulation genetic diversity of O. ovata found in Malaysian waters. Results showed a low level of sequence divergence within populations. At the interpopulation level, the rRNA gene sequence distinguished two groups of genetically distinct strains, representative of a Malacca Straits group (isolates from Port Dickson) and a South China Sea group (isolates from Pulau Redang and Kota Kinabalu). Part of the sequences in the ITS regions may be useful in the design of oligonucleotide probes specific for each group. Results from this study show that the ITS regions can be used as genetic markers for taxonomic, biogeographic, and fine-scale population studies of this species. Received September 15, 2000; accepted December 15, 2000