Mutually exclusive epigenetic modification on SIX6 with hypermethylation for precancerous stage and metastasis emergence tracing

Dear Editor,Aberrant DNA methylation gets involved in cancer initiation,progression,and recurrence,which in turn makes it an ideal cancer biomarker.Various methylation markers or their panels have been developed in diverse cancer types.However,the model-constructing based marker mining strategy and incompatibility of application have greatly impeded their ways to clinic.Thus,single methylation marker applicable to all/most cancer types and multiple clinical scenarios is desperately needed.The hope came from the unexpected observation that HIST1H4F was universally hypermethylated in all 17 cancer types;thus,we raised the concept of“Universal Cancer Only Marker(UCOM)”and established a paradigm for discovery and clinical application of UCOM.1 Recently,a novel UCOM,hypermethylated PCDHGB7,was identified and found to advance cervical cancer(CC)screening to the precancerous stage.2 During the screening of UCOM,we discerned a bunch of cancer cell-differentially methylated regions.1 Among them,sine oculis(SIX)homeobox family of transcription factors,which were found to function as tumorigenesis regulator by promoting epithelial-to-mesenchymal transition and metastasis recently in addition to their traditional roles in tissue formation and organogenesis,3 sparked our special attention.Herein,we interrogate whether SIX6 methylation could serve as a novel UCOM and its potential applications.