DIAPH3 Governs the Cellular Transition to the Amoeboid Tumour Phenotype

Therapies for most malignancies are generally ineffective once metastasis occurs. While tumour cells migrate through tissues using diverse strategies, the signalling networks controlling such behaviours in human tumours are poorly understood. Here we define a role for the Diaphanous-related formin-3 (DIAPH3) as a non-canonical regulator of metastasis that restrains conversion to amoeboid cell behaviour in multiple cancer types. The DIAPH3 locus is close to RB1, within a narrow consensus region of deletion on chromosome 13q in prostate, breast and hepatocellular carcinomas. DIAPH3 silencing in human carcinoma cells destabilized microtubules and induced defective endocytic trafficking, endosomal accumulation of EGFR, and hyperactivation of EGFR/MEK/ERK signalling. Silencing also evoked amoeboid properties, increased invasion and promoted metastasis in mice. In human tumours, DIAPH3 down-regulation was associated with aggressive or metastatic disease. DIAPH3-silenced cells were sensitive to MEK inhibition, but showed reduced sensitivity to EGFR inhibition. These findings have implications for understanding mechanisms of metastasis, and suggest that identifying patients with chromosomal deletions at DIAPH3 may have prognostic value

Computed Tomographic Imaging of Subchondral Fatigue Cracks in the Distal End of the Third Metacarpal Bone in the Thoroughbred Racehorse Can Predict Crack Micromotion in an Ex-Vivo Model - Figure 2

<p>Subchondral fatigue crack dimensions were measured in transverse (<b>A</b>) and reconstructed frontal plane (<b>B</b>) computed tomography (CT) images. In addition, the area of the crack array was measured in the parasagittal plane (<b>C</b>).</p

Relationship between computed tomography measurement of parasagittal fatigue crack dimensions and detection of crack micromotion during mechanical loading.

<p><b>Note:</b> A logistic regression model was used to determine whether there was a significant relationship between fatigue crack dimensions determined by measurement from computed tomography images and crack micromotion under clinically relevant joint loads in an ex-vivo model (micromotion corrected to 15% above baseline) (n = 38 condyles from 21 bones from 18 horses). Within the multivariate models of CT measurement parameter and horse identity, parasagittal crack area was the only CT measurement that yielded a significant result.</p

Relationship between athletic history and severity of pathologic change observed in the joint surface of the distal end of the third metacarpal of racing Thoroughbreds.

<p><b>Note:</b> Correlations with severity scoring of palmar osteochondral disease were not significant for any athletic history parameter (n = 32 condyles).</p

Distribution of fetlock joint abnormalities in Thoroughbred racehorses identified by radiographic imaging and direct observation.

<p><b>Note:</b> One hundred fourteen condyles from 57 MC3 bones from 38 horses were dissected and digested to evaluate the articular surface (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101230#pone-0101230-g001" target="_blank">Fig. 1</a>). Subchondral plate observations were made after cartilage digestion.</p

Photograph illustrating the custom-made jig that secures the distal end of the MC3 bone to the platen of a materials testing machine (MTS 858, Minneapolis, MN).

<p>(<b>A</b>) Drill holes 1.25 mm in diameter were made on the lateral and medial side of the artificial slot or crack array in the parasagittal condylar groove. (B) Hypodermic needles (18 g) were then placed in the drill holes and attached to an extensometer to measure motion across the slot or crack. The actuator consisted of a metal rod that was contoured to conform to the curved surface of the condyle.</p