Regulation of α₂-adrenoceptor gene expression by chronic lithium treatment in rat brain

One of the approaches for the treatment of bipolar disorder involves the coadministration of lithium, a mood stabilizer, with α₂-adrenoceptor antagonists possessing an antidepressant effect. Since lithium accelerates the recovery of α₂(D)-adrenoceptors following their irreversible inactivation with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), our aim was to examine if it could be to some changes in Adra2A gene expression which codifies these adrenoceptors. Animals were treated with lithium chloride (120 mg/kg i.p.) or saline once a day for 10 days. A group of lithium- or saline-treated rats was killed 48 h after the last injection. The remaining animals were treated with EEDQ and were killed at 0.25, 4 and 14 days following this administration. Total RNA was extracted from cerebral cortex and Adra2A gene expression was measured by RT-QPCR. The results show that chronic lithium raised the Adra2A gene expression (P < 0.05), and after EEDQ administration this expression decreased to the basal level. No change in Adra2A gene expression was detected in the saline-treated group. However, EEDQ administration produced an insignificant increase in α₂-adrenoceptors mRNA levels followed by a progressive decrease until basal levels. Lithium produced an overexpression of the Adra2A gene after chronic treatment that made the neuron ready to produce α₂-adrenoceptors to deal with their inactivation.

Tumour CD133 mRNA expression and clinical outcome in surgically resected colorectal cancer patients

BACKGROUND

Human prominin-1 (CD133) is a novel pentaspan membrane protein which was originally classified as a marker of primitive haematopoietic and neural stem cells. Cancer stem cells have been isolated and expanded from leukaemia and several solid tumours, and have been associated with metastasis, chemoresistance and relapse. CD133 is recognised as a stem cell marker and is capable of identifying a tumour-initiating subpopulation in brain, colon, melanoma and other solid tumours.

METHODS

We assessed CD133 mRNA expression levels by RT-QPCR in tumour and matched normal tissue from 64 stages I-III colorectal cancer (CRC) patients and correlated tumour CD133 levels with clinicopathological characteristics and clinical outcome.

RESULTS

In four patients, CD133 mRNA was not expressed in tumour or in normal tissue. In the remaining 60 patients, expression levels were higher in tumour than in normal tissue (p=0.001). Higher levels of CD133 expression were associated with shorter relapse-free interval (RFI) (p=0.004) and overall survival (OS) (p<0.0001). In the multivariate analyses, CD133 levels emerged as a prognostic marker for RFI and OS.

CONCLUSIONS

We have observed longer RFI and OS in patients with lower levels of CD133, regardless of adjuvant treatment and other clinical characteristics. If these findings are confirmed in larger prospective studies, CD133 assessment may prove useful for new diagnostic and therapeutic procedures for CRC patients.

Cluster mir-17–92 is differentially expressed in colon cancer patients and embryonic colon tissue and may contribute to carcinogenesis through E2F1 expression

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Background: Mature microRNAs (miRNA) are small RNA molecules that act as negative regulators of gene expression, either inhibiting mRNA by blocking its translation into protein or destroying it by RNA interference. Many miRNAs participate in essential processes, including normal embryonic development and carcinogenesis. Methods: We have assessed 156 mature miRNAs in colon tissue from eleven 7–12-week human embryos and 44 colorectal human samples. Data were analyzed using TIGR Multiexperiment viewer. Two multivariate permutation test were performed. Potential target genes of differentially expressed miRNAs are evaluated by western blot. Results: 28 miRNAs were expressed in stage I tumor tissue but not in the corresponding normal tissue, and 13 of these 28 miRNAs (46%) were also expressed in embryonic tissue. Sixty-four miRNAs were differentially expressed in stage II tumor tissue, and 29 of these 64 miRNAs (45%) were also expressed in embryonic tissue. Some miRNAs that are active during embryogenesis, such as mir-17–92, miR-181a, miR-181b and miR-181c (linked to HOXA11), and miR-10a (linked to HOXB8)23, are also expressed during tumor growth. The analysis of 156 miRNAs by K-means support revealed two well-differentiated groups: the embryos of 7–8 weeks and those of 9–12 weeks. Lower miRNA expression was also observed in tumor tissue from stage I in comparison with stage II disease (P=0.014). Analysis of potential target genes revealed that cluster mir-17–92 is differentially expressed in colon cancer and embryonic tissue and may contribute to carcinogenesis through E2F1 expression. Conclusions: Our findings indicate that miRNAs expressed during the embryonic development of the human colon are also expressed in colon tumor tissue. During colon organogenesis, miRNA expression is at first high, while cells are still undifferentiated, but expression levels decrease as cells become more differentiated. In contrast, during the development of colorectal cancer, this process is reversed.

No significant financial relationships to disclose.