Galectin-1 has potential prognostic significance and is implicated in clear cell renal cell carcinoma progression through the HIF/mTOR signaling axis.

BACKGROUND: Metastatic clear cell renal cell carcinoma (ccRCC) patients have <9% 5-year survival rate, do not respond well to targeted therapy and eventually develop resistance. A better understanding of molecular pathways of RCC metastasis is the basis for the discovery of novel prognostic markers and targeted therapies. METHODS: We investigated the biological impact of galectin-1 (Gal-1) in RCC cell lines by migration and invasion assays. Effect of Gal-1 expression on the mitogen-activated protein kinase pathway was assessed by proteome array. RESULTS: Increased expression of Gal-1 increased cell migration while knocking down Gal-1 expression by siRNA resulted in reduced cellular migration (P<0.001) and invasion (P<0.05). Gal-1 overexpression increased phosphorylation of Akt, mTOR and p70 kinase. Upon hypoxia and increased HIF-1α, Gal-1 increased in a dose-dependent manner. We also found miR-22 overexpression resulted in decreased Gal-1 and HIF-1α. Immunohistochemistry analysis showed that high Gal-1 protein expression was associated with larger size tumor (P=0.034), grades III/IV tumors (P<0.001) and shorter disease-free survival (P=0.0013). Using the Cancer Genome Atlas data set, we found that high Gal-1 mRNA expression was associated with shorter overall survival (41 vs 78 months; P<0.01). CONCLUSIONS: Our data suggest Gal-1 mediates migration and invasion through the HIF-1α-mTOR signaling axis and is a potential prognostic marker and therapeutic target.

Cdyl, a new partner of the inactive X chromosome and potential reader of H3K27me3 and H3K9me2.

X chromosome inactivation is a remarkable example of chromosome-wide gene silencing and facultative heterochromatin formation. Numerous histone posttranslational modifications, including H3K9me2 and H3K27me3, accompany this process, although our understanding of the enzymes that lay down these marks and the factors that bind to them is still incomplete. Here we identify Cdyl, a chromodomain-containing transcriptional corepressor, as a new chromatin-associated protein partner of the inactive X chromosome (Xi). Using mouse embryonic stem cell lines with mutated histone methyltransferase activities, we show that Cdyl relies on H3K9me2 for its general association with chromatin in vivo. For its association with Xi, Cdyl requires the process of differentiation and the presence of H3K9me2 and H3K27me3, which both become chromosomally enriched following Xist RNA coating. We further show that the removal of the PRC2 component Eed and subsequent loss of H3K27me3 lead to a reduction of both Cdyl and H3K9me2 enrichment on inactive Xi. Finally, we show that Cdyl associates with the H3K9 histone methyltransferase G9a and the MGA protein, both of which are also found on Xi. We propose that the combination of H3K9me2 and H3K27me3 recruits Cdyl to Xi, and this, in turn, may facilitate propagation of the H3K9me2 mark by anchoring G9a.

RNA and protein actors in X-chromosome inactivation.

In female mammals, one of the two X chromosomes is converted from the active euchromatic state into inactive heterochromatin during early embryonic development. This process, known as X-chromosome inactivation, results in the transcriptional silencing of over a thousand genes and ensures dosage compensation between the sexes. Here, we discuss the possible mechanisms of action of the Xist transcript, a remarkable noncoding RNA that triggers the X-inactivation process and also seems to participate in setting up the epigenetic marks that provide the cellular memory of the inactive state. So far, no functional protein partners have been identified for Xist RNA, but different lines of evidence suggest that it may act at multiple levels, including nuclear compartmentalization, chromatin modulation, and recruitment of Polycomb group proteins.

HTLV-1 tax oncoprotein represses the p53-mediated trans-activation function through coactivator CBP sequestration.

The human T-cell leukemia virus type 1 (HTLV-1) Tax oncoprotein repressed the transcriptional activity of wild-type p53 through its N-terminal trans-activation domain. Although Tax did not directly bind to p53, this repression required the activation of CREB pathway by Tax. In contrast to a recent report by Pise-Masison et al. (1998a, b) we found that the phosphorylation of p53 on Ser 15 is not a major cause of the Tax-mediated inactivation of p53. However, Tax with a mutation in the coactivator CBP-binding site (K88A), which activates NF-kappaB but not the CREB pathway, could not repress the p53 trans-activation function. Moreover, Tax inhibited p53 binding to CBP in vitro and inhibited synergistic activation of transcription by CBP and p53. Thus, Tax is likely to compete with p53 in binding with CBP, thereby repressing its trans-activation function.

Mode of action of estra-1,3,5(10)-triene-3,17 beta-diol 3-benzoate 17-[4-(4-bis(2-chloroethyl)amino)phenyl)-1-oxobutoxy)acet ate) on human breast carcinoma xenografts in nude mice.

To elucidate the mode of action of busramustine (KM2210), 17 beta- and alpha-busramustine, estradiol and chlorambucil were used for experimental chemo- and endocrino-therapy against hormone-dependent (T-61) and independent (MX-1) human breast carcinomas serially transplanted into BALB/cA female nude mice. Busramustine was administered po daily for 3 weeks at doses of 12.5-300 mg/kg for the beta-isomer and 25-300 mg/kg for the alpha-isomer. Five to 50 mg of estradiol per kg was administered im once, and 3 to 6 mg of chlorambucil per kg was administered po daily for 3 weeks. All of the compounds were effective against estrogen receptor-positive T-61 with a clear dose-response relationship, while estrogen receptor-negative MX-1 was sensitive to all of the agents except estradiol. Since the alpha-isomer of busramustine was effective against both tumor lines, the mode of action of 17 beta-busramustine may not be related to estrogenic action by estradiol released from the maternal compound. However, 17 beta-busramustine generated the estrogen receptor system of T-61 tumor and resulted in the endometrial hyperplasia of tumor-bearing nude mice, suggesting that this compound also has estrogenic action on transplanted human breast carcinoma and tumor-bearing host mice, besides non-estrogenic antitumor activity on human breast carcinoma xenografts.