Author Correction: PHGDH heterogeneity potentiates cancer cell dissemination and metastasis

In the version of this article initially published, we unintentionally omitted to indicate that Extended Data Fig. 2h and Extended Data Fig. 3f display images from the same experiment. The upper panel in Extended Data Fig. 3f represents green and red channels of the same tumour region as the panel on the top left in Extended Data Fig. 2h. The lower panel in Extended Data Fig. 3f represents green and red channels of the same tumour region as the panel on the top right in Extended Data Fig. 2h. This has now been clarified in Extended Data Fig. 2h and Extended Data Fig. 3f legends and in the Methods “Orthotopic mouse models: Melanoma” subsection, as reflected in the HTML and PDF versions of the article.

Extended Data Fig. 2h. Representative pictures of PHGDH protein expression in primary and metastatic melanoma mouse model (Tyr::N-Ras^+/Q61K;Ink4a^−/−). Left panels represent tumours from mice injected with melanoma cells alone; middle and right panels represent tumors from mice co-injected with melanoma and Bend3 endothelial cells (ratio 1:4). Green, Phgdh; red, dsRed tumour cell marker; blue, DAPI nuclear staining.

Extended Data Fig. 3f. Representative pictures of PHGDH protein expression in primary melanoma model (Tyr::N-Ras^+/Q61K;Ink4a^−/−) from mice injected with melanoma cells alone or co-injected with melanoma and Bend3 endothelial cells (ratio 1:4). Outcome of this experiment is also depicted in Extended Data Fig 2h. Upper panel represents green and red channels of the same tumor region as the panel on the top left in Extended Data Fig. 2h. Lower panel represents green and red channels of the same tumour region as the panel on the top right in Extended Data Fig. 2h. Green, Phgdh; red, dsRed tumour cell marker; blue, DAPI nuclear staining. Scale bar 200 μm.

Methods “Orthotopic mouse models: Melanoma” subsection.

Primary melanoma tumour from Tyr::N-Ras^Q61K;Ink4a^−/− (Tyr::cre^ERT2) animals was dissociated into small pieces using forceps and scissors. Tissue was digested using a mix of collagenase I (2 mg ml⁻¹, Sigma-Aldrich, C0130) and IV (2 mg ml⁻¹, Sigma-Aldrich, C5138) for 20 min at 37 °C followed by a trypsin (trypsin-EDTA 0.05%, Thermo Fisher Scientific, 25300054) digestion for 5 min at 37 °C. Single cells were separated from the remaining tissue using a 40 μm cell strainer and cultured in vitro using DMEM supplemented with 10% fetal bovine serum and 100 μg ml⁻¹ penicillin–streptomycin.

Tyr::N-Ras^+/Q61K;Ink4a^−/− mouse melanoma cells stably expressing dsRed-encoding lentiviruses and Bend3 immortalized endothelial cells stably expressing GFP encoding lentiviruses were mixed at a ratio 1:4 (10⁵ melanoma, 4 × 10⁵ endothelial cells) and resuspended in Matrigel (5 mg ml⁻¹; Thermo Fisher Scientific, 356255). Then, melanoma cells alone or mixed with Bend3 cells were injected subcutaneously into the back skin of Foxn1^nu mice. Mice were euthanized when tumours and organs were collected, 25 days after melanoma initiation. Tumour volume was monitored using callipers and the volume was calculated using the following formula: V = (π/6) × length × width × height.

Mice were housed in filter-top cages and IVC cages. Housing and experimental animal procedures were approved by the Institutional Animal Care and Research Advisory Committee of KU Leuven, Belgium. The animal study complies with ethical regulations and was approved by the KU Leuven ethics committee. Humane end points were determined as follows: tumour size of 1.8 cm³, loss of ability to ambulate, unhealthy fur; difficult respiration because of lung metastasis, surgical infection or weight loss over 20% of initial body weight. Mice were monitored and, after detection of one of the above-mentioned symptoms, the mouse was euthanized.