A ferrocene-containing nucleoside analogue targets DNA replication in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is a disease that remains refractory to existing treatments including the nucleoside analogue gemcitabine. In the current study we demonstrate that an organometallic nucleoside analogue, the ferronucleoside 1-(S,Rp), is cytotoxic in a panel of PDAC cell lines including gemcitabine-resistant MIAPaCa2, with IC50 values comparable to cisplatin. Biochemical studies show that the mechanism of action is inhibition of DNA replication, S-phase cell cycle arrest and stalling of DNA-replication forks, which were directly observed at single molecule resolution by DNA-fibre fluorography. In agreement with this, transcriptional changes following treatment with 1-(S,Rp) include activation of three of the four genes (HUS1, RAD1, RAD17) of the 9-1-1 check point complex clamp and two of the three genes (MRE11, NBN) that form the MRN complex as well as activation of multiple downstream targets. Furthermore, there was evidence of phosphorylation of checkpoint kinases 1 and 2 as well as RPA1 and gamma H2AX, all of which are considered biochemical markers of replication stress. Studies in p53-deficient cell lines showed activation of CDKN1A (p21) and GADD45A by 1-(S,Rp) was at least partially independent of p53. In conclusion, because of its potency and activity in gemcitabine-resistant cells, 1-(S,Rp) is a promising candidate molecule for development of new treatments for PDAC.

Organometallic nucleoside analogues: effect of the metallocene metal atom on cancer cell line toxicity

A new chiral organometallic nucleoside analogue containing ruthenocene is reported, in which alkylthymine and alkylhydroxyl groups are attached in adjacent positions on one cyclopentadienyl ring. The synthetic procedures for this metallocene derivative and two control compounds are described, along with their characterisation by cyclic voltammetry and X-ray crystallography. Their biological activities in a human pancreatic cancer cell line (MIA-Pa-Ca-2) were significantly lower than those of three previously reported analogous ferrocene compounds, indicating that the choice of metallocene metal atom (Fe or Ru) plays a pivotal role in determining the anticancer properties of these nucleoside analogues, which in turn suggests a different mode of action from that of a conventional nucleoside analogue.

Effect of Regiochemistry and Methylation on the Anticancer Activity of a Ferrocene-Containing Organometallic Nucleoside Analogue

Four new bis-substituted ferrocene derivatives containing either a hydroxyalkyl or methoxyalkyl group and either a thyminyl or methylthyminyl group have been synthesised and characterised by a range of spectroscopic and analytical techniques. They were included in a structure-activity-relationship (SAR) study probing anticancer activities in osteosarcoma (bone cancer) cell lines and were compared with a known lead compound, 1-(S,R_p ), a nucleoside analogue that is highly toxic to cancer cells. Biological studies using the MTT assay revealed that a regioisomer of ferronucleoside 1-(S,R_p ), which only differs from the lead compound in being substituted on two cyclopentadienyl rings rather than one, was over 20 times less cytotoxic. On the other hand, methylated derivatives of 1-(S,R_p ) showed comparable cytotoxicities to the lead compound. Overall these studies indicate that a mechanism of action for 1-(S,R_p ) cannot proceed through alcohol phosphorylation and that its geometry and size, rather than any particular functional group, are crucial factors in explaining its high anticancer activity.

A psychiatric study of nonorganic chronic headache patients

Nonorganic chronic headache is a common, challenging presentation in clinical practice. The aim of this study was to investigate the frequency of associated psychiatric psychopathology, personality disorders, or traits. In addition, the study attempted to investigate possible relationships of nonorganic chronic headache with alexithymia, locus of control, and pain perception. Psychiatric pathology, personality traits, and pain profiles were examined in 100 randomized patients with chronic headache lacking an obvious organic basis, and they were compared with 100 subjects, 50 with headache of a known organic cause and 50 seemingly healthy persons, by using structured clinical interviews. Somatoform pain disorder was diagnosed in 43% of the nonorganic and 20% of the organic headache group. Nine percent of the former group had major depression, 16% had dysthymia, and 8% had both. In the organic group, 56% had no psychiatric disorder and 20% had somatoform pain disorder. Seventy-seven percent of the patients in the nonorganic pain group had personality disorders, mostly of the mixed and multiple types, compared with 24% of the organic headache patients. The study sample was more alexithymic than the other groups (in 65% of subjects) and had a culturally influenced locus of control and a pain profile characterized by dramatization, vagueness, lower pain threshold, and lower pain tolerance. The nonorganic chronic headache patients showed a high prevalence of somatoform, depressive, and other forms of psychiatric disorders. The high frequency of personality disorders, mostly the mixed and multiple types, the high alexithymic pattern, and low pain threshold and tolerance in the study group should be taken into consideration in the evaluation and management of nonorganic headache patients.