Identification of the Privileged Position in the Imidazo[1,2-a]pyridine Ring of Phosphonocarboxylates for Development of Rab Geranylgeranyl Transferase (RGGT) Inhibitors

Members of the Rab GTPase family are master regulators of vesicle trafficking. When disregulated, they are associated with a number of pathological states. The inhibition of RGGT, an enzyme responsible for post-translational geranylgeranylation of Rab GTPases represents one way to control the activity of these proteins. Because the number of molecules modulating RGGT is limited, we combined molecular modeling with biological assays to ascertain how modifications of phosphonocarboxylates, the first reported RGGT inhibitors, rationally improve understanding of their structure-activity relationship. We have identified the privileged position in the core scaffold of the imidazo[1,2-a]pyridine ring, which can be modified without compromising compounds' potency. Thus modified compounds are micromolar inhibitors of Rab11A prenylation, simultaneously being inactive against Rap1A/Rap1B modification, with the ability to inhibit proliferation of the HeLa cancer cell line. These findings were rationalized by molecular docking, which recognized interaction of phosphonic and carboxylic groups as decisive in phosphonocarboxylate localization in the RGGT binding site.

Synthesis and characterization of novel phosphonocarboxylate inhibitors of RGGT

Phosphonocarboxylate (PC) analogs of the anti-osteoporotic drugs, bisphosphonates, represent the first class of selective inhibitors of Rab geranylgeranyl transferase (RabGGTase, RGGT), an enzyme implicated in several diseases including ovarian, breast and skin cancer. Here we present the synthesis and biological characterization of an extended set of this class of compounds, including lipophilic derivatives of the known RGGT inhibitors. From this new panel of PCs, we have identified an inhibitor of RGGT that is of similar potency as the most active published phosphonocarboxylate, but of higher selectivity towards this enzyme compared to prenyl pyrophosphate synthases. New insights into structural requirements are also presented, showing that only PC analogs of the most potent 3rd generation bisphosphonates inhibit RGGT. In addition, the first phosphonocarboxylate-derived GGPPS inhibitor is reported.

Prediction of excessive gestational weight gain from week-specific cutoff values: a cohort study

OBJECTIVE

To assess the prognostic validity of the Institute of Medicine/National Research Council (IOM/NRC) week-specific cutoff values for inadequate or excessive total gestational weight gain (GWG) by 4-week intervals.

STUDY DESIGN

We merged data from two German cohorts (LMU cohort (all maternal-weight categories) and PEACHES cohort (obese women)) to provide information on GWG for 749 women (365 normal weight, 199 overweight and 185 obese). We calculated the prognostic values for suboptimal and excessive GWG according to the IOM/NRC cutoff values.

RESULT

The positive predictive values for excessive total GWG for those who experienced excessive GWG early in pregnancy was 70.1% (95% confidence interval (CI) 60.5; 78.6) as of week 12/1 to 16/0 in normal-weight women, 89.5% (95% CI 75.2; 97.1) and 95.2 (76.2; 99.9) 95.2% (95% CI 76.2; 99.9) as of week 8/1 to 12/0 for overweight and obese women, respectively. In absence of excessive GWG as of week 12/1 to 16/0, normal-weight women had 77.5% (95% CI 77.1; 83.1) probability of not experiencing excessive total GWG (negative predictive value). In overweight and obese women, the negative predictive value was considerably lower up to week 24/1 to 28/0 (60.0% (95% CI 48.8; 70.5) in week 20/1 to 24/0 and 50.6% (95% CI 39.3; 61.9) in week 24/1 to 28/0). Most women with inadequate GWG in the first and second trimester had adequate total final GWG (positive predictive value for total inadequate GWG <50% up to week 16/1 to 20/0 in all groups).

CONCLUSION

As women with excessive weight gain can be identified with high confidence if the GWG exceeds the IOM/NRC week-specific cutoff values, interventions may be initiated early in pregnancy.