IGF-1 regulates LARP6-mediated collagen metabolism in vaginal fibroblasts of POP patients via the PI3K/AKT pathway.

Pelvic organ prolapse (POP) and its subtypes are serious concerns affecting a woman's quality of life and pose a challenge for her social reintegration. Prolonged labor leading to trauma of the pelvic floor muscles during delivery, surgical or other trauma, aging and menopause, lifestyle changes, and genetic factors may contribute to the tissue degeneration and prolapse of pelvic organs. The purpose of this research was to evaluate the potential contributions of IGF-1 and LARP6 to the pathophysiology of poliomyelitis- dysplastic scoliosis and help in devising preventive and therapeutic measures. This study included a population of 15 women suffering from POP as a case group and a control group of 15 women who underwent total hysterectomy for benign gynecological diseases. Their vaginal wall tissue samples were obtained, and differences in expression of IGF-1, LARP6, Collagen I/III and MMP2 were analyzed using Western blot (WB), immunohistochemistry (IHC), and multiplex immunofluorescence (mIHC) techniques. Collagen deposition and other histopathological changes were examined by HE staining and Masson staining. Patients' with POP's vaginal wall tissues were used for isolating and culturing primary fibroblasts, which were then subjected to varying concentrations and time durations of IGF-1 treatment to optimize the culture conditions, measuring Collagen I and III expression levels as indicators. Changes in the expression levels of LARP6, collagen metabolism related proteins, and PI3K/AKT signaling pathway were investigated using WB and RT-qPCR, further analysis was done by applying PI3K/AKT signaling pathway inhibitors; CCK-8 and Tunnel histomorphology analysis were used to evaluate cell proliferation and apoptosis, respectively. Moreover, a LARP6 knockdown model was created whereby siRNAs specifically targeting the LARP6 transcript were transfected into cells, and subsequently, the protein and mRNA levels of collagen I, III, MMP2, and TIMP1 were analyzed by WB and RT-qPCR. LARP6 and IGF-1 expression was found to be significantly lower in the vaginal wall tissues of POP patients compared with controls. Histological staining revealed that collagen fiber structures in the POP group were loose, disorganized, and discontinuous. In primary fibroblasts, IGF-1 was able to up-regulate LARP6 and collagen expression in a dose- and time-dependent manner and favorable to the secretion of LARP6 and collagen through PI3K/Akt signaling pathway. The knockdown of LARP6 by siRNA technology demonstrated significant reduction of collagen secretion expression suggesting interferences of LARP6 inhibits collagen synthesis in fibroblasts. IGF-1 has a strong correlation with LARP6 in relation to the development of POP. The reduction in fibroblasts in the subepithelial layer of the vaginal wall is probably associated with POP, while depletion of collagen synthesis and escalation of collagen breakdown may serve as the pathophysiologic foundation for POP. In patients suffering from POP, IGF-1 has the capability to enhance the expression of LARP6 and collagen in their fibroblasts, which highly depends on the activity of the PI3K/AKT signaling pathway. This study unveils new insights and possible molecular approaches to the pathophysiology of POP.