Understanding the tumor microenvironment (TME) and extracellular matrix (ECM) is crucial in cancer research due to their impact on tumor progression. Collagens, major ECM components, regulate cell signaling and behavior. Of the 28 reported collagens, type XII collagen is known to be vital for ECM organization. Over-produced by cancer-associated fibroblasts (CAFs), its upregulation correlates with poor survival in various cancers. This study aimed to develop an ELISA for quantifying circulating type XII collagen as a cancer biomarker. A specific ELISA targeting the C-terminal of type XII collagen was developed and used to analyze serum samples from cancer patients (n = 203) and healthy controls (n = 33). Additionally, type XII collagen expression was assessed in CAFs and normal fibroblasts (NFs) from different tissues, both under TGF-β stimulated and non-stimulated conditions. The nordicPRO-C12 ELISA demonstrated robustness and specificity for type XII collagen. PRO-C12 levels were significantly elevated in patients with various cancers compared to healthy controls and effectively distinguished between cancer patients and controls. Findings were validated using gene expression data. Furthermore, Western blot analysis revealed increased type XII collagen expression in both CAFs and NFs upon TGF-β1 stimulation, suggesting a potential role of TGF-β1 in modulating the expression of type XII collagen in cancerous and normal tissue microenvironments. This study unveils a promising avenue for harnessing PRO-C12 as a non-invasive serum biomarker, enabling the quantification of type XII collagen fragments in cancer patients. Further investigations are warranted to explore the potential of PRO-C12 across different cancer types and disease stages, shedding light on its multifaceted role in cancer development.

Collagen XII, a member of a protein family called fibril associated collagen with interrupted triple helices (FACIT), is an important component of extracellular matrix and is essential for bridging the neighbouring fibrils. Mutations in collagen XII have been recently described to cause a rare extracellular matrix-related myopathy in those whose phenotype resembles collagen VI-related dystrophies and were negative for pathogenic variants in COL6A genes. The authors report a 4-year old girl presented with a phenotype mimicking Ullrich congenital muscular dystrophy and genetically confirmed to have pathogenic variants in COL12A1 gene thus, expanding the phenotypic spectrum of COL12A1-related myopathy.

The expression of cytoplasmic poly (A) binding protein-1 (PABPC1) has been reported in multiple cancer types. This protein is known to modulate cancer progression. However, the effects of PABPC1 expression in pancreatic adenocarcinoma (PAAD) have not been investigated. Here, we investigate the regulatory targets and molecular mechanisms of PABPC1 in PAAD.
PABPC1 and collagen type XII α1 chain (COL12A1) expression in PAAD and their role in tumor prognosis and tumor stage were investigated using The Cancer Genome Atlas database analysis. After silencing PABPC1, messenger RNA sequencing and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. The expression of differentially expressed genes (DEGs), cell viability, apoptosis, and cell migration and invasion were explored using reverse transcription-quantitative polymerase chain reaction, Cell Counting Kit-8 assay, flow cytometry assay, and transwell assay, respectively. The relationship between PABPC1 and COL12A1 expression was assessed by Pearson\'s correlation analysis. The regulatory function of COL12A1 in PABPC1-affected BXPC3 cell behavior was studied after COL12A1 was overexpressed.
PABPC1 and COL12A1 expression was upregulated in patients with PAAD and was linked to poor prognosis. Four hundred and seventy-four DEGs were observed in BXPC3 cells after PABPC1 silencing. GO and KEGG analyses revealed that the top 10 DEGs were enriched in cell adhesion pathways. Additionally, PABPC1 silencing inhibited cell viability, migration, and invasion and accelerated apoptosis in BXPC3 cells. PABPC1 silencing increased AZGP1 and ARHGAP30 expression and decreased CAV1 and COL12A1 expression in BXPC3 cells. PABPC1 positively mediated COL12A1 expression, whereas PABPC1 knockdown induced the inhibition of BXPC3 cell proliferation, migration, and invasion.
The results of this study indicate that PABPC1 may function as a tumor promoter in PAAD, accelerating BXPC3 cell proliferation and metastasis by regulating COL12A1 expression.

BACKGROUND: Mutations within the COL12A1 gene have been linked with the onset of congenital Ullrich muscular dystrophy 2 (UCMD2) and Bethlem myopathy. The severity of the symptoms exhibited is dependent on the mutation\'s type and whether it is heterozygous or homozygous.
METHODS: We used whole-exome sequencing to identify disease-causing variants in a nine-year-old Iranian patient who had weakness, joint contractures, delayed motor development, and other symptoms. We confirmed the pathogenicity of the identified variant using in silico tools and verified its novelty using various databases. We also performed a co-segregation study and confirmed the presence of the variant in the patient\'s parents by Sanger sequencing.
RESULTS: Our analysis identified a novel homozygous missense variant in the affected patient in COL12A1 (c.8828 C > T; p.Pro2943Leu). This is the second reported family with UCMD2 caused by a mutation in COL12A1. Our findings confirm that this mutation results in significantly more severe symptoms than Bethlem myopathy.
CONCLUSIONS: Our investigation contributes to the expanding body of evidence that links mutations in COL12A1 with UCMD2. Our findings confirm that the homozygous mutation in COL12A1 caused this condition and suggest that genetic testing for this mutation may be useful for diagnosing patients with this disease.

Myopathic Ehlers-Danlos syndrome (mEDS) is a subtype of EDS that is caused by abnormalities in COL12A1. Up-to-date, 24 patients from 15 families with mEDS have been reported, with 14 families showing inheritance in an autosomal dominant manner and one family in an autosomal recessive manner. We encountered an additional patient with autosomal recessive mEDS. The patient is a 47-year-old Japanese man, born to consanguineous parents with no related features of mEDS. After birth, he presented with hypotonia, weak spontaneous movements, scoliosis, and torticollis. He had soft palms but no skin hyperextensibility or fragility. Progressive scoliosis, undescended testes, and muscular torticollis required surgery. During adulthood, he worked normally and had no physical concerns. Clinical exome analysis revealed a novel homozygous variant in COL12A1 (NM_004370.6:c.395-1G > A) at the splice acceptor site of exon 6, leading to in-frame skipping of exon 6. The patient was diagnosed with mEDS. The milder manifestations in the current patient compared with previously reported patients with mEDS might be related to the site of the variant. The variant is located in the genomic region encoding the first von Willebrand factor A domain, which affects only the long isoform of collagen XII, in contrast to the variants in previously reported mEDS patients that affected both the long and short isoforms. Further studies are needed to delineate comprehensive genotype-phenotype correlation of the disorder.

Immunotherapy has shown promising efficacy for breast cancer (BC) patients. Yet the predictive biomarkers for immunotherapy response remain lacking. Based on two GEO datasets, 53 differentially expressed genes associated with durvalumab treatment response were identified. Using least absolute shrinkage and selection operator (LASSO) and univariate Cox regression, four genes (COL12A1, TNN, SCUBE2, and FDCSP) revealed prognostic value in the TCGA BC cohort. COL12A1 outperformed the others, without overlap in its survival curve. Survival analysis by Kaplan-Meier plotter demonstrated that COL12A1 was negatively associated with BC patients\' prognosis. A COL12A1-based nomogram was further developed to predict the overall survival in BC patients. The calibration plot revealed an optimal agreement between nomogram prediction and actual observation. Moreover, COL12A1 expression was significantly up-regulated in BC tissues and COL12A1 knockdown impaired the proliferation of MDA-MB-231 and BT549 cells. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Gene Set Enrichment analysis pathway indicated that the function of COL12A1 was related to immunity-related pathways. Immunological analyses illustrated that COL12A1 was correlated with M2 macrophage infiltration and M2 macrophage markers (transforming growth factor beta 1 (TGFB1), interleukin-10, colony stimulating factor 1 receptor (CSF1R) and CD163) in BC. Immunohistochemistry staining further revealed a highly positive relationship of COL12A1 with TGF-β1. The co-incubated models of BC cells and M2 macrophges showed COL12A1 knockdown suppressed M2 macrophage infiltration. Additionally, silencing COL12A1 suppressed TGF-B1 protein expression, and treating with TGFB1 could reverse the inhibitory effects on M2 macrophage infiltration by COL12A1 knockdown. Using immunotherapy datasets, we also found elevated expression of COL12A1 predicted poor response to anti-PD-1/PD-L1 therapy. These results reinforce the current understanding of COL12A1\'s roles in tumorigenesis and immunotherapy response in BC.

Corneal biomechanical failure is the hallmark of keratoconus (KC); however, the cause of this failure remains elusive. Collagen type XII (COL12A1), which localises to Bowman\'s layer (BL), is thought to function in stress-bearing areas, such as BL. Given the putative protective role of COL12A1 in biomechanical stability, this study aims to characterise COL12A1 expression in all corneal layers involved in KC.
TaqMan quantitative PCR was performed on 31 corneal epithelium samples of progressive KC and myopic control eyes. Tissue microarrays were constructed using full-thickness corneas from 61 KC cases during keratoplasty and 18 non-KC autopsy eyes and stained with an antibody specific to COL12A1. Additionally, COL12A1 was knocked out in vitro in immortalised HEK293 cells.
COL12A1 expression was reduced at transcript levels in KC epithelium compared with controls (ratio: 0.58, p<0.03). Immunohistochemical studies demonstrated that COL12A1 protein expression in BL was undetectable, with reduced expression in KC epithelium, basement membrane and stroma.
The apparent absence of COL12A1 in KC BL, together with the functional importance that COL12A1 is thought to have in stress bearing areas, suggests that COL12A1 may play a role in the pathogenesis of KC. Further studies are necessary to investigate the mechanisms that lead to COL12A1 dysregulation in KC.

Collagen type XII alpha 1 chain (COL12A1) is associated with human cancer progression. Nevertheless, the expression pattern and the function of COL12A1 in intrahepatic cholangiocarcinoma (iCCA) remain unknown. The present study was performed to assess the role of COL12A1 in iCCA.
A total of 1669 genes, differentially expressed between iCCA and nontumor liver tissue samples, were identified as potential tumor-specific biomarkers for iCCA patients. Of these, COL12A1 was significantly upregulated in clinical iCCA tissue samples and correlated with epithelial-mesenchymal transition gene set enrichment score and advanced tumor stage in clinical iCCA. COL12A1-high expression was associated with the poor prognoses of iCCA patients (n = 421) from four independent cohorts. Promoter hypermethylation-induced downregulation of miR-424-5p resulted in COL12A1 upregulation in clinical iCCA. Experimental knockout of COL12A1 inhibited the proliferation, invasiveness and growth of iCCA cells. MiR-424-5p had a therapeutic potential in iCCA via directly targeting COL12A1.
Promoter hypermethylation-induced miR-424-5p downregulation contributes to COL12A1 upregulation in iCCA. COL12A1 is a promising druggable target for epigenetic therapy of iCCA.

Omidenepag isopropyl (OMDI) is an intraocular pressure (IOP)-lowering drug used to treat glaucoma. The active form of OMDI, omidenepag (OMD), lowers elevated IOP, the main risk factor for glaucoma, by increasing the aqueous humor outflow; however, a detailed understanding of this mechanism is lacking. To clarify the IOP-lowering mechanism of OMDI, the effects of OMD on the mRNA expression of the extracellular matrix, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) were evaluated in human trabecular meshwork cells. Under 2D culture conditions, the mRNA expression of FN1, COL1A1, COL1A2, COL12A1, and COL13A1 decreased in a concentration-dependent manner after 6 or 24 h treatment with 10 nM, 100 nM, and 1 μM OMD, while that of COL18A1 decreased after 6 h treatment with 1 μM OMD. Significant changes in expression were observed for many MMP and TIMP genes. Under 3D culture conditions, the extracellular matrix-related genes COL12A1 and COL13A1 were downregulated by OMD treatment at all three concentrations. Under both 2D and 3D culture conditions, COL12A1 and COL13A1 were downregulated following OMD treatment. Reduction in the extracellular matrix contributes to the decrease in outflow resistance, suggesting that the downregulation of the two related genes may be one of the factors influencing the IOP-lowering effect of OMDI. Our findings provide insights for the use of OMDI in clinical practice.

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