[Effect of acupotomy on expressions of cellular senescence markers p16Ink4a and p21Waf1/Cip1 in cartilage tissue of rabbits with knee osteoarthritis]

OBJECTIVE

To observe the effect of acupotomy on the expressions of p16Ink4a and p21Waf1/Cip1 in knee osteoarthritis (KOA) rabbits，so as to analyze whether acupotomy can treat KOA by inhibiting the cellular senescence of chondrocytes.

METHODS

Twenty-four New Zealand male rabbits were randomly divided into normal, model, acupotomy and electroacupuncture (EA) groups, with 6 rabbits in each group. The KOA model was established by left hindlimb straightening fixation. After modeling, rabbits in the acupotomy group were treated with acupotomy loosening therapy on high stress points around the affected knee joints such as tendons attachment points of vastus medialis, vastus lateralis, rectus femoris, biceps femoris and pes anserine bursa, once a week for 3 weeks. In the EA group, "Xuehai"(SP10), "Liangqiu" (ST34),"Neixiyan" (EX-LE4) and "Waixiyan" (ST35) on the affected hindlimb were selected for EA treatment (3 mA, 2 Hz/100 Hz), 20 min each time, once every other day for 3 weeks. Before and after treatments, the knee Lequesne MG score and passive range of motion (PROM) of the affected knee joint were evaluated. After the treatments, the expressions of p16Ink4a and p21Waf1/Cip1 in the cartilage tissue of the affected knee joint were detected by immunohistochemistry and Western blot respectively.

RESULTS

Before and after treatment, compared with the normal group, the Lequesne MG score was significantly increased (P<0.01), the PROM was significantly decreased (P<0.01) in the model group. After treatment, compared with the normal group, the positive expression and protein expression levels of p16Ink4a and p21Waf1/Cip1 were significantly increased (P<0.01) in the model group; compared with the model group, the Lequesne MG score was significantly decreased (P<0.01), the PROM was significantly increased (P<0.01), the positive expression and protein expression levels of p16Ink4a and p21Waf1/Cip1 were significantly decreased (P<0.01，P<0.05) in the acupo-tomy and EA groups; compared with the EA group, the Lequesne MG score was decreased (P<0.05), the PROM was increased (P<0.05), the positive expression and protein expression levels of p16Ink4a and p21Waf1/Cip1 were decreased (P<0.05，P<0.01) in the acupotomy group.

CONCLUSION

Acupotomy intervention can down-regulate the expressions of cellular senescence markers p16Ink4a and p21Waf1/Cip1 in chondrocytes, indicating that acupotomy therapy may alleviate cartilage degeneration by inhibiting chondrocyte premature cellular senescence to treat KOA.

p15INK4B is an alternative marker of senescent tumor cells in colorectal cancer

Senescent tumor cells are nonproliferating tumor cells which are closely related to cancer progression by secreting senescence-related molecules, called senescence-associated secreting phenotypes. Therefore, the presence of senescent tumor cells is considered a prognostic factor in various cancer types. Although senescence-associated β-galactosidase staining is considered the best marker for detection of senescent tumor cells, it can only be performed in fresh-frozen tissues. p16^INK4A, a cyclin-dependent inhibitor, has been used as an alternative marker to detect senescent tumor cells in formalin-fixed paraffin-embedded tissues. However, other reliable markers to detect senescent tumor cells is still lacking. In the present study, using public single-cell RNA-sequencing data, we found that p15^INK4B, a cyclin-dependent kinase inhibitor, is a novel marker for detection of senescent tumor cells. Moreover, p15^INK4B expression was positively correlated with that of p16^INK4A in colorectal cancer tissues. In in vitro studies, mRNA expression of p15^INK4B was increased together with that of p16^INK4A in H₂O₂- and therapy-induced cancer senescence models. However, the mRNA level of p15^INK4B did not increase in the oncogene-induced senescence model in primary colonic epithelial cells. In conclusion, p15^INK4B is a potential alternative marker for detection of senescent tumor cells together with conventional markers in advanced stages of colorectal cancer.