Milling plant and soil material in plastic tubes over-estimates carbon and under-estimates nitrogen concentrations

Peer reviewedPostprin

The distribution of the therapeutic monoclonal antibodies cetuximab and trastuzumab within solid tumors

<p><b>Abstract</b></p> <p>Background</p> <p>Poor distribution of some anticancer drugs in solid tumors may limit their anti-tumor activity.</p> <p>Methods</p> <p>Here we used immunohistochemistry to quantify the distribution of the therapeutic monoclonal antibodies cetuximab and trastuzumab in relation to blood vessels and to regions of hypoxia in human tumor xenografts. The antibodies were injected into mice implanted with human epidermoid carcinoma A431 or human breast carcinoma MDA-MB-231 transfected with <it>ERBB2 </it>(231-H2N) that express high levels of ErbB1 and ErbB2 respectively, or wild-type MDA-MB-231, which expresses intermediate levels of ErbB1 and low levels of ErbB2.</p> <p>Results</p> <p>The distribution of cetuximab in A431 xenografts and trastuzumab in 231-H2N xenografts was time and dose dependent. At early intervals after injection of 1 mg cetuximab into A431 xenografts, the concentration of cetuximab decreased with increasing distance from blood vessels, but became more uniformly distributed at later times; there remained however limited distribution and binding in hypoxic regions of tumors. Injection of lower doses of cetuximab led to heterogeneous distributions. Similar results were observed with trastuzumab in 231-H2N xenografts. In MDA-MB-231 xenografts, which express lower levels of ErbB1, homogeneity of distribution of cetuximab was achieved more rapidly.</p> <p>Conclusions</p> <p>Cetuximab and trastuzumab distribute slowly, but at higher doses achieve a relatively uniform distribution after about 24 hours, most likely due to their long half-lives in the circulation. There remains poor distribution within hypoxic regions of tumors.</p

The comparative osmoregulatory ability of two water beetle genera whose species span the fresh-hypersaline gradient in inland waters (Coleoptera: Dytiscidae, Hydrophilidae).

A better knowledge of the physiological basis of salinity tolerance is essential to understanding the ecology and evolutionary history of organisms that have colonized inland saline waters. Coleoptera are amongst the most diverse macroinvertebrates in inland waters, including saline habitats; however, the osmoregulatory strategies they employ to deal with osmotic stress remain unexplored. Survival and haemolymph osmotic concentration at different salinities were examined in adults of eight aquatic beetle species which inhabit different parts of the fresh-hypersaline gradient. Studied species belong to two unrelated genera which have invaded saline waters independently from freshwater ancestors; Nebrioporus (Dytiscidae) and Enochrus (Hydrophilidae). Their osmoregulatory strategy (osmoconformity or osmoregulation) was identified and osmotic capacity (the osmotic gradient between the animal's haemolymph and the external medium) was compared between species pairs co-habiting similar salinities in nature. We show that osmoregulatory capacity, rather than osmoconformity, has evolved independently in these different lineages. All species hyperegulated their haemolymph osmotic concentration in diluted waters; those living in fresh or low-salinity waters were unable to hyporegulate and survive in hyperosmotic media (> 340 mosmol kg(-1)). In contrast, the species which inhabit the hypo-hypersaline habitats were effective hyporegulators, maintaining their haemolymph osmolality within narrow limits (ca. 300 mosmol kg(-1)) across a wide range of external concentrations. The hypersaline species N. ceresyi and E. jesusarribasi tolerated conductivities up to 140 and 180 mS cm(-1), respectively, and maintained osmotic gradients over 3500 mosmol kg(-1), comparable to those of the most effective insect osmoregulators known to date. Syntopic species of both genera showed similar osmotic capacities and in general, osmotic responses correlated well with upper salinity levels occupied by individual species in nature. Therefore, osmoregulatory capacity may mediate habitat segregation amongst congeners across the salinity gradient

TRAP1 regulates stemness through Wnt/β-catenin pathway in human colorectal carcinoma

Colorectal carcinoma (CRC) is a common cause of cancer-related death worldwide. Indeed, treatment failures are triggered by cancer stem cells (CSCs) that give rise to tumor repopulation upon initial remission. Thus, the role of the heat shock protein TRAP1 in stemness was investigated in CRC cell lines and human specimens, based on its involvement in colorectal carcinogenesis, through regulation of apoptosis, protein homeostasis and bioenergetics. Strikingly, co-expression between TRAP1 and stem cell markers was observed in stem cells located at the bottom of intestinal crypts and in CSCs sorted from CRC cell lines. Noteworthy, TRAP1 knockdown reduced the expression of stem cell markers and impaired colony formation, being the CSC phenotype and the anchorage-independent growth conserved in TRAP1-rich cancer cells. Consistently, the gene expression profiling of HCT116 cells showed that TRAP1 silencing results in the loss of the stem-like signature with acquisition of a more-differentiated phenotype and the downregulation of genes encoding for activating ligands and target proteins of Wnt/β-catenin pathway. Mechanistically, TRAP1 maintenance of stemness is mediated by the regulation of Wnt/β-catenin signaling, through the modulation of the expression of frizzled receptor ligands and the control of β-catenin ubiquitination/phosphorylation. Remarkably, TRAP1 is associated with higher expression of β-catenin and several Wnt/β-catenin target genes in human CRCs, thus supporting the relevance of TRAP1 regulation of β-catenin in human pathology. This study is the first demonstration that TRAP1 regulates stemness and Wnt/β-catenin pathway in CRC and provides novel landmarks in cancer biology and therapeutics

Differential radiosensitisation by ZD1839 (Iressa), a highly selective epidermal growth factor receptor tyrosine kinase inhibitor in two related bladder cancer cell lines

The epidermal growth factor receptor (EGFR) is expressed in a wide variety of epithelial tumours including carcinoma of the bladder. Stimulation of the EGFR pathway is blocked by ZD1839 (Iressa), a highly selective EGFR tyrosine kinase inhibitor. Radical radiotherapy is an established organ sparing treatment option for muscle invasive bladder cancer and this study has explored the possibility for the use of ZD1839 as a radiosensitiser in this scenario. The effect of combination treatment with ZD1839 (0.01 μM) and ionising radiation in the established bladder cancer cell lines MGH-U1 and its radiosensitive mutant clone S40b was measured by clonogenic assays. A highly significant radiosensitising effect was seen in both cell lines (P<0.001 for MGH-U1 and S40b cell lines). This effect was independent of the concentration of the drug and the duration of exposure prior to treatment with ionising radiation. Cell cycle kinetics of both cell lines was not significantly altered with ZD1839 (0.01 μM) as a single agent. A modest induction of apoptosis was observed with ZD1839 (0.01 μM) as a single agent, but a marked induction was observed with the combination treatment of ZD1839 and ionising radiation. These results suggest a potentially important role for ZD1839 in combination with radiotherapy in the treatment of muscle invasive bladder cancer

Reduction of PTEN protein and loss of epidermal growth factor receptor gene mutation in lung cancer with natural resistance to gefitinib (IRESSA)

Gefitinib (IRESSA), an epidermal growth factor receptor (EGFR) tyrosine kinase (TK) inhibitor, has antitumour activity in the advanced non-small-cell lung cancer (NSCLC) setting. However, in chemotherapy-naïve patients with advanced NSCLC, the addition of gefitinib to standard chemotherapy regimens failed to increase survival. These results suggest the need for improved patient selection and combination rationales for targeted therapies. We have identified subpopulations of an adenocarcinoma cell line that are naturally resistant to gefitinib, and have analysed the cDNA expression profiles, genomic status of EGFR gene and the effect of gefitinib on signalling pathways in these cell lines in order to identify key mechanisms for naturally acquired resistance to gefitinib. Gefitinib-resistant subpopulations demonstrated increased Akt phosphorylation (not inhibited by gefitinib), reduced PTEN protein expression and loss of the EGFR gene mutation when compared with parental cell lines. These differences in Akt and PTEN protein expression were not evident from the cDNA array profiles. These data suggests that (1) the EGFR gene mutation may be possibly lost in some cancer cells with other additional mechanisms for activating Akt, (2) reintroduction of PTEN or pharmacological downregulation of the constitutive PI3K–Akt-pathway activity may be an attractive therapeutic strategy in cancers with gefitinib resistance

Alterations of BCCIP, a BRCA2 interacting protein, in astrocytomas

<p>Abstract</p> <p>Background</p> <p>Loss of heterozygosity of chromosome 10q26 has been shown to be associated with the aggressiveness of astrocytic tumors (or astrocytomas), but the responsible gene(s) residing in this region has not been fully identified. The <it>BCCIP </it>gene is located at chromosome 10q26. It encodes a BRCA2 and CDKN1A (p21) interacting protein. Previous studies have shown that down-regulation of BCCIP impairs recombinational DNA repair, G1/S cell cycle checkpoint, p53 trans-activation activity, cytokinesis, and chromosome stability, suggesting a potential role of <it>BCCIP </it>in cancer etiology. In this study, we investigated whether <it>BCCIP </it>is altered in astrocytomas.</p> <p>Methods</p> <p>Genomic DNA from 45 cases of grade IV astrocytic tumor (glioblastoma) tissues and 12 cases of normal tissues were analyzed by quantitative PCR. The BCCIP protein expression in 96 cases of grade II–IV astrocytic tumors was detected by immunohistochemistry (IHC). IHC staining of glial fibrillary acid protein (GFAP), a marker for astrocytic cells, was used to identify cells of the astrocytic lineage.</p> <p>Results</p> <p>We found that BCCIP protein is expressed in normal cells with positive staining of GFAP. However, BCCIP protein expression was not detectable in ~45% of all astrocytic tumors, and in > 60% in the grade IV glioblastoma. About 45% glioblastoma have significant (p < 0.01) reduction of <it>BCCIP </it>gene copy number when compared to normal DNA. Furthermore, the frequency of lacking BCCIP expression is associated with the aggressiveness of astrocytic tumors.</p> <p>Conclusion</p> <p>Our data implicate a role of BCCIP in astrocytic tumorigenesis, and lack of <it>BCCIP </it>may be used as a marker for astrocytomas.</p