Nab-paclitaxel and gemcitabine or FOLFIRINOX as first-line treatment in patients with unresectable adenocarcinoma of the pancreas: does sequence matter?

BACKGROUND: Locally advanced or metastatic adenocarcinoma of the pancreas remains - despite the implementation of new chemotherapy protocols - a disease with short overall survival (OS). METHODS: Eighty-three patients were treated with locally advanced or metastatic adenocarcinoma of the pancreas with either FOLFIRINOX or nab-Paclitxel and Gemcitabine (nabPGem) as first- or second line therapy. We analysed the outcome for OS and progression-free survival (PFS) in terms of treatment regimen and sequence. RESULTS: The majority of patients presented in good performance status (PS) with a median age of 68 years. Fourty-two patients received FOLFIRINOX as first-line therapy, 41 patients were treated with nabPGem as first line therapy. Forty-eight patients received both treatments. The OS of all 83 patients was 12.6 months (95% CI: 10.7-14.6), resulting in a 1-year OS of 54%. Forty-eight patients received FOLFIRINOX followed by nabPGem or vice versa. There was no significant difference in OS or PFS for either of the two sequences (p = 0.9). The OS for FOLFIRINOX followed by nabPGem or nabPGem followed by FOLFIRINOX was 13.7 months (95% CI: 12.6-14.7) and 13.8 months (95% CI: 8.6-19), respectively. CONCLUSIONS: The sequence FOLFIRINOX followed by nab-Paclitaxel and Gemcitabine or vice versa lead to an equal OS outcome.

The YTH domain is a novel RNA binding domain.

The YTH (YT521-B homology) domain was identified by sequence comparison and is found in 174 different proteins expressed in eukaryotes. It is characterized by 14 invariant residues within an alpha-helix/beta-sheet structure. Here we show that the YTH domain is a novel RNA binding domain that binds to a short, degenerated, single-stranded RNA sequence motif. The presence of the binding motif in alternative exons is necessary for YT521-B to directly influence splice site selection in vivo. Array analyses demonstrate that YT521-B predominantly regulates vertebrate-specific exons. An NMR titration experiment identified the binding surface for single-stranded RNA on the YTH domain. Structural analyses indicate that the YTH domain is related to the pseudouridine synthase and archaeosine transglycosylase (PUA) domain. Our data show that the YTH domain conveys RNA binding ability to a new class of proteins that are found in all eukaryotic organisms.

Haploinsufficiency of the germ cell-specific nuclear RNA binding protein hnRNP G-T prevents functional spermatogenesis in the mouse.

Human HNRNPGT, encoding the protein hnRNP G-T, is one of several autosomal retrogenes derived from RBMX. It has been suggested that HNRNPGT functionally replaces the sex-linked RBMX and RBMY genes during male meiosis. We show here that during normal mouse germ cell development, hnRNP G-T protein is strongly expressed during and after meiosis when proteins expressed from Rbmx or Rbmx-like genes are absent. Amongst these Rbmx-like genes, DNA sequence analyses indicate that two other mouse autosomal Rbmx-derived retrogenes have evolved recently in rodents and one already shows signs of degenerating into a non-expressed pseudogene. In contrast, orthologues of Hnrnpgt are present in all four major groups of placental mammals. The sequence of Hnrnpgt is under considerable positive selection suggesting it performs an important germ cell function in eutherians. To test this, we inactivated Hnrnpgt in ES cells and studied its function during spermatogenesis in chimaeric mice. Although germ cells heterozygous for this targeted allele could produce sperm, they did not contribute to the next generation. Chimaeric mice with a high level of mutant germ cells were infertile with low sperm counts and a high frequency of degenerate seminiferous tubules and abnormal sperm. Chimaeras made from a 1:1 mix of targeted and wild-type ES cell clones transmitted wild-type germ cells only. Our data show that haploinsufficiency of Hnrnpgt results in abnormal sperm production in the mouse. Genetic defects resulting in reduced levels of HNRNPGT could, therefore, be a cause of male infertility in humans.

Ramucirumab plus paclitaxel or FOLFIRI in platinum-refractory advanced or metastatic gastric or gastroesophageal junction adenocarcinoma-experience at two centres.

BACKGROUND: Ramucirumab is a VEGFR-2 antibody that has proven to prolong overall survival (OS) in patients with pretreated metastatic gastric/gastrooesophageal junction (GEJ) adenocarcinoma. We present data from patients treated with ramucirumab and paclitaxel or FOLFIRI after failure of at least one platinum- and 5-FU-containing chemotherapy (CHT) regimen. METHODS: In this retrospective two-center study, 56 patients with metastatic gastric cancer (47%) or adenocarcinoma of the GEJ (53%) were treated with paclitaxel and ramucirumab (n=38) as second-line (75%) or beyond second-line (25%) therapy. FOLFIRI-ramucirumab (FOLFIRI-R) (n=16) was given to patients with a short interval between taxane-based perioperative CHT and occurrence of metastatic disease or to those ineligible for paclitaxel. RESULTS: The median progression-free survival (PFS) and OS for patients treated with paclitaxel-ramucirumab (pacl-R) were 2.9 (95% CI: 2.3-3.6) and 4.4 (4.1-4.7) months, respectively, and those for patients treated with FOLFIRI-R were 5.9 (95% CI: 0.35-11.4) and 8.3 (6.6-10) months, respectively (P=0.05). We observed a trend towards prolonged PFS after perioperative taxane-based FLOT CHT (n=12) with FOLFIRI-R compared with pacl-R. Adverse events were manageable, with neutropenia and polyneuropathy (PNP) being the most common events. More than two treatment lines were given to 48.2% of patients. CONCLUSIONS: The use of ramucirumab in combination with FOLFIRI showed favourable PFS and OS in patients with prior treatments with platinum and/or taxane-based agents and allows further treatment lines after progression. In patients with taxane pretreatment or persistent high-grade PNP, the combination of FOLFIRI-R might be a promising combination.

Rat pineal arylalkylamine-N-acetyltransferase: cyclic AMP inducibility of its gene depends on prior entrained photoperiod.

The nocturnal biosynthesis of melatonin in the rat pineal depends on strongly enhanced expression of the enzyme N-acetyltransferase [arylalkylamine N-acetyltransferase (AA-NAT); EC 2.3.1.87]. AA-NAT transcription is stimulated during darkness by adrenergic inputs to the pineal from the suprachiasmatic nucleus (SCN). Nocturnal activation of the AA-NAT promotor following stimulation of pinealocyte adrenoceptors involves cAMP-dependent stimulation of protein kinase A (PKA). The nocturnal rise in AA-NAT depends on the lighting conditions. As compared with light/dark (LD) 12:12, the delay between dark onset and the nocturnal rise in AA-NAT is shortened under long photoperiods and prolonged under short photoperiods. Here, we report that the rapidity of nocturnal AA-NAT induction depends on cAMP inducibility of the gene. Accordingly, cAMP produces a strong AA-NAT response in pineals obtained from rats housed under long photoperiods and a weak AA-NAT response under short photoperiods. Changes in AA-NAT inducibility are fully developed not earlier than after seven cycles. This observation suggests that long-term changes in the photoperiod are necessary to achieve full adjustment of cAMP inducibility of the gene. A direct relationship was found between cAMP-dependent AA-NAT inducibility and the pineal protein kinase A (PKA) activity. As compared to LD 12:12, PKA activity was increased under LD 20:4 and attenuated under LD 4:20. On the basis of the present findings, we suggest that the photoperiod determines the effectiveness of nocturnal AA-NAT induction by long-term modulation of the intrapineal pathway that transmits the cAMP signal to the AA-NAT gene.

Heterogeneous nuclear ribonucleoprotein G regulates splice site selection by binding to CC(A/C)-rich regions in pre-mRNA.

Almost every protein-coding gene undergoes pre-mRNA splicing, and the majority of these pre-mRNAs are alternatively spliced. Alternative exon usage is regulated by the transient formation of protein complexes on the pre-mRNA that typically contain heterogeneous nuclear ribonucleoproteins (hnRNPs). Here we characterize hnRNP G, a member of the hnRNP class of proteins. We show that hnRNP G is a nuclear protein that is expressed in different concentrations in various tissues and that interacts with other splicing regulatory proteins. hnRNP G is part of the supraspliceosome, where it regulates alternative splice site selection in a concentration-dependent manner. Its action on alternative exons can occur without a functional RNA-recognition motif by binding to other splicing regulatory proteins. The RNA-recognition motif of hnRNP G binds to a loose consensus sequence containing a CC(A/C) motif, and hnRNP G preferentially regulates alternative exons where this motif is clustered in close proximity. The X-chromosomally encoded hnRNP G regulates different RNAs than its Y-chromosomal paralogue RNA-binding motif protein, Y-linked (RBMY), suggesting that differences in alternative splicing, evoked by the sex-specific expression of hnRNP G and RBMY, could contribute to molecular sex differences in mammals.

Protein phosphatase 1 binds to the RNA recognition motif of several splicing factors and regulates alternative pre-mRNA processing.

Alternative splicing emerges as one of the most important mechanisms to generate transcript diversity. It is regulated by the formation of protein complexes on pre-mRNA. We demonstrate that protein phosphatase 1 (PP1) binds to the splicing factor transformer2-beta1 (tra2-beta1) via a phylogenetically conserved RVDF sequence located on the RNA recognition motif (RRM) of tra2-beta1. PP1 binds directly to tra2-beta1 and dephosphorylates it, which regulates the interaction between tra2-beta1 and other proteins. Eight other proteins, including SF2/ASF and SRp30c, contain an evolutionary conserved PP1 docking motif in the beta-4 strand of their RRMs indicating that binding to PP1 is a new function of some RRMs. Reducing PP1 activity promotes usage of numerous alternative exons, demonstrating a role of PP1 activity in splice site selection. PP1 inhibition promotes inclusion of the survival of motoneuron 2 exon 7 in a mouse model expressing the human gene. This suggests that reducing PP1 activity could be a new therapeutic principle to treat spinal muscular atrophy and other diseases caused by missplicing events. Our data indicate that the binding of PP1 to evolutionary conserved motifs in several RRMs is the link between known signal transduction pathways regulating PP1 activity and pre-mRNA processing.

WT1 interacts with the splicing protein RBM4 and regulates its ability to modulate alternative splicing in vivo.

Wilm's tumor protein 1 (WT1), a protein implicated in various cancers and developmental disorders, consists of two major isoforms: WT1(-KTS), a transcription factor, and WT1(+KTS), a post-transcriptional regulator that binds to RNA and can interact with splicing components. Here we show that WT1 interacts with the novel splicing regulator RBM4. Each protein was found to colocalize in nuclear speckles and to cosediment with supraspliceosomes in glycerol gradients. RBM4 conferred dose-dependent and cell-specific regulation of alternative splicing of pre-mRNAs transcribed from several reporter genes. We found that overexpressed WT1(+KTS) abrogated this effect of RBM4 on splice-site selection, whereas WT1(-KTS) did not. We conclude that the (+KTS) form of WT1 is able to inhibit the effect of RBM4 on alternative splicing.