The Planning Commission shall consider from time to time any amendment to regulations imposed and districts created under this chapter that may be presented to the Planning Commission by the City Council, either upon the Council's initiative or in response to a properly prepared petition to the Council signed by a majority of the property owners in the area proposed to be affected. The Planning Commission shall conduct public hearings with respect to any and all such proposed amendments, and all hearings conducted by the Planning Commission shall be open to the public. Notice shall be given of the time and place of every public hearing not more than 30 days nor less than 15 days before the hearing, by publishing a notice thereof at least once in one or more newspapers published in the City, or, if no newspaper is published therein, then in one or more newspapers having a general circulation within the City.